This circuit is from 1967 General Electric documentation. It uses SUS which are not very common components today. The maximum frequency should not exceed a few kilohertz.
This circuit is from a Popular Electronics from 1993. The magazine is no longer printed, but the...
Found in a Popular Electronics from the 90s, this circuit can be adapted to use LEDs. The power...
This sensitive medium wave (MW) radio pick up the local station without the need of an external...