DOD / MXR: 250, Distortion + component values table

This is probably where it all started in terms of opamp-driven distortion -  in one side of 741 opamp, out the other with some hard clippers.  

DOD 250 / MXR DISTORTION + SCHEMATIC

Direct link to Google Doc

741 SPECS

Numbers vary slightly by manufacturer and grade, but these headline specs are what give the 741 its “personality” in effects land:

• Supply voltage: works on dual or single supplies (it was designed with ± supplies in mind, but can be run single-supply with proper biasing).

• Gain-bandwidth product: around ~1 MHz class.

• Slew rate: about ~0.5 V/µs typical.

• Input bias current: tens of nA typical (bipolar input).

• Not rail-to-rail: inputs/outputs can’t swing anywhere near the rails, especially on a 9V battery. 

What that means in practice: a 741 can sound/feel a bit rounder and more easily pushed in simple dirt circuits, partly because it’s relatively slow and because it doesn’t have huge clean output swing on a 9V single supply.

LM741 PINOUTS

Note the little tab on the side of the opamp is pin 8.

OFFSET NULL

Offset null is a pair of pins on the 741 that lets you trim out its small DC offset so the output sits where you want it (often 0V on a dual-rail supply). 

In pedals it’s usually ignored because stompboxes are typically single-supply with a virtual ground and AC-coupled stages, so capacitors block DC and the tiny offset isn’t audible.

While the pins aren't used, be sure to isolate them anyway.