DIAC Basic Operation

Diode for alternating current is a trigger diode which conducts current only after the DIAC reach the breakdown voltage. The breakdown voltage of DIAC is 30 V. It has construction like an open base NPN transistor. The DIAC can be used in many application such as motor speed controls and light dimmers circuit. Figure below shows the DIAC block construction, […]

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SCR Basic Operation

The diagram below  shows us a simple block construction of an SCR (upper left) and its schematic diagram (upper right).  The lower diagram shows us the operation of a PNPN device can best visualized as a specially coupled pair of transistor. When a proper gate signal is applied to the base of the NPN transistor, the connections between the two […]

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Clap Triggered Switch

This is circuit of Clap Triggered Switch. When the circuit detects tap, or short whistle or a clap, this circuit will toggle the LEDs. 33k and 5K6 charge The second 10u. The negative excursion of the waveform takes the positive end of the 10u towards the 0v rail, when a sound is detected. the two 1N4148 diodes will be pulled […]

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Auto OFF Light

This is Auto OFF Light circuit. After the switch is pressed, the bulb is kept illuminated for a few seconds. To increase the “ON” time, The 10k should be  replaced by 100k. Here is the circuit: You can use this delayed auto-off lamp circuit to give temporary lighting for  your stairway, or your dashboard, your bookshelf, or many more.

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Nonvolatile STANDBY/ON Switch

STANDBY/ON switch below is appropriate for applications (industrial and telecom, for example) in which the circuitry must remember its state (STANDBY or ON) after a power failure that occurs when there is no operator. Because the state can be lost if leakage current drains the battery, we can not just rely on an alternative approach based on battery (or supercapacitor) […]

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Alternating Relay Switch

Our reader Andrea (andrea[dot]perugia[-at-]gmail[dot] com) sent his circuit to us, and he creates the circuit for educational intent. The main purpose is to show that you can toggle an output state electronically, although physically you use only a push button switch. Here is what he said about the cicuit : This simple circuit can be utilized to drive a monostable […]

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