This old circuit is suitable for signaling applications. The lamp must be incandescent, and the triac must be mounted on a heat sink. The frequency is adjusted in the 1 M trimpot.
Found in a publication for radio amateurs from the 1990s, this circuit makes it possible to...
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
This simple transistorized receiver with earphone was found in a Japanese publication from the...