Lie Detector Circuit Using Two Transistors

Lie Detector Circuit Using Two Transistors

Lie detector circuit using two transistors

This simple lie detector consists of two transistors and other additional components and can detect if a person does not tell truth (the person is lying), using two sensors placed directly on the skin.

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Surge Protection Circuit (Voltage Delay Circuit)

Surge Protection Circuit (Voltage Delay Circuit)

Surge Protection Circuit (Voltage Delay Circuit)

This Surge protection circuit is placed between the DC voltage source and the circuit that you want to power. This circuit delays the voltage given by the power source and allows the voltage to be applied to the circuit or device a few moments later. 

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How to Make a Diode Tester Circuit using 741?

How to Make a Diode Tester Circuit using 741?

How to Make a Diode Tester Circuit using 741?

This diode tester circuit checks if the diode is in good condition and also determines its polarity. To accomplish our goal, we use an 741 operational amplifier (IC1) configured as an oscillator.

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How to make a Light Sensitive Sound Generator Circuit?

How to make a Light Sensitive Sound Generator Circuit?

How to make a Light Sensitive Sound Generator Circuit?

An oscillator circuit may have many applications. The diagram below shows how to make it work as a light sensitive sound generator using a LDR and a 741 operactional amplifier.

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Electronic Doorbell Circuit using a 555 and CD4017

Electronic Doorbell Circuit using a 555 and CD4017

Electronic Doorbell Circuit using a 555 timer and a CD4017 decade counter

This electronic doorbell circuit gives us all the possibility to change the tone of each of the 10 musical notes that the circuit can have. This means we can create our own sound sequence.

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