How to build and Use a Basic Testing Rig

[jkokura]

This post may get scrapped at some point in time, but in the meantime...

Here's how to make yourself an easy testing rig! I built a new one for myself recently and decided to take a pair of pictures of the process.

Because the mantra of the tech helpers is "rock it before you box it" (meaning that you should always test your circuit board BEFORE you actually go about wiring your pedal inside an enclosure), a testing rig is one of the best ways to go about ensuring your pedal works properly. There are a number of different ways to do so, but this is the way I prefer. It's simple, it works, and it's incredibly helpful for ensuring things don't get hairy after you've spent 2 hours wiring your pedal together only to find out something doesn't work. If you "rock it before you box it" you will KNOW that it's the not the circuit board that's the problem, it's the wiring. Right?

*BONUS* I built my rig with an BUILT IN SIGNAL PROBE! You do not have to do this as well, it is entirely optional. I built it into mine so it will function in a dual purpose for me, both being my board tester and a debugging too. Any time you see these ** remember that this has to do with the OPTIONAL signal tester.

So first off - what do you need to build one? Well, in the least you will need:
1x enclosure (I used a 125 B, but a 1590B/1590NS/1590BB or any number of enclosures will work)
2x mono jacks (I used open frame mono switchcraft style ones)
1x DC Jack (isolated is important)
2-4x Alligator clip cords (2 if you don't mind having some identical colours, 4 if you need different colours. 4 is much better)
*1x 0.1uF Film Cap (important for an audio probe)*
*1x multimeter test lead (This is your probe)*



First off, you'll have to drill your enclosure. I used an enclosure that had a former life as a headphone amp for me. I cannibalized it for my breadboard rig (another upcoming post... I hope), and I had no use for the funny way I had drilled I used it before. Fortunately, I thought up this project. Anyway, as I was saying - you will need to have holes for the DC Jack, and the two 1/4" jacks for sure, and my enclosure has those holes at the 'end' of the enclosure. Next you will need at least one hole for your alligator clips *and audio probe* to come out of the enclosure. You can have them all come out of one hole, or you can have them all come out of individual holes, it's up to you. I already had two holes to use, so I used them.

After that, you need to cut all your alligator clip cords. I cut mine in half, and it gave me lots of cord to work with. This is where colour options come in. Obviously, you should use the colours that make the most sense to you, but if you need to, you can use all of one colour and then find a way to label all the alligator clips so you know which one is which. You will ultimately end up with 4 alligator clips: power, ground, input and output.

Next up you will need to begin to work on the wiring (Refer to the picture below for stuff in brackets). The DC Jack ground connects to one of the jack's sleeves (green wire). The DC Jack's power out connects to an alligator clip (Red wire). Now attach another alligator clip to ground (white wire). Next, you will need to attach another alligator clip to the input jack's tip (yellow wire) and then finally, you'll need to attach another alligator clip to the output jack tip (black wire). *To include an Audio Probe, you will also need to attach your Film Cap to the output jack tip also. Then you will attach your probe cord to the other end of the film cap.* Check out this picture for my finished version! Note that the zipties are for anchoring my cords. You do not have to do this, but I did it to prevent the soldered ends of the cords from becoming weakened by my yanking on them.



And here's the finished product! When I want to use this, I hook up the yellow wire to the input of my circuit board, the red to the board's +9v in, the black to the board's output, and the white to the board's ground. *To use the probe, I would leave the output alligator clip attached to the board, but I can now use the probe to 'preempt' the output alligator clip. Now the probe will allow you to find where there is active signal. This is especially helpful for both debugging a non working circuit, and for calibrating some circuits like delays. I recommend everyone have some sort of probe to use, whether or not it's built into a testing rig like this is up to you!*



^Please note, I'm hoping Brian will find the spare time to make up a 'madbean approved' wiring diagram for this, stay tuned if the description and picture isn't enough!^

Jacob

[jkokura]

Here's a Demo for you guys to check out on how to use the Testing Rig! This demo outlines how I would use my rig to test a PCB *and shows how to use an audio probe in short format as well (not a full debugging tutorial, just a basic example of how it could be useful).*

Here's the link - it's a private video, so you can only access it through the link - not searchable on Youtube

http://www.youtube.com/watch?v=KYS2bpR9o6Q

And here it is embedded.

Enjoy!

Jacob

[madbean]

Well, this is just above and beyond. Thank you Jacob! Everyone needs to read this post!

Jacob wins the post of the day!

[jstbrowsin]

Here's the link - it's a private video, so you can only access it through the link - not searchable on Youtube

Err . . . and not accessible through the link either (unless your a friend) oh well I guess I can only imagine what it is like then eh  

[aziltz]

i need to build me one of these, but put a bypass switch on it as well.

[jkokura]

Fixed! You should be able to see the video now.

Jacob

[irmcdermott]

Great video Jacob! Great contribution!

[bigmufffuzzwizz]

this is a great topic to talk about! Extremely necessary if your interested in building any type of DIY circuits ie vero, perf, p-t-p, or even madbean pcbs . now what can i put it in to save money on the enclosure for more madbean boards!!!  

[jkokura]

You can use anything really, anything you feel will hold up to the strain of having the jack holes drilled in them. I thought about using this great tin my wife gave me that used to have travel candies in them. It's about 2 inches tall, and maybe 3 across, and it would look aweseome! I could have drilled the three holes for the jacks, and then left all the cords inside, and then popped the lid off everytime I wanted to use it, it would have kept the alligator clips safe and inside when not in use and might have been easy to store. Now it's kinda like a floppy octopus with the alligator clips all hanging out.

But I chose to use an old enclosure. Lots of us end up with unused or misdrilled enclosures from failed projects or rehouses. It's pretty common to see actually.

I have a cool project coming up soon where I'm taking a non working Boss PH-3 and I'm going to strip the paint off, shine up the enclosure, and put a four knob overdrive in it. It may not happen till the end of the year, but reusing cool or old enclosures is part of the whole DIY thing. Anything can be an enclosure really. I saw a guy used a stuffed toy once, a firbee or something like that. Another guy used an old shoe, and I've seen enough crazy electrical boxes and former pots and pans to know that you can pretty much be as creative as you want.

Jacob

[bigmufffuzzwizz]

Thats what I'm thinking. Something creative and different, but hopefully compact!! I have some metal boxes that don't have boxes on the back i think would be perfect for this!!
Now I'm glad i didn't spend $100+ on a beavis board! especially since i can build one for under 10 dollars it seems!!! I found an easy layout for a voltage sag knob to add into this so i can morph my muffs into sagging beasts.
As i mentioned before... ESSENTIAL!

[jkokura]

Ah. I want to clarify. This basic testing rig is NOT a replacement for a beavis board. A tutorial on that will be coming.

Jacob

[bigmufffuzzwizz]

yes! can't wait for that!!

[jstbrowsin]

great vid Jacob thanks for fixing the link 

[maysink]

Stellar work, Jacob.

[JeffdaMaori]

Hi there, this is all great, cheers Jakob! Just for another version here's my little test rig on a piece of plywood. An aluminum bracket with slots to hold pots (which I find very handy when giving it a test drive), input / output jacks on rear, battery power and ground all to hook up with alligator leads. Could be easily modifyied to have a bypass switch too so you can compare effect/bypass signal.
Just as another idea and inspiration and yes, testing before boxing makes things a looooot less painful....!
Cheers
Andy

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