We found this circuit with transistors in a Philips documentation from 1968. The double transistor can be replaced by discrete married types. The power supply is symmetrical.
This squelch is activated by its own noise, acting automatically. It is used in communications...
This circuit for a simple alarm system was suggested in an article in Electronics Now magazine. The...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...