Noise Gate: problem.

[choklitlove]

using the layout, etc. from Tonepad (http://www.tonepad.com/project.asp?id=18).
it pretty much didn't do anything at first.  then, after looking at the build reports, i switched Q3 around (for which i used a 2N5485).  now, it's better than it was, but still messed up.

it bypasses fine.  but when the effect is engaged, it amplifies the signal and seems to have no gate properties.  there is also something weird that happens when the effect is bypassed: the threshold pot creates a very high-pitched tone when turned 3/4.  this strikes me as very strange, especially when it shouldn't even be in the circuit when by-passed.

has anyone had any of these problems?  maybe even with other builds...

i have seen the troubleshooting thread, but i am close to clueless with a meter.


please point me in the right direction.

[choklitlove]

nothing?

[calpolyengineer]

What you want to do is take your multimeter and set it on dc voltage with the range on 20, put the black lead to ground (negative side of battery or groud pad on board) and then touch the red lead to each leg of the IC and bipolars and keep track of the voltages (and the leg it came from). Then post a list of all of them right here.

-Joe

[choklitlove]

mine only has 10, 50, 250, and 500.

also, mine's analog.  which numbers do i look at on the top where the needle points?



sorry, this is the worst noobosity ever.

[choklitlove]

also, should the effect be on or anything plugged in, or what?

[calpolyengineer]

Oh, ok. There should be a few different bars running in arcs along the needle path. Either the different ones are labeled, or they are color coded to match the selector dial. You want to look at the row of numbers along the track for DC Voltage (it might just be a symbol that looks like a solid horizontal line with three dashes underneath it, or it could just be labeled V).

So set your meter on 10 (since 9v is the max voltage you can have at any place in the circuit), you do have to have the battery hooked up but running sound through it is not necessary. If you have it hooked up with a stereo input jack that will disconnect the battery when nothing is plugged in, you need to have a cord plugged in it but the other side of the cord doesn't need to be connected to anything.

I am also just wondering, what functions does your analog meter do? What brand/model is it?

[choklitlove]

it's a sperry SP-6A:


and this page should explain what it can do well enough:
http://www.awsperry.com/cgi-bin/db_search2.cgi?name=SP-6A&sort_by=8&submit_search=More&session_key=&exact_match=on&item=sp-6a

[choklitlove]

okay.  i measured the ic and the diode using the scale labelled "V.mA".

i hope it's right.

i measured the IC as if pin 5 is across from 1.  as for the other things i want to measure, they are not named individually in the layout.  this is a problem for the doubles of values...
IC1:
1 = 3.5
2 = .4
3 = 3
4 = 0
5 = 8.5
6 = 4.5
7 = 4.5
8 = .1

D1:
A = 0
K = 3

[calpolyengineer]

Well first off, the legs are numbered down from the top left and then up the right so pin 8 is across from pin 1. I don't know if this means anything as far as whether you routed stuff to the wrong leg or not, but you should probably edit the pin numbers in your post (just switch the value of 5 and .

Also Q1 and Q2, with the flatside facing up and the leads pointing left, the pinout is C, B, E from the top down (on the schem, B is the one sticking into the middle of the verticle line, E has the arrow, and C is the leftover)
And Q3, again with flatside up and leads left, pinout is D, S, G (G is the one sticking in the middle, D is on top, S is on bottom) You need to measure the voltages at each of these as well. And also measure your battery voltage.

-Joe

[choklitlove]

everyone: be prepared to cast me into the pit of shame.


i've decided to put this in the "do it later" pile.

i needed a gate sooner than i was able to finish this, and ordered a $20 behringer gate.


i'm sorry.  someday, this thread will make it back to the top with finished pictures of the pedal. 

it will be beautiful...