This simple Bargraph photometer with 4 LEDs was found in a 1997 documentation. The scale is adjusted in a trimpot and the sensor can be any common LDR. Power can be supplied by cells or battery.
Although MOSFETs of the type indicated are not very easy to obtain, one can have the circuit as a...
This power source takes advantage of an old valve transformer that is no longer used and can...
Found in 90s Popular Electronics, this circuit fires a load through a MOSFET from an audio signal...