New breadboard blues, or, A poor workman blames his tools.

Started by onboard, August 10, 2004, 08:44:17 AM

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onboard

Hey all, over the last 6 months or so I tried to break my DIY pedal addiction w/no avail... :evil: I was in RS to get a printer cartridge and couldn't help looking around and there was a breadboard. Game over.

My question is this, shouldn't a component to ground read 0.00V when power is on? All my grounds test good at 0.00 ohms.

There's a 90% functional Nurse Quacky stuffed on there right now and I'm convinced the issue is w/grounding. I'm getting 0.6mV at pin 4 0.2mV at the tranny's emmiter. The circuit works great when I hit it with a Muff Master, but straight from the guitar there's no envelope action and the tone is at the bottom end of the sweep.

Pin 8 reads full +V, pin 3 reads 1/2 +V, the LED's are both happy, all grounds read good, no orientaion or wiring mistakes. (funny how all this comes right back to you)

Could it be the LF353 doesn't have the gain? A TL702 didn't fair any better, nor did upping the envelope follower's feedback R. Leaky electrolytic?

I love breadboard now that I have one, but methinks it could be the culprit. Has anyone else ever run into a bum board? (The problem couldn't be me :wink: )
-Ryan
"Bound to cover just a little more ground..."

onboard

Did I actually mispell "breadboard" in the post title   :oops:

ahhhh, the magic of "edit".
-Ryan
"Bound to cover just a little more ground..."

petemoore

Well pin four should be ground? Yes, Dual IC, pin four should read exactly .0v . I'd try running a ground to it and see whappens then.
 NQ is input sensative, ie voltage at input determines the quack amout...so twiddling values at the front end, or adding a boost for weaker pickups may be needed...I know I have to set mine up for a given circumstance at the input to get the quack quack-ing-g.
Convention creates following, following creates convention.

onboard

The jumper from pin 4 to ground tests as a solid connection, I'll try different points along the grounding bus.

The 2N3904's emitter should read .0V also, and it's showing millivolts as well.  

Now I know why I got hooked on this in the first place, I love a challange.
-Ryan
"Bound to cover just a little more ground..."

Paul Perry (Frostwave)

When you say 0.6mV, do you really mean that, or are you really seeing 0.6 V, that is to say, 600 mV?
Because, 0.6mV isn't a problem, it is just contact resistance or error from dissimilar metals or similar horseshit.

onboard

Good point, a double check does show 0.6mV (my family gave me an auto-ranging DMM for Christmas, lot of help they are;) so the problem must be elsewhar.

At least I'm not getting a reading like this..........

-Ryan
"Bound to cover just a little more ground..."

petemoore

TOO FUNNY PIC!!!
 I just go with DMM 'beep mode' to check for ground connections, just clipping one lead on the battery clip neg, or on the board ground, then test all grounds from there with the other lead.
 I forget where it actually starts to beep, but it is extremely low resistance, I've never noticed it 'beeping' at the grounds and having a prob with grounds.
Convention creates following, following creates convention.

Torchy

Thats my DMM ... THATS MY DMM  :lol:  :lol:  :lol:

well, on anything Ive made that has more than one transistor anyways ...