We found this circuit in American documentation from the 1980s. Transistors can be of general use. The frequency range of the generated signals ranges from 500 kHz to 10 MHz.
If the input voltage falls below 12 V the LED glows up. Other voltages can be monitored by...
Found in an old Popular Electronics, this circuit warns when a remote lighting system is not...
This generator is more complete than the previous one, being able to generate pulses as indicated...