This turntable filter was found on an 80's Elektor. The circuit makes use of operational features that are easily obtainable today.
The power supply shown in the figure provides voltages between 0 and approximately 15 volts, with...
Another triggered oscillator that we found in the November 1984 Radio Electronics magazine. The...
Found in a 1980s German publication, this circuit tests batteries by type. The circuit is based on a...