The circuit is from the manual of the integrated circuit used in the excitation of power transistors. The 30 V symmetrical supply should have a few amps of capacity.
In the figure we have a simple way to produce tone in a piezoelectric transducer. The frequency depends...
This absolute value amplifier was found in a 90's EDN. Equivalent amplifiers can be used. The...
The integrated circuit used in this configuration for noise reduction on FM radios is not common...