We found this code switch circuit in the January 1999 Electronics Now magazine. Some of the components are integrated circuits from that era.
We found this amplifier for hearing aids or hearing aid using only transistors in a documentation from the...
Found in an English publication from 1977, this circuit uses only 1 LED. Unlit means heads and lit...
We found this circuit in an old documentation. The indicated solenoid is of low current type,...