Building the Mod Kits DIY Trill Tremolo Guitar Pedal

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Quite a while ago, I decided I wanted to try a pedal kit. Not only because of the challenge of building the kit, but also because of the cost of pedals. The kit was only $43.95 and shipping was free. I decided on the Trill Tremolo kit as I love the old Fender Tremolo. Here’s how the build went…

I ordered the kit on a Sunday afternoon and it arrived on my doorstep Wednesday from Tempe, AZ. Nice, prompt service, as I live out on the Oregon coast, where freeways and four lanes are few and far between. The kit was packed for shipment in a small box with plenty of paper wrapping for protection and came through the USPS system without a scratch. In my excitement, I opened it up and looked it over before taking pictures and had to re-wrap everything for a photo shoot.

I had originally wanted to build the “Persuader”, a “Tube Screamer” type pedal from MOD Kits, but then decided to get the MOD 102 Amp Kit and I didn’t need a tube pedal if I had a full tube amp. I did want to try a pedal, though, so I opted for the Tremolo instead.

Unpacking & Inventory

Click any image to enlarge!


The packaging is nicely done and everything is protected well. Your first thought is that all the components are missing until you realize how heavy the pedal case is.


Ahhh… there’s the rest of the stuff, safely tucked inside the case.

It would be a good idea to work on the kit in an area free from cats, dogs, children and other inquisitive creatures lest your small parts enter the twilight zone when you aren’t looking.

Pedal CaseWiring

Figure 6 shows the case how it comes and figure 7 shows my mods. The result of reading the reviews of many of the kits on the MOD Kits website (, is shown in figure 7. Many reviewers complained that the washers provided didn’t cut through the paint and the kits wouldn’t work. It seems to me that a lack of common electronic knowledge is at work here. Paint is an insulator, people. You must remove it from the contact points. It took me about 5 minutes and I had to find my tool first!


inside of the case

Inside of the case

Figure 8 shows the hardware and component inventory. The resistors are not easy to see on the rug. (Don’t ask me how I know this.. er… it’s just common sense!)


Finally… let’s get started!

Assemble the pedal

Putting in the hardware, the pots, foot switch and terminal strips, is the first project. Paying attention to orientation is required here.

Assembly begins

If you don’t have a multi-meter, one that measures resistance (ohms), Voltage (both AC and DC) and current (amps), you need to invest in one before building a kit. Even Walmart has them for sale. $9.95 will buy a nice one.

Testing with a multi-meter

Figure 11 shows me checking my grounds for continuity, using the resistance (ohms) scale.

Testing with a multi-meter

More checking of the grounds in figure 12. The pedal will not work right, or not at all, if you have a bad ground somewhere. You also want to make sure that you tighten down the screws and nuts that hold the terminal strips in. Tighten the pots, the switch, the jacks… anything that bolts to the case needs to be tight.

Testing with a multi-meter

Figure 13 shows the first stage of the wiring. This is the lowest layer of components to be installed. If you have a problem here, you are going to have a problem reaching down through the components you will be adding on top of these. Take your time. Being anal about the connections is a plus here.


Figure 14 shows more stuff in there. It gets tight and hard to follow, depending on how meticulous you are in your installation.


You can see what I mean in figure 15. It’s a little busy. I have been checking as I go but it’s still easy to miss something.

It’s not particularly pretty, but everything is there and nothing is touching something it shouldn’t.


Whew… I did it in an evening (about 2.5 to 3 hrs). As I’ve said before, I have experience!

The tryout wasn’t uneventful though. My Depth control didn’t work. (In figure 16, that’s the left knob. The right is Speed.) I’ll have to label them.

I found an unsoldered connection at the switch, on the input to the trem oscillator. OOPS! I checked that area, too. I know I did. See how easy it is to screw up? I fixed that and it works as advertised. Now, it’s time to make my mods.


Setting The Trill Up For Pedal Power

I don’t want to rely on a battery once the pedal is installed on my pedal board so I installed an external power jack on my pedal. MOD Kits does not supply this, nor do they give you instructions for doing it. Luckily, I have experience (gotcha again!) with electronics and this mod is easy to do… well, sort of.



The Trill connects the negative battery to ground and the positive to the circuit. The standard pedal power unit uses the 5.5 mm plug center pin as negative and the sleeve as positive. The trouble comes in when you use a metal socket with the Trill’s aluminum case.

Typical of pedals, the Trill uses a stereo input plug. The power is connected to the ring contact, which grounds the ring to the sleeve when a non-stereo (your guitar cord) plug is inserted. Since the sleeve on our power input socket is the positive, we are connecting the center pin (neg) to the sleeve (pos) when the input plug is inserted… no power, anywhere, as this short shuts down the power supply! It finally dawned on me that the sleeve of the power jack must be isolated from the case of the Trill.

Don’t ask me why I didn’t jump right on this because I have no answer except stupidity! (Lotta good all that experience is now, huh?) My training is all sleeve=ground=negative, tip=positive. Throw a monkey wrench in there, like reverse the polarity of the connections, and I’m lost if it doesn’t work. I WILL NOT forget that lesson!

Figure 18 shows my temporary solution to the problem and the jack and wiring I did. I had to drill the hole oversize so I could get some electrical tape in there to isolate the jack from the case. Then I wired it into the circuit as it should be.

Mod #2 is the black wire at the bottom of the case. You can see it running from the input jack to the output jack. I connected the sleeve tab (ground) on both jacks so my guitar signal doesn’t have to depend on the pedal case as a signal path. Jacks have been known to come loose, even after I’ve tightened them.

The Instructions Included

The instruction package for the kit is very thorough and comprehensive without putting you to sleep when you read it. As with all projects, familiar to you or not, read through the instructions to get the gist of things.

There’s a complete list of all the materials included in the kit and they even show the resistor color code for each resistor so you can find them easily.

The soldering tips are illustrated and show the correct way to accomplish the hookups for all the components.


Figure 20 shows the final drawing, but there are several intermediate drawings as well. The drawings show the location and routing of all the components in the step-by-step directions and are progressive – drawing 1 shows less than drawing 2 which shows less than drawing 3, etc…


Please realize that if you decide to try this kit, or any other kit, yourself, build it and test it before you start playing with it to change things. You can always just put a battery eliminator connector on it and plug that into your power supply. I’m impressed with the circuit. It withstood my fooling around with reversed polarity and stuff without a whimper. Some pedals will bite the dust if you do to them what I managed to do to this one. Amplified Parts isn’t responsible if you blow yours up making modifications, though. Me neither!

Figure 21 shows the step-by-step, checked off in my case. Once you complete all the components on one drawing, check your work and proceed on to the next drawing, and corresponding step-by-step, to continue your build. Each phase is long enough so you make progress without over taxing your abilities or getting tired bending over your work area.


Figure 22 has an image of the tools I used to build the kit. Most of these came from my guitar toolbox.



Figure 23 shows the Trill Tremolo in its new home. The build was easy and the pedal works pretty well. It’s not an old Fender optical Vibrato that I remember from way back, but it is very useable and it was an enjoyable experience to build it.

The instructions were clear, concise and easy to follow. I liked that the description of each resistor included the color code so locating the right one was a simple process. Very nice touch. Same on the transistors.

The Emitter, Base and Collector were spelled out in several locations (the instructions, the inventory and the drawings) so you had to try to install them incorrectly.

Overall, this kit is a good one for a first time kit builder. It has just enough complication to be challenging without being intimidating. The end result is a great value for 44 bucks!

I’m looking forward to building my next project from Amplified Parts (MOD Kits DIY).

So, How Does it Sound?

Here’s a track that illustrates the sound of the Trill Tremolo:

[soundcloud url=”″ params=”” width=” 100%” height=”166″ iframe=”true” /]



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Doug Knight

Our “Man on the Street” reporter, with his “What’s New in Music Stores?” series, resides in Coos Bay, OR. You can find him on Friday nights at The Small Events Center at OrCoast Music in Coos Bay.

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9 years ago

Wait ’till you see what’s coming up!

9 years ago

Thanks, Nick. Once you learn this stuff, it really isn’t very hard. It’s a little like golf… playing is easy… playing well is a little more work!

9 years ago

Wow. I’ve never tried anything even close to this, so I’m a bit in awe.

Nicely done, Doug.

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