We found this circuit in the July 1969 Radio Electronics magazine. The circuit uses a coupler made with a lamp and an LDR. The power of the lamp determines the types of diodes.
This circuit was found in the May 1989 issue of Radio Electronics magazine. The components can be...
Using the 741 this basic circuit was found in the November 1973 Radio Electronics magazine. The...
This circuit came out in an English magazine from 1977, but it can be easily assembled today, as...