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.
LTC7841 PolyPhase® Synchronized Boost Controllers Mouser Announces Analog Devices LTC7841...
This interesting circuit is for controlling a small robot that searches for a light source. The...
This VCO or Voltage Controlled Oscillator was found in a Popular Electronics from 1991 but can be...