Electronics guys... Circuit layout help please!

rikus

I need some advice with a problem that I'm having and which I suspect is due to the layout.

I built a buffer pedal a while back based on this circuit.

I built it according to a layout I found on the web on a multi project board thingy (here). It worked perfectly, the only problem was that it was huge...

This is were my problem starts... I decided to build a smaller one on veroboard to fit one of those thin hammond pedal boxes I did a lot of googling and borrowed a couple of ideas I found. I came up with the following layout:

I built it today, but something is wrong. It it letting signal through, but it is hissing. Loudly. I used the exact same components as the first one, which is super quiet, which leads me to believe that I screwed up the layout. Can anyone check my layout to see if I screwed up or comment why it hisses so much when the other build doesn't? Electronics is a paint by number exercise for me, I can use a layout to see what I need to put where (mostly), but not why, so any help would be greatly appreciated.

AlanRatcliffe

Not sure if it makes a difference, but you have connected pin 5 to ground.

TomCat

Alan Ratcliffe wrote Not sure if it makes a difference, but you have connected pin 5 to ground.

Alan..I think you have hit the proverbial nail on the head.....I was looking at that as well and Pin-5 is offset Null-2 and in this application would probably be floating and not terminated to anything.....

Nicholas-L

Agreeing with the boys... cut the track between pin 4 and 5 and see what happens.

rikus

:goodtimes:

Cheers guys! Problem solved! Pin 5 was the culprit. Thanks so much for the input.

I really need to figure out how this stuff works... ???

AlanRatcliffe

Well, :goodtimes: to you too. I just learned about null offsets thanks to this... ?

Nicholas-L

:goodtimes: :dance:

rikus

And here it is. Working perfectly thanks to you guys.

This is the old one... veeeery big:

New one:

Side by side... :dance:

This morning I changed the little ceramic cap on the input side with a beefier film cap... I don't know if I can hear a difference, but it looks nicer!

Nicholas-L

NIce 8) looking good there

Gearhead

Change the electrolytic as well, then you'll hear. This is your achilles heel at the moment, I reckon.

rikus

Thanks Nicholas.

@Gearhead... thanks for the tip, but I don't know enough to tell a good electrolytic from a bad one... any suggestions? Would Yebo for example stock better quality ones or would I need to shop online?

Nicholas-L

If you want seriously better you might start with Rs Components or if you wanted to do branded names like sprague you'd have to source it on ebay, but maybe someone on the forum has an extra one for you. Yebo typically stock your all day everyday components, not really aimed at the tone/sound fanatic who likes the "magic" of certain caps.

Nicholas-L

uhm GH did you mean change the cap from say 10uF 16V to say 10uF 100V (physically bigger cap, same value) or change the cap value?

Gearhead

Same value cap same spec, only metallised polyester or some other high end construction. Price is a dead giveaway for quality on these things, and the most you are going to pay is about R40. Join in on a group buy from TubeDepot or something and you can open up the sound of your pedal audibly.

AlanRatcliffe

Gearhead wrote Same value cap same spec, only metallised polyester or some other high end construction.

What about tantalum electrolytic caps? Small, polarized and fine at the low voltages used in most pedals.

Gearhead

I don't know if I would hear the difference or which one is better. My point was actually if you're going to go through the trouble of sourcing, paying for, collecting and soldering in your cap you might as well do yourself the favour of getting the best you can. Same like you don't build your own guitar using second hand Samick/Ritmuller/SantaFe parts. The location of this cap is in the signal path, probably right at the beginning of the signal chain.

rikus

I gotcha! Thanks for the info. I might just do that. Then I can get some nice switchcraft jacks too!

Nicholas-L

Cool man

Nicholas-L

oh wait cap constructions.... I see now yes indeed I do.

ezietsman

Alan Ratcliffe wrote
Gearhead wrote Same value cap same spec, only metallised polyester or some other high end construction.
What about tantalum electrolytic caps? Small, polarized and fine at the low voltages used in most pedals.

They also tend to explode and set fire to the rest of it when things go wrong ? Prob not at the low voltages. I was told to stay away from them unless I REALLY have to use one.