This small low current inverter operates at 20 kHz frequency. We found it in documentation from the 1980s. The integrated circuit is from that time.
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...