Pedal build diary - blow by blow account

thermionic

Adam_MD said:

Philtre said:

aord43 said:

Tantalum caps are good to keep the size down if you don't want to use chunky electrolytics.  I used them for the first time this week (Keeley 4-knob compressor) and it worked fine.  The only potential gotcha is identifying the polarity.

Interesting. I might check these out.

The only word of caution I have with tants is make sure you don’t exceed the stated voltage and never install them the wrong way round.  If they fail they go bang.  

I used to work in electronics and I once specced a test board for a buck converter chip I'd designed. The boards were populated by a sub-contractor, and had a bank of about 6 beefy tantalum caps smoothing the output. I had about five of these, with various versions of my chip on them. Unbeknownst to me, one of the boards had the caps in the wrong way, but as most of the testing was done using a 12V input converted down to 1.2V, they could cope with about a volt of reverse bias. One day I was testing something like 24V down to 12V, and I had picked the one board with the reversed polarity caps... The height of the flames was impressive, but they extinguished themselves quite quickly!

The worst part was there was an engineer in the lab with me, from an outside company servicing a piece of equipment. He didn't bat an eyelid.

Adam_MD

thermionic said:

Adam_MD said:

Philtre said:

aord43 said:

Tantalum caps are good to keep the size down if you don't want to use chunky electrolytics.  I used them for the first time this week (Keeley 4-knob compressor) and it worked fine.  The only potential gotcha is identifying the polarity.

Interesting. I might check these out.

The only word of caution I have with tants is make sure you don’t exceed the stated voltage and never install them the wrong way round.  If they fail they go bang.  

I used to work in electronics and I once specced a test board for a buck converter chip I'd designed. The boards were populated by a sub-contractor, and had a bank of about 6 beefy tantalum caps smoothing the output. I had about five of these, with various versions of my chip on them. Unbeknownst to me, one of the boards had the caps in the wrong way, but as most of the testing was done using a 12V input converted down to 1.2V, they could cope with about a volt of reverse bias. One day I was testing something like 24V down to 12V, and I had picked the one board with the reversed polarity caps... The height of the flames was impressive, but they extinguished themselves quite quickly!

The worst part was there was an engineer in the lab with me, from an outside company servicing a piece of equipment. He didn't bat an eyelid.

I'd probably have been hiding under a chair 

Philtre

Part 11

Right, let's get on with this thing. I'm going to connect the vero board up to the test harness and see if this thing rocks. Or not...


Testing Board

As I said before, I'm not going to connect it to the actual pots and jacks that I'll be using in an enclosure just yet. I have a testing breadboard that I can quickly connect everything to. Here it is:




Starting from the left, there's a jack socket for the guitar input, one for the guitar output and then 5 trim pots that are stand-ins for the 5 potentiometers that I'll use later.

The jack sockets are attached to the breadboard and there are two small lengths of black wire connecting the ground terminals to the negative ground rail (the blue strip on the breadboard).

These sockets are 6.3mmm Mono Jack Sockets from Bitsbox

The trim pots are also from from Bitsbox. I bought a Trimmer Kit containing 45 of these pots with a range of values from 100R to 1M ohms. Very handy for prototyping.

From left to right the ones I've attached to the breadboard are:

- 100k (Density)
- 50K (Bias)
- 10K (Fuzz)
- 10K (Filter)
- 100K (Level)

The rubric in the layout diagram specifies that some of the pots are Linear and some are Logarithmic:

"Density 100K Lin, Bias 50K Lin, Fuzz 10K Lin, Filter 10K Log, Level 100K Log"

These trim pots are all Linear but for testing it doesn't matter. At this stage I just want to ensure that the circuit basically works. In fact, sometimes I use trim pots that are not the exact value specified but close enough.


Breadboard connections

Now I'll refer to the layout diagram again to make the connections:




The first thing I do is see if there are any connections that I can make on the breadboard:

Density 1 & 2 - this wire will connect to the first two connections of the Density pot. So I can connect these two together on the breadboard.
Bias 1 & 2 - this wire will connect to the first two connections of the Bias pot. Again, I can connect these two together on the breadboard.
Level 2 / Filter 2 & 3 - this wire needs to connect to three places. I can connect all three with jumper wire on the breadboard.
Level 1 and Fuzz 3 to ground - this means that I can connect a short jumper wire from each of these to the breadboard's negative ground rail.
Level 3 to output - this means I need to add a jumper wire from the third connection of the Level pot over to the output connection on the output jack socket.

Here's what those connections look like:




You can see the long blue jumper wire connecting from the Level pot to the output jack socket. Also, the two short black jumpers connecting to ground. Ignore the LED in the top-right as I just put it there to remind me to connect it up later.


Connecting the Vero Board

Now I'll connect all the wires from the vero to the breadboard. Here's a list of the connections as specified in the layout diagram, working from the top-left and then the top-right downwards:

9V - connects to the red power rail of the breadboard
Sw3 - (this wire is already soldered to the switch)
LED+ - connects to the positive side of the LED that I'll add to the breadboard
Density 1 & 2 - connects to the Density pot terminal 1 or 2
Sw1 - (this wire is already soldered to the switch)
Density 3 - connects to the Density pot terminal 3
Sw2 - (this wire is already soldered to the switch)
Input - connects to the Density pot terminal 1 or 2

Bias 3 - connects to the Bias pot terminal 3
Bias 1 & 2 - connects to the Bias pot terminal 1 or 2
Level 2 / Filter 2 & 3 - connects to either of the Level terminal 2 or Filter 2 or 3 terminals (since they're all connected together)
Filter 1 - connects to the Filter pot terminal 1
Fuzz 2 - connects to the Fuzz pot terminal 2
Ground - connects to the black power rail of the breadboard

And here it is connected up:




Note that I've connected the 3mm red LED between the negative ground rail and the connection coming from the vero board.

I've connected a 9v battery (courtesy of Electro-Harmonix) to the breadboard's power rails and I've also plugged in a guitar and an amp. :-)

And I'm ready to rock....and I'm hitting a power chord on my Strat...

....does it work?

Tune into tomorrow's thrilling episode to find out!

thermionic

That's a cool little testing setup you have there.

Philtre

Part 12

Yes, it works!

I connected the battery, the guitar and the amp, gently turned up the volume.... and was regaled with a loud siren-like oscillation. I was prepared for this, though, as the Supersonic Fuzz Gun is supposed to do that.

When I built a Fuzz Factory earlier this year a similar thing happened and I spent a long time re-checking all my solder connections looking for errors. Then I thought, "Wait. Go on Youtube and find out what this thing is supposed to sound like". Yep, it was supposed to sound like a wailing banshee with certain settings. Same with the Fuzz Gun. Flipped the SPDT switch and it sounded relatively normal.

So I played around with it for a while, adjusting the trim pots with a screwdriver. Good fun.

Here's the plan for some experiments before I start planning the enclosure:

• I'd like to try some 2N5088 transistors in place of the 2N5089s to hear what difference they make (here's where using sockets for the transistors helps)
• I'd like to change R5, the 10K resistor, for a pot so I can control the oscillation rather than it just being either on or off. Not sure how best to do this as I don't want to de-solder R5.
  

I'll report back later...

Philtre

Part 13

I tried the experiments:

• The 2N5088 transistors sounded like a wet fart. There was no oscillation in that mode. Back to the 2N5089s!
• I disconnected the SPDT switch and connected a 10k pot (also tried a 5K pot) to the "Sw1" and "Sw2" connections. All the pot did was change the frequency of the oscillation and then turn it off past a certain point. As turning the "Density" pot already changed the frequency of the oscillation it doesn't bring much to the party. So, back to the SPDT switch.
  

Enclosure

So now I need to think about what enclosure to use and the artwork.

A 1590B might be a bit tight for 5 pots and a switch, although I have built a Fuzz Factory with 5 pots but no switch. But a 1590B wouldn't leave much real estate for artwork. I could use a larger 1590BB enclosure. Not sure what to do.

Here's some examples I found on Google Image Search:

The original from DBA:



A Fuzz Hound:




A Super Weapon:




A Wooden Version:




Something Else:




Chemistry Set:




Er, OK:




More Chemistry:




Suggestions on a postcard please!

FatPete

How are you intending to apply the artwork?

Philtre

FatPete said:

How are you intending to apply the artwork?

Inkjet printer onto sticky white paper. Stick this to the top of the enclosure, and then cover with Envirotex Lite.

FatPete

Philtre said:

FatPete said:

How are you intending to apply the artwork?

Inkjet printer onto sticky white paper. Stick this to the top of the enclosure, and then cover with Envirotex Lite.

That sounds a lot easier than the nightmarish time I've just been having using waterslides. Next time...

Philtre

FatPete said:

That sounds a lot easier than the nightmarish time I've just been having using waterslides. Next time...

What problems have you had?

I'm still not convinced that Envirotex is the ultimate solution. It can go wrong, takes a long time to harden, and scratches easily.

It would be great to find a solution where you could just stick a printed label on the enclosure and then use a brush to cover it with some kind of thin, transparent, smooth, brush-stroke free finish that dries quickly.

Adam_MD

Philtre said:

FatPete said:

That sounds a lot easier than the nightmarish time I've just been having using waterslides. Next time...

What problems have you had?

I'm still not convinced that Envirotex is the ultimate solution. It can go wrong, takes a long time to harden, and scratches easily.

It would be great to find a solution where you could just stick a printed label on the enclosure and then use a brush to cover it with some kind of thin, transparent, smooth, brush-stroke free finish that dries quickly.

Thats weird I’ve never had any pedals coated in envirotex scratch I think it’s pretty hard stuff once it’s cured.  Yes it takes a week or so to fully harden but doesn’t take a lot of prep or effort to pour.  If you do several enclosures at once you can get on with building the circuits while it cures.  

Its definitely a lot easier and a lot less hassle than trying to spray clear coats.  

FatPete

Philtre said:

FatPete said:

That sounds a lot easier than the nightmarish time I've just been having using waterslides. Next time...

What problems have you had?

...

Probably just what you'd expect using waterslides covering the whole top of a pedal enclosure, especially as one was the larger 1590BB. I had Rothko & Frost print them for me and their stuff is a lot less inclined to fall apart than the diy sheet I tried previously, despite being thinner. It still was impossible (for an oaf like me) to stop it wanting to fold under itself, wrinkle, catch air bubbles etc. etc. On the plus side it's nice to have the metallic ink and to see my poorly applied metallic paint through it.

Octafish

Philtre said:

FatPete said:

That sounds a lot easier than the nightmarish time I've just been having using waterslides. Next time...

What problems have you had?

I'm still not convinced that Envirotex is the ultimate solution. It can go wrong, takes a long time to harden, and scratches easily.

It would be great to find a solution where you could just stick a printed label on the enclosure and then use a brush to cover it with some kind of thin, transparent, smooth, brush-stroke free finish that dries quickly.

I've not got round to ordering any Envirotex yet (looks like you can only get it from the US so takes a few weeks to turn up) and have been using clearcoat aerosol laquer which is not has tough as Envirotex, but still looks good and is very easy and quick to apply. I've also found I get better results from the transparent adhesive vinyl rather than the white. These are best ones so far, I really need to get a new camera, pics look a bit grainy....

Les Luis and Small Stone.
https://i.imgur.com/om01nhe.jpg
Electra Drive with diode/cap choice.
https://i.imgur.com/O8vNoUB.jpg

Philtre

Adam_MD said:

Thats weird I’ve never had any pedals coated in envirotex scratch I think it’s pretty hard stuff once it’s cured.  Yes it takes a week or so to fully harden but doesn’t take a lot of prep or effort to pour.  If you do several enclosures at once you can get on with building the circuits while it cures.  

Its definitely a lot easier and a lot less hassle than trying to spray clear coats.  

I agree that it's the better solution compared to spraying clear coat. It's probably fine after more time hardening. I'm searching for the holy grail solution... ;-)

Philtre

@Octafish The ET from Amazon does come from the states, but it only took about 4 days to arrive from when they shipped it.

Those pedals look great.

The transparent vinyl works best on the plain aluminium it seems. Not so good on a dark colour.

What brand of clearcoat aerosol laquer do you use?

Octafish

Cheers yeah transparent works best on lighter coloursed enclosures with stronger colours. I'll have to order some Envirotex, thin kwas on Amazon it said 2-3 weeks to deliver, but that often is over-conservative. I've just been using Hycote clear laquer , you can get It from The Range for £4.99. I do 4 or 5 thin coats with 5 or so min between each. You can handle it within a few hours, but I do leave it a 24-48 hours to harden before fitting up. Don't think there's any quick drying option.

Edit - I also used some of this on earlier pedals, not sure if it's any tougher and took a bit longer to properly harden.

Adam_MD

Philtre said:

I agree that it's the better solution compared to spraying clear coat. It's probably fine after more time hardening. I'm searching for the holy grail solution... ;-)

If I was going to do a run of pedals I’d have them screen printed but for small batches and one offs I haven’t found anything as easy to use with as high a gloss or as hassle free as envirotex.  

Philtre

Part 14

And now I'm going to drill the enclosure and print out the artwork.

I spent a lot of time yesterday umming and ahhing about what size enclosure to use. I played around with placing 5 knobs and a stomp on a 1590B sized enclosure and, even though I could probably pack everything on, I don't think there'd be much room left for artwork. So I decided to use a grey 159BB size enclosure (bought from Tayda).

Earlier today I spent some time thinking about the artwork with the theme being "supersonic" and "gun", or "ray gun". A Google search provided me with the solution which I found here. I then spent a lot of faffing around in the image editing software ensuring everything lined up.

Onward...

So now I gather all the pots and knobs and switches and wrap the enclosure in masking tape. This offers some protection from drill bits, metal shavings, and also means its easier to mark out the drill points:




Then I print out the artwork on a black and white laser printer to check if everything lines up with the hardware. Some of the text doesn't line up so I adjust that and try again:




Now I measure where the holes are going to be for the pots, switches and sockets. I use a centre punch to mark these out:

 


Then I drill some 3mm guide holes and then use the stepper drill to drill out all the holes:

Mini-switch = 6mm
Pots = 7mm
Jack Sockets = 10mm
Stomp Switch = 12mm
DC Socket = 12mm

 


This is it drilled. Five holes across the top for the pots, then a hole for the mini-switch, a small hole for the LED and the big hole is for the stomp switch. You can't see the holes for the DC socket or the jack sockets, as they are on the sides:

 


Here's the artwork (not my handiwork, I found it on Google Image Search) printed on glossy sticky paper:

 


And then I stick it onto the enclosure and cut out the holes with an X-acto knife (the LED hole lines up with the end of the ray gun):

 

It's not perfectly centred on the box, but sod it, it's close enough.

Now I'll put it to one side and get ready for the Envirotex stage.

Adam_MD

That decal looks excellent Phil I’m doing an envirotex pour tonight as well if I can find the time.  

FatPete

Can we just say the 'great minds' thing and never mention this again?