This servo circuit was found in 1969 Motorola documentation. Integrated circuits and transistors are types of the time, hard to find today.
This circuit activates a relay when the conducting bars (probes) are held by a person. The circuit is...
This circuit in the National Semiconductor Fast IC Power Transistor manual uses a special power...
This wireless intercom has a range of about 300 meters using an integrated circuit that is not...