This circuit can be adjusted between 0.2 and 2 V to trigger with chosen voltages comparing them with the input voltages. We found it in a 1967 documentation.
The circuit shown fires an auxiliary flash from a flash commanded directly by the camera. The sensor...
This circuit, obtained in an old publication, causes a second telephone bell to be played in a...
The project is from a 1992 publication, but totally current by the components it uses. The LEDs...