This very complex circuit in terms of the number of transistors was found in Radio Electronics from March 1966. The circuit is for low impedance headphones. The transistors are from the time.
We found this circuit in a Popular Electronics of the 90s. The MOSFET can be of any type,...
In fact, the correct name would be a hearing aid amplifier. However, we use the name of the...
This circuit controls a relay causing it to open and close its contacts at a speed that depends on the...