This is a typical point scale or moving bar circuit with the LM3915. We found it in old American documentation. The operational amplifier supports an equivalent modern type.
This '80s circuit drives an infrared LED, producing a modulated signal. Modern higher power LEDs...
We found this circuit in the February 1987 issue of Radio Electronics magazine. It is based on an...
This simple 1 transistor circuit was found in an American documentation from the 60's. The...