Free Circuit Diagram

This is a Colpitts-crystal oscillator circuit. It is suitable for low frequency crystal oscillator circuits. Using the 2N3823 JFET, this circuit has excellent stability because the temperature will not vary the 2N3823 JFET circuit loading. Here is the circuit : [Source: National Semiconductor Application Note]

LM386 is one of my favorite small audio amplifier integrated circuit chip. The LM386 is a power amplifier designed for use in low voltage consumer applications. The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The gain is internally set to 20 to keep external part count low, [...]

For battery operated devices, this class D amplifier is suitable because its high efficiency (85%) helps extend the battery life. In the internal circuitry, a boost converter  with over 90% efficiency is provided to step-up the voltage supply, and need only one external inductor as the additional component for this function. When driving 8 ohm [...]

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 [...]

These are circuits of high impedance low capacitance buffer and high impedance low capacitance  amplifier. First figure is a high impedance low capacitance buffer circuit, it uses the 2N446 JFET that features low input capacitance. The feedback buffer a wide-band unity gain amplifier is made from this 2N446 JFET. Here is the circuit : [...]

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 [...]