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 electroni...

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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...

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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,...

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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...

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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 oth...

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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...

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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 @ 6...

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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),...

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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...

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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...

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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...

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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...

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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 -...

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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...

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