Omega Boost Help!

[Ell]

I've tried to build the Omega boost from ROG. http://www.runoffgroove.com/omega.html
I followed the perfboard layout on that page almost exactly (just giving myself more or less space here or there, all the connections are the same). I have a 2N5457 for Q1 and a BS170 for Q2.
It lets no sound through when it's on, but the bypass and the LED both work fine.

Q1:
D: 9.17
S: 4.14
G: 0

Q2:
D: 9.19
G: 5.69
S: 3.91

If someone can help me that would bne fantastic. I've built many many pedals in the past but I've been failing more and more recently.

[Brymus]

Try using 2n5457 for both Qs or a 2n7000 for Q2

[Ell]

Try using 2n5457 for both Qs or a 2n7000 for Q2

I don't have many spare transistors and neither of them. Are you certain that it's the BS170?

[Auke Haarsma]

Use the trimpot to get the Drain of Q1 to 4,5V. Any sound now?

[Ell]

I've got the drain of Q1 to 4.12, that's as high as it goes.

[Brymus]

Try using 2n5457 for both Qs or a 2n7000 for Q2

I don't have many spare transistors and neither of them. Are you certain that it's the BS170?

No Im not certain, it was just on my build I couldnt make it work with the bs170
I put in a different transistor and it worked and it worked even better with both of them as 2n5457s.

[Brymus]

Thinking about it mine is set to 7.0v as I didnt like it at 4.5v so Auke is proly right.
I will bias mine down to 4 and report back.

[Ell]

Try using 2n5457 for both Qs or a 2n7000 for Q2

I don't have many spare transistors and neither of them. Are you certain that it's the BS170?

No Im not certain, it was just on my build I couldnt make it work with the bs170
I put in a different transistor and it worked and it worked even better with both of them as 2n5457s.

Which layout did you use? The perfboard one on ROG has a different transistor pin layout for each of the transistors, so I recon it's designed for the BS170 as well as another transistor. If I put a 2n5457 into the Q2 position, wouldn't this be an issue? Then again, if you used the ROG layout...

[Brymus]

I used the perf layout pretty much ,I just transfered the schematic to perf.Mine is a little bigger is all.
http://i419.photobucket.com/albums/pp276/Bry928/Pedals%20and%20effects/Omega%20Top%20Boost%20build/BooteekPedals021.jpg
more pics
http://s419.photobucket.com/albums/pp276/Bry928/Pedals%20and%20effects/Omega%20Top%20Boost%20build/
But I lied ...I do have a BS170 in Q2 so I forget which one I was having trouble with,it was the pin out was different in the end I know that for sure.
Here are my voltages if it helps
Q1)D 6.3 G 1.4 S 0
Q2)D 8.1 G 6.9 S 4.6   battery=9v

I also added polarity diode and a 100uf filter node after a 100r resistor.

I get get sound biased all the way down to 2v

[PRR]

> Q1:
> D: 9.17
> S: 4.14
> G: 0

This is impossible if the FET is wired according to plan.



How can you pull 4V across the 100K pot, yet have NO voltage drop across the 33K+68K string, not any other way for current to get to the 100K?

Yet there IS apparent current in the 33K+68K string... -backward- in the 33K.

And something is  sucking the 68K, because Q2 Gate is at 6V, and Q2 appears to be amplifying.

But nothing adds-up.

Therefore it is not wired the way you think it is.

> layout on that page almost exactly

Every time I change a layout, I add an error. Minor changes are very tricky, psychologically more treacherous than major changes.

Can you post the actual layout, or even a photo?

[Ell]

By changes to the circuit I just mean that I made the board itself a few grid sizes bigger, so the components stretch a tiny bit further than they would otherwise to make it a little easier. I'm very very new to perfboard, I normally work with stripboard, so I figured I'd just allow myself more room for error.

I just happened to find a 2n7000 so I put that in Q2. Here are the new readings:

Q1:
D: 3.72
S: 3.74
G: 0.00

Q2:
D: 9.19
G: starts off high and constantly decreases, I'm assuming till it reaches 0.
S: 8.57


This isn't making a lot of sense is it... And what annoys me most is that simple pedals never work for me, yet I just successfully finished the Tonemender which has more components than the Omega or the Tillman (which also doesn't work and I will probably do a debug for soon too).

[PRR]

> 2n7000

That's a MOSFET. You want a JFET.

[B Tremblay]

Here are the pin voltages from my build:

Q1 (J201)
D: 4.71
S: 1.27
G: 0

Q2 (BS170)
D: 9.17
G: 6.16
S: 4.21

Triple-check your pinouts.

[Brymus]

By changes to the circuit I just mean that I made the board itself a few grid sizes bigger, so the components stretch a tiny bit further than they would otherwise to make it a little easier. I'm very very new to perfboard, I normally work with stripboard, so I figured I'd just allow myself more room for error.

I just happened to find a 2n7000 so I put that in Q2. Here are the new readings:

Q1:
D: 3.72
S: 3.74
G: 0.00

Q2:
D: 9.19
G: starts off high and constantly decreases, I'm assuming till it reaches 0.
S: 8.57


This isn't making a lot of sense is it... And what annoys me most is that simple pedals never work for me, yet I just successfully finished the Tonemender which has more components than the Omega or the Tillman (which also doesn't work and I will probably do a debug for soon too).

I swapped Q1 for an mpf 102 and the voltages were identicle to the ones you posted for Q1 except my drain was slightly higher instead of lower and wouldnt bias above 4v,although it still worked just very low output.
Q2 stayed the same.
In the pic above -in the link I have a 2n7000,when I swapped to a bs170 I had to turn the Fet the other way ,so they are both oriented the same.
I still couldnt make a 2n5457 work in Q2 and I would swear I had done so prior,When I was trying to find the quietest combo,at any rate a 2n5457 Q1 and a 2n7000 Q2 should work.
I just swapped them in and they DO work.
Like Trembly said triple check your pin outs against the data sheets I know that was the problem I had when I built mine.

[sevenisthenumber]

Simple but....   
1)make sure your grounds on the perf are all  corrected
2)transistor orientation

it happens to the best of us.