Guitar Effect Test Box

I’m in var­i­ous stages of com­ple­tion for sev­er­al gui­tar effects at the moment and I’ll cer­tain­ly try to write a post for each of those in turn. How­ev­er, I first fig­ured I should post about my gui­tar effect PCB test box I put togeth­er. I by no means first came up with the idea. Paul of DIY Gui­tar Ped­als in Aus­tralia is who I first saw use & rec­om­mend one. In search­ing around for fur­ther ideas, I came across some notes on DIY Stomp Box­es about adding the probe, which can be used in diag­nos­ing PCBs that aren’t work­ing.

A MXR MicroAmp cir­cuit hooked up to the test box

As you can see, I went with a fair­ly large enclo­sure for this project. As it’s real­ly just the off-board wiring stan­dard to most any ped­al project, with no cir­cuit board, this is some­what a waste of space. How­ev­er, I want­ed to leave a bit of space for poten­tial­ly adding some more fea­tures at some point in the future1. This is a pow­der-coat­ed, alu­minum enclo­sure which is not at all nec­es­sary for this, as the wiring is out­side so the met­al box isn’t shield­ing any­thing. So the enclo­sure was a bit of a splurge. But as Mam­moth cur­rent­ly sells these 1590BB enclo­sures pow­der coat­ed for under $10, it’s not exact­ly a bank-buster. The entire test box is less than $25, and many of the parts I already had in my parts bin.

I cut up some cheap alli­ga­tor clips I bought off of Amazon.com to use for the con­nec­tors. They have lit­tle cov­ers over the clips, so they work quite well even when con­nect­ing into close­ly spaced wiring leads. I did knot these just inside the box to pro­vide some strain relief (though it’s not as though this thing is get­ting roughed up much). I used a Mam­moth Elec­tron­ics bypass wiring board just to sim­pli­fy things a bit. I tend to use a stan­dard wiring col­ors for all my projects: red for 9v, black for ground, green for sig­nal to board, and yel­low for sig­nal back from board.

The spa­cious guts of my test box

The one trick my box has is that I added a tog­gle switch to use a test­ing probe. This switch basi­cal­ly hi-jacks the sig­nal return (yel­low) and con­nects the probe (white) direct­ly to the box out­put jack. So if sig­nal isn’t com­ing back from the cir­cuit, I can flip this switch and then use the probe (which is noth­ing more than a 1μf capac­i­tor) to touch along the cir­cuit to trace where the fault is. It’s very sim­ple but incred­i­bly help­ful.

So to quote Paul of DY Gui­tar Effects, if you’re going to even build just more than a cou­ple of gui­tar effects your­self, you’re going to want to build some­thing like this. It’s so invalu­able to be able to test your PCB as soon as you get the com­po­nents installed but before you try to com­plete all the off board wiring & stuff­ing it into an enclo­sure. It’s also extreme­ly fun to hook up to a bread­board and test that way!

A Bazz Fuzz bread­board cir­cuit on the test box
My enclo­sure drill pat­tern
Wiring dia­gram for my test box


  1. For exam­ple, I also saw this post where some­one has added in the abil­i­ty to change the volt­age and add a volt­age sag (to sim­u­late a dying bat­tery), which is real­ly cool. []

Tremolo Pedal Build

Christ­mas in 2018 was a lot of fun and my fam­i­ly got me a lot of won­der­ful things. Among them, my broth­er, Dave, got me a gui­tar ped­al effects kit. This was a tremo­lo ped­al, which is def­i­nite­ly some­thing I would­n’t have got­ten myself. If you don’t know, a tremo­lo ped­al mod­u­lates the ampli­tude of the sig­nal. That is, it’s as if some­one is turn­ing the vol­ume knob up and down reg­u­lar­ly. This effect was built into many ear­ly elec­tric gui­tar ampli­fiers. In the late 50’s an Aus­tralian elec­tron­ics mag­a­zine had an arti­cle on a rel­a­tive­ly sim­ple cir­cuit for this effect. That design has since been mod­i­fied and incor­po­rat­ed into many pop­u­lar gui­tar effects. The kit I got is by Arca­dia Elec­tron­ics and uses the EA Tremo­lo design.

This kit has all of the com­po­nents, even jacks and switch, all direct­ly sol­dered onto the print­ed cir­cuit board (or PCB). This sim­pli­fies build­ing and is, in fact, what most com­mer­cial ped­als uti­lize to speed up fab­ri­ca­tion (and even allow for auto­mat­ed com­po­nent sol­der­ing). As such, it was a rel­a­tive­ly straight-for­ward build process that prob­a­bly took me under three hours total. And mind you, I am inten­tion­al­ly slow with this things because I want to real­ly enjoy the process and also to pre­vent mak­ing any easy avoid­able mis­takes.

Pop­u­lat­ed PCB for the Aca­dia Tremo­lo ped­al. You can see that I inten­tion­al­ly bent over a cou­ple of the elec­trolyt­ic capac­i­tors to keep them well clear of the Depth con­trol poten­tiome­ter.

The instruc­tions with the Aca­dia kits are very sparse. They basi­cal­ly include of a print­out of the PCB (which is very nice­ly screen print­ed and clear­ly marked, though) and a com­po­nent list. That’s it, there’s no oth­er instruc­tions or build steps giv­en. So, if this was a kit for a new builder, I’d sug­gest down­load­ing the instruc­tions for one of the oth­er Tremo­lo ped­als at Mam­moth Elec­tron­ics. They’re gen­er­al­ly sim­i­lar builds and pro­vide some good infor­ma­tion if you’re new to ped­al build­ing or elec­tron­ics. The Aca­dia kit came with high qual­i­ty com­po­nents. I test­ed some of the resis­tors and they were clos­er to nom­i­nal val­ues than the ones I pur­chase. The sin­gle diode in the kit had legs that real­ly did­n’t fit into the drilled through holes, but I just swapped it out for anoth­er 1N4001 in my parts bin. It’s not that the part was cheap; just that the pcb design as-drilled can’t accom­mo­date this par­tic­u­lar part. There’s prob­a­bly sev­er­al solu­tions to this, but this would be pret­ty frus­trat­ing for a first-time builder, I think. Oth­er­wise, I real­ly have no issues with this kit. It’s the first ped­al build I’ve done that I did­n’t have to trou­bleshoot at least one mis­take!

I labeled the ped­al once it was all closed up for test­ing. I’ll paint and dec­o­rate the case anoth­er day.

I got the hard­ware all sol­dered onto the board. I did add some elec­tri­cal tape to the back of the pots as well as to the inside of the case back. This is prob­a­bly not nec­es­sary, but I want­ed to pre­vent any pos­si­bil­i­ty of the pots or com­po­nents ground­ing out.

The ped­al sounds great. The vol­ume boost on this was pret­ty sur­pris­ing, in fact. Just dial­ing the Rate and Depth con­trols to zero makes this a pret­ty effec­tive clean boost, even. The range of the tremo­lo is all the way from noth­ing to com­plete vol­ume clip­ping. I record­ed a fair­ly poor sam­ple for this post, but the sound is real­ly great in per­son.

Tremo­lo Ped­al Demo

Repairing a Kid’s Bed

As part of my goals for 2019, I am going to try to write about some of my DIY and mak­er projects. So, here’s an unex­pect­ed one to start off the year…

The oth­er evening, I heard a thud and an “uh-oh” from my 11yo daugh­ter’s room. Turns out, when hop­ping on to the bed to read that night, the bed rail snapped. The bed rail was made from press­board, veneered to look like the rest of the fur­ni­ture (which I think is of slight­ly high­er qual­i­ty). Our daugh­ter felt ter­ri­ble about break­ing the bed, but in real­i­ty it’s a won­der it last­ed for the 7 years it did. An aver­age size tod­dler could break this stuff, let alone an aver­age size 11 yo girl. The press­board had cracked in two pieces, right through one of the screw holes for hold­ing the slats.

We con­sid­ered pur­chas­ing a new IKEA bed or sim­i­lar, but she said she real­ly like this bed and would pre­fer if we could just fix it. Maybe that was part­ly her still feel­ing bad for hav­ing done it, despite my wife and I assur­ing her it was­n’t real­ly her fault at all. The only down­side to this was that I was going to have to pur­chase a full size sheet of ply­wood at the big box store to get the 6′-6″ rails out of them. I nor­mal­ly have the store cut the board along the short dimen­sion, so that it’s less than 7′ long as to fit into my Hon­da Pilot. How­ev­er, in hind­sight, I should have had them then rip down some strips to make it eas­i­er to man­age. A 6′-8″ by 4′ sheet of 3/4″ ply­wood is only slight­ly eas­i­er to man­age by your­self than a full size sheet.

Old, press­board rail (bro­ken) and new, improved rails with hard­ware

I did get to try my hand at edge band­ing the ply­wood. Edge band­ing is a nar­row, thin strip of veneer (almost exact­ly like the sur­faces of hard­wood ply­wood) that has a heat-acti­vat­ed glue on the back­side. You sim­ply iron-on this to the edge of your cut ply­wood.1 It’s actu­al­ly a lot of nice fur­ni­ture and cab­i­netry is made and it’s a pret­ty amaz­ing trans­for­ma­tion. Of course, it’s also how a lot of cheap fur­ni­ture is made, too, but that’s often a plas­tic veneer rather than actu­al hard­wood. I could­n’t find maple veneer at my big box store, so I took a trip to my local Wood­craft shop. There, I also got a self-cen­ter­ing drill bit. I’d always con­sid­ered one of those to be for some­one who makes a lot of fur­ni­ture or cab­i­netry, but it’s worth it to buy some even for DIY’ers like me. It’s a huge time­saver for mount­ing hard­ware and real­ly makes the process more accu­rate.

Using a self-cen­ter­ing bit made mount­ing the hard­ware a breeze

So, I ripped down the near­ly full sheet of ply­wood on my lit­tle band saw. Again, I should have had the store cut this down, because it’s just not easy for one per­son to do this on even a high-end cab­i­netry saw, let alone a my small Ryobi2. It result­ed in some not-so-straight cuts, but they were good enough for this as I was­n’t joint­ing any­thing. I straight­ened out some of the bend met­al slat sup­ports in my machine vice and then got all the screw holes drilled out.

I did a small test piece with the edge band­ing and tried using one of those spring loaded edge band­ing trim­mers. The band­ing went on easy, but the trim­mer was not so great. It end­ed up tear­ing the band­ing in a lot of places. I still tried using it one the first rail, which was a mis­take. When try­ing to sand every­thing, the orbital sander grabbed one of those tears and ripped off a huge chunk of the band­ing. For­tu­nate­ly, I was able to cut out that piece by re-heat­ing the glue and Angela helped me put on a patch. It end­ed up look­ing just fine for our kid’s bed, but I learned my les­son. For the sec­ond rail, I sim­ply flipped the piece over and cut along the edge with a box-cut­ter blade. I then light­ly sand­ed over the cor­ner with a sand­ing block.

I used a sin­gle (though pret­ty heavy) coat of wipe-on polyurethane for the fin­ish. The final step was to stamp the work and then it was ready for assem­bly this after­noon. The final clip slid­ing in to place was so sat­is­fy­ing! The maple match­es the fur­ni­ture, but of course it will have to dark­en over time with expo­sure to light to ful­ly match. But, I’m pleased with the final result and I’m con­fi­dent this will last longer than the orig­i­nal.

Stamped and in place
Like new again!
  1. If you want to know more about edge band­ing, Bob of ILTMS made an excel­lent “Bits” video on the sub­ject late last year. []
  2. It’s actu­al­ly my old­er broth­er’s table saw. He just need­ed a place to keep it and I need­ed one to use, so that worked out for us. []

Learning to Weld

Some­thing I had want­ed to learn for many years is basic weld­ing. I’m not plan­ning on switch­ing careers or any­thingTh­ough you can make an excel­lent liv­ing as a welder and I would encour­age any young per­son inter­est­ed to learn about that trade.; I just want­ed to try it myself. As a struc­tur­al engi­neer, I’ve spec’d count­less welds on paper. I’ve only ever done very lim­it­ed met­al work (most­ly just cut­ting, drilling, & bolt­ing), and I want­ed to get a feel for what it’s like to join met­al with welds. I’ve learned from some of my engi­neer­ing friends, as well as watch­ing Grady at Prac­ti­cal Engi­neer­ing, that I’m not alone in this inter­est.

But it’s not nec­es­sar­i­ly easy to find a teacher for a curi­ous per­son rather as opposed to a stu­dent who is seek­ing a career. I don’t have a lot of friends that weld, either. But, mak­er spaces often have intro­duc­to­ry cours­es. So, I found a great “Intro to Met­als” course at Fort Hous­ton here in Nashville.

For bet­ter or worse, I was the only per­son who signed up that Sat­ur­day, so I got a three hour, one-on-one course from Court­ney Dai­ly, who is a local artist who hap­pens to work & teach at Fort Hous­ton. I real­ly rec­om­mend check­ing out Fort Hous­ton for all sorts of class­es. Court­ney, espe­cial­ly is a great teacher (and, from what I saw of her work, a tal­ent­ed artist and damn fine welder).

Fort Hous­ton Met­al Shop

I first made a bunch of real­ly ugly test welds to prac­tice on some scrap. We also prac­ticed cut­ting & drilling, which though not new to me was (is) still some­thing I had a lot to learn about.

Ugly welds

My lit­tle begin­ner project was to make a frame. I made a rec­tan­gle out of 1″ angles. Since we had the extra time, I also got to spend some time grind­ing it down (which prob­a­bly took longer than actu­al­ly weld­ing did, giv­en my work). It end­ed up look­ing bet­ter than I would have expect­ed for the my first project. I’ll prob­a­bly find a way to mount some art in it (or maybe use it for a gui­tar ped­al board, though it weighs a lot for that).

Ready to grind

Fin­ished frame

Ground to the core

So, as I was fin­ish­ing up grind­ing I made the com­ment that it looked shiny now, but it’d prob­a­bly rust over by the next day. Court­ney cor­rect­ed me that the steel would stay fair­ly pol­ished where I ground it for a long time. Well, it’s over three months lat­er and it has­n’t rust­ed a bit.

  • Smart welder lady: 1
  • Know-it-all dude: 0

Reminds me I always need to lis­ten & learn.

My First Stomp Box Project

For my birth­day, I decid­ed to work a com­plete­ly new project: build a gui­tar effects ped­al. I pur­chased the “Con­fi­dence Boost” project kit from BuildYourOwnClone.com (as in clones of pop­u­lar gui­tar stomp box­es). It’s a great project for about $15 which comes with detailed instruc­tions and makes a pret­ty decent lit­tle boost effect. The kit itself only comes with the print­ed cir­cuit board, elec­tron­ic com­po­nents, and off-board wiring such as jacks and poten­tiome­ter.

PCB com­po­nents and ini­tial off-board wiring

I sol­dered up the com­po­nents and off-board wiring and plugged-it up. And noth­ing. It did­n’t make any sound! I post­ed a cou­ple of pho­tos to the dis­cus­sion board and quick­ly got a response: the input jack was wired back­ward. In oth­er words, the sig­nal from my gui­tar was just going to ground and noth­ing was going on to the effect (or amp). I quick­ly re-worked the input jack and it worked. The tiny poten­tiome­ter (blue screw dri­ver knob in the pho­to above) was a bit tough to use.

I decid­ed it would be fun to go ahead and wire this up as an actu­al stomp box, so I ordered a few more com­po­nents and an enclo­sure. I spent some time paint­ing and fin­ish­ing the enclo­sure. I just used a white pen to draw out the label­ing, but it turned out just fine for this project. I read up on how to wire a footswitch for true bypass (when it’s off, it does­n’t affect the sig­nal at all) and with an LED indi­ca­tor light.

Enclo­sure design
Ful­ly wired effect in the enclo­sure
Wired up and turned on

But of course, it only real­ly mat­ters how it sounds. I’m far from a capa­ble gui­tar play­er and even worse when try­ing to film my play­ing, but here’s a small sam­ple.