Free Circuit Diagram

Basic interruptible Power Supply Circuit consist of regular power supply adapter and battery connection. This basic system is a “hot” battery connection, meaning that there is no switching mechanism in connecting and disconnecting the battery, the battery is always connected! This hot connection is very simple to implement and very robust because there would [...]

The circuit below is the basic for standard symmetrical power supply. If your circuit need high current then this circuit is suitable. Here you can see the circuit’s schematic diagram. You need a center-tapped transformer to build this symmetric power supply. This power supply circuit is widely used in op-amp application, as [...]

Electroscope is a device that is used to detect electrostatic charges. Operation: To reduce AC noise this circuit uses C1, but it will lower the sensitivity a bit. As a voltage divider we use the MPF102 and R1. The divider’s output will be about 4.5V diving a half-scale reading on M1, a 200-uA [...]

For any electrically conductive liquid level measurement, this single chip circuit is very compact and simple. This circuit is an ac excited fluid level sensor, which uses alternating current to provide biasing for the sensor probe to avoid electrolysis of the probes.  This ac excitation makes the sensing probe has longer lifetime. This circuit can [...]

Precision accelerometers needs inverting mode amplifier since they are usually charge-output  devices. This amplifier convert charges into voltage output. The circuit below is an example of accelerometer with DC servo. The charge from the transducer is converted to a voltage by C1, which should equal the transducer capacitance plus the input capacitance of [...]

Feedback in public address amplifier is something that should be avoided. The ideal solution is by adjusting the microphone and the speaker position, but it’s not always possible in many situation. Using frequency shifter to change the output frequency 10Hz lower than the input frequency can solve the problem, but it’s too expensive for [...]