Light activated switch circuit with LDR and Operational Amplifier.

This circuit has many applications. It could act as a photocell and switch off a light in a room or turn on the radio when it is dawning, etc.

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.

Variable voltage regulator using 7805 and 741.

Very simple variable voltage regulator with very few components. Output Voltage from 5 to 30 volts

Mini variable power supply.

Totally transistorized with 0 to 30V output voltage range, and it can be used for projects where the current consumption is 1A max.

Automatic night light circuit with one LED

This automatic night light circuit with an LED is simple, interesting and very easy to do. The circuit allows a better understanding of the operation of a phototransistor and thus be able to use it in other applications.

This blown fuse indicator circuit warns us, lighting a LED, when there is a problem in an electrical installation protected by the fuse.

It is very important to correct the faults in the electrical system of an automobile or motorcycle or other, as soon as possible. This circuit will warn us when this happens.

555 IC Tester Circuit (PCB)

This 555 IC tester circuit, allows us to make sure that this integrated circuit works properly. This same test can be achieved by operating the 555 as astable multivibrator, but this test does not allow
to observe its operation in detail.

Current Limiter circuit for a Power Supply using a transistor and a resistor.

If the load current exceeds its maximum, an over current protection is needed

DC motor speed control with 4049 (PWM)

This DC motor speed control with 4049, is a circuit that allows varying the speed of small DC motors of 3 or 6 Volts that are often found in toys or small electronic devices.

Car battery monitor circuit using 4 LEDs

This simple Car battery monitor, allow us to know the voltage of the battery at all times. To achieve this 4 leds are placed somewhere on the dash of the car. Each LED has a label indicating the battery voltage at that time.

DC motor speed controller circuit using 555

This simple DC motor speed controller circuit, works with 12 volts and controls a DC motor using the 555 integrated circuit.

400 watts Stereo Amplifier Circuit using STK4050

This 400 watts stereo amplifier circuit uses the Sanyo STK4050 hybrid IC, a high quality low noise amplifier. Its maximum output power is 200W per channel