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

Two Transistor Logic Probe

This Two Transistor Logic Probe is a very simple circuit that can be implemented using two NPN bipolar transistors (T1, T2) in a Darlington configuration.

Doorbell for Deaf People.

When a deaf person is alone in a house, it would be very difficult to realize that someone is knocking on the door without any visual warning signal.

The main component for the Doorbell for the deaf circuit is the CMOS 4001 integrated circuit, which has four two input NOR gates

12 volt Power Supply using 7805

This 12 volt power supply circuit is simple and useful. Sometimes we need to get 12 VDC, but we only have 5 or 9 volts regulators (7805, 7809).

This Electric Current Flow Indicator gives a visual indication that there is a current flow. Possible applications for this small circuit may be: a battery charger, a voltage power source, etc.

In order to achieve our objective we place 3 rectifier diodes in series, which in turn are in series with the load / battery.