This variable filter circuit was found in July 1975 Radio Electronics magazine. The circuit uses 3 general purpose op-amps like the 741 and must use a symmetrical source.
This 50% active cycle TTL clock generates signals from 4 to 20 Hz. Its power must be supplied with 5 V...
This diode tester was found in an English publication from the 1980s. Transistors are...
Using a 4046 PLL we found this circuit in the December 1989 issue of Radio Electronics magazine. The...