Missing pulse detector circuit or No pulse detector circuit.

This circuit is very interesting because it can detect or warn of the absence or delay of an expected pulse, which under normal conditions should be received at predefined intervals.

12V Power Supply using Zener and 741 Op. Amp.

This 12V Power Supply has, as its main characteristic, a low output impedance. This is a very desirable feature in voltage sources and is achieved with a large open loop gain that the operational amplifier has.

Bike Flashing LED Lights Circuit

Bike Flashing LED Lights Circuit. If you’re a cycling fan and you like biking, night and day, this useful circuit will make you to be visible and safe

Temperature alarm circuit with 741 operational amplifier

This temperature alarm circuit with operational amplifier activates a relay when the temperature of the place to be controlled exceeds a set level. Useful for an oven temperature control or a cooling system

This continuity tester using 741 operational amplifier, operates as a differential amplifier.

A good application for this circuit would be to test welds made on a printed circuit board. It could be also used to test continuity of wires, connections, etc.

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).

Light-Emitting diode connected to 120/240 VAC

This circuit shows one or two Light-Emitting Diodes connected to 120/240 VAC. The reduction of the AC input is achieved using a capacitor and a resistor

1 Input – 4 Outputs Stereo Audio Splitter

This 1 Input – 4 Outputs Stereo Audio Splitter has a single input and 4 independent outputs, each amplified with an operational amplifier. Each op amp is configured as a voltage follower, to take advantage of its high input impedance and low output impedance, thus avoiding distortion in sound.

Time Delay circuit using Triac and 555 timer

This Time delay Circuit using Triac and 555 Timer is very useful when we want to activate or switch on, appliances or devices that works on alternating current (AC), after a preset time.

Differential Temperature Controller.

This circuit measures the temperature difference between 2 sensors and activates a relay when they are different. It is also possible to detect a temperature change, even when the two measured temperatures are normally different.

This darkness detector circuit beeps when the light drops below a certain level.

The main elements of this circuit are the 555 integrated circuit, working as an astable multivibrator and an LDR which is used as darkness sensor.

Dimmer / AC motor speed controller

If you want to control the light level of a room or if you want to control the speed of a drill or a fan (devices that use AC motors), this is the circuit you are looking for