This circuit generates rectangular signals from 2 Hz to 20 kHz using an operational amplifier. The circuit is from 1984 Radio Electronics. The power supply must be symmetrical.
Found in old English documentation this circuit can be made with a BF245 or equivalent. Coils are...
This circuit is indicated for the generation of signals in the 40 meters range. The circuit was...
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...