This low noise microphone preamplifier circuit was found in American documentation from the 90s. The circuit requires special care with the layout. The power can be between 9 and 18 V.
The figure shows how to implement an OR function with two inputs, using a relay. The relay...
The integrated circuit used in this 1987 project is not very common these days. However, if found...
Found in American documentation from the 1980s, this circuit has a diode feedback. At the exit we...