Tonepad FSH-1 questions

[calculating_infinity]

Hey all, I just got this tonepad fsh-1 pcb in.  I am wanting to only use the S&H side of things.  I am unsure how to do this properly...  Does the range control effect the sample and hold?  I figure I can use fixed resistors for the attack, decay, and resonance settings.  Also if I am not using the Filter side of things I wont need the switches.  How do I omit them properly?  Thanks in advance.

-Jonathan

[soggybag]

I think only the rate and resonance effect the sample and hold.

Figure out the switching arrangement at the H&H/Envelope switch and run a couple jumpers to these pads.

You could probably omit all of the parts for the envelope. That would be IC2 and pretty much all the parts in general vicinity.

Of course I have been known to connect power supplies backwards and contemplate why things aren't working while thinking it would be a lot easier to see what was going on if all that smoke wasn't blocking my view.

[calculating_infinity]

So from the Tonepad layout ( http://tonepad.com/getFileInfo.asp?id=96 ) would I connect A0 to B0 and A2 to B2 in order for it to be in S&H mode?  Would B1 not be connected?  Thanks.

[oldrocker]

It's too bad you're not interested in the auto wah portion of the circuit.  It's the best auto wah I've heard.

[calculating_infinity]

I am actually interested in the auto-wah part, however right now I'm only building the S&H part.  I'm trying to build it into a 125B and my skills cant fit all the pots if I were to build both sections.  If I can keep it one or two pots that it will be much easier.  I will plan on building both sections when I can afford a 1590BB.  I am really short on cash as I lost my job recently. 

[calculating_infinity]

So from the Tonepad layout ( http://tonepad.com/getFileInfo.asp?id=96 ) would I connect A0 to B0 and A2 to B2 in order for it to be in S&H mode?  Would B1 not be connected?  Thanks.

Can anyone confirm that this would be correct?  I dont want to have to do redo jumpers after i populate the board.  Thanks.

[handwire]

I think it needs the filter portion to create the S&H, so you need to build that section, maybe use small trimpots.

[Hambo]

So from the Tonepad layout ( http://tonepad.com/getFileInfo.asp?id=96 ) would I connect A0 to B0 and A2 to B2 in order for it to be in S&H mode?  Would B1 not be connected?  Thanks.

Can anyone confirm that this would be correct?  I dont want to have to do redo jumpers after i populate the board.  Thanks.

Yes that will simply remove the switch and leave it in S+H mode.

[calculating_infinity]

So from the Tonepad layout ( http://tonepad.com/getFileInfo.asp?id=96 ) would I connect A0 to B0 and A2 to B2 in order for it to be in S&H mode?  Would B1 not be connected?  Thanks.

Can anyone confirm that this would be correct?  I dont want to have to do redo jumpers after i populate the board.  Thanks.

Yes that will simply remove the switch and leave it in S+H mode.

Exactly what I wanted to hear.  Thanks again for your help Andy!  Thanks for your help as well handwire.  I figured I would have to build that part and was actually going to set up a small daughter board with the trimmers on it.  Thanks again!

[calculating_infinity]

Ok so I built this over the weekend and well it works sort of.  It works but I think its stuck in filter mode rather than s&h mode.  Though only the resonance pot effects the sound so it cant be in filter mode can it?  I am unsure what adjustments are needed for the trimmers as well.  I do not have the up/down switch jumpered.  I only have A2 to B2 and A0 to B0 jumpered.  Any help or suggestions would be appreciated.

[alex frias]

Some transistor may not work properly for the noise source.
Wich ones did you have tried out?

[soggybag]

You'll need to audition transistors for noise. Plug them in and adjust the trim pot. The 10k trim sets the level of the noise fed into the sample and hold. The 100k trim sets the range. You need to find a noisy transistor, then adjust these two trimmers until the sample and hold effect is sounding good.

The 100k trim should center the range of sample and hold while the 10k sets range. Try and adjust them so you are getting a a range of sounds. Rather than hearing resonance at the high or low end more often.

[calculating_infinity]

Hey guys, thanks for the responses.  I have tried a NTE123AP and a 2N3904.  I will try more trannies and report back. 

[calculating_infinity]

Ok so I tried out some 2n2222A's and 2N3904 and still not randomness.  Do the duals you use matter?  Right now I am using 2x OP2277 Hi precision op-amps.     Grr.

[Hambo]

Yeah, I buillt this one twice and considered myself lucky to get one working! Its can be a bit of a beligerant circuit. However I did have  symptoms like you describe for a while, like a filtery sound but no variation and could faintly hear the clock ticking away. My advice is therefore to check, double check and then TRIPLE  check the orientation of ALL of the FETS. If you used bf245s like me.. I beleive they go in the other way to how its shown on the layout. This had me slapping my head for quite a while after I realised. Good luck man!

[soggybag]

If you have a scope probe the area around the noise transistor and see if you see noise on the scope. Turn the volt scale down because the noise signal will be weak. Then check around the op-amp and see if you are getting the amplified noise there.

[calculating_infinity]

Hey guys, thanks for the help, I don't have an o-scope and wouldn't know how to use it properly even if I did.     I will check my fets again.  Hambo I am having the exact problem you are I think.  Only I only got ticking noises once I tried out the 2N2222's.  I am using J201 for the fets, I checked out the orientation on the layout and I am pretty sure that it is correct.  I will try replacing them all maybe one of them is dead who knows. 

[soggybag]

If you don't have a scope make up an audio probe and test with that. You can probe for noise where it comes out of the op-amp it should be loud enough to hear there. You can also probe to see where your signal is not getting through the system.