Pedal build diary - blow by blow account

Philtre

Introduction

I started a thread here 3 months ago, C18Q1 Learn electronics and build a pedal, where I chronicled my challenge of learning basic electronics and building a guitar effects pedal. With the valuable help of forum members here and elsewhere I ended up building ten pedals and gaining a much better understanding of basic electronics.

I'm by no means an expert but I have learnt many things the hard way and so I want to pass on some of that experience mainly so that others can avoid the mistakes I made and it might inspire someone to have a go at putting a pedal together. So I thought I would do a blow by blow account of building a pedal as a kind of diary. If anything goes wrong and I mess up, I'll post that here too with steps to fix the problem. It might go horribly wrong!

Philtre

Part 1

So, the first thing to do is choose a pedal to build. You can buy kits where a PCB and all the components are supplied and you just solder them together, but, hey, where's the challenge in that? (Well, OK, it is a kind of challenge). But let's go back to basics, and so here's the criteria:

• The circuit will be built using "vero" board, or strip board
• Components will be sourced from various electronics components suppliers
• It'll fit inside of a metal enclosure like the Hammond 1590B
• It will be relatively simple

The best site for this kind of thing is Guitar FX Layouts where you can find various layouts for all kinds of pedals.

I've decided to go for the Death By Audio Supersonic Fuzz Gun.

Here's a video of it in action:

Philtre

Part 2

Going back to the Death By Audio Supersonic Fuzz Gun website the first thing I look for is the date and the tag "verified". This layout was published 6 years ago to the day in 2012 and it's tagged as "verified". This means that it's tried and tested and so any errors and tweaks should have been ironed out by now. That's a good start.

So what have we got?

An image of a vero layout and some comments. That's it!

I always read through the comments to see if there are any gotchas or problems that builders have encountered. Let's list a few of those:

• Some discussions around what transistors to use
• Some discussions around some minor mods
• Some build errors
  

So nothing serious. OK, let's do it!

Here's the layout:



The first image represents the front facing view of the vero board with all of its components and connections, while the second image represents the back of the vero board but still looking at it from the front (imagine you had x-ray vision). We'll come back to this later. For now I'll summarise what there is in the first image:

• A small vero board measuring 20 x 9 holes (we measure in holes not size)
  
• Some components - resistors, capacitors, and transistors
• Some off-board connections - these are the connections to the power supply ("9V", "Ground"), a switch ("Sw1", "Sw2", "Sw3"), a LED ("LED+"), "Input", and some potentiometer controls ("Density 1 & 2", "Density 3", "Bias 3", etc)

The three black components are transistors and they are labelled "Q1", Q2", and "Q3". In the rubric it says "Q1 and Q2 are 2N5089, Q3 is 2N5306" - this tells us the types of transistors. The other components' values are labelled directly in the vero layout, It also says "Switch is SPDT", but more on that later.

So....I need to make a bill of materials from this layout. I'll do that now:

Resistors (the cyan things):

2 x 180k
4x 910k
1x 10k
1x 2K2
1x 4M7
1x 750R

Capacitors - there are three types of capacitors here: ceramic (the light brown one), electrolytic (the blue ones) and the brownish red ones. These last ones can be polyester film caps. Here's what I need:

1x 470pF ceramic
1x 10nF polyester
2x 100nF polyester
1x 330nF polyester
2x 4.7uF electrolytic
1x 100uF electrolytic

And the transistors:

2x 2N5089
1x 2N5306

The rubric lists the potentiometers:

1x 100k linear
1x 50k linear
1x 10k linear
1x 10k logarithmic
1x 100k logarithmic

Actually, that's 5 potentiometers, or "pots". I'm not sure these will fit in a 1590B sized enclosure. I'll come back to that later. Also, the difference between "linear" and "logarithmic".

There's also mention of a "SPDT" switch. This stands for "Single Pole, Double Throw". What does that mean? Fuck knows. I'll come back to that later...

Philtre

Part 3

Oh yes, I think it's useful to have the schematic to cross reference and see the theory behind it all. After Googling "Death By Audio Supersonic Fuzz Gun Schematic" I found this:

Philtre

Part 4

OK, I'm going to order the parts. I can get most things from:

Bitsbox - a great place for audio components
CPC - good for general purpose stuff like resistors and capacitors
RS - like CPC, good for general stuff
Tayda - a really great and cheap company in Thailand - they do a 15% discount code about twice a month - keep a lookout on their Facebook page.

But to be honest, I've already stocked up on some resistors and capacitors since it's cheaper to buy in larger quantities.

Here's my buying guide:

• Knobs, Potentiometers and Enclosures - from Tayda. Cheap and good quality.
• Stomp switches - https://www.ebay.co.uk/itm/Alpha-Taiwan-3PDT-Footswitch-with-Solder-Lugs-/253111548438?hash=item3aee9fba16
• Resistors - I bought a pack like this one https://www.ebay.co.uk/itm/2600pcs-130-Values-1-4W-Metal-Film-Resistors-Resistance-Assortment-Kit-Set-1-/263532240889?hash=item3d5bbedff9 - and now I top up with 50 packs of the common values like 1k, 10k, 22k etc from CPC.
• Electrolytic Capacitors - I bought 50 or 100 multi-packs from CPC in values of 1uF, 3.3uF, 4.7uF, 10uF, 22uF, 33uF, 47uF, 100uF
• Polyester box film Capacitors - I get these from Bitsbox or eBay. Values range from 1nF to 0.1uF.
• NP0/C0G Capacitors from RS Online - 220pF, 470pF, 100pF, 150pF, 47pF, 22pF, 10pF (more on these later)
• Chips, Transistors, Diodes usually from Bitsbox or whoever has them. But I buy these only when I know what pedals I'm going to build.
• I compare prices between Bitsbox, CPC, RS Online, and Tayda. And whoever does the best postage deals.
  

The only tricky component was the 2N5306 transistor which I couldn't find at CPC, RS, or Bitsbox, but Tayda have some so I ordered a few, at the same time as stocking up on some more enclosures and knobs.

Philtre

Part 5

So the plan, over the coming days, is:

• Collect the various components
• Cut and prepare the vero board
• Make the first connections and add some components

Oh yes, I get the vero board from Bitsbox. I buy it in packs of 5 or so and it looks like this:

You can also get it on Amazon:

Philtre

Part 6

And, as if by magic (or in the tradition of Blue Peter's "here's one I prepared earlier"), I have the components!





From the left there are 4 polyester box capacitors, a 470pF multilayer ceramic C0G capacitor, three electrolytic capacitors, the three transistors and, at the top, the resistors.

• The four polyester box capacitors are from Bitsbox. These are generally a good size, not too tall and fit nicely on a veroboard
• The 470pf multilayer ceramic C0G capacitor is from RS (link), I chose a "C0G" type (or "NP0") because it has a better tolerance than plain ceramic, and less likely to be microphonic. Also, because the gurus on this forum advised me to use C0G/NP0 types for ceramics where possible
• The three electrolytic capacitors are made by Panasonic and are from CPC. I chose to use a better quality rather then cheaper brands because I can. ;-) (Notice one of the caps has short stubby leads. I salvaged it from another project.)
• The three transistors are from Tayda. I'm not sure about the quality of these so I'm not going to directly solder them onto the vero board, but will instead use sockets in case I need to swap them out.
• Notice there are eleven resistors, not ten. The circuit uses a 4.7M ohm ("4M7") resistor which I don't have and I didn't want to order a pack of 100. ;-) I do, however, have a 3M ohm resistor and a 1.5M ohm resistor so, using the magic of Ohm's law I can combine them in series to give me 4.5M ohms, which is close enough. I'll need to think about how to solder them together so it doesn't look messy.

At this stage I'm not concerned with the SPDT switch, nor the pots. For now I just want to prepare the vero board and solder these components onto it.

Philtre

Part 7

Now I need to cut a piece of vero board to size. When I buy this stuff I get it in sizes of 24 tracks by 37 holes. The vero that's used in the circuit is 9 tracks by 20 holes so I need to cut it to size with a Stanley knife.

TOP TIP - double check that you have the vero board the right way round. That is, you need 9 tracks going horizontally. A few times now I've cut it the wrong way round and ended up with the tracks going vertically. D'oh!

Here's a piece of vero that I'm using from a previous cut. At the moment it's 23 tracks by 20 holes. So I need to make another cut to reduce it to 9 tracks in height. I mark out a line on each side of the board with a pencil on the 10th row. It makes sense to cut through a row of holes:



Then, holding down a steel ruler with one hand acting as a guide, I make a series of scores with the Stanley knife with the other hand starting on the copper side, flip it over, and cut another series of scores on the other side:



I keep scoring it with the knife until I get a clean cut:



Be careful of the dust, it's nasty stuff and you don't want to breathe it in. Also, watch your fingers. What you can't see in the last photo is a piece of my fingernail where the knife took out a nice chunk. ;-)

Philtre

Part 8

Now that the vero board is cut to size I need to make a few cuts in the copper tracks and solder in one wire connection as per the vero layout diagram above. The vero layout's 2nd image shows what needs to be done:



The red squares represent 9 cuts in the copper tracks on the back-side of the vero board and the black line represents one wire connection on the front of the vero board.

Remember that this image shows the cuts as if you are looking from the non-copper side of the vero board (pretend that you have x-ray vision). This means that when you are actually making the cuts the board is flipped over horizontally and so you need to work with a mirror image of the cuts diagram. I use image editing software to create a flipped mirror image:



Now I work from this image and not the original one. Using a pen or pencil I mark on the vero board where the cuts will be:



The cuts are made using a 3mm drill bit, turning it clockwise just enough so that it creates a break in the copper track. Not too much pressure is needed. I bought one of these to make my life easier:



I twist and cut each one like so:



Here's the finished job:



At this stage it's a good idea to grab a multimeter and set it to continuity mode to make sure that the cuts are true, and that there are no fragments of copper that might still allow a connection across the tracks.

I now need to add one wire connection. This time the vero layout shows it correctly because the connection will be added to front of the vero board. It's just a short piece of wire cut to the appropriate length. With a pen I mark the two holes on the front-side of the vero board:



(Notice my favourite tool - a big blob of blu-tack. I use this to hold the vero board in place when I'm working on it. Also I use it to hold the components in place when soldering).

I'll bend the wire so it pokes through the two holes then solder it on the other side and snip off any excess wire with some cutters:






That's enough for today. Next time I'll solder the components onto the vero board.

paulnb57

Interesting stuff, thanks for sharing!

aord43

@Philtre ;
"I use image editing software to create a flipped mirror image:"  That's a damn good idea.  More than once I have put a cut in the wrong place because the image is backwards.  Now I am paranoid and count the rows and columns at least twice before making any cut.
Also I check every cut with a meter as you stated.  And after every solder joint I run a craft knife along the gaps between tracks to ensure no micro-bridges.

Philtre

Part 9

Today I'm going to solder the components to the vero board. This is the fun part. In fact, I think this is probably the easiest part of the whole process. :-)

I like to add the shortest in height components first so that I build up the board from low to high. It makes it easier to fix the components to the board and my blob of blu-tack ("Barry") likes it that way. So the usual order for soldering the components is:

- resistors
- diodes
- small ceramic capacitors
- sockets for integrated circuits and transistors
- polyester capacitors
- electrolytic capacitors

As this circuit doesn't use any diodes we can miss out that stage (although later I'll add a diode to protect against reverse polarity from the power supply but it will be off-board).


Resistors

I solder on the resistors first working from left to right:



It's worth double-checking the value of each resistor before soldering it. You can do this from the coloured bands if your eyesight is good or by checking the impedance on a multimeter. These ones are metal film resistors with a 1% tolerance so their values are pretty close to what they should be. You can use other types and tolerances like carbon film 5% tolerance, but these ones seem to be good quality and are cheap enough when bought in bulk.

Remember that I said I didn't have a 4.7M ohm resistor? At the top-right you can see where I've soldered a 3M ohm resistor and a 1.5M ohm resistor together in series. I made a loop back from one of the leads of the resistors and soldered it to the lead of the other one. It looks a bit weird but it will do the trick since 3M ohm + 1.5M ohm = 4.5M ohm which is close enough.


Blu Tack

When I solder components I push their leads through the vero board holes and then flip the whole thing over using Barry the Blob of Blu-tack to hold the component in place and stick it to the desk:



Once each lead of a component is soldered to the board I nip off any excess with some edge cutters and put the leads in a bag so I can re-use them for connections and jumpers on future projects (also, I'm as tight as Norbert Colon).


Small capacitor and transistor sockets

Now, I'll add the small ceramic capacitor and some sockets for the three transistors. I could solder the transistors directly to the board but there are two main reasons not to do that. Using a socket for these delicate components ensures that (1) the heat of the soldering iron doesn't damage the transistor and (2) if I have a duff transistor, or put it in the wrong way around, or want to experiment with a different type, I can very easily swap these components out.

To make the three transistor sockets I bought a strip of "40 Pin DIP SIP IC Sockets Adaptor" from Tayda. It looks like this:



Using a Stanley knife I cut off three short lengths of three pins, one for each transistor:



And, together with the small blue ceramic capacitor (it's dinky, see if you can spot it), solder them to the board:



Next, I solder the four poly box capacitors to the board, bending their leads in some cases so that they span the required distance:



And then the three (blue) electrolytic capacitors (they remind me of tiny beer cans):



Be careful with electrolytic capacitors as they are polarised. They have a negative and a positive side so it's very important to place them the right way around. Looking at the vero layout diagram you can see that they are represented by blue circles, and on one side of each blue circle there is a small white mark. In each case this small white mark is facing downwards. This is the negative side. The actual electrolytic capacitor will also have a white negative marking on its body and its lead will be shorter than the other one. If in doubt, check it out!


Final stages

Finally I push the transistors into their respective sockets.

The leads on these are too long so I snip them with my wire cutters and, making sure I have them the right way around, gently push them into their sockets:



And that's it, all the components are now soldered to the vero board!

But before continuing to the next stage it's worth double-checking all the solder joints to make sure there are no duff connections, or that you haven't inadvertently welded a blob of solder across the copper tracks. Time spent inspecting your solder work now under a magnifying glass and a good light will be time well spent.

As this vero board will be sitting inside of an enclosure and on top of the backs of the potentiometers, height is an issue. If any of the components are too tall, you won't be able to get the back of the enclosure on.

Here's a side view of the board:



The tallest components are the electrolytic capacitors and the height of the whole edifice is about 13mm. That should be OK to allow enough clearance in the enclosure. We'll find out if this is enough later on...

Philtre

aord43 said:

@Philtre ;
"I use image editing software to create a flipped mirror image:"  That's a damn good idea.  More than once I have put a cut in the wrong place because the image is backwards.  Now I am paranoid and count the rows and columns at least twice before making any cut.
Also I check every cut with a meter as you stated.  And after every solder joint I run a craft knife along the gaps between tracks to ensure no micro-bridges.

"Now I am paranoid and count the rows and columns at least twice before making any cut." - Only at least twice? I'm getting older and I probably count them an unhealthy number of times. ;-)

nick79

Excellent thread, thank you very much

SteveF

@Philtre I've got some polybox and ceramic caps on the way, but I'm a bit confused by which electrolytic ones to buy.  Does it matter what series/voltage/tolerance etc they are?  Looking in the stores, there seems to be a huge choice and price variance.  Presumably they need to be at least 12V rated but does it matter if they're way over?  A lot of the tolerances seem to be around 20% which seems high when compared to resistors etc.  

As an example, if I filter on CPC for Panasonic electrolytic caps at 22uF, there are 29 options rated between 16V and 100V, some of which (50 and 100) are specified as 50/100VDC whilst none of the others seem to have the DC specification.  All have a tolerance of 20%.  http://cpc.farnell.com/c/electronic-electrical-components/capacitors/aluminium-electrolytic-capacitors/prl/results?brand=panasonic-electronic-components&capacitance=22uf ;

Any advice appreciated  

Adam_MD

SteveF said:

@Philtre I've got some polybox and ceramic caps on the way, but I'm a bit confused by which electrolytic ones to buy.  Does it matter what series/voltage/tolerance etc they are?  Looking in the stores, there seems to be a huge choice and price variance.  Presumably they need to be at least 12V rated but does it matter if they're way over?  A lot of the tolerances seem to be around 20% which seems high when compared to resistors etc.  

As an example, if I filter on CPC for Panasonic electrolytic caps at 22uF, there are 29 options rated between 16V and 100V, some of which (50 and 100) are specified as 50/100VDC whilst none of the others seem to have the DC specification.  All have a tolerance of 20%.  http://cpc.farnell.com/c/electronic-electrical-components/capacitors/aluminium-electrolytic-capacitors/prl/results?brand=panasonic-electronic-components&capacitance=22uf ;

Any advice appreciated  

You want to make sure the voltage is at least 25v to be safe whether you’re running a pedal at 9v or 18v.  It also doesn’t mater if they’re way over that the 1uf caps I buy are rated to 50v and work fine that just means what voltage they can safely handle.  

I’d also expand your search beyond Panasonic to include nichicon their caps are also made in Japan and are very high quality.  As to the tolerance 20% is pretty much what you get with electrolytic caps which is the same tolerance your pots will be but they’re more often in the power section than the audio path.

As to sizes I usually search for height at 5mm and 7mm.  Both Panasonic and Nichicon do some ranges of mini caps in those sizes which will give you plenty of room to fit them in any enclosure.

I hope that helps @SteveF ;

SteveF

@Adam_MD thanks, that's great  So just to check as long as I have the capacitance correct, the rated voltage is over 25V and the height is around 5-7mm I should be fine?  Series doesn't make any difference - e.g. AK and AD series with Panasonic?

i.e. these should all be fine (I will look at the other brand too): http://cpc.farnell.com/w/c/electronic-electrical-components/capacitors/aluminium-electrolytic-capacitors/leaded-aluminium-electrolytic-capacitors?brand=panasonic-electronic-components&capacitance=22uf&voltage-rating=25v|35v|50v&height=5mm|7mm

Can't see any Nichicon on CPC but there are some Multicomp ones which seem to be around a third of the price but similar in spec? CompareProductsDisplay

SteveF

Oh, and the 'DC' in the voltage rating doesn't matter?

Adam_MD

Yes that cap you posted will be fine I wouldn’t sweat too much between the different Panasonic mini ranges you honestly won’t be able to hear any difference between them.  

Multicomp are also fine I just prefer Panasonic and nichicon for quality and reliability.  

SteveF

Thanks a lot for your help I'll keep you all posted how I get on.

Philtre

@SteveF - exactly as @Adam_MD says.  

Ideally you want at least 25v rating, although I bought some multipacks rated at 16v because that's all they had in packs of 50 and 100, and also because I know that I'm only going to build pedals with 9v DC supply.

For me, the important thing is their physical size, especially height, which is why it's always good to read the provided data sheets. A lot of the electrolytics are 11mm in height which can be too tall if the board sits above a mini jack switch mounted in the enclosure, say, but will be OK if the board is resting on the back of the pots. You can solder them on with some extra lead length and then bend them downwards to gain more height like this:



As @Adam_MD says, some of the other brands are good, too, like, Rubycon - http://cpc.farnell.com/rubycon/50ml1mefc4x5/capacitor-1uf-50v/dp/CA07525?CMP=TREML007-005

BTW - I find the CPC and RS sites a real pain in the butt to navigate and filter. ;-)