Nurse Quacky funny voltages

[Marek]

Hi!

I just discovered that, the way I connected my 'Nurse Quacky to be' on the perf, on the output of the first half of the opamp  I have ~ 8,1 volts!! Crazy, no? And on the + and - inputs of the first part of the opamp somewhere near 1,6 V.  (Measuring reference - pin 4 of the opamp).

My battery is 9,36V, as seen on the pin 8 of the opamp, and the +/- inputs are around 4,6V and so is the output of the second part.

Now, the crazy part of the story: (OK, not THAT crazy, but anyway..)

When I keep measuring DC voltage between GND and pin 1 of the opamp, and hit the strings, the voltage actually drops, depending on how hard I hit the strings, down to 2,5 - 3 volts, and then, the moment I stop, it goes back to ~8,1V.

The poor LED on the opamp output does not glow, but when I check it's health status with the DMM LED test, it lights... (so it's not dead...     ...yet)

I've checked the orientation of the led somewhere like 1000 times, and I'll recheck again, if you people suggest that that LED is guilty for my Nurse Quacky not workin...

The other LED, between +9V & GND, through the 10K resistor glows (constantly).

Now, I'm looking for some suggestions on debugging this thing! ( all the components are 'stock' values, except for the resistor between the LED & Attack pot, which is 47R instead of 51R, but that's no biggy, is it?)

Thanks in advance!

All answers/opinions welcome! :-)

Marek

[Marek]

anyone?

[Sic]

no direct answers for ya bud... but from personal experience and from talking to others when i did mine... second time is a charm.

I had all sorts of weird voltages...i had
(digs through little notebook)
0- 1.02         0- 2.89
0- 1.02         0- 1.07
0- 0.30         0- 0.30
0- 0.0           0- 0.0

i had all sorts of weird problems, so i scrapped it and started again...

Second time was EASY, found a small ground error, and then fired up NO PROBLEM!

I love my nurse quacky... my most challenging build so far, and its nice bragging rights to non-DIYers ( :p )


you doing perf?

Home Wrecker Nurse Quaky Layout


What i would recommend is re-drawing a layout FROM your perf... and then compare to the layout here...

When i have a problem with something, i draw up a schem from my layout and then compare... really helpful in making sure my layout is correct (with polarities too), then i can move on to making sure all the values are right... all the 100ohm are not 100k accidentally... and vise versa

You didn't put the dual op-amp in upside down did ya? just wondering there should be a small circle on the op-amp... that will signify pin 1

good luck, i hope someone can be of some better hope...

[Marek]

People, I found the faulty connection...

Actually, there was NO connection between OpAmp pin 1 & 2 ( 3M3 resistor ). I connected pin 2, but forgot to connect the other side of the resistor to pin 1 of the opamp.

All the best, thanks for help. ( And,... yes, it's easier to build a new one than to debug a non-working one.... )

Marek

[Sic]

awesome!

How ya like it?

[Marek]

This is really a nice 'n' easy build.

I do like it a lot. Yesterday I was sitting here quacking all day instead of working on my rigips walls ( we're renovating our flat. duh...)

Put an LPB or similar buffer thing in front of Nurse Quacky, it helps if your pickups dont produce enough AC...

Ah, almost forgot: there is an 'issue' about this design, tho'. Sometimes it seems to work as a kind of phaser, with all the swooooshes in the background... Dunno, I got an auto-wah overdose yesterday, so I don't really know what's what... maybe I'm just trippin' it out...

BTW, here's some inspirational material for all ya wah-headz:  (mp3 samples)

http://www.recordkingz.com/shop/catalog/widedefault.php?cPath=24&sort=3a&page=2&osCsid=3b713e8b8bfaeb69814feb03a77eaac2

Greetings,
Marek

[Sic]

yeah, i noticed the swoosh too, i thought it may have just been a flaw in my building skills. its kinda cool tho.