# Harmonic Percolator- Tagboard.. switch wiring?



## megatrav (Jun 26, 2021)

Hey all,

I decided to try doing a hand wired pedal. I am doing the Harmonic Percolator that I found online. It seems to be a modified version with a switch that takes out the diodes.
I am just not sure how I am suppose to wire the switch and jacks since it doesn't state effect in/out
Any help is appreciated.


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## Feral Feline (Jun 27, 2021)

How do you usually wire up your 3PDTs?


For me, comme ça:
IN-JACK> LUG2 3PDT / LUG1 > BOARD IN (Harmonics Lug 3 in IVIark's HP diagram. 
Middle row for LED
PCB OUT (Vol 2 above) > LUG7 3PDT / LUG8 > OUT JACK

For the HP Switch above, I'd take a wire off lug 3 of the vol pot to the middle lug of the SPDT, then one of the outer lugs to the a Diode that's on the diode-end not connected to ground.

It's mostly already there in the diagram, just not the 3PDT, and there are many ways to wire a 3PDT — use your preferred method for Hope that helps.


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## Mcknib (Jun 27, 2021)

With vero, tag etc the in and out is always the effect / pcb in and out

As @Feral Feline says you'd just wire it as you always do, the easiest way to remember it is with what you already know ie how a 3PDT works

The jacks carrying your audio signal always go to the middle common row enabling you to route / switch or throw it to either of the outer rows to send your signal through the effect circuit or straight from the in to out jack bypassing the circuit ( connecting as shown with the purple and red lines)

I used this image till I got it in my head it can be confusing your first time, in reality as you know you don't need the in and out pcb pads you could just solder your jack tips to the 1st and last components and that's what you're doing with tag, vero etc in the absence of IN and OUT pads (don't forget to ground your IN and OUT jacks etc)

This is the same as ppcb 3PDT wiring easy to remember INs to the left OUTs to the right LED to the middle poles

I love tag cheers for posting this I might just give it a go, I've gone all tagboard recently after finding some from my NOS 'must be vintage' stage that most go through! Didn't have this layout





A wee edit here's one I'm about to wire up showing IN and OUT tags to 3PDT


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## fig (Jun 27, 2021)

@Mcknib, I see the _OC44 Inside_ is proudly displayed!


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## megatrav (Jun 27, 2021)

Sorry, I should clarify. I was going to use this for the switch




I am not sure where to connect the effect send and return on the board but I think I understand now. I was overthinking it.
I may try some of the suggestions above.
Thanks!


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## megatrav (Jun 27, 2021)

Feral Feline said:


> For the HP Switch above, I'd take a wire off lug 3 of the vol pot to the middle lug of the SPDT, then one of the outer lugs to the a Diode that's on the diode-end not connected to ground


Do you mean do this in addition to how it is shows it wired or instead of how it shows it wired?


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## Mcknib (Jun 27, 2021)

Yeah that 3PDT wiring would confuse me and I'd never remember it off by heart

I see what you mean took me a while to figure out how it switches

Effect send looks like pcb in, effect return pcb out the diagonal wire would obviously connect input straight to output ground input, turn off the LED and bypass the circuit god knows why that jacks ain't on the same common row it's a lot easier to visualise how it switches and remember it

Well for me anyway!


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## Feral Feline (Jun 28, 2021)

megatrav said:


> Do you mean do this in addition to how it is shows it wired or instead of how it shows it wired?


RE SPDT: NOT in addition to (sort of instead of).
Depending on where your switch is placed in the enclosure relative to the pots and board, it might make more sense to wire the centre-lug of the SPDT directly to the VolPot's lug 3 — it's what I'd do if it meant a shorter wire (equalling less spaghetti and less antennae to attract radio interference).


Maybe you're still thinking too physically. What I mean is ...
I still have trouble getting past the physical elements and placements — electricity doesn't really care how three components are all physically connected to the same point, an electrical node; so in this case whether you connect the SPDT middle lug to the board or the pot doesn't matter so long as it's the correct shared node.

Look at the lavender wire running from lug 3 to the board. Doesn't matter where along that you connect, you could interrupt that wire and stick the middle lug of the SPDT in there, then continue the run of the rest of the lavender wire from the middle lug to the board as show in the layout diagram. Physically, lug 3 is no longer connected directly to the board, but electrically nothing has changed (hence the "sort of instead of" comment at the top of this post). Splicing into the lavender wire could be the best way for you to physically arrange things in your build (or not).

For ex: If Mcknib were to add a SPT switch to his build, it would make sense to put the SPDT between pots. Mirroring his build for yours: Switch and pots together, SPDT middle lug direct to Vol 3, then run a wire from SPDT middle lug hidden under the board to its proper contact point and you've got a cleaner looking build.

🕛📍🕛
 ___|___
|_____*.*_|


Is there any reason you're using that specific 3PDT connection method? To ground the input of the effect during bypass?
It is a bit confusing, until you break it down. Easiest way I've found to get my head around 3PDT layouts is to omit the pole with the LED — just look at the in/out connections, then add the LED aspect back in. There are other 3PDT layouts that still ground the effect in bypass, but have the jacks wired to common-lugs.


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## megatrav (Jun 30, 2021)

Quick update. I ended up finishing the pedal. I followed the diagram just so that I wouldn't screw anything up...
I haven't done an audio test, but I did plug it in to see if the light comes on. It does! But it stays on even if I click the switch. I'm going to test audio to see if it does bypass and come on.

here are some pics. I know it's spaghetti right now but I plan to do some tidying once I confirm it's working.


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## megatrav (Jul 1, 2021)

I think I realized the issue. I wired the LED incorrectly


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## megatrav (Jul 1, 2021)

So, I have the LED working now. But the audio is weak. I am going to go over my solder connections later and make sure everything is wired right


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## megatrav (Jul 5, 2021)

So, I got everything wired up and I get a bypass sound, but when engaged it just squeals.
I thought that I might have wired the germanium transistor wrong, but when I flipped it (still crossing the middle lug), it still does the same thing.
I took some pics and maybe someone can point out something I'm doing wrong.


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## megatrav (Jul 5, 2021)

Any help or suggestions is great appreciated


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## megatrav (Jul 6, 2021)

Anybody? I know this isn't the typical thing for here, but I am really stumped and I am not sure what to check for


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## Mcknib (Jul 6, 2021)

This isn't a very technical approach but with squealing, oscillation etc If voltages don't reveal anything I usually go by the wiggle test where I'll touch solder points on and off with my finger or something non conductive like a pencil, pot lugs etc to see if it alters anything

There's a few things that can cause it as you know

It is difficult to see everything even with all the pics you've provided what have you got insulating the underside of the board

There is a thread here with feedback/ oscillation problems 





__





						Harmonic Percolator - make one!
					

Harmonic Percolator - make one!



					www.diystompboxes.com


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## megatrav (Jul 6, 2021)

Mcknib said:


> This isn't a very technical approach but with squealing, oscillation etc If voltages don't reveal anything I usually go by the wiggle test where I'll touch solder points on and off with my finger or something non conductive like a pencil, pot lugs etc to see if it alters anything
> 
> There's a few things that can cause it as you know
> 
> ...


Thanks! I will read that thread when I get a chance. Under the board is a piece of card stock and some double sided tape. Is it possible that I need more than that?


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## Mcknib (Jul 6, 2021)

As long as it's insulated and youve no short possibilities should be fine

Easy enough to continuity check nothing's touching

It is a bit of a weirdo circuit from what I've read I keep meaning to build one 

Here's the transistor voltages from the madbean pepper spray build doc for reference


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## Mcknib (Jul 6, 2021)

Guess what I'm building ?

Stop inspiring me @megatrav I've got enough on my 'oohh somebody's posted a tagboard layout' plate

And to make matters worse I've got to go out now, I wonder if she'll understand when I say sorry I'm late but I had to put a coupla 100ns in





I'll be joining you in feedback city soon!


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## Mcknib (Jul 7, 2021)

Right finished building it and tested on my test box 

It worked perfectly those transistor voltages are accurate 

I used a 2N404 hFE 100 very little leakage and a 2N3904 and built it stock

From my readings on this circuit

Most folks say it should be a low hFE germanium but this works fine with a highish hFE for a germ 

I tried it using humbuckers and single coils didn't notice any difference albeit my humbucker isn't particularly hot 

Hopefully you'll find your problem soon because it is a good sounding pedal with lots of sustain the switch is a good addition it does sound a tad dark till you flick it

Anyway here it is for reference you may see something comparing it to yours

I do use the holes to secure the wires so you'll see them going down here and there green is in, yellow out, red 9v, black ground with the brown ground bottom left jumpered up to the main grounds on the underside


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## fig (Jul 7, 2021)

Why do I have this sudden craving for turrets?


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## Mcknib (Jul 7, 2021)

fig said:


> Why do I have this sudden craving for turrets?


You know you want it!

Turret I like working with particularly this type which is more tag than turret and it don't break the bank

It is sometimes a pain trying to get long leads through the holes especially with axial stuff, I cut one side in half, slide the longer one in then the shorter one if there's more than one lead in the same tag I don't solder till I've got them all in

I'll then just tack solder to hold in place and remelt to position everything, I use croc clips a lot with tag especially with wires

With this one for the weird 750K I suddenly thought use 1/8th watts for a nice small tepee series job, so you do learn as you go I'll do that in all future builds if I need an oddball value


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## megatrav (Jul 7, 2021)

Mcknib said:


> Right finished building it and tested on my test box
> 
> It worked perfectly those transistor voltages are accurate
> 
> ...


Don't rub it in man lol


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## megatrav (Jul 7, 2021)

This might be a dumb question but do all grounds need to be connected to each other? 
like the grounds on one side of the turret need to be connected to the other, etc?


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## fig (Jul 7, 2021)

megatrav said:


> This might be a dumb question but do all grounds need to be connected to each other?
> like the grounds on one side of the turret need to be connected to the other, etc?


_There can be only one. -_Highlander


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## fig (Jul 7, 2021)

To actually answer, there needs to exist continuity within the ground plane...so yes, by hook or by crook all grounds lead to the same place (in most cases).

btw, that is NOT a dumb question.


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## Mcknib (Jul 7, 2021)

As long as they all go to ground on the power supply you can have as many seperate ground wires on your board as you like but as @fig said they all need to be connected to your power supply ground ( the same place) on the DC jack or battery ground connection.

Us older dudes will remember star grounding where your wiring looked like a dead octopus

You'll get it sussed I've done many tag builds so it wasn't a conscious rubbing it in

but......

nah, nah nuh nah nah


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## megatrav (Jul 7, 2021)

Okay well I am going to try adding a ground from one side of the board to the other which would connect all grounds together. I'm also going to test my voltages on the multimeter and see what it comes out to!
Thanks again for the input. I will report back later


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## Mcknib (Jul 7, 2021)

Here's the underside of mine where you can see the brown jumpers connecting all the grounds

That may well be your problem with over voltage making your trannies oscillate


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## megatrav (Jul 7, 2021)

Mcknib said:


> Here's the underside of mine where you can see the brown jumpers connecting all the grounds
> 
> That may well be your problem with over voltage making your trannies oscillate
> 
> View attachment 13378


I think that was it. That was the one wire I was missing. 
I like how you went under the board. I will have to remember that the next time I do one of these.
Off topic, where do you get your boards?
I ordered one from the UK


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## Coda (Jul 7, 2021)

fig said:


> To actually answer, there needs to exist continuity within the ground plane...so yes, by hook or by crook all grounds lead to the same place (in most cases).
> 
> btw, that is NOT a dumb question.


The only dumb questions are those left unasked...


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## Mcknib (Jul 7, 2021)

I get mine on eBay I'm UK based so from this seller









						2 x 36 way Solder Tag Terminal Strip on Paxolin / Bakolite Board (2 Strip)   | eBay
					

Find many great new & used options and get the best deals for 2 x 36 way Solder Tag Terminal Strip on Paxolin / Bakolite Board (2 Strip)  at the best online prices at eBay! Free delivery for many products!



					www.ebay.co.uk


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## megatrav (Jul 7, 2021)

https://www.hificollective.co.uk/catalog/tag-board-p-695.html

this is where I got mine. Not sure if it's the same seller


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## Mcknib (Jul 7, 2021)

Thanks that site looks pretty good if you want to do the vintage look tagboard

Those Allen Bradley 1/8 and 1/4 watt resistors ain't too bad

That eBay seller's the guy that runs this site Mark Hindes 





__





						vintage-parts.com
					

Valves and germanium transistors for old radio and tv repairs



					markhindes.easywebstore.co.uk


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## megatrav (Jul 7, 2021)

Update- adding the ground wire did indeed stop the oscillating. However, the pedal still doesn't work. If I turn the volume and harmonics up all the way it is spitty and very very quiet compared to the bypass tone. So, would this mean that the transistors are in the wrong way?



Based on the diagram I have seen for the 2N404A it should be (left to right) Emitter, Base, Collector. I actually tried moving it around in some different ways and it didn't really do anything.



based on the data sheet for a 2N3904 this should also be correct (left to right) Emitter, Bass, Collector. 

I did double check the board and it looks like all the parts are in the right spot.

I'm really stumped. If these transistors are in the correct way, I would have to be missing something else obvious


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## Mcknib (Jul 7, 2021)

You've got the transistor pinouts correct and from your previous pics and posts you have the 2N404 base pin bent over to the left followed by collector and emitter so that's the correct way to solder it in left to right B,C,E

What's the voltages on your C,B,E transistor pins

It's difficult to trace everything with the big caps in the way can't see the 91K for example

It does sound like your transistors aren't biasing correctly I don't know whether 70K difference in having a 680K instead of 750K feedback resistor would cause mis biasing to that extent

You could try lifting a leg of the 680K out and adding a 67K in series ie tepee them together


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## megatrav (Jul 8, 2021)

Mcknib said:


> You've got the transistor pinouts correct and from your previous pics and posts you have the 2N404 base pin bent over to the left followed by collector and emitter so that's the correct way to solder it in left to right B,C,E
> 
> What's the voltages on your C,B,E transistor pins
> 
> ...


I took the build out of the enclosure last night, but I didn't have time to take out the multimeter. Hopefully today I can check all of my parts and voltages


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## megatrav (Jul 8, 2021)

This may also be a silly question- the electrolytic cap I am using here- I believe its non polarized.. that wouldn't cause any issues would it?


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## fig (Jul 8, 2021)

megatrav said:


> This may also be a silly question- the electrolytic cap I am using here- I believe its non polarized.. that wouldn't cause any issues would it?


no.


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## megatrav (Jul 8, 2021)

Alright so classic mistake. Resistors in the wrong spot... and one of legs of the GE tranny came off.  So, I'm going to order another one.. and some smaller caps since these 640's are the definition of overkill.
Thanks so much for all the help. I'll report back once parts show up


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## Mcknib (Jul 8, 2021)

Yeah just use green mylar! I too fell into the trap of using vintage looking axial stuff for my first tagboard efforts 

I only do that now if it's requested 

You can use any PNP germanium in there if you've other types kicking about in your parts bin and of course any cap of the correct value 

I don't normally tepee resistors like yourself I'll just use the nearest value but coz I'd read this is a bit of an oddball I decided to do it


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## megatrav (Jul 17, 2021)

Update time!
I put in a new 2N34A and a new 2N3565. I also swapped those large caps for smaller ones.
Good news is it makes sound.. sort of. I am able to hear the guitar coming through but there is a crazy amount of feedback and oscillation. When I flip the switch it just oscillates. No distinguishable notes from the guitar come through. I made sure my pin out was right on the 2N34A and I even tried swapping the 2N3565 and it did the same thing with it in either way.
Could my 2N34A be in the wrong way?


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## megatrav (Jul 17, 2021)

I know that I need to check my voltages. I will report back once I have done so.
The  2N3565 pin out isn't obvious since it is the older style. It's fully round on the top


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## megatrav (Jul 18, 2021)

Okay so unless I am not sure if I am testing these correctly. I am taking the ground from the multimeter and touching a ground point and then using the hot to go between the different legs.
These are the results I got-
2N34a
B: .867
C: .8
E: .81

2N3565
E: .87
B: 1.4
C: 5.67

I am not sure what this means, other than those numbers do not match the ones in the chart.
I have double checked all of my resistors and capacitors to make sure they are the right value and in the right spot.

Not sure what's going wrong


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## megatrav (Jul 19, 2021)

I am genuinely stumped. I spent last night and some of this morning verifying the board and the wires to make sure everything is going to the right place.


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## megatrav (Jul 19, 2021)

@Mcknib @fig any thoughts?


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## fig (Jul 19, 2021)

What value resistor is between BC of the transistor? It calls for a 750kΩ

Edit: Sorry, the 3565


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## megatrav (Jul 19, 2021)

fig said:


> What value resistor is between BC of the transistor? It calls for a 750kΩ
> 
> Edit: Sorry, the 3565


Looks like I might have stuck a 680k in there. I will swap it for a 750k


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## megatrav (Jul 19, 2021)

If that works, I am going to change my name on here to "Biggest dumb dumb on earth"


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## Feral Feline (Jul 19, 2021)

Careful what you wish for, Megatrav. 

Besides, I'm not giving up my title that easily...


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## Bricksnbeatles (Jul 19, 2021)

Where are you all getting your tag board? I rarely use it (only for BS vintagey looking stuff), but I always used to get it on eBay and the seller I used to buy from disappeared— can’t find anyone else on eBay who doesn’t charge an arm and a leg for shipping to the US


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## megatrav (Jul 19, 2021)

Bricksnbeatles said:


> Where are you all getting your tag board? I rarely use it (only for BS vintagey looking stuff), but I always used to get it on eBay and the seller I used to buy from disappeared— can’t find anyone else on eBay who doesn’t charge an arm and a leg for shipping to the US


https://www.hificollective.co.uk/search/site?text=tag board

This is where I ordered mine


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## Feral Feline (Jul 19, 2021)

Local shop and Amplified Parts is where I got mine.


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## Mcknib (Jul 19, 2021)

Is that rust on top of your 2N404?

Your transistors aren't biasing correctly looking at your voltages, did you try tepee'ing a 67K to the 680K as I said I don't know what effect a 70K difference would have

Take voltage both sides of the 91K resistor, to me albeit I know little about this circuit that's where I'd start your 2N3565 collector voltage is high and may be having a knock on effect driving the 2N404

It could be something as simple as a dodgy solder joint


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## megatrav (Jul 19, 2021)

Mcknib said:


> Is that rust on top of your 2N404?
> 
> Your transistors aren't biasing correctly looking at your voltages, did you try tepee'ing a 67K to the 680K as I said I don't know what effect a 70K difference would have
> 
> ...


Thanks  for the input! It is not rust, I think it got a little too close to my iron. 
I have a 750k resistor I am going to swap out. 
I will also check the voltages on each side of the 91k and see what's up.

To my eyes, my solder joints look good, but I may start checking the wires off board as well.
I appreciate any advice on what I should check.
I want to learn as much as I can so I can be more self sufficient in the future.
I am glad it's a simple circuit


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## Feral Feline (Jul 19, 2021)

megatrav said:


> It is not rust, I think it got a little too close to my iron.



🙀








⁉️


EDIT: old gif got scratched, here's a new'n'


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## Mcknib (Jul 20, 2021)

As @Feral Feline says it may be toast germaniums are more susceptible to heat damage 

I'd test it if you've got a transistor tester or use your dmm 



			https://vetco.net/blog/test-a-transistor-with-a-multimeter/2017-05-04-12-25-37-07


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## megatrav (Jul 21, 2021)

I just ordered more 2N404a's. I couldn't get a consistent reading from the one installed.


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## Mcknib (Jul 21, 2021)

megatrav said:


> I just ordered more 2N404a's. I couldn't get a consistent reading from the one installed.


Just checking did you take it out of circuit to test

Also as you know you'd expect a lower fwd voltage with germanium 0.2 to 0.4v ish


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## megatrav (Jul 21, 2021)

Mcknib said:


> Just checking did you take it out of circuit to test
> 
> Also as you know you'd expect a lower fwd voltage with germanium 0.2 to 0.4v ish


Yessir I took it out to test. Couldn't get a clear reading on any of the legs. It would jump some but mostly it say -0.0


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## Mcknib (Jul 21, 2021)

Again you probably do this but I'm always a bit more careful with germaniums especially expensive one's so I use a croc clip as a heatsink to protect against possible heat damage like this 

If you've any other PNP germaniums or lowish hFE PNP silicons like 2N3906 you could try them whilst you wait


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## megatrav (Jul 21, 2021)

Mcknib said:


> Again you probably do this but I'm always a bit more careful with germaniums especially expensive one's so I use a croc clip as a heatsink to protect against possible heat damage like this
> 
> If you've any other PNP germaniums or lowish hFE PNP silicons like 2N3906 you could try them whilst you wait
> 
> View attachment 13902


Thanks for the tip. I did not do this, but I definitely will.
Can you tell me, is the tab on this transistor facing in towards the board or facing away from the board. Looking at the pin out, mine has been facing the outside but I wanted to make sure


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## Mcknib (Jul 21, 2021)

Yes pinout from left to right would be base, collector and emitter with the tab 

Middle base pin bent out to the left collector bent into the middle then emitter with the tag on it to the right as I think you  had it


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## megatrav (Jul 21, 2021)

Mcknib said:


> Yes pinout from left to right would be base, collector and emitter with the tab
> 
> Middle base pin bent out to the left collector bent into the middle then emitter with the tag on it to the right as I think you  had it View attachment 13905


You're the man


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## megatrav (Jul 21, 2021)

This is also the pin out I found for the si transistor so I've been following that


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## megatrav (Jul 23, 2021)

Update! New 2N404a installed and I am in velcro heaven!


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## fig (Jul 23, 2021)

A thing of beauty, no less. Nicely done!


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## megatrav (Jul 23, 2021)

Thank you!

I have come to the conclusion that this pedal is cursed.. or has some other issue going on. 
it worked and then stopped


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## Mcknib (Jul 23, 2021)

I've had a few of the cursed jobs is it secured in place

Could be something shorting when it's the right way up ie dropping down and making bare metal contact


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## megatrav (Jul 23, 2021)

Mcknib said:


> I've had a few of the cursed jobs is it secured in place
> 
> Could be something shorting when it's the right way up ie dropping down and making bare metal contact


I pulled the board up and it still isn't working. My guess is a bad solder joint but I will have to spend some time troubleshooting


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## megatrav (Jul 23, 2021)

Its not possible to short out the transistor is it?
I maybe need to check my 220k resistor. I poked around a little when it was plugged in and when I touched it, it buzzed


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## Mcknib (Jul 23, 2021)

It is possible but the 220K is on the same tag as the 404 base and collector you can check it's all good by continuity checking the base and collector pins, just make sure you snip off any excess wiring or component legs so they can't short on anything if accidentally moved

You know it works so I'm sure you'll find your problem soon, carry on giving things a prod and wiggling wires see it it springs into life

If it worked there's a good chance it's a poor connection I'd start with a wee wiggle of the in, out, power, ground and pot wires whilst putting audio through it


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## Feral Feline (Jul 23, 2021)

Great looking build, I'm sure you'll sort it with Mcnib's help.


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## megatrav (Jul 23, 2021)

You guys are the best. Thanks for the encouragement


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## megatrav (Jul 24, 2021)

Alright, so tried tracing the short and decided to rewrite the whole thing. Took me a couple hours but it's working consistently now. I jammed on it for a few hours and it's showing no issues!!

I can only wonder how much time was wasted on a shorted wire. This was one of the hardest and simplest pedals I've done. So glad it's finished haha


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## Mcknib (Jul 24, 2021)

Brilliant I knew you'd get it done

Yer ahead of me on it too, my box currently has it's first clearcoat drying

I was happy though decided to go toner transfer for the labelling and 2 or 3 clearcoats, the transfer went on perfect at the first try, normally takes me 2 or 3 attempts till I'm happy so yer spreading the good vibes

Try this one next I made one years ago that sat in a drawer then someone in a band over here asked if I could make one so I said I've got one handwired and started playing with it ended up wishing I'd kept it you can get lots of great sounds out of it


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## megatrav (Jul 24, 2021)

Mcknib said:


> Brilliant I knew you'd get it done
> 
> Yer ahead of me on it too, my box currently has it's first clearcoat drying
> 
> ...


Oh I definitely will! 
I have some tag board left and I am thinking about doing an Si Fuzz Face


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