USB Powered, Stereo Computer Speaker

This is the circuit diagram of USB powered computer speaker, or it widely known as multimedia speakers for PCs. The circuit has single-chipbased design, low-voltage electrical power supply, compatibility with USB power from computer, simple heat-sinking, inexpensive, large flexibility and wide temperature tolerance. At the heart of the circuit is IC TDA2822M. This IC is, actually, monolithic type in 8-lead mini DIP (Dual Inline Package)....

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Converter 9V to 13.5kV

This high voltage source is formed by an inverter, around the transistor, which provides pulses of 150V to the inverter formed by the thyristor and capacitor in series with the transformer 2. This pulse output of 4.5kV to be multiplied with the network so as to achieve the output voltage of 13.5kV.  Neon lamps (marked LN) form the thyristor triggering pulses. The transformer T1 has a ratio 3000:500 Ω of the type used in audio output transistor....

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Laptop Protector

Here the notebook anti theft protector circuit to secure your important netbook / notebook from stealing. Basically, this is a mini security alarm generator. Fixed inside the notebook case, it will definitely sound a noisy alarm when a person attempts to grab the notebook. This very sensitive circuit utilizes a homemade tilt switch to turn on the alarm system through tilting of the laptop computer case. The circuit utilizes readily available...

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220V AC Lamp Touch Dimmer

Here the 220V AC lamp touch dimmer circuit. By only touching this touch dimmer you are able to increase the light intensity of incandescent lamps in three stages. The touch dimmer is designed all around 8-pin CMOS IC TT8486A/TT6061A especially produced for touch dimmer applications. In the beginning, when mains switch is “on”, the lamp is “off”. Now, when you touch the touch plate, the lamp glows dimly. On second touch, the lamp provides medium...

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Simple Traffic Light Controller

Here the simple traffic light controller which is could be used to educate kids rudiments of traffic light guidelines. The circuit utilizes easily available electronic parts. It generally consists of rectifier diodes (1N4001), a 5V regulator 7805, two timers circuit using IC 555, two relays (5V, single-changeover), three 15W, 230V light bulbs and also several discrete parts. Mains electrical power is stepped down by transformer X1 to provide...

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Simple Symmetrical Power supply +25v -25v

This symmetrical unregulated power supply is used to feed the audio amplifier based on LM1875 amplifier module National Semiconductor. With symmetrical 30V DC source the amplifier capable of delivering up to 30W of power using 8 ohm load. The diagram above shows how the DC +25 V and-25V DC can be obtained. Ready to provide power to two stereo amplifiers, one 80VA transformer with 240V input and 36V output, with the center tap is used. The output...

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Touch switch electronic circuit based on a Schmitt trigger

This touch switch electronic circuit is based on a Schmitt trigger with latching, built IC1a, IC1b and R3. IC1b's output signal comes back to IC1a input through R3, resulting in maintaining stable condition of both gates. While the circuit is at rest, the anode of D1 is at "0" and the cathode of D2 is at level "1" retain their status. When contact is shorted by finger touch, the voltage drop across R8 increases. This increase is translated...

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