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.

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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

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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

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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.

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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

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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.

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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

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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.

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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).

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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

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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

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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.

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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.

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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.

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