We found this circuit in the November 1975 issue of Radio Electronics magazine. It uses a digital module from the time with several adjustments. The power supply must have the indicated voltage.
Found in English documentation from the 1980s, this circuit can use any germanium diode. The...
This configuration, which requires a symmetrical power supply for the 741, can be implemented with other...
This 3-digit code switch was obtained from an old American documentation. The capacitor is 470 uF...