Free Simple Circuit Diagram
Sound similar to a loud clicking clock that is usually attached to a timed bomb is produced by this circuit. Use this circuit for fun, don’t use it for terror. The 200k pot adjust the frequency of the tick. By charging the 2u2, the circuit starts and when 0.65v is on the base of the NPN transistor, it starts to […]
Read moreDynamic microphone uses a moving coil around magnetic field to convert mechanical movement into electrical signal. The ordinary mini speaker is turned into a very sensitive microphone. Although it looks like misusing the speaker as a microphone, but actually a real standard dynamic microphone uses the same principle as this speaker. We can use any NPN transistors such as BC […]
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The circuit below consists of two multivibrators. The first multivibrator provides the speed of the change from “hee” to “haw” and operates at a low frequency. By allowing full voltage to appear at the bottom of the 220R and then a slightly lower voltage when LED is illuminated will modified the voltage to the tone multivibrator.
Read moreThis is aquiz bell/alarm circuit. This circuit indicate “fastest finger first”. This circuit has one bulb for Quiz master and one for each contestant. The bulb will illuminate when a button is pressed. the cathode of the 9v1 zener sees approx mid-rail voltage. The Quiz Master bulb is also illuminated. Here is the circuit: There is no other bulbs can […]
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