# Electronic – Highly accurate constant current source

current-sourceledlightoperational-amplifier

I want a continuous and highly stable light from an LED for around a couple of hours, for which I need a highly constant and highly stable current source. I prefer an opamp-based circuit for the same. What should I use?

(1) Even if you have a perfect current source, LED output varies with temperature. So they must be operated at a stable temperature. We chose to heat them to about $$\75^\circ\text{C}\$$ using a closed loop control. That solved the temperature drift problem.