This low frequency oscillator circuit was found in an Electronic Design from the 90s. The transistors are common types, and the frequency is given by the crystal.
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,...