DOD 250 dual OpAmp

[motterpaul]

This is such an easy project - what could be wrong? Is it my IC? (it tests as working)

The only thing I did different was I used a 63n in place of the 56n (didn't have one)

BTW: this is the second pedal I have built that works in my test box when I turn on the built-in oscillator, but not when I use a guitar. I can hear the guitar on bypass, but not when I switch the effect on (in test box).







I checked all rows - no copper shorts, voltages look good for IC. I get oscillator on IC and Diodes with audio probe.

Pots are wired correctly.

But it seems like it just doesn't work with the guitar, but other circuits I use in the test box work with the guitar. Am I crazy?

[Neil mcNasty]

The only thing that pops into my mind is the fact that you have used a Tantilum cap for the 4.7uf.
Have you checked the orientation? Could it be reversed?
I would recommend that you do not use Tantilums in pedals unless specified, as these are notorious for creating problems in audio circuits (as far as I understand)

[Ciaran Haslett]

Could be just the pic but your right most 22K doesn't look like 22K....and the 470K looks like a 570K.

But anyway...I'd be more suspicious of your test box.  Is your jack input/oscillator switched like mine?  I'd open that and take a look.  Intermittent connection/dodgy jack/dodgy switch etc.  You know the drill.

[motterpaul]

I admit the one thing I haven't checked is resistors - that sounds like it could be it. Its rare for me but has been known to happen.

The tant is oriented correctly. I just bought a cap tester, so maybe I need to check if its good.

I did check out my test box really well. Yep, the oscillator is switched. I can also use with an audio probe or just feeding the circuit straight thru.

Thanks for input.

[dexxyy]

There`s something weird happening with the pics, the bottom pic looks like a mirror image of how i would expect it to look

[Neil mcNasty]

dexxyv is correct.
The cuts are done mirrored

The copper side of the vero layout can not be transfered directly!
It must be flipped for it to match the top side.
Remember: that's the bottom side of the board, and therefore it must be mirrored in order to match the top side...

[motterpaul]

Funny - I didn't think about people drawing the conclusion the cuts were physically mirrored. The fact is that I just flipped the picture horizontally so it would be easier to compare the cuts side to the components side. You can see the cuts on the front side picture (bigger holes).

Trust me, the cuts are not done backwards.

[motterpaul]

Ciaran... winner. It was a 1k resistor instead of a 22k - that fixed it.

I have never learned how to read resistors without a chart (plus I can never tell brown from red).

Is there some acronym on how to read resistor codes that is easy to remember. Feel free to email me if it is politically incorrect - I heard rumblings that it might be but I do not care (either way)  -  just need to have something.

Thank you!

[Travis]

There are a few offensive ones. You might be thinking of "Black boys rape our young girls but virgins go without" or something like that.

I find that harder to remember than the actual code itself personally. Once you get a big bag of mixed resistors you just remember the code

[Ciaran Haslett]

Yay....what do I win?

Same as Travis...I never bothered with mnemonics.  I arrange my resistors by multiplier band as I don't have enough trays to do it individually.  After a while it sinks in. I do have a great free app on my iPhone called Keysight Electronic Handbook but I'm referring to it less and less.

[motterpaul]

Funny - I have them all in individual bags (over 100 of them) in one long box. BUt I guess in your case you get used to looking at the colors so you learn to read them. That would be handy in the long run.

I'll send you a big manly drink someday....

[motterpaul]

Thx Trav... that is even more offensive than I expected. Now I understand why no one ever told me.

A commentary on our society, tho, that most guys probably learned that at one time.

[motterpaul]

By the way - isn't also just the old Roy G Biv -- with black and white on the outsides?

(RoyGBiv is the color spectrum from infrared to ultraviolet) except they leave out indigo.

Black Brown - RoyGBv - Gray White  (then gold & silver) - so really it is the colors of pigment in order from darkest to lightest.

[Travis]

Exactly. That's why it's easier for me to remember the code than the mnemonics. The code itself makes perfect sense, the mnemonics are weird.

Black, brown, rainbow (Roy g biv), gray, white.

They leave out indigo because it would be too easy to confuse it with violet or blue. I have a hard time reading the codes on the blue resistors from tayda. I find it easier to differentiate the colors on beige carbon film or brown carbon comps

[Beaker]

"Bad Beer Rots Our Young Guts But Vodka Goes Well"

That's the one I use.