The Eternity Overdrive is kind of like the Big Muff of Lovepedal in that it has a ton of different versions (there are over 10 I believe), but it’s basically a Tube Screamer without the input/output buffers. I’ve drawn up 2 versions here, the Black and the Burst. The main difference between the 2 is the clipping stage. The Black version has an asymmetrical clipping stage, while the Burst has a 4 diode symmetrical clipping stage. The other differences are just minor value changes.
I’ve added polarity protection and put the LED resistor on the board. I’ve also added a 47pf cap in parallel with the clipping diodes in the Burst version that MadBean added in his Drunken Dragon version of the Eternity. Sean from Lovepedal says that the secret behind the Eternity is a LM1458, but any dual op-amp should work fine (JRC4558, NE5532, TL072, etc.). They’ll just sound different, so adjust to taste.
