How to make 12V 1A power supply using zener diode and transistors?

This 12V 1A power supply using zener diode and transistors allows us to obtain an output of approximately 11.4 volts with a very small percentage variation for a wide variety of loads.

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.

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. 

A Time Delay Light switch circuit

This circuit is useful to illuminate locations where a light source of low power is needed. A closet, a car trunk, are good examples.

Police Style Strobe Light Circuit.

This circuit shows the familiar lights which are used on police cars. It uses a 555 timer as a clock for the 4017B decade counter, two transistors and twelve LEDs

Logic Probe using NOT Gates (Inverters)

This logic probe using NOT Gates is implemented with three NOT gates, one rectifier diode, two LEDs and two resistors.

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.

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.

How to Protect the 500 mA Fuse of a Multimeter?

It is very important to protect the 500 mA fuse of a Multimeter due to the high frequency that these are burned.

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.

Flashing Lights for Pedestrians made 4011B IC.

This is a simple circuit that uses high-intensity white LEDs that turn on and off continuously. It may be placed in any part of the body such as an arm.

How to make a car temperature alarm?
This car temperature alarm check the car engine temperature and warns us, by means of a sound signal, when the temperature exceeds a seted value