Nurse Quacky bypass screw up?

[Canucker]

http://www.generalguitargadgets.com/pdf/ggg_nurse_quacky.pdfSo I put together a Nurse Quacky and its pretty fun but I screwed up something in wiring my switch because even in bypass mode the one LED in the circuit remains on...so I'm draining the battery even when in bypass mode. This is how I wired ithttp://www.diystompboxes.com/tbbox/tbbox.jpg 

[reverberation66]

I built this years ago and don't have the schematic in front of me but I'm not sure it's a screw up, I think that might just be the way it works. 

[reverberation66]

oh, I misunderstood, I guess it's the led that is the on/off indicator for the effect that you're talking about...hmmm, dunno.

[artifus]

led on pins 3 and 4 bias the op amp and should be lit. led on pin 1 should light on note detection. led on switch should extinguish in bypass. your circuit wants power in bypass mode. remove input jack to switch off.

[Mark Hammer]

The biasing scheme that Jack Orman devised for the Dr. Quack permitted use of any dual op-amp, rather than requiring a 1458 and nothing else.  That biasing scheme uses an LED.  Depending on the efficiency of the particular LED you use, there may be enough current pulled through it to light it up....or may not.  Whether it glows or not is separate from its forward voltage, which is the aspect being exploited here.

Some years back, I used the circuit to make a Haloween mask for my kid.  By using several superbright LEDs, and a little electret mic capsule, he had a robot head that flashed LEDs in the nose holes as he talked.  The key was using the suprerbrights.  Using something rated at 600mcd or less would have "worked" as an envelope follower...just not as a visual effect.

[Canucker]

its the one in the circuit (coming off the op amp)...they aren't numbered one and two in the layout...the note indicator one works as it should (so cool!)...I used 5mm LEDs because thats what I have. The design calls for 3mm...maybe that would help? Everything works fine I'm just thinking that if its on my pedal board with a battery I'm using it up for the whole show not just when the pedal is engaged. I pull patch cables out when I'm not playing of course....Thanks for the feedback you guys rule!

[Canucker]

just looked at the info again and it says "two matched leds"....they are both red and 5mm but I didn't put them up to the volt meter or anything....is that something I should have done? Should this effect just be used with an adapter and not a battery?

[Mark Hammer]

"Matched" means they have the same forward voltage, which will mean the same colour.  So, use a pair of reds, rather than a red and a green.  Apart from fitting on the board layout, size won't matter, and neither will brightness.

[Hemmel]

The biasing scheme that Jack Orman devised for the Dr. Quack permitted use of any dual op-amp, (...)

Does this mean I could use a TL072 instead of the LM358 ? Or are there specs I that differ too much between the 2 chips (and that I don't understand) ?
I looked at the pinouts of both and they are the same.

[Mark Hammer]

technically, that's what it was supposed to permit.

[Canucker]

funny I think I used a TL702 but don't know where I read that I should...I'll have to check that tonight. I did something like that with the Rat before and could never find where it was again that they told me a different chip (not a tl702) worked....but it did. Have to look at that too.

[Canucker]

edit...I meant TL072....and yes it is indeed what I used. It works and there is no way I came up with the idea of using it on my own because I don't have much knowledge on IC's . Had to have read it somewhere cus I specifically remember going "whoo hoo I have a few of those".

[Canucker]

Ok so I swapped out that chip and it sounds no different. I also figured out why I had the LED lighting up....I was using a battery and used mono jacks for input and output. I kick ass!!!

[jimilee]

I also figured out why I had the LED lighting up....I was using a battery and used mono jacks for input and output. I kick ass!!!

Crazy,someone else was JUST asking why they had to use a stereo jack....

[Canucker]

Thats funny. Who was it?
I didn't actually make the change yet....I just brainstormed and figured that with changing the jack the light will still stay on until I unplug my patch chord... not quite perfect but not as bad as before.

[jimilee]

Oh yeah,that was you! I don't ever remember who starts topics at all.Getting old blows man, I don't recommend it!