Why isn't my did 250 clone working?

[snow123]

So I have a dod 250 circuit from Hammond tomeworks, and think I finished the circuit but when the pedal is on it only lets out a VERY weak signal, and the led doesn't turn on. And Im also using an IC clip, a 1458 instead of the lm741, and a 22pf cap instead of the 25pf cap, and I have op amp upside down since I'm getting a signal that way, but if I have it right side up I don't get any signal at all. And heres the layout and stuff: https://f00b4c64-464c-4139-8e44-a4e74f95e94f.filesusr.com/ugd/a73e2e_670b8a80e3154dabab74edc43cabff42.pdf and pics of how I have everything done:

[RickL]

The 1458 is a dual op amp and the 741 is a single op amp. The pin outs are different. It will work with most other single op amps as long as they have the same pin out.

[snow123]

ohhhhh that makes sense.

[snow123]

'cause most of the issues i was having seems to have to do with the pinout

[snow123]

ok now if i use a tl081 it still doesnt work

[iainpunk]

i suggest you look at this link:debugging guide
its especially the voltage readings on the pins we appreciate in order to help you figure it out.

cheers, Iain

[snow123]

i just got a ua741 and popped it in, and it still isnt working, so heres the voltages:

p1 = 0.00
p2 = 04.2
p3 = 03.1
p4 = 0.00
p5 = 0.00
p6 = 04.6
p7 = 09.2
p8 = 0.00

and i had the dial on the DMM on 200 dcv, and got 9.2v on the 9v jack

[idy]

The voltages on the IC look right: you have +9 on pin 7 and 0 on 4. The opamp is putting out 4.6 on pin 6, and your inputs (2- and 3+) are probably being "loaded" by your meter; they dip when you measure them but the 4.6 on the output suggests that they are also at 4.6 and the IC is working correctly.

I would start "signal probing" to follow the sound and find where it dies. Signal probe is just a cable to a small amp with an alligator clip or something to attach the ground and a capacitor on the "hot" lead to keep the DC in the circuit. Hook up some noise source to the input of the pedal so you don't need to keep strumming.

LED not working likely caused be switch wiring or reversed polarity. You are using a board for the switch.... is it getting voltage when the circuit is engaged? Does the side of the LED that goes towards ground have a path to ground (continuity)?

The wiring is hard to sort out visually. You will have to double check each wire going to a pot, jack, switch. And/or signal probe it!

[snow123]

i just got it working lol, i think the filter cap was too high of a value, it was 220 pf (i though it was 22pf since it said 220k) and i swapped it out for a 33pf and the pedal works now!

[snow123]

but the led still doesnt turn on tho

[stallik]

Wiring or led orientation

[snow123]

well the led only turns on when i check the continuity between the positive side of the led and the resistor.

[snow123]

[snow123]

i just have a 4k7 resistor there

[snow123]

i tried different resistors and stuff and still got nothing

[snow123]

ok i just added a jumper wire there and its fixed now

[stallik]

Well done. Enjoy your pedal