The expansion rate of this circuit is determined by R. The circuit can use any operational amplifier and the power supply must be symmetrical. Resistor R must be less than 10k.
This circuit is from the 1983 Intersil Databook. The circuit operates on a 9 V battery and has a...
This circuit is from a Popular Electronics from the 90s. The circuit has a tone frequency...
This circuit is suggested by Motorola and allows to obtain a much higher voltage for switching a power...