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.
This circuit provides an output voltage when the input voltage is in the range between V1 and V2...
We found this circuit in an English magazine in 1975, but it can be easily assembled, as the...
We found this circuit in an English publication from the 60's. The transistors are of germanium of the...