Happy little accident . . .

[paul.creedy]

I've recently begun making my own pedals after putting together some kits, and I've successfully finished three stripboard layouts found on another site.

I'm learning as I go, so freely admit I know very little at this point, but I'm having fun, which is half the reason I started

However, the first layout I attempted was a simple fuzz, which has so far defeated all attempts to get a working circuit despite its simplicity. My first attempt made no sound whatsoever, so I quickly made a second board with parts from the same suppliers and that didn't work either.
I took off all the outboard wiring and made a third board (a different layout) which worked perfectly, so I was able to narrow down the issue to the board.

After a couple more successful builds I went back to the first board, in the hope that working towards a solution I would learn far more than I would from a working circuit.

I have bought a cheap component tester and have a DMM so having stripped the OK board I remade it using new components and some transistor sockets.

The completed MKIII board makes noise, which is progress, but it only worked with the input pot maxed out (it sweeps between a 100nF and a 10nF and prefers the 100nF) and then only if I strum hard, the note/s dying off really quickly as the signal drops.

So yesterday I spent a little time trying all of the transistor types I've so far acquired to see what would happen.

Swapping Q1 (an MPSA18) made very little difference by and large, and leaving it out altogether didn't change things too greatly either !

So then I tried Q2 (another MPSA18) and changes were again only making small differences, until I tried an MPSA13.

This made the circuit into a fuzzy square wave tremolo, which varies its speed dependent on the strength of the input signal. It isn't an OK, but I like it The input pot works across its full range too, so everything is "working" even if it isn't what I set out to build.

I'll still be working on the first layout because it will still teach me something, but if nothing else the result of my experimenting is unexpected but fun.

- - - - - - - - - - - - - -

Apologies for posting before reading the "read this before you post" topic, I should know better.

I've edited the post to remove anything that might be considered against the rules, or at least I hope I have, let me know if I missed something.

[paul.creedy]

Post edited and apology added - I'll draw out a schematic of what I have now if it's ok now I've changed components (I'm guessing probably not, as the circuit is essentially the same).

I'm also tempted to simplify the circuit further to see what happens, updates will follow if it a) makes a noise and b) nothing catches fire

[vigilante397]

Welcome to the forum

There are lots of friendly and knowledgeable people on here, I'm sure someone will be able to help you get it sorted. It will definitely be a lot easier with some pictures to look at though 

[bluebunny]

updates will follow if . . . nothing catches fire

Wrong.  We definitely need updates if something catches fire.  In fact, videos are preferable.   

Welcome to the nuthouse...   

[Kipper4]

Yer welcome mate.
Show us your schematic please.
Take some voltages. Come back with a list, related to your scheme.
Sounds like 1 or more transistors could be misbiased.
I'm pissing in the wind without a drawing though.
AND defo video evidence of pyrotechnics is a must. 

Some people like pics of the build and a layout. Your layout might help too.

[paul.creedy]

I did post a schematic, but as the pedal was once commercially available I wasn't sure if I should leave it up, so I took it down.

I'll put it back now, but I'm happy to take it down again if it's against the rules.



I haven't got voltages right now, but I'll see if I can get them later.

I should add that when I had MKIII working (before I started swapping transistors) it needed a good strum with a guitar fitted with humbuckers to get it making a sound and as the sound decayed it quickly went completely silent.

As I've said, I'm happy with what I've ended up with and intend to keep it, but understanding why the pedal I was trying to make hasn't yet worked properly (whether because I've somehow done something wrong every time or because I'm lacking the knowledge to change one component for a higher or lower value to compensate for another component not quite doing as much as it should) will be valuable information, so I'm grateful for any wisdom you can pass on

[Kipper4]

I'll have a look when I get a min.

Your replacement of the mpsa18 (bjt) with an mpsa13 (Darlington). Hmmmm
Still wasn't biased right. I could be wrong about this.
I'll try and breadboard it.

What circuit is it? A fuzz.

[paul.creedy]

I'll have a look when I get a min.

Your replacement of the mpsa18 (bjt) with an mpsa13 (Darlington). Hmmmm
Still wasn't biased right. I could be wrong about this.
I'll try and breadboard it.

What circuit is it? A fuzz.

Yes, it's a fuzz.

When building from a known circuit is it sometimes necessary to bias when a transistor which is marked as "correct" isn't giving the desired result ?

The MPSA13 is replacing the MPSA18 which is paired with the 2N2907 in the schematic.

As I'm very new to all this I haven't yet got the hang of doing things "correctly" and also I'm intrigued by what might happen if random choices are made (which is why the MPSA13 ended up in a place it really shouldn't have been if all I was trying to do was make a working pedal).

[BetterOffShred]

Welcome Paul 

This place is great for theory and build help!

-BoS

[vigilante397]

I did post a schematic, but as the pedal was once commercially available I wasn't sure if I should leave it up, so I took it down.

For future reference the only schematic forbidden to be posted here (due to an agreement with the forum owner IIRC) is the Klon Centaur. Any other schematic is fine as long as it isn't expressly forbidden by the author

[paul.creedy]

This is a quick muck about with the circuit (it's not in a box yet, nor does it have a footswitch, it's just the board, two pots, a battery clip and two jack sockets.

http://www.arrowheadguitars.co.uk/pics/Ok-ish.mp3

I didn't touch the controls (the input pot now works as a tone control by letting more or less bass through, the other pot is just a vol.) or add in any other pedals (and there are a LOT after it   ) and you can hear that the less you put in the slower or less you hear the effect and giving it some oomph speeds things up almost to the point you can't hear anything but fuzz.

As I say, it's not what I thought I was building, but I really like what I have

[paul.creedy]

I realised that I hadn't listened to the original demo for ages, and having done so I can see that what I've got right now isn't as far away as I remembered.

The stutter is there, which is the bit I thought I'd stumbled on as if by magic , but I think mine is a little more straight forward fuzz than the 8 bit synthy fuzz I hear in the demo.

Maybe with a little more transistor swapping I could get closer, but I like it as it is, so I doubt I'll bother.

So time for boxing up and then it's back to my work-in-progress, a Parallel Universe II.

[duck_arse]

that's the best, the funniest thing I've heard in a while. what happens to the stuuttterr if you lift the Emitter leg of the upper/first/forward MPSA18? [or if you whack a compressor in front?]

and a late welcome.

[paul.creedy]

that's the best, the funniest thing I've heard in a while. what happens to the stuuttterr if you lift the Emitter leg of the upper/first/forward MPSA18? [or if you whack a compressor in front?]

and a late welcome.

Thanks

I'm all about pedals that make interesting, unusual or downright weird noises.

I've reached a point where I've run out of commercially available pedals, and a lot of the boutique stuff is either too expensive, too hard to get hold of (I've missed out a number of times on flash sales) or they overlap too much with things I've already got.

So clearly the time has come for me to make the pedals to make the weird noises myself

I have everything I need except an oscilloscope, and I reckon it's only a matter of time before I have one of those too

Not only that but I've got two fire extinguishers in the workshop, so I'm more than happy to set things ablaze in the search for new and alarming sounds    

If anyone's interested in where the sounds end up, then feel free to have a listen (or not, I do it all for my own amusement so I don't mind).

[duck_arse]

paul - I have some mods can be made to your circuit. I won't call them controls, that would be taking things too far, but they add some variations to the madness. I have it on the bb at the mo, and when I put a bazz fuss in front of, it just went batshit. as batsiht as anything I've heard for a while. harmonic percolator did for it, too, so I'm tossing up whether to add a bazz and a bazz-bypass switch to the basic or not.

my circuit, first draw, izz here. (I've called it Frobbing after the Ring Frobnicator, which I could never get to frob enough for my liking.)

- deleted, replaced - [edit]

[BetterOfShred, if you are watching, this might be your next build .....]

[rutabaga bob]

Welcome aboard!  Interesting 'accident'!  I know a guy who might really love this!  Thanks!  Cheers!  Larry

[paul.creedy]

paul - I have some mods can be made to your circuit. I won't call them controls, that would be taking things too far, but they add some variations to the madness. I have it on the bb at the mo, and when I put a bazz fuss in front of, it just went batshit. as batsiht as anything I've heard for a while. harmonic percolator did for it, too, so I'm tossing up whether to add a bazz and a bazz-bypass switch to the basic or not.

my circuit, first draw, izz here. (I've called it Frobbing after the Ring Frobnicator, which I could never get to frob enough for my liking.)

https://i.imgur.com/mhAQ4pF.png

[BetterOfShred, if you are watching, this might be your next build .....]

I've boxed mine up and added it to my set up, it does add another layer of madness which I like

I'm also amused that my uneducated tweaking has given inspiration - I'll have to check out those modifications when I get a moment, anything that makes it even more entertaining is fine by me and working out how to create that circuit on a stripboard will be good for me too

I should make it clear again that the circuit isn't mine, I'm only responsible for putting an MPSA13 where an MPSA18 should be because for some reason I've been unable to make my build work properly

[duck_arse]

draw your circuit with your parts, add notes to the drawing, name the circuit, and it is yours. [edit :] add credit for the original circuit, obvs ......

have you tried with a fuzz in front?

[paul.creedy]

I have tried it with a number of pedals

I've tried a kit Parasit Into The Unknown, a Data Corrupter and a self-built Random Number Generator in front, and a kit Parasit Raygun Youth and Hyperion 2 after, plus a Miku and a CSIDMAN which I run through a feedback looper.

Not unsurprisingly, it behaves a little differently depending on where in the chain I put it (and it's a big chain, currently 30 pedals ), and in its current position the input pot works better than it did when I had it at the front, backing it off softens the wave a little and it warbles later than if I turn it up full.

[paul.creedy]

Here it is in the box - not the final look, I was trying out some new paint pens



Next to it is another recent build - a Random Number Generator, not sure I'm a huge fan of it, so it may well become something else eventually.