This circuit consists of a stereo audio compressor. We found it in Radio Electronics magazine from October 1968. The circuit uses an opto-coupler made with a neon lamp and LDR.
This circuit was found in an American documentation from the 90's. The circuit can use almost any...
This circuit triggers a relay when light strikes a sensor. The sensitivity is adjusted in the...
We found this circuit on the internet, but it has some problems. It will be convenient to limit the...