This circuit was found in a 90s Wels' Think Tank. The frequency depends on C2 and R3. The handset or speaker must be at least 80-ohm. Observe the low supply voltage.
With a touch of the push button the lamp is switched on. A new touch and the lamp go out, in this...
The LMV321 is a low voltage operational amplifier from ON Semiconductor. The following diagram,...
We find this circuit in an old American documentation. It can provide a 25 dB compression in a...