This circuit was published in a recent magazine as a past project. It is a crystal radio from October 1986 Radio Electronics magazine. The article detailed the assembly.
Found in a 90s Popular Electronics, this circuit uses two PLL tone recognizers to trigger by touch an...
This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is...
This circuit is from 1995 documentation. In the original, the source is symmetrical at 12 V, but...