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.

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.

Inverting Summing Amplifier using Op Amp

The inverting summing amplifier using op amp outputs a voltage equal to the sum of the voltages it has in its inputs. The following explanation is based on an adder of three inputs, but applies to an adder of any number of inputs

What is an Op Amp? What is an Op Amp Open Loop?

Op Amp Open Loop Gain – Operational Amplifier Open Loop gain is given when there is no feedback path between the output and one of the two inputs

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 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

4-channel audio mixer using LM3900 IC

4 operational amplifiers, some resistors and capacitors to implement an audio mixer with a very simple design.

This temperature to voltage converter circuit, convert the sensed temperature by a thermistor into a voltage level.

The circuit achieves an acceptable performance between 0 and 24°C

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

Over-temperature alarm using operational amplifier.

This over-temperature alarm circuit uses a common semiconductor diode as a temperature sensing element.

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.