We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as sensors and drives relays. The relays must have voltages according to the power supply.
This circuit is based on the Texas Instruments LMC662 and has the function of monitoring the audio...
Yes, tunnel diodes can also be used in voltage regulators, as shown in this circuit from a Radio...
Based on operational amplifiers of the time, this circuit from the 1980s has high input impedance. The...