This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF depending on the generated frequency. Equivalent transistors may be employed.
This circuit protects galvanometers that are excited by low impedance amplifiers. The circuit is...
This variation of the previous circuit produces a pulsating sound when the sensor is activated. The...
The National Semiconductor LM675 operational amplifier can provide up to 3 A of output current. In the...