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.
This configuration, which does not have a very high Q, uses a 741 operational amplifier, but other...
This circuit is from the 70's by A. Fanzeres. We kept the original text. It has already been said...
We found this circuit in an old English publication. The resistor not indicated can be 2k2 and the...