Found in American documentation from the 90s, this circuit is ideal for wearables and can be powered by voltages that depend on the number of LEDs.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...