Report The ultimate DIY? A Stax SRM-T2! in Do It Yourself Posted May 1, 2021 Nice! Looks like around 2ma would give the least impact to the circuit due to LED aging 😄. Joking aside, the LED part you used doesn’t seem to have a sharp curve. If I’m not mistaken, the LED in the circuit here is expected to act like a zener diode with low dynamic impedance. Maybe it’s time to pick a different P/N.