GSM Controlled Robot
In the project the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. In the course of a call, if any button is pressed a tone corresponding to the button pressed is heard at the other end called ‘Dual Tone Multiple frequency’ (DTMF) tone.
8x8 Dotmatrix Scrolling LED Display
Here 64 leds which are connected to an Matrix display. The Anodes are drived through an Driver IC UDN2981 and the cathodes are drived through ULN2803. The Atmega8515 is used in this project to control the display. The microcontroller is programmed with Bascom AVR.
50 Watt Amplifier Circuit
This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.
Parts List-
R1 - 1 - 200 Ohm 1/4 W Resistor
R2 - 1 - 200K 1/4 W Resistor
R3 - 1 - 30K 1/4 W Resistor
R5 - 1 - 1K 1/4 W Resistor
R6 - 1 - 5K 1/4 W Resistor
R7,R10 - 2 - 1 Meg (5%) 1/2 W Resistor
R8,R9 - 2 - 0.4 Ohm 5 W Resistor
R11 - 1 - 10K Pot
R12,R13 - 2 - 51K 1/4 W Resistor
R14 - 1 - 47K 1/4 W Resistor
C1 - 1 - 100uF 35V Electrolytic Capacitor
C2 - 1 - 0.011uF Capacitor
C3 - 1 - 3750pF Capacitor
C4,C6 - 2 - 1000pF Capacitor
C5,C7,C8 - 3 - 0.001uF Capacitor
C9 - 1 - 50pF Capacitor
C10 - 1 - 0.3uF Capacitor
C11,C12 - 2 - 10,000uF 50V Electrolytic Capacitor
U1,U2 - 2 - 741 Op Amp
U3 - 1 - ICL8063 Audio Amp Transister Driver thingy
Q1 - 1 - 2N3055 NPN Power Transistor
Q2 - 1 - 2N3791 PNP Power Transistor
BR1 - 1 - 250 V 6 Amp Bridge Rectifier
T1 - 1 - 50V Center Tapped 5 Amp Transformer
S1 - 1 - SPST 3 Amp Switch
S2 - 1 - DPDT Switch
F1 - 1 - 2 Amp Fuse
SPKR1 - 1 - 8 Ohm 50W Speaker
MISC - 1 - Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2
Notes-
1. I know I skipped R4. That is not a problem :-)
2. Distortion is less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
3. I haven't been able to find anyone who sells a suitable T1. You can always use two 24V 5A units in series. If you are building two amps (for stereo), then I would suggest using an old microwave transformer and rewinding it. Follow the instructions in the 12V To 120V Inverter, execpt wind 26 turns, twist a loop (center tap) and wind 26 more turns. That should work out to around 50 volts. You may need to add or remove turns depending on your transformer.
4. Q1 and Q2 will require heatsinks.
Parts List-
R1 - 1 - 200 Ohm 1/4 W Resistor
R2 - 1 - 200K 1/4 W Resistor
R3 - 1 - 30K 1/4 W Resistor
R5 - 1 - 1K 1/4 W Resistor
R6 - 1 - 5K 1/4 W Resistor
R7,R10 - 2 - 1 Meg (5%) 1/2 W Resistor
R8,R9 - 2 - 0.4 Ohm 5 W Resistor
R11 - 1 - 10K Pot
R12,R13 - 2 - 51K 1/4 W Resistor
R14 - 1 - 47K 1/4 W Resistor
C1 - 1 - 100uF 35V Electrolytic Capacitor
C2 - 1 - 0.011uF Capacitor
C3 - 1 - 3750pF Capacitor
C4,C6 - 2 - 1000pF Capacitor
C5,C7,C8 - 3 - 0.001uF Capacitor
C9 - 1 - 50pF Capacitor
C10 - 1 - 0.3uF Capacitor
C11,C12 - 2 - 10,000uF 50V Electrolytic Capacitor
U1,U2 - 2 - 741 Op Amp
U3 - 1 - ICL8063 Audio Amp Transister Driver thingy
Q1 - 1 - 2N3055 NPN Power Transistor
Q2 - 1 - 2N3791 PNP Power Transistor
BR1 - 1 - 250 V 6 Amp Bridge Rectifier
T1 - 1 - 50V Center Tapped 5 Amp Transformer
S1 - 1 - SPST 3 Amp Switch
S2 - 1 - DPDT Switch
F1 - 1 - 2 Amp Fuse
SPKR1 - 1 - 8 Ohm 50W Speaker
MISC - 1 - Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2
Notes-
1. I know I skipped R4. That is not a problem :-)
2. Distortion is less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
3. I haven't been able to find anyone who sells a suitable T1. You can always use two 24V 5A units in series. If you are building two amps (for stereo), then I would suggest using an old microwave transformer and rewinding it. Follow the instructions in the 12V To 120V Inverter, execpt wind 26 turns, twist a loop (center tap) and wind 26 more turns. That should work out to around 50 volts. You may need to add or remove turns depending on your transformer.
4. Q1 and Q2 will require heatsinks.
Transformerless Power Supply
Parts List-
C1 - 1 - 0.39uF 250V Capacitor
C2 - 1 - 220uF 25V Electrolytic Capacitor
D1 - 1 - 1N4741 11V Zener Diode (See Notes)
BR1 - 1 - 1 Amp 200V Bridge Rectifier
MISC - 1 - Line Cord, Board, Wire, Case
Notes-
1. The value of C1 can be increased to increase the amount of current the circuit can supply. With the values shown, the circuit can supply up to about 15mA. Remember to increase the size of C2 also.
2. <>A different value can be used for D1 to increase or decrease the voltage as needed.
3. Please note that this circuit is not isolated from 120VAC. Because of this, the circuit must be treated with caution and encosed at all times. Do not work on the circuit (or any other circuits attached to it) when it is plugged in.
4. You may want to add a resisor in series with C1 to limit current if the circuit is plugged in and the mains is at its full voltage.
5. If you are running the circuit from 220VAC, then use a capacitor rated at greater than 400V for C1.
6. If you want isolation from the AC line, you can connect up a small isolation transformer at the inputs of the circuit. Small 600ohm:600ohm audio transformers work nicely.
Fixed Voltage Power Supply
Parts List-
C1 - 1 - 2200uF 35V Electrolytic Capacitor
C2, C4 - 2 - 0.1uF Ceramic Disc Capacitor
C3 - 1 - 10uF 35V Electrolytic Capacitor
D1, D2 - 2 - 1N4007 Silicon Diode
BR1 - 1 - 2A 30V Bridge Rectifier
U1 - 1 - Regulator (See Notes)
T1 - 1 - Transformer (See Notes)
S1 - 1 - SPST 2 Amp Switch
F1 - 1 - 2A 250V Fuse and Holder
MISC - 1 - Heatsink For U1, Line Cord, Case, Wire
Notes-
1. Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
2. U1 will reauire a heatsink.
3. You will need to choose T1 and U1 to match the voltage you want. Use the table below as a reference.
Output Voltage
T1U1
5V 6V, 1.5A 7805
6V 6V, 1.5A 7806
9V 12V, 1.5A 7809
12V 12V, 1.5A 7812
15V 24V, 1.5A 7815
18V 24V, 1.5A 7818
Laser Power Supply
Parts List-
R1 - 1 - 10 Ohm 10W Or Greater Resistor
R2 - 1 - Ballast Resistor, See "Notes"
D1, D2, D3 - 3 - 1N4007 Silicon Diode
C1, C2, C3 - 3 - 0.1 uF 2000V Capacitor
T1 - 1 - 9V 1A Transformer
S1 - 1 - 115V 2A SPST Switch
MISC - 1 - Case, Wire, Binding Posts (for output), Line Cord
Notes-
1. T1 is an ordinary 9V 1A transformer connected backwards for step up.
2. R1 MUST be installed on a LARGE heatsink. A good heatsink is the metal case the supply is built in.
3. R2 Protects the laser tube from excess current. It should be soldered directly to the anode terminal on the tube. To find R2, start with a 500K 10W resistor and work down until the tube lights and remains stable.
4. If you have trouble with the tube not starting easily, use a longer anode lead that is wrapped around the tube.
5. Depending on the transformer you use, the circuit may or may not work. I cannot guarantee the operation of this circuit. Build at your own risk. Some transformers contain very few secondary windings which will quickly saturate the core and basically act like a direct short. The more secondary windings (that is, primary in this circuit) the better.
Clap Switch Circuit
The transformer is 220V to 15V -0V-15V transformer of a minimum of 10VA. You can replace the 1N4001 diodes of any types with similar ratings.The relay is 12V with 5A output current capacity or higher. You can replace also the transistor of any general purpose type.
Note: This clap activated relay is connected to main supply (220VAC). Do not try to touch the main supply to avoid electrocution or do not try to construct if you do not have any idea in electronics.
Led emergency light using cellphone battery and charger
Emergency lighting system uses LED and powered by a 3.6V cellphone battery or any battery of the same voltage. The battery is charge by a cellphone charger with a current of 350mA. During the
charging process, transistor Q1 is off so are the LEDs. When the power is cutoff (brownout), transistor is energized an delivers 25mA current to the four LED. The emergency light consumes about 0.5W and a fully charge battery can last up to 5hours.
Parts List
D2, D3, D4, D5- preferably white LEDs
Q1- 9012 or any general purpose pnp transistor
cellphone battery or similar
Battery charger
1000uF /10V capacitor
4.7k and 220 ohms 0.25W resistor
5 ohms 1W resistor
Simple LED Emergency Light Circuit
Emergency light project is simple, cheap and easy to build. The circuit do the charging of the battery and when the main source is not available such as in brownouts, the white LEDs
automatically turn on.
Initially, the voltage output from 220V to 12V converter is fed to the input of LM317 regulator. Then this voltage is regulated down to 7.37V using 240 ohms and 1.2K resistor combination (see LM317 Calculator). At this instant, the battery is in charging mode and the transistor Q1 is off. Indicator LED serves two purpose, one primarily is to give us idea
that the battery is charging and another is to ensure that the Q1 is off. During brownouts, the transistor Q1 is on and delivers current to 16 white LED of about 20mA each, thus a fully charged battery (6V/4.5Ah) can last up to 14 hours.
The charger has no built in over-current control but still it protects the battery from overcharging since the charging voltage is set only to 7.4V.
Project materials:
1pc - transformer - 220V to 12V-0-12V , center tap 12VA
16pc - 120 ohms resistor 1/4 W
16pc - white LED min 3V@30mA
1pc - red LED
1pc - 1000uF/25V electrolytic capacitor
3pc - 1N4001 diode
1pc - LM317 regulator
1pc - 1.5K resistor 1/4W
1pc - 240 ohms resistor 1/4W
1pc - 1.2k resistor 1/4W
1pc - 9012 pnp transistor or any of much higher capacity
1pc - 6V 4.5ah battery
6V to 12V dc-dc boost converter by 555 timer
This 6V to 12V dc-dc boost converter can drive a load in 12V about 3A current.The 555 timer IC is operated in astable mode, generates about 29Khz frequency of about 54% duty cycle drives the input of TIP41C transistor.1000uF capacitor smoothens the output voltage of the dc-dc converter.LED and 1.5Kohm resistor serves as indicator and load for output stability when no load is connected.You can add a 12V zener diode (1N5242B)across output to ground for further output stability.
The 39ohm resistor at the base of transistor is rated 1W, the rest 1/4W or more.Inductor can be made out of #22AWG wire wound around on an old transistor radio ferrite core.Number of turns more than 30T, but not critical.Change the values and experiment more using this circuit.
12V to 5V DC converter using 7805 regulator IC
This simple converter project uses 7805 IC to convert 12V dc from a battery to 5V DC. This converter also can be made even only one component, the 7805 regulator. Converter can produce a maximum current of 1.5A (with heatsink) at 5V from an input of 8V to 15V. The capacitors are optional and can be omitted.
This is suitable for powering devices that uses 5V DC such as chargers,USB devices and others
3V Electronic Stun Gun Circuit
Schematic-
This circuit above is a cheap version stun gun circuit that is powered by two AA baterry. The output of this electronic project is about 350V dc.
The heart of the circuit is the oscillator that is composed of Windings and transistor.
Primary winding P is composed of 16 turns of #24 AWG wire, feedback F is composed of 8 turns of #24 AWG wire, and secondary winding S is composed of 270 turns of #30 AWG magnetic wire. The output of Sec winding is rectified by diode bridge. The output capacitor is an electrolytic type that is rated 400V above. Capacitance of the output capacitor depends on what available on hand,but always keep in mind that the higher the value the better. this simple electronic project is dangerous when accidentally touched, thus avoid holding the output and discharge the capacitor before and after using.
This circuit above is a cheap version stun gun circuit that is powered by two AA baterry. The output of this electronic project is about 350V dc.
The heart of the circuit is the oscillator that is composed of Windings and transistor.
Primary winding P is composed of 16 turns of #24 AWG wire, feedback F is composed of 8 turns of #24 AWG wire, and secondary winding S is composed of 270 turns of #30 AWG magnetic wire. The output of Sec winding is rectified by diode bridge. The output capacitor is an electrolytic type that is rated 400V above. Capacitance of the output capacitor depends on what available on hand,but always keep in mind that the higher the value the better. this simple electronic project is dangerous when accidentally touched, thus avoid holding the output and discharge the capacitor before and after using.
220V led lamp (AC powered LED)
220V led lamp (AC powered LED)
Schematic-
This LED lamp is powered by an ac source available in your outlet.
To build this LED lamp you will need 20 white LED and capacitor.
the Lamp consumes about 4w of power.
Note:
Capacitor C1 is mylar type and do not use electrolytic capacitor. Avoid touching any part of the circuit
since it is powered directly to the main ac source.
Capacitor of this LED lamp is as follows:
220nF if ac line is 220V @ 60Hz
270nF if ac line is 220V @ 50Hz
470nF if ac line is 110V @ 60Hz
578nF if ac line is 110V @ 60Hz
Schematic-
This LED lamp is powered by an ac source available in your outlet.
To build this LED lamp you will need 20 white LED and capacitor.
the Lamp consumes about 4w of power.
Note:
Capacitor C1 is mylar type and do not use electrolytic capacitor. Avoid touching any part of the circuit
since it is powered directly to the main ac source.
Capacitor of this LED lamp is as follows:
220nF if ac line is 220V @ 60Hz
270nF if ac line is 220V @ 50Hz
470nF if ac line is 110V @ 60Hz
578nF if ac line is 110V @ 60Hz
22 Watt Audio Amplifier Circuit
The 22 watt amp is easy to build, and very inexpensive. The circuit can be used as a booster in a car audio system, an amp for satellite speakers in a surround sound or home theater system, or as an amp for computer speakers. The circuit is quite compact and uses only about 60 watts.
Schematic-
Parts List-
R1 - 1 - 39K 1/4 Watt Resistor
C1,C2 - 2 - 10uf 25V Electrolytic Capacitor
C3 - 1 - 100uf 25V Electrolytic Capacitor
C4 - 1 - 47uf 25V Electrolytic Capacitor
C5 - 1 - 0.1uf 25V Ceramic Capacitor
C6 - 1 - 2200uf 25V Electrolytic Capacitor
U1 - 1 - TDA1554 Two Channel Audio Amp Chip
MISC - 1 - Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input), Wire, Board
Notes-
1) The circuit works best with 4 ohm speakers, but 8 ohm units will do.
2) The circuit dissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed.
3) The circuit operates at 12 Volts at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat.
4) Printed circuit board is preferred, but universal solder or perf board will do. Keep lead length short.
Schematic-
Parts List-
R1 - 1 - 39K 1/4 Watt Resistor
C1,C2 - 2 - 10uf 25V Electrolytic Capacitor
C3 - 1 - 100uf 25V Electrolytic Capacitor
C4 - 1 - 47uf 25V Electrolytic Capacitor
C5 - 1 - 0.1uf 25V Ceramic Capacitor
C6 - 1 - 2200uf 25V Electrolytic Capacitor
U1 - 1 - TDA1554 Two Channel Audio Amp Chip
MISC - 1 - Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input), Wire, Board
Notes-
1) The circuit works best with 4 ohm speakers, but 8 ohm units will do.
2) The circuit dissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed.
3) The circuit operates at 12 Volts at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat.
4) Printed circuit board is preferred, but universal solder or perf board will do. Keep lead length short.
Voltage Inverter Circuit
This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will operate at an input voltage from around 5V to 20V and produce a output from +-2.5V to +-10V.
Schematic-
Parts List-
R1 - 1 - 1M Linear Pot
C1,C2 - 2 - 15uf 25V Electrolytic Capacitor
U1 - 1 - LM380 Audio Amp Chip
MISC - 1 - Heatsink For U1, Binding Posts (For Input/Output), Wire, Board
Notes -
1) U1 dissipates around 1W and will therefore require a heatsink.
2) R1 is used to equalize the outputs. The first time you use the circuit, it should be set to mid range and then adjusted with the aid of a voltmeter. Measure each output while adjusting. The circuit is calibrated when both outputs read the same voltage (either positive or negative).
Schematic-
Parts List-
R1 - 1 - 1M Linear Pot
C1,C2 - 2 - 15uf 25V Electrolytic Capacitor
U1 - 1 - LM380 Audio Amp Chip
MISC - 1 - Heatsink For U1, Binding Posts (For Input/Output), Wire, Board
Notes -
1) U1 dissipates around 1W and will therefore require a heatsink.
2) R1 is used to equalize the outputs. The first time you use the circuit, it should be set to mid range and then adjusted with the aid of a voltmeter. Measure each output while adjusting. The circuit is calibrated when both outputs read the same voltage (either positive or negative).
Computer Controlled Frequency Counter/Logic Probe Circuit
This circuit is a stable frequency counter accurate to 5 significant digits. The range is 0 - 30MHz with an input sensitivity of greater then 100mV. The probe connects to the PC serial port. So by using the crystal oscillator already present on your PC serial card and software calibration, the Probes' external circuitry is kept to a minimum. Probe 9 can also be used as a logic probe/analyzer using included software (LPROBE92.EXE).
Schematic-
Parts List-
R1,R2,R3,R4 - 4 - 100K 1/4W Resistor
R5 - 1 - 10M 1/4W Resistor
R6, R7 - 2 - 3.3K 1/4W Resistor
R8 - 1 - 390 Ohm 1/4W Resistor
R9 - 1 - 1M 1/4W Resistor
C1, C4 - 2 - 0.1uF Ceramic Disc Capacitor
C2, C3 - 2 - 100uF 16V Electrolytic Capacitor
D1 - 1 - 1N4148 Signal Diode or Any 200mA silicon signal diode
D2, D3 - 2 - 3.3V Zener Diode
D4 - 1 - 6.2V Zener Diode
U1 - 1 - 74HC00 Quad Highspeed NAND Gate
U2, U3, U4 - 3 - 4021 8 Stage Shift Register
U5 - 1 - 74HC393 Dual Highspeed 4 Bit Counter
U6 - 1 - 4040 12 Stage Binary Counter
MISC - 1 - PC Board, Wire, Suitable Probe, DB9/DB25 Connector
Notes-
1) The software to use this probe can be downloaded using the following link. Note that this software is compiled for Intel x86 platforms and runs under DOS, Win95, Win98 and WinMe. It does not run under any Windows version based on NT including Windows NT 3.51, WinNT4, Win2K, Win2K3, WinXP and Windows Vista. This is because NT based operating systems do not allow direct hardware access.
Download Probe Software, Zipped, 19K
2) SETPROBE.EXE is the frequency counter calibration program. To give accurate readings the Probe must be calibrated to your PC. SETPROBE.EXE calculates the constant error correction factor for the particular PC serial card the probe is to be used on. The frequency counter corrects for this slight constant error in crystal frequency by using the correction factor contained in PROBE.DAT. To calculate this correction factor, a reliable oscillator of known frequency (eg 2MHz Crystal Oscillator) is required. When CALIBRAT.EXE is run, the Probe will sample the frequency and then ask for the true frequency value in HZ. The frequency entered must be to 1 Hz accuracy (no decimal points) or an error will occur (for example "200123" not "200123.34" or "2003.421 kHz"). The program then calculates constant error correction factor and stores it to PROBE.DAT. Calibration is only necessary once.
3) LPROBE92.EXE is the logic analysis program . Logic states are displayed in real time. This program runs best under DOS (not a DOS window). The sampling speed is adjusted by using the left and right arrow keys.
The three triggering modes are:
* TRIG: Starts each scan (left-right of screen) on a negative going edge of logic signal.
* KEY TRIG: Waits for a key to be pressed before beginning each scan.
* FREE RUNNING: Not triggered.
To Toggle between these use the UP / DOWN arrow keys. To quit from LPROBE press escape.
4) FPROBE92.EXE is the frequency counter program. The measured frequency is displayed in Hz with commas indicating KHz and MHz. To quit from FPROBE press any key.
5) Serial port pinouts are as follows.
9pin - 25 pin
TD - 3 - 2
RTS - 7 - 4
DTR - 4 - 20
DSR - 6 - 6
CTS - 8 - 5
SG 5 7
Schematic-
Parts List-
R1,R2,R3,R4 - 4 - 100K 1/4W Resistor
R5 - 1 - 10M 1/4W Resistor
R6, R7 - 2 - 3.3K 1/4W Resistor
R8 - 1 - 390 Ohm 1/4W Resistor
R9 - 1 - 1M 1/4W Resistor
C1, C4 - 2 - 0.1uF Ceramic Disc Capacitor
C2, C3 - 2 - 100uF 16V Electrolytic Capacitor
D1 - 1 - 1N4148 Signal Diode or Any 200mA silicon signal diode
D2, D3 - 2 - 3.3V Zener Diode
D4 - 1 - 6.2V Zener Diode
U1 - 1 - 74HC00 Quad Highspeed NAND Gate
U2, U3, U4 - 3 - 4021 8 Stage Shift Register
U5 - 1 - 74HC393 Dual Highspeed 4 Bit Counter
U6 - 1 - 4040 12 Stage Binary Counter
MISC - 1 - PC Board, Wire, Suitable Probe, DB9/DB25 Connector
Notes-
1) The software to use this probe can be downloaded using the following link. Note that this software is compiled for Intel x86 platforms and runs under DOS, Win95, Win98 and WinMe. It does not run under any Windows version based on NT including Windows NT 3.51, WinNT4, Win2K, Win2K3, WinXP and Windows Vista. This is because NT based operating systems do not allow direct hardware access.
Download Probe Software, Zipped, 19K
2) SETPROBE.EXE is the frequency counter calibration program. To give accurate readings the Probe must be calibrated to your PC. SETPROBE.EXE calculates the constant error correction factor for the particular PC serial card the probe is to be used on. The frequency counter corrects for this slight constant error in crystal frequency by using the correction factor contained in PROBE.DAT. To calculate this correction factor, a reliable oscillator of known frequency (eg 2MHz Crystal Oscillator) is required. When CALIBRAT.EXE is run, the Probe will sample the frequency and then ask for the true frequency value in HZ. The frequency entered must be to 1 Hz accuracy (no decimal points) or an error will occur (for example "200123" not "200123.34" or "2003.421 kHz"). The program then calculates constant error correction factor and stores it to PROBE.DAT. Calibration is only necessary once.
3) LPROBE92.EXE is the logic analysis program . Logic states are displayed in real time. This program runs best under DOS (not a DOS window). The sampling speed is adjusted by using the left and right arrow keys.
The three triggering modes are:
* TRIG: Starts each scan (left-right of screen) on a negative going edge of logic signal.
* KEY TRIG: Waits for a key to be pressed before beginning each scan.
* FREE RUNNING: Not triggered.
To Toggle between these use the UP / DOWN arrow keys. To quit from LPROBE press escape.
4) FPROBE92.EXE is the frequency counter program. The measured frequency is displayed in Hz with commas indicating KHz and MHz. To quit from FPROBE press any key.
5) Serial port pinouts are as follows.
9pin - 25 pin
TD - 3 - 2
RTS - 7 - 4
DTR - 4 - 20
DSR - 6 - 6
CTS - 8 - 5
SG 5 7
Car Alarm Arming Horn Beep Canceller Circuit
It's a great convenience that most modern cars come with a built in alarm, however it is nothing but noise pollution that the horn sounds when the alarm is armed. Disconnecting the alarm system from the horn relay will eliminate this, but prevent the horn from sounding in the even of an actual alarm. This circuit serves to silence the arming beep yet maintain the alarm by introducing a small delay into the signal. It sits between the alarm and horn relay. The alarm must provide a constant horn signal for at least 3 seconds before the horn relay is activated. That way the quick "beep" will never activate the horn relay, while the constant alarm signal will.
Schematic-
Parts List-
C1 - 1 - 0.01uF Ceramic Disc Capacitor
C2 - 1 - 100uF 35V Electrolytic Capacitor
R1 - 1 - 1K 1/4W Resistor
R2 - 1 - 10K 1/4W Resistor
R3 - 1 - 15K 1/4W Resistor
R4 - 1 - 470 Ohm 1/4W Resistor
D1, D3, D4 - 3 - 1N4004 Rectifier Diode
D2 - 1 - Red LED
U1 - 1 - 555 Timer IC
K1 - 1 - SPST 12V Automotive Relay
MISC - 1 - Board, Wire, Socket For U1, Case
Schematic-
Parts List-
C1 - 1 - 0.01uF Ceramic Disc Capacitor
C2 - 1 - 100uF 35V Electrolytic Capacitor
R1 - 1 - 1K 1/4W Resistor
R2 - 1 - 10K 1/4W Resistor
R3 - 1 - 15K 1/4W Resistor
R4 - 1 - 470 Ohm 1/4W Resistor
D1, D3, D4 - 3 - 1N4004 Rectifier Diode
D2 - 1 - Red LED
U1 - 1 - 555 Timer IC
K1 - 1 - SPST 12V Automotive Relay
MISC - 1 - Board, Wire, Socket For U1, Case
Automatic Headlight Brightness Switch Circuit
Driving the highway with your high-beam headlights can really increase your visibility, but can be a blinding hazard for other drivers. This simple circuit can be wired into your headlight switch to provide automatic switching between high and low beam headlights when there is oncoming traffic. It does this by sensing the lights of that traffic. In this way, you can drive safely with your high-beams on without blinding other drivers.
Schematic-
Parts List-
R1 - 1 - 5K 1/4W Resistor
R2, R3, R4 - 3 - 5K Pot
Q1 - 1 - NPN Phototransistor
Q2 - 1 - 2N3906 PNP Transistor
K1 - 1 - Low Current 12V SPST Relay
K2 - 1 - High Current 12V SPDT Relay
S1 - 1 - SPST Switch
B1 - 1 - Car Battery
MISC - 1 - Case, wire, board, knobs for pots
Notes-
1) Q1 should me mounted in such a way so it points toward the front of the car with a clear line of site. Suitable places are on the dashboard, in the front grill, etc.
2) Adjust all the pots for proper response by testing on a deserted road.
3) S1 enables and disables the circuit.
4) B1 is, obviously, in the car already.
5) Before you try to connect this circuit, get a wiring diagram for your car. Some auto manufacturers do weird things with wiring.
6) Connection A goes to the high beam circuit, B goes to the headlight switch common and C connects to the low beam circuit.
Schematic-
Parts List-
R1 - 1 - 5K 1/4W Resistor
R2, R3, R4 - 3 - 5K Pot
Q1 - 1 - NPN Phototransistor
Q2 - 1 - 2N3906 PNP Transistor
K1 - 1 - Low Current 12V SPST Relay
K2 - 1 - High Current 12V SPDT Relay
S1 - 1 - SPST Switch
B1 - 1 - Car Battery
MISC - 1 - Case, wire, board, knobs for pots
Notes-
1) Q1 should me mounted in such a way so it points toward the front of the car with a clear line of site. Suitable places are on the dashboard, in the front grill, etc.
2) Adjust all the pots for proper response by testing on a deserted road.
3) S1 enables and disables the circuit.
4) B1 is, obviously, in the car already.
5) Before you try to connect this circuit, get a wiring diagram for your car. Some auto manufacturers do weird things with wiring.
6) Connection A goes to the high beam circuit, B goes to the headlight switch common and C connects to the low beam circuit.
Solid State Tesla Coil/High Voltage Generator Circuit
This is a fun and useful circuit for demonstrating high frequency high voltge. It can produce up to about 30KV, depending on the transformer used. It is cheap and easy to make, thanks to the standard TV flyback transformer used. It can power LASERS (although I have never tried), and even cause a fluorescent bulb to light from as much as 2 feet away.
Parts List-
R1 - 1 - 27 Ohm 5W Resistor
R2 - 1 - 240 Ohm 5W Resistor
BR1 - 1 - 50 Volt, 6 Amp Bridge Rectifier
C1 - 1 - 8000uf, 35 Volt Capacitor
Q1, Q2 - 2 - 2N3055 NPN Power Transistor
T1 - 1 - 24V 5A Transformer (See "Notes")
T2 - 1 - TV Flyback Transformer (See "Notes")
S1 - 1 - 115V 3A SPST Switch
MISC - 1 - Case, Wire, Heatsinks, Line Cord
Notes-
1) T2 is a high voltage flyback transformer salvaged from an old TV, or ordered from Fair Radio Sales (see Where To Get Parts). Look for the biggest, most intimidating transformer you can find. Old tube TV's are a good place to look. The transformer should not have a rectifier built in.
2) You will need to rewind the transformer's primary. First, remove the old primary, being careful not to damage the high voltage secondary. If the transformer is wound with all windings incased in plastic, use another transformer. Second, wind on 5 turns of 18 AWG wire, twist a loop (center tap), and then wind on 5 more turns. This becomes winding C-D. Now, wind on 2 turns of 22 AWG wire, twist a loop, and wind on 2 more turns. This becomes winding A-B.
3) Q1 and Q2 will run HOT if not used with a large heatsink. After the circuit has been running for a minute or two, you should still be able to put your finger on the transistors without being burnt. Also, R1 and R2 will run hot.
4) If you experience arcing on the exposed transformer leads, select a lower voltage for T1. If you are powering the circuit with a power supply (see Power Supply), just crank down the voltage.
5) For a real high voltage output, connect a voltage multiplier (from an old TV or computer monitor) to the output of T2.
6) If the circuit does not work, reverse connections A and B.
7) I finally got around to taking some pictures of the circuit in operation. Here they are:
The first picture is the high voltage generator without the voltage multiplier. Notice how hot the arc looks. The second picture is the high voltage generator with a voltage multiplier installed. Notice how much brighter the arc is.
Parts List-
R1 - 1 - 27 Ohm 5W Resistor
R2 - 1 - 240 Ohm 5W Resistor
BR1 - 1 - 50 Volt, 6 Amp Bridge Rectifier
C1 - 1 - 8000uf, 35 Volt Capacitor
Q1, Q2 - 2 - 2N3055 NPN Power Transistor
T1 - 1 - 24V 5A Transformer (See "Notes")
T2 - 1 - TV Flyback Transformer (See "Notes")
S1 - 1 - 115V 3A SPST Switch
MISC - 1 - Case, Wire, Heatsinks, Line Cord
Notes-
1) T2 is a high voltage flyback transformer salvaged from an old TV, or ordered from Fair Radio Sales (see Where To Get Parts). Look for the biggest, most intimidating transformer you can find. Old tube TV's are a good place to look. The transformer should not have a rectifier built in.
2) You will need to rewind the transformer's primary. First, remove the old primary, being careful not to damage the high voltage secondary. If the transformer is wound with all windings incased in plastic, use another transformer. Second, wind on 5 turns of 18 AWG wire, twist a loop (center tap), and then wind on 5 more turns. This becomes winding C-D. Now, wind on 2 turns of 22 AWG wire, twist a loop, and wind on 2 more turns. This becomes winding A-B.
3) Q1 and Q2 will run HOT if not used with a large heatsink. After the circuit has been running for a minute or two, you should still be able to put your finger on the transistors without being burnt. Also, R1 and R2 will run hot.
4) If you experience arcing on the exposed transformer leads, select a lower voltage for T1. If you are powering the circuit with a power supply (see Power Supply), just crank down the voltage.
5) For a real high voltage output, connect a voltage multiplier (from an old TV or computer monitor) to the output of T2.
6) If the circuit does not work, reverse connections A and B.
7) I finally got around to taking some pictures of the circuit in operation. Here they are:
The first picture is the high voltage generator without the voltage multiplier. Notice how hot the arc looks. The second picture is the high voltage generator with a voltage multiplier installed. Notice how much brighter the arc is.
Dual Polarity Power Supply Circuit
When working with electronics, you always need one basic thing; power. This power supply is great for powering all kinds of electronic projects. It produces a well filtered, variable 1.2-30 volts at 5 amps. It is easy to build and the parts are realitively easy to find.
Schematic-
Parts List-
C1 - 1 - 14000uF or 10000uf 40 VDC Electrolytic Capacitor
C2 - 1 - 100uF 50Vdc Electrolytic Capacitor
C3 - 1 - 0.1uF Disc Capacitor
C4 - 1 - 0.01uF Disc Capacitor
R1 - 1 - 5K Pot
R2 - 1 - 240 Ohm 1/4 W Resistor(See Notes)
U1 - 1 - LM338K 1.2 to 30 Volt 5 Amp Regulator
BR1 - 1 - 10 Amp 50 PIV Bridge Rectifier
T1 - 1 - 24 V 5 Amp Transformer
S1 - 1 - SPST Toggle Switch
MISC - 1 - Wire, Line Cord, Case, Binding Posts (for output)
Notes-
1) The regulator comes in a TO-3 case and MUST be used with a LARGE heatsink. You may want to mount a small fan to blow air across the regulator (I did).
2) The filter capacitor is large. It won't fit on any board so bolt it to the case.
3) You can, of course, add a volt and amp meter.
4) Since this project operates from 120 VAC, you must include a fuse and build the project in a case.
5) R2 may need to be decreased to 120 Ohm if you experience voltage drift at light loads. 240 Ohm may not load the output appropriately on some regulators. The datasheet for the LM338K does specify 120 Ohm (I suggest you use a 1/2W unit) so you may just want to use 120 Ohm and not bother with the 240 Ohm resistor showin the parts list.
Schematic-
Parts List-
C1 - 1 - 14000uF or 10000uf 40 VDC Electrolytic Capacitor
C2 - 1 - 100uF 50Vdc Electrolytic Capacitor
C3 - 1 - 0.1uF Disc Capacitor
C4 - 1 - 0.01uF Disc Capacitor
R1 - 1 - 5K Pot
R2 - 1 - 240 Ohm 1/4 W Resistor(See Notes)
U1 - 1 - LM338K 1.2 to 30 Volt 5 Amp Regulator
BR1 - 1 - 10 Amp 50 PIV Bridge Rectifier
T1 - 1 - 24 V 5 Amp Transformer
S1 - 1 - SPST Toggle Switch
MISC - 1 - Wire, Line Cord, Case, Binding Posts (for output)
Notes-
1) The regulator comes in a TO-3 case and MUST be used with a LARGE heatsink. You may want to mount a small fan to blow air across the regulator (I did).
2) The filter capacitor is large. It won't fit on any board so bolt it to the case.
3) You can, of course, add a volt and amp meter.
4) Since this project operates from 120 VAC, you must include a fuse and build the project in a case.
5) R2 may need to be decreased to 120 Ohm if you experience voltage drift at light loads. 240 Ohm may not load the output appropriately on some regulators. The datasheet for the LM338K does specify 120 Ohm (I suggest you use a 1/2W unit) so you may just want to use 120 Ohm and not bother with the 240 Ohm resistor showin the parts list.
Portable CD Player Adapter For Car Circuit
Whenever I'm in the car listening to my favourite CD, it always happens; my batteries go dead. To solve that problem, I built this extremely simple regulator circuit. It steps down the 12V from the lighter socket to 9V which is used by the CD player. Different CD players (I have a Sony Discman) may require different voltages, so just use the correct regulator. All the 78xx series regulators have the same pin out, so the circuit is universal.
Schematic-
Parts List-
C1 - 1 - 1000uF 25V Electrolytic Capacitor
C2 - 1 - 10uF 25V Electrolytic Capacitor
C3 - 1 - 1uF 15V Elextrolytic Capacitor
C4 - 1 - 0.1uF 15V Electrolytic Capacitor
U1 - 1 - 7809 Or Other Regulator (See "Notes")
MISC - 1 - Cigarette Lighter Plug, Plug For CD Player (See "Notes"), Heat Sink For U1, Wire, Case.
Notes-
1) The voltage your CD player needs will determine which regulator you use. For 9V, use the 7809. For 6V, use the 7806. For the unlikely 5V use the 7805. Remember that whatever regulator you use, you will need to heat sink it. The metal case or metal cover on the case makes a great heat sink.
2) I built the circuit in a small case with the long wire to the cigaratte lighter plug coming out one end, then another, slightly shorter wire going out the other end to the CD player.
3) Triple check your wiring. You would hate to ruin an expensive CD player because you reversed one of the connections or hooked the regulator up backwards.
Schematic-
Parts List-
C1 - 1 - 1000uF 25V Electrolytic Capacitor
C2 - 1 - 10uF 25V Electrolytic Capacitor
C3 - 1 - 1uF 15V Elextrolytic Capacitor
C4 - 1 - 0.1uF 15V Electrolytic Capacitor
U1 - 1 - 7809 Or Other Regulator (See "Notes")
MISC - 1 - Cigarette Lighter Plug, Plug For CD Player (See "Notes"), Heat Sink For U1, Wire, Case.
Notes-
1) The voltage your CD player needs will determine which regulator you use. For 9V, use the 7809. For 6V, use the 7806. For the unlikely 5V use the 7805. Remember that whatever regulator you use, you will need to heat sink it. The metal case or metal cover on the case makes a great heat sink.
2) I built the circuit in a small case with the long wire to the cigaratte lighter plug coming out one end, then another, slightly shorter wire going out the other end to the CD player.
3) Triple check your wiring. You would hate to ruin an expensive CD player because you reversed one of the connections or hooked the regulator up backwards.
Light/Dark Detector Circuit
This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.
Schematic-
Parts List-
R1 - 1 - 100K Pot
Q1 - 1 - 2N3904 NPN Transistor
Q2 - 1 - NPN Phototransistor
RELAY - 1 - 9V Relay
MISC - 1 - Board, Wire, 9V Battery Snap (if battery used), Knob For R1
Notes-
1) R1 Adjusts sensitivity
Schematic-
Parts List-
R1 - 1 - 100K Pot
Q1 - 1 - 2N3904 NPN Transistor
Q2 - 1 - NPN Phototransistor
RELAY - 1 - 9V Relay
MISC - 1 - Board, Wire, 9V Battery Snap (if battery used), Knob For R1
Notes-
1) R1 Adjusts sensitivity
IR Remote Control Jammer Circuit
Don't like your little brother's TV channel selection? Hate the volume your wife sets the stereo at? Want to just annoy someone? This circuit does all that and more by jamming most IR remote signals. The circuit releases a flood of pulsing IR light that confuses the reciever by corrupting the data stream.
Schematic-
Parts List-
R1 - 1 - 100K 1/4W Resistor
R2 - 1 - 150K 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 22 Ohm 1/4W Resistor See "Notes"
C1 - 1 - 10nF Ceramic Disc Capacitor
C2 - 1 - 1uF Electrolytic Capacitor
D1, D2, D3 - 3 - High Output IR LED
Q1 - 1 - 2N4403 PNP Transistor
Q2 - 1 - 2N4401 NPN Transistor
S1 - 1 - Normally Open Momentary Push Botton
B1 - 1 - 4.5V Battery (Three "AA"'s In Series)
MISC - 1 - Wire, Case, Board
Notes-
1) You may need to adjust the value of R3 for the right frequency. A pot can be used.
2) You may only need one IR LED.
3) It goes without saying that this circuit should be used with descretion.
4) The value of R5 depends on your supply voltage and LED. For a standard 4.5V supply and standard IR LED, use 22 Ohm as specified on the parts list. This forum topic covers this resistor as well as a few other issues with the circuit.
Schematic-
Parts List-
R1 - 1 - 100K 1/4W Resistor
R2 - 1 - 150K 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 22 Ohm 1/4W Resistor See "Notes"
C1 - 1 - 10nF Ceramic Disc Capacitor
C2 - 1 - 1uF Electrolytic Capacitor
D1, D2, D3 - 3 - High Output IR LED
Q1 - 1 - 2N4403 PNP Transistor
Q2 - 1 - 2N4401 NPN Transistor
S1 - 1 - Normally Open Momentary Push Botton
B1 - 1 - 4.5V Battery (Three "AA"'s In Series)
MISC - 1 - Wire, Case, Board
Notes-
1) You may need to adjust the value of R3 for the right frequency. A pot can be used.
2) You may only need one IR LED.
3) It goes without saying that this circuit should be used with descretion.
4) The value of R5 depends on your supply voltage and LED. For a standard 4.5V supply and standard IR LED, use 22 Ohm as specified on the parts list. This forum topic covers this resistor as well as a few other issues with the circuit.
Dual Polarity Power Supply Circuit
This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage.
Schematic-
Parts List-
C1, C2 - 2 - 2200uF 35V Electrolytic Capacitor
C3, C4, C5, C7 - 4 - 1uF 35V Electrolytic Capacitor
C6, C8 - 2 - 100uF 35V Electrolytic Capacitor
R1, R4 - 2 - 5K Pot
R2, R3 - 2 - 240 Ohm 1/4 W Resistor
BR1 - 1 - 2A 30V Bridge Rectifier
U1 - 1 - LM317 Adjustable Positive Regulator
U2 - 1 - LM337 Adjustable Negative Regulator
T1 - 1 - 30V Center Tapped 2 Amp Transformer
S1 - 1 - SPST 2 Amp Switch
MISC - 1 - Heatsinks For U1 And U2, Line Cord, Case, Knobs For Pots, Wire
Notes-
1) Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
2) U1 and U2 get quite hot and will require heatsinks. A fan is usually not needed.
3) You can, of course, add a volt and amp meter.
4) U1 and U2 can only go down to a minimum of +-1.2V. If you need to go lower, you can add two 1N4003 diodes in series with the output of the regulator. The diodes drop about 0.6V each, which will allow the supply to go to 0. Note that this will also decrease your maximum output voltage by 1.2V. (Thanks to Steve Horvath for the suggestion).
Schematic-
Parts List-
C1, C2 - 2 - 2200uF 35V Electrolytic Capacitor
C3, C4, C5, C7 - 4 - 1uF 35V Electrolytic Capacitor
C6, C8 - 2 - 100uF 35V Electrolytic Capacitor
R1, R4 - 2 - 5K Pot
R2, R3 - 2 - 240 Ohm 1/4 W Resistor
BR1 - 1 - 2A 30V Bridge Rectifier
U1 - 1 - LM317 Adjustable Positive Regulator
U2 - 1 - LM337 Adjustable Negative Regulator
T1 - 1 - 30V Center Tapped 2 Amp Transformer
S1 - 1 - SPST 2 Amp Switch
MISC - 1 - Heatsinks For U1 And U2, Line Cord, Case, Knobs For Pots, Wire
Notes-
1) Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
2) U1 and U2 get quite hot and will require heatsinks. A fan is usually not needed.
3) You can, of course, add a volt and amp meter.
4) U1 and U2 can only go down to a minimum of +-1.2V. If you need to go lower, you can add two 1N4003 diodes in series with the output of the regulator. The diodes drop about 0.6V each, which will allow the supply to go to 0. Note that this will also decrease your maximum output voltage by 1.2V. (Thanks to Steve Horvath for the suggestion).
Car Battery Charger
This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the battery is fully charged, the circuit switches off and lights a LED, telling you that the cycle has finished.
Schematic-
Parts List-
R1 - 1 - 500 Ohm 1/4 W Resistor
R2 - 1 - 3K 1/4 W Resistor
R3 - 1 - 1K 1/4 W Resistor
R4 - 1 - 15 Ohm 1/4 W Resistor
R5 - 1 - 230 Ohm 1/4 W Resistor
R6 - 1 - 15K 1/4 W Resistor
R7 - 1 - 0.2 Ohm 10 W Resistor
C1 - 1 - 0.1uF 25V Ceramic Capacitor
C2 - 1 - 1uF 25V Electrolytic Capacitor
C3 - 1 - 1000pF 25V Ceramic Capacitor
D1 - 1 - 1N457 Diode
Q1 - 1 - 2N2905 PNP Transistor
U1 - 1 - LM350 Regulator
U2 - 1 - LM301A Op Amp
S1 - 1 - Normally Open Push Button Switch
MISC - 1 - Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output
Notes-
1) The circuit was meant to be powered by a power supply, which is why there is no transformer, rectifier, or filter capacitors on the schematic. There is no reason why you cannot add these.
2) A heatsink will be needed for U1.
3) To use the circuit, hook it up to a power supply/plug it in. Then, connect the battery to be charged to the output terminals. All you have to do now is push S1 (the "Start" switch), and wait for the circuit to finish.
4) If you want to use the charger without having to provide an external power supply, use the following circuit.
5) The first time you use the circuit, you should check up on it every once and a while to make sure that it is working properly and the battery is not being over charged.
Schematic-
Parts List-
R1 - 1 - 500 Ohm 1/4 W Resistor
R2 - 1 - 3K 1/4 W Resistor
R3 - 1 - 1K 1/4 W Resistor
R4 - 1 - 15 Ohm 1/4 W Resistor
R5 - 1 - 230 Ohm 1/4 W Resistor
R6 - 1 - 15K 1/4 W Resistor
R7 - 1 - 0.2 Ohm 10 W Resistor
C1 - 1 - 0.1uF 25V Ceramic Capacitor
C2 - 1 - 1uF 25V Electrolytic Capacitor
C3 - 1 - 1000pF 25V Ceramic Capacitor
D1 - 1 - 1N457 Diode
Q1 - 1 - 2N2905 PNP Transistor
U1 - 1 - LM350 Regulator
U2 - 1 - LM301A Op Amp
S1 - 1 - Normally Open Push Button Switch
MISC - 1 - Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output
Notes-
1) The circuit was meant to be powered by a power supply, which is why there is no transformer, rectifier, or filter capacitors on the schematic. There is no reason why you cannot add these.
2) A heatsink will be needed for U1.
3) To use the circuit, hook it up to a power supply/plug it in. Then, connect the battery to be charged to the output terminals. All you have to do now is push S1 (the "Start" switch), and wait for the circuit to finish.
4) If you want to use the charger without having to provide an external power supply, use the following circuit.
5) The first time you use the circuit, you should check up on it every once and a while to make sure that it is working properly and the battery is not being over charged.
Load Sensing Power Switch Circuit
This circuit will automatically switch on several mains-powered "slave" loads when a "master" load is turned on. For example, it will switch on the amplifier and CD player in a stereo system when the receiver is turned on. It works by sensing the current draw of the "master" device through a low value high wattage resistor using a comparator. The output of that comparator then switches on the "slave" relay. The circuit can be built into a power bar, extension cord or power center to provide a convenient set of "smart" outlets that switch on when the master appliance is powered (turn on the computer monitor and the computer, printer and other peripherals come on as well).
Schematic-
Parts List-
C1, C3 - 2 - 10uF 35V Electrolytic Capacitor
C2 - 1 - 1uF 35V Electrolytic Capacitor
R1 - 1 - 0.1 Ohm 10W Resistor
R2 - 1 - 27K 1/2W Resistor
R3, R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 470K 1/4W Resistor
R6 - 1 - 4.7K 1/2W Resistor
R7 - 1 - 10K 1/4W Resistor
D1, D2, D4 - 3 - 1N4004 Rectifier Diode
D3 - 1 - 1N4744 15V 1 Watt Zener Diode
U1 - 1 - LM358N Dual Op Amp IC
Q1 - 1 - 2N3904 NPN Transistor
K1 - 1 - Relay, 12VDC Coil, 120VAC 10A Contacts
S1 - 1 - SPST Switch 120AVC, 10A
MISC - 1 - Board, Wire, Socket For U1, Case, Mains Plug, Socket
Notes-
1. This circuit is designed for 120V operation. For 240V operation, resistors R2 and R6 will need to be changed.
2. A maximum of 5A can be used as the master unless the wattage of R1 is increased
3. S1 provides a manual bypass switch.
4. THis circuit is not isolated from the mains supply. Because of this, you must exercise extreme caution when working around the circuit if it is plugged in.
Schematic-
Parts List-
C1, C3 - 2 - 10uF 35V Electrolytic Capacitor
C2 - 1 - 1uF 35V Electrolytic Capacitor
R1 - 1 - 0.1 Ohm 10W Resistor
R2 - 1 - 27K 1/2W Resistor
R3, R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 470K 1/4W Resistor
R6 - 1 - 4.7K 1/2W Resistor
R7 - 1 - 10K 1/4W Resistor
D1, D2, D4 - 3 - 1N4004 Rectifier Diode
D3 - 1 - 1N4744 15V 1 Watt Zener Diode
U1 - 1 - LM358N Dual Op Amp IC
Q1 - 1 - 2N3904 NPN Transistor
K1 - 1 - Relay, 12VDC Coil, 120VAC 10A Contacts
S1 - 1 - SPST Switch 120AVC, 10A
MISC - 1 - Board, Wire, Socket For U1, Case, Mains Plug, Socket
Notes-
1. This circuit is designed for 120V operation. For 240V operation, resistors R2 and R6 will need to be changed.
2. A maximum of 5A can be used as the master unless the wattage of R1 is increased
3. S1 provides a manual bypass switch.
4. THis circuit is not isolated from the mains supply. Because of this, you must exercise extreme caution when working around the circuit if it is plugged in.
Automatic 12V Lead Acid Battery Charger Circuit
This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged.
Schematic-
Parts List-
R1, R3 - 2 - 330 Ohm 1/4W Resistor
R2 - 1 - 100 Ohm 1/4W Pot
R4, R5, R7, R8 - 4 - 82 Ohm 2W Resistor
R6 - 1 - 100 Ohm 1/4W Resistor
R9 - 1 - 1K 1/4W Resistor
C1 - 1 - 220uF 25V Electrolytic Capacitor
D1 - 1 - P600 Diode Any 50V 5A or greater rectifier diode
D2 - 1 - 1N4004 Diode 1N4002, 1N4007
D3 - 1 - 5.6V Zener Diode
D4 - 1 - LED (Red, Green or Yellow)
Q1 - 1 - BT136 TRIAC
Q2 - 1 - BRX49 SCR
T1 - 1 - 12V 4A Transformer See Notes
F1 - 1 - 3A Fuse
S1 - 1 - SPST Switch, 120VAC 5A
MISC - 1 - Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output, Fuse Holder
Notes-
1. R2 will have to be adjusted to set the proper finish charge voltage. Flooded and gel batteries are generally charged to 13.8V. If you are cycling the battery (AGM or gel) then 14.5V to 14.9V is generally recommended by battery manufacturers. To set up the charger, set the pot to midway, turn on the charger and then connect a battery to it's output. Monitor the charge with a voltmeter until the battery reaches the proper end voltage and then adjust the pot until the LED glows steadily. The charger has now been set. To charge multiple battery types you can mount the pot on the front of the case and have each position marked for the appropriate voltage.
2. Q1 will need a heatsink. If the circuit is mounted in a case then a small fan might be necessary and can generally be powered right off the output of D1.
3. T1 is a transformer with a primary voltage appropriate to your location (120V, 220V, etc.) and a secondary around 12V. Using a higher voltage secondary (16V-18V) will allow you to charge 16V batteries sometimes used in racing applications.
4. If the circuit is powered off, the battery should be disconnected from it's output otherwise the circuit will drain the battery slowly.
Schematic-
Parts List-
R1, R3 - 2 - 330 Ohm 1/4W Resistor
R2 - 1 - 100 Ohm 1/4W Pot
R4, R5, R7, R8 - 4 - 82 Ohm 2W Resistor
R6 - 1 - 100 Ohm 1/4W Resistor
R9 - 1 - 1K 1/4W Resistor
C1 - 1 - 220uF 25V Electrolytic Capacitor
D1 - 1 - P600 Diode Any 50V 5A or greater rectifier diode
D2 - 1 - 1N4004 Diode 1N4002, 1N4007
D3 - 1 - 5.6V Zener Diode
D4 - 1 - LED (Red, Green or Yellow)
Q1 - 1 - BT136 TRIAC
Q2 - 1 - BRX49 SCR
T1 - 1 - 12V 4A Transformer See Notes
F1 - 1 - 3A Fuse
S1 - 1 - SPST Switch, 120VAC 5A
MISC - 1 - Wire, Board, Heatsink For U1, Case, Binding Posts or Alligator Clips For Output, Fuse Holder
Notes-
1. R2 will have to be adjusted to set the proper finish charge voltage. Flooded and gel batteries are generally charged to 13.8V. If you are cycling the battery (AGM or gel) then 14.5V to 14.9V is generally recommended by battery manufacturers. To set up the charger, set the pot to midway, turn on the charger and then connect a battery to it's output. Monitor the charge with a voltmeter until the battery reaches the proper end voltage and then adjust the pot until the LED glows steadily. The charger has now been set. To charge multiple battery types you can mount the pot on the front of the case and have each position marked for the appropriate voltage.
2. Q1 will need a heatsink. If the circuit is mounted in a case then a small fan might be necessary and can generally be powered right off the output of D1.
3. T1 is a transformer with a primary voltage appropriate to your location (120V, 220V, etc.) and a secondary around 12V. Using a higher voltage secondary (16V-18V) will allow you to charge 16V batteries sometimes used in racing applications.
4. If the circuit is powered off, the battery should be disconnected from it's output otherwise the circuit will drain the battery slowly.
6V to 12V Converter Circuit
This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also modify it for different voltages.
Schematic-
Parts List-
R1, R4 - 2 - 2.2K 1/4W Resistor
R2, R3 - 2 - 4.7K 1/4W Resistor
R5 - 1 - 1K 1/4W Resistor
R6 - 1 - 1.5K 1/4W Resistor
R7 - 1 - 33K 1/4W Resistor
R8 - 1 - 10K 1/4W Resistor
C1,C2 - 2 - 0.1uF Ceramic Disc Capacitor
C3 - 1 - 470uF 25V Electrolytic Capcitor
D1 - 1 - 1N914 Diode
D2 - 1 - 1N4004 Diode
D3 - 1 - 12V 400mW Zener Diode
Q1, Q2, Q4 - 3 - BC547 NPN Transistor
Q3 - 1 - BD679 NPN Transistor
L1 - 1 - See Notes
MISC - 1 - Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board
Notes-
1. L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter.
2. Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages the circuit might not perform as well and may not produce as much current. You may also need to use a larger C3 for higher voltages and/or higher currents.
3. You can use a larger value for C3 to provide better filtering.
4. The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V.
Schematic-
Parts List-
R1, R4 - 2 - 2.2K 1/4W Resistor
R2, R3 - 2 - 4.7K 1/4W Resistor
R5 - 1 - 1K 1/4W Resistor
R6 - 1 - 1.5K 1/4W Resistor
R7 - 1 - 33K 1/4W Resistor
R8 - 1 - 10K 1/4W Resistor
C1,C2 - 2 - 0.1uF Ceramic Disc Capacitor
C3 - 1 - 470uF 25V Electrolytic Capcitor
D1 - 1 - 1N914 Diode
D2 - 1 - 1N4004 Diode
D3 - 1 - 12V 400mW Zener Diode
Q1, Q2, Q4 - 3 - BC547 NPN Transistor
Q3 - 1 - BD679 NPN Transistor
L1 - 1 - See Notes
MISC - 1 - Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board
Notes-
1. L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter.
2. Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages the circuit might not perform as well and may not produce as much current. You may also need to use a larger C3 for higher voltages and/or higher currents.
3. You can use a larger value for C3 to provide better filtering.
4. The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V.
Time Delay Relay Circuit
A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts specified. The current capacity of the circuit is only limited by what kind of relay you decide to use.
Schematic-
Parts List-
R1 - 1 - 1 Meg Pot
R2 - 1 - 10 K 1/4 Watt Resistor
C1 - 1 - 10uf 25V Electrolytic Capacitor
C2 - 1 - 0.01uf Ceramic Disc Capacitor
D1,D2 - 2 - 1N914 Diodes
U1 - 1 - 555 Timer IC
RELAY - 1 - 9V Relay
S1 - 1 - 1A 120V SPST Switch
MISC - 1 - Board, Wire, Socket For U1
Notes-
1. R1 adjusts the on time.
2. You can use a different capacitor for C1 to change the maximum on time.
3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.
Schematic-
Parts List-
R1 - 1 - 1 Meg Pot
R2 - 1 - 10 K 1/4 Watt Resistor
C1 - 1 - 10uf 25V Electrolytic Capacitor
C2 - 1 - 0.01uf Ceramic Disc Capacitor
D1,D2 - 2 - 1N914 Diodes
U1 - 1 - 555 Timer IC
RELAY - 1 - 9V Relay
S1 - 1 - 1A 120V SPST Switch
MISC - 1 - Board, Wire, Socket For U1
Notes-
1. R1 adjusts the on time.
2. You can use a different capacitor for C1 to change the maximum on time.
3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.
Voltage Inverter
This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn't add much in the way of size and cost to a project.
Schematic-
Parts List-
R1 - 1 - 24K 1/4 Watt Resistor
R2 - 1 - 56K 1/4 Watt Resistor
C1 - 1 - 3300pF 25V Ceramic Capacitor
C2 - 1 - 47uF 25V Electrolytic Capacitor
C3 - 1 - 10uF 25V Electrolytic Capacitor
C4 - 1 - 100uF 25V Electrolytic Capacitor
D1, D2 - 2 - 1N4148 Silicon Diode
U1 - 1 - 555 Timer
MISC - 1 - Wire, Board
Schematic-
Parts List-
R1 - 1 - 24K 1/4 Watt Resistor
R2 - 1 - 56K 1/4 Watt Resistor
C1 - 1 - 3300pF 25V Ceramic Capacitor
C2 - 1 - 47uF 25V Electrolytic Capacitor
C3 - 1 - 10uF 25V Electrolytic Capacitor
C4 - 1 - 100uF 25V Electrolytic Capacitor
D1, D2 - 2 - 1N4148 Silicon Diode
U1 - 1 - 555 Timer
MISC - 1 - Wire, Board
One Tube Regenerative Radio Circuit
A regenerative radio works by feeding back a small amount of amplified output of the detector back into the input. Thus it achieves sensitivity far beyond what only a detector could alone. This simple regen radio uses a single tube as it's detector and amplifier; the "Audion". It's a great first project for those wishing to bring back some nostalgia by building one of the first amplified radio sets. Built on a board using point to point wiring and a set of period headphones, it can be a great functional conversation piece.
Schematic-
Parts List-
R1 - 1 - 50K Linear Taper Pot
R2 - 1 - 2.2 Meg 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
C1 - 1 - 250pF 100V Ceramic Disc Capacitor
C2 - 1 - 365pF Air Variable Tuning Capacitor
C3, C4 - 2 - 120pF 100V Ceramic Disc Capacitor
C5 - 1 - 0.1uF 100V Ceramic Disc Capacitor
V1 - 1 - 3A4 Audion Tube 3S4, 3Q4 (See Notes)
L1 - 1 - 30 Turns 26 AWG Magnet Wire (See Notes)
L2 - 1 - 80 Turns 26 AWG Magnet Wire (See Notes)
L3 - 1 - 20 Turns 26 AWG Magnet Wire (See Notes)
S1 - 1 - SPST Switch
HEADPHONE - 1 - High Impedance Headphones (2K or Greater)
ANT1, ANT2 - 2 - See Notes
MISC - 1 - Board, Wire, Sockets For V1, Case, Knob for R1, Clips for Antenna and Batteries.
Notes-
1. L1 - L3 are constructed on the same coil form. A toilet paper tube will be the coil form. Secure the 26 AWG wire to the form by punching two holes close together and winding the wire once around the "bridge" between them. Alternately, just a drop of hot glue can be used. Leave about 6" of wire. Wind on twenty turns close together but never overlapping. Make a tap by securing the wire with a drop of glue and twisting a loop. This is L3. Wind 80 more turns in the same direction and then secure the end, leaving about 6" of wire at the end. This is L2. Now secure the 26 AWG wire 1/8" from the end of L2 and wind 30 turns in the same direction as the other coils, making sure that this coil is spaced 1/8" evenly from L2. Secure the end and leave about 6" lead. This is coil L1. Now trim the extra length of the coil form and spray the coil with several coats of lacquer to hold the wires in place.
2. R1 and S1 can be one unit if you purchase a pot with a built in switch. This will avoid turning the set on with full regen and causing a nasty squeal from the headphones.
3. The 3S4 or 3Q4 can be substituted for the 3A4 in the connections of pin 3 and pin 4 are swapped.
4. An antenna of only a few feet can be used for ANT1 for easy indoor installation. Far better is an antenna of 50 feet or more outside, which would be connected to ANT2.
5. Note that this circuit requires a good Earth ground. A suitable location is a metal cold water pipe.
6. To use the set, place C2 at about midway, set R1 fully counterclockwise and then turn on S1 and allow the tubes several seconds to warm up. Increase R1 until the headphones squeal, then back off. That is when the set is most sensitive. Now tune C2 to the desired frequency. You may have to readjust R1 as you tune different frequencies. With some practice you will figure out how much regen you need as you change stations.
7. If R1 seems to have no effect, swap the connections to L1.
Schematic-
Parts List-
R1 - 1 - 50K Linear Taper Pot
R2 - 1 - 2.2 Meg 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
C1 - 1 - 250pF 100V Ceramic Disc Capacitor
C2 - 1 - 365pF Air Variable Tuning Capacitor
C3, C4 - 2 - 120pF 100V Ceramic Disc Capacitor
C5 - 1 - 0.1uF 100V Ceramic Disc Capacitor
V1 - 1 - 3A4 Audion Tube 3S4, 3Q4 (See Notes)
L1 - 1 - 30 Turns 26 AWG Magnet Wire (See Notes)
L2 - 1 - 80 Turns 26 AWG Magnet Wire (See Notes)
L3 - 1 - 20 Turns 26 AWG Magnet Wire (See Notes)
S1 - 1 - SPST Switch
HEADPHONE - 1 - High Impedance Headphones (2K or Greater)
ANT1, ANT2 - 2 - See Notes
MISC - 1 - Board, Wire, Sockets For V1, Case, Knob for R1, Clips for Antenna and Batteries.
Notes-
1. L1 - L3 are constructed on the same coil form. A toilet paper tube will be the coil form. Secure the 26 AWG wire to the form by punching two holes close together and winding the wire once around the "bridge" between them. Alternately, just a drop of hot glue can be used. Leave about 6" of wire. Wind on twenty turns close together but never overlapping. Make a tap by securing the wire with a drop of glue and twisting a loop. This is L3. Wind 80 more turns in the same direction and then secure the end, leaving about 6" of wire at the end. This is L2. Now secure the 26 AWG wire 1/8" from the end of L2 and wind 30 turns in the same direction as the other coils, making sure that this coil is spaced 1/8" evenly from L2. Secure the end and leave about 6" lead. This is coil L1. Now trim the extra length of the coil form and spray the coil with several coats of lacquer to hold the wires in place.
2. R1 and S1 can be one unit if you purchase a pot with a built in switch. This will avoid turning the set on with full regen and causing a nasty squeal from the headphones.
3. The 3S4 or 3Q4 can be substituted for the 3A4 in the connections of pin 3 and pin 4 are swapped.
4. An antenna of only a few feet can be used for ANT1 for easy indoor installation. Far better is an antenna of 50 feet or more outside, which would be connected to ANT2.
5. Note that this circuit requires a good Earth ground. A suitable location is a metal cold water pipe.
6. To use the set, place C2 at about midway, set R1 fully counterclockwise and then turn on S1 and allow the tubes several seconds to warm up. Increase R1 until the headphones squeal, then back off. That is when the set is most sensitive. Now tune C2 to the desired frequency. You may have to readjust R1 as you tune different frequencies. With some practice you will figure out how much regen you need as you change stations.
7. If R1 seems to have no effect, swap the connections to L1.
Single Chip AM Radio
The ZN414 IC contains an entire automatic gain controlled AM receiver in a small three pin package. With only a few external components, a simple radio with excellent selection and reception can be constructed. Since the chip also uses a low supply voltage of only 1.3V, 3V coin cell battery can make for a physically small circuit with many covert uses. The chip has a wide bandwidth of between 150KHz and 3MHz, so by playing with values in the tuning circuit you can pick up a wide variety of signals.
Schematic-
Parts List-
R1 - 1 - 100K 1/4W Resistor
R2 - 1 - 470 Ohm 1/4W Resistor
R3 - 1 - 1K 1/4W Resistor
C1 - 1 - 0.04uF Ceramic Disc Capacitor
C2 - 1 - 365pF Variable Tuning Capacitor
C3 - 1 - 0.01uF Ceramic Disc Capacitor
D1, D2 - 2 - 1N4148 Signal Diode
U1 - 1 - ZN414 Radio IC MK484
L1 - 1 - See Notes
MISC - 1 - Board, Holder For Batteries, Wire, Coil Form For L1
Notes-
1. The ZN414 is obsolete. The MK484 is it's replacement, but like all special purpose ICs, it can be hard to find. At the time of this writing, there are many suppliers online that carry the IC. The ZN416 is functionally the same but with the additiion of a built in headphone amplifier.
2. L1 is made by winding 40 turns of 28 AWG magnet wire around a 4" non-magnetic coil form. Cardboard tubes or paper cups are ideal forms.
3. The audio output of the circuit is about 0.1V peak to peak, which will drive a set of crystal earphones or other very high impedance phones. A small audio amplifier made with an LM386 will allow you to use modern dynamic headphones or a small speaker.
4. L1, C1 and C2 are the tuning circuit. By changing them around, you can change the range of frequencies the radio is capable of. Easiest to change is L1. Simply by altering the number of coils or moving the windings farther apart, you can shift the circuit to different frequency ranges.
Schematic-
Parts List-
R1 - 1 - 100K 1/4W Resistor
R2 - 1 - 470 Ohm 1/4W Resistor
R3 - 1 - 1K 1/4W Resistor
C1 - 1 - 0.04uF Ceramic Disc Capacitor
C2 - 1 - 365pF Variable Tuning Capacitor
C3 - 1 - 0.01uF Ceramic Disc Capacitor
D1, D2 - 2 - 1N4148 Signal Diode
U1 - 1 - ZN414 Radio IC MK484
L1 - 1 - See Notes
MISC - 1 - Board, Holder For Batteries, Wire, Coil Form For L1
Notes-
1. The ZN414 is obsolete. The MK484 is it's replacement, but like all special purpose ICs, it can be hard to find. At the time of this writing, there are many suppliers online that carry the IC. The ZN416 is functionally the same but with the additiion of a built in headphone amplifier.
2. L1 is made by winding 40 turns of 28 AWG magnet wire around a 4" non-magnetic coil form. Cardboard tubes or paper cups are ideal forms.
3. The audio output of the circuit is about 0.1V peak to peak, which will drive a set of crystal earphones or other very high impedance phones. A small audio amplifier made with an LM386 will allow you to use modern dynamic headphones or a small speaker.
4. L1, C1 and C2 are the tuning circuit. By changing them around, you can change the range of frequencies the radio is capable of. Easiest to change is L1. Simply by altering the number of coils or moving the windings farther apart, you can shift the circuit to different frequency ranges.
Simple Two Speed Contactor DC Motor Controller
The simplest of all motor controllers (besides a straight on/off switch) is the contactor controller. I designed this contactor controller for use in my electric scooter project. It is based around three 12V relays, two 12V batteries, two switches and of course a motor. Having no silicon to "fry", it is quite reliable and robust. A contactor controller works by rearranging the two (or more) supply batteries between series and parallel. This gives the motor a slow speed (batteries in parallel, current adds) and a fast speed (batteries in series, voltage adds). This assures that both batteries are discharged equally. When the circuit is "at rest", the batteries are connected in parallel, which allows easy recharging.
Schematic-
Parts List-
K1, K2, K3 - 3 - 12V 30A SPDT Relay (See Notes)
S1, S2 - 2 - SPST Switch or Button
B1, B2 - 2 - 12V Battery (See Notes)
M1 - 1 - 12V or 24V Motor (See Notes)
MISC - 1 - Case, Wire, etc.
Notes-
1. S1 closes K3 and thus causes M1 to operate. S2 activates K1 and K2, reconfiguring the batteries for series operation and thus causes M1 to operate at "fast" speed.
2. B1 and B2 should be chosen based on the current requirements of M1. Often, sealed lead-acid type batteries are available at local suppliers for surprisingly low prices. These batteries are ideal for things such as scooters, go-karts, etc.
3. The relays are standard automotive type relays, available cheaply from any auto parts store.
4. Your motor will depend on your requirements. 12V motors will normally run fine at 24V, and vice versa.
5. You will notice that in series mode, all three relays only pull power from B2. This is because the relays have 12V coils, and it is impossible to switch the batteries from series to parallel and keep power to the coils at the same time. This does, however, mean that B2 is discharged slighty before B1. This should normally not be an issue unless the batteries are being drained completely "dead". Draining a battery dead is not good for it in any situation, and should be avoided. If you wish, you can use a small 12V battery to run the relays separately.
6. You can add two more speeds to this controller using the schematic below. It connects at points A and B shown above on the controller schematic.
K1 is simply another of the same relay as used in the controller. S1 is another switch. R1 needs to be chosen based on your motor, but it will be of low value (under 10 Ohm) and high wattage (normally at least 100W). It must be capable of handling the full current drawn by the motor. This is not exactly an efficient way to limit current to the motor as excess current is dissipated as heat by the resistor, so it is normally only used for a "starter" speed.
Schematic-
Parts List-
K1, K2, K3 - 3 - 12V 30A SPDT Relay (See Notes)
S1, S2 - 2 - SPST Switch or Button
B1, B2 - 2 - 12V Battery (See Notes)
M1 - 1 - 12V or 24V Motor (See Notes)
MISC - 1 - Case, Wire, etc.
Notes-
1. S1 closes K3 and thus causes M1 to operate. S2 activates K1 and K2, reconfiguring the batteries for series operation and thus causes M1 to operate at "fast" speed.
2. B1 and B2 should be chosen based on the current requirements of M1. Often, sealed lead-acid type batteries are available at local suppliers for surprisingly low prices. These batteries are ideal for things such as scooters, go-karts, etc.
3. The relays are standard automotive type relays, available cheaply from any auto parts store.
4. Your motor will depend on your requirements. 12V motors will normally run fine at 24V, and vice versa.
5. You will notice that in series mode, all three relays only pull power from B2. This is because the relays have 12V coils, and it is impossible to switch the batteries from series to parallel and keep power to the coils at the same time. This does, however, mean that B2 is discharged slighty before B1. This should normally not be an issue unless the batteries are being drained completely "dead". Draining a battery dead is not good for it in any situation, and should be avoided. If you wish, you can use a small 12V battery to run the relays separately.
6. You can add two more speeds to this controller using the schematic below. It connects at points A and B shown above on the controller schematic.
K1 is simply another of the same relay as used in the controller. S1 is another switch. R1 needs to be chosen based on your motor, but it will be of low value (under 10 Ohm) and high wattage (normally at least 100W). It must be capable of handling the full current drawn by the motor. This is not exactly an efficient way to limit current to the motor as excess current is dissipated as heat by the resistor, so it is normally only used for a "starter" speed.
Simple Servo Controller Circuit
Schematic-
Parts List-
R1 - 1 - 820 Ohm 1/4W Resistor
R2 - 1 - 68K 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 1K Linear Taper Pot
C1 - 1 - 1uF 16V Electrolytic Capacitor
Q1 - 1 - 2N3904 NPN Transistor 2N2222, Most Small Signal Transistors
U1 - 1 - 555 Timer IC
MISC - 1 - Board, Wire, Knob For R1, 8 Pin Socket For U1
Notes-
1. R1 adjusts the position of the servo.
2. Connect the servo to the circuit as shown in the schematic. For common Futaba servos, the red wire is power, the black wire is ground, and the white wire is control.
Parts List-
R1 - 1 - 820 Ohm 1/4W Resistor
R2 - 1 - 68K 1/4W Resistor
R3 - 1 - 10K 1/4W Resistor
R4 - 1 - 1K 1/4W Resistor
R5 - 1 - 1K Linear Taper Pot
C1 - 1 - 1uF 16V Electrolytic Capacitor
Q1 - 1 - 2N3904 NPN Transistor 2N2222, Most Small Signal Transistors
U1 - 1 - 555 Timer IC
MISC - 1 - Board, Wire, Knob For R1, 8 Pin Socket For U1
Notes-
1. R1 adjusts the position of the servo.
2. Connect the servo to the circuit as shown in the schematic. For common Futaba servos, the red wire is power, the black wire is ground, and the white wire is control.
Polarity Tester Circuit
Parts List-
R1 - 1 - 1K 1/4W Resistor
D1 - 1 - Green LED
D2 - 1 - Red LED
D4, D5, D6, D7 - 4 - 1N4001 Silicon Diode
MISC - 1 - Board, Wire, Case, Probes
Notes-
1. Email Dudley LeRoux with questions, comments, etc.
2. To use the circuit, just connect your probes to the source under test. If D1 lights up, the left most probe (on the schematic) is connected to positive. The opposite is true if the left probe is negative. If both LEDs are on, the source being probed is AC.
3. Be careful when using this tester not to probe a source greater than about 12V.
Pine Racecar Victory Judge
Parts List-
R1, R2 - 2 - 100 Ohm 1/4W Resistor
R3, R4 - 2 - 100K 1/4W Resistor
D1, D2 - 2 - Standard LED
SCR1, SCR2 - 2 - 6A, 200V SCR (such as the 106B)
S1, S2 - 2 - See Notes
K1 - 1 - Small 12V Relay
MISC - 1 - Board, Wire
Notes
1. S1 and S2 are small lever type micro switches. Most any kind will do, as long as they are sensitive enough to be activated by the wheels of the cars. They should be positioned on the track so that the front wheels of the cars will run over them as the cars just cross the finish line.
2. To reset the circuit, disconnect and then reconnect power. You can add a normally closed switch in series with the power supply to make this easier.
3. There is no reason this circuit cannot be used to tell the winner of a foot race, bike race, slot car race, etc.
Low Voltage Alarm
Parts List-
R1, R3 - 2 - 1K 1/4W Resistor
R2 - 1 - 5K Pot
U1 - 1 - LM339 Op Amp IC
D1 - 1 - 1N5233B Zener Diode
D2 - 1 - LED
BZ1 - 1 - Piezo Buzzer
MISC - 1 - Board, wire, socket for IC
Notes-
1. The circuit will operate from 9V to 12V.
2. Adjust R2 until the alarm goes off at the correct voltage.
Simple Air Flow Detector
Parts List-
R1 - 1 - 100 Ohm 1/4W Resistor
R2 - 1 - 470 Ohm 1/4W Resistor
R3 - 1 - 10k 1/4W Resistor
R4 - 1 - 100K 1/4W Resistor
R5 - 1 - 1K 1/4W Resistor
C1 - 1 - 47uF Electrolytic Capacitor
U1 - 1 - 78L05 Voltage Regulator
U2 - 1 - LM339 Op Amp
L1 - 1 - #47 Incandescent lamp with glass removed (See "Notes")
D1 - 1 - LED
MISC - 1 - Board, Wire, Sockets for ICs, etc.
Notes-
1. The glass will have to be removed from L1 without breaking the filament. Wrap the glass in masking tape and it in a vise. Slowly crank down until the glass breaks, then remove the bulb and carefully peel back the tape. If the filament has broken, you will need another lamp.
Simple Touch Switch
Parts List -
R1 - 1 - 10 Meg 1/4W Resistor
R2 - 1 - 47K 1/4W Resistor
R3 - 1 - 120k 1/4W Resistor
R4 - 1 - 470 Ohm 1/4W Resistor
C1 - 1 - 15uF Electrolytic Capacitor
D1 - 1 - 1N4007 Silicon Rectifier Diode
Q1 - 1 - 2N5458 N Channel Field Effect Transistor
Q2 - 1 - 2N2222 NPN Transistor 2N3904
Q3 - 1 - 2N3906 PNP Transistor
K1 - 1 - Relay w/12V Coil, Contacts To Suit Application
MISC - 1 - Board, Wire, Small Metal Pad For Touch Pad
Notes
1. The touch pad can be most easily made by cutting a small square of PCB material and then soldering on a single wire. Alternatively, something like a penny glued to a plastic backing will do the job.
2. As mentioned, a latching relay can be used so that a momentary touch activates the relay and it remains active. To turn off a latching relay, power must be interrupted. So a 2nd circuit with a normal relay can be used to cut power (use the NC contacts on the 2nd circuit). Placed side by side, two touch pads form an "on" and an "off" pad.
Simple Lie Detector Circuit
Parts List-
R1 - 1 - 33K 1/4W Resistor
R2 - 1 - 5K Pot
R3 - 1 - 1.5K 1/4W Resistor
C1 - 1 - 1uF 16V Electrolytic Capacitor
Q1 - 1 - 2N3565 NPN Transistor
M1 - 1 - 0-1 mA Analog Meter
MISC - 1 - Case, Wire, Electrodes (See Nots)
Notes
1. The electrodes can be alligator clips (although they can be painful), electrode pads (like the type they use in the hospital), or just wires and tape.
2. To use the circuit, attach the electrodes to the back of the subjects hand, about 1 inch apart. Then, adjust the meter for a reading of 0. Ask the questions. You know the subject is lying when the meter changes.
