Monday, October 8, 2012

Apollo 13: Basic Wiring

*deep breath*

YOWZA, it's been since nam since I last posted and for that I sincerely apologize. As I said in the post before this, I had Maker Faire coming up fast on the schedule so I was rather tied up. Then before I knew it, I was off researching my next project, one thing led to another...and then within the past week a friend posts on my facebook wall "Hey congratulations on making this site!" I thought, "What site? Why would I be on a website?"

But then I saw this in my then minimized browser window...

You can read the article here, ( To say the least, it's incredibly well written, flattering, and more than anything reminded me of the following...

I made a promise to write these posts, and I am going to do just that.
So let's get started. Ahem. K. I'm ready.

Basic Wiring: Faders and Knobs
If there is one thing that may scare a lot of people about this project (assuming you weren't frightened or scared off already) is dealing with first hand with electronics. My college curriculum had three electrical engineering courses thrown at me, and they only slightly provided some help throughout this entire debacle. Fortunately for you, electronics, circuits, and all of this stuff has become crazily cheap to do.

My first ever self assembled board.

What you're looking at in the above picture is the A/B send return board. There are two in the assembly of this project each containing 6 "mini faders" see the parts sections for these little guys.

The above photo shows what I'm up against. I need 2 boards with 6 mini faders on each of them. In addition to this, you also can see I have a single complete launch channel consisting of 6 buttons for 6 clips of audio and the two buttons above each channel - record and cue. When I in my first post that "I need to break this thing down into it's respective parts" I did that by breaking down what a single channel of control offered up to the software. 1 volume slider, 10 buttons (A/B cross fader assign, 6 launch, 2 rec/cue, channel on/off), 2 mini faders, and 4 knobs - totalling 17 unique controls per channel over the course of 6 channels.

But back to the boards, because buttons weren't something I was ready to tackle then. Those were more complex in wiring, linear and rotary potentiometers (faders and knobs) were something I was ready to do immediately and know I could quickly produce preliminary results with. The perf board used in all photos and this project was purchased from Radio Shack and has no copper coating - it is plain. But you can get copper coated ones, doesn't change the end result. In hindsight, it may have been easier to do with those.

Potentiometers here are types of analog controls and to break down what it is and how these things work, allow me the following picture I found by a Google search.

A rotary potentiometer

A rotary (knob) or linear (slider) potentiometers has (at the minimum) three pins for wiring. In the above example and in the case of every knob I've seen there is a pin dedicated to Off, Wiper, and On. I'm sure the words "On" and "Off" make instant sense to you, but wiper? What's that? The wiper is the pin that simply put - conveys the data. It's the thing providing the value. It's the thing saying how much or how little something is happening. But to get that value, we need to run electricity through the two other pins - in one and out the other.

Go full screen super size on this one so you can the melted solder. I used the tool to hold the knob in place so I could have a soldering iron in one hand and the wire/solder somehow held in the other. You can see here the pin layout I described. Wiper is middle!

Yup. Lot's of soldering. Also, this is where I realized that Version 4 of the faceplate couldn't work because the 8 random knobs running along the right of the mixer (left side in the picture) were facing out towards the eventual box edge!

Green is the wiper, i was gearing up for one of my first tests of a single channel of 4 knobs. No solder here, just tightly wound wire to wire.

Now the final wiring changed only slightly from the above picture, instead of pseudo-braiding each knobs wires together I braided a row of knobs ground, wipers, and lead (high) wires respectively. So that way I could distribute power to a single source, ground to a single, and run all my wipers to a similar central location.

Let's Talk About Electricity!
So applying this concept to an electrical circuit 5V flows into the first pin, the knob is turned all the way to left (off) the third pin has 0V coming out of it. You turn the dial a bit, suddenly the third pin is releasing energy. You turn it more and more, and eventually the electricity freely flows through the circuit until the whole 5V is coming out of the third pin. As you turn the dial the reistance in the circuit is decreasing, but the electrical output is increasing. Resistance should make sense in this example - you are resisting the flow of electricity.  Imagine turning a faucet on slowly. How bout that analogy? The Wiper pin is sending data to something. In the case of our MIDI controller it's sending it's resistance value outbound to the control board.

Enough of that, more wiring.

Fortunately these linear faders also have three pins, a low, a wiper, and a high. I'm intentionally color coding my wiring. Black is 0/off/ground(GND) and Red is hot/on/5v/. This also serves the added benefit that I don't put these things in backwards. I know what the "bottom" of the fader is. But it isn't the bottom because I soldered a black cable to the pin, its 0/gnd/off because the data sheet from the manufacturer tells me so.

It tells me on this 3 pin linear fader further away from the other two is high/on. The pin between the two further is the wiper, and the remaining one is the ground/off pin. Brilliantly simple. I want to add this is a generally safe assumption to make of faders pin layout.

Wait, 3 minimum? Faders can have more?
Yes they can. Because more complex, expensive faders may output to two different sources. They may take in multiple sources. Some are motorized and have extra pins to supply power to the motor. If I ever get crazy enough to do this project again, apart from a lot of things I'd do differently now that I have the knowledge is that I'd do motorized faders and call it Apollo 11.

In the above photo you can see the results. I have two wires coming off of each fader, the remaining pin (closest to the black wire/pin) is the wiper which I used green wire for. If I had access to radioactive looking yellow/green I probably would have used that in a heartbeat. Even though no one will see it when it's done for me I thought "Well, that'd be cool." But alas, didn't do it. Just used what was around me.

The wire is 18GA wire from Radio Shack. They sell it in packs of three featuring red, black, and green.

So what about those plastic things? Those white tubes jutting out from your board? What are those things? Why do you need them? Plus, why do you have knife out? The plastic things are Nylon Standoffs ( Try to visualize the following - I have a faceplate and components underneath it. Those components need to mount somehow. 3/4" nylon stand off sink these faders enough to shorten there rather crazy long physical fader and...well yeah, it puts some distance between the board and the faceplate. They are made out of nylon and help things stand off from a surface. So simply named right? I suppose, because when I first heard about them I had no idea why I'd need them. That link also features the page for matching screws.

The knife in the picture (blade is by Xikar, don't believe they make it anymore) has a fine point (obviously) - so I used it to widen the holes by twisting the blade around in the hole on the perf board to something I could poke a screw through and tighten the stand off onto. Crazy simple right?! But talk about a lot of widdling.

Regardless, the end result is the knobs are completely wired, the mini faders are mounted on the perf board and the pins poke through the back just enough to wire them. OH! Right, before someone is wondering how I "mounted" the fader into the perf board - I just used tinier holes so they had to snap more or less into place. This vs. the screws which I widdled large enough holes they simply just fell into.

Finally I should add the large faders used for the volume, master volume, and BPM are the same exact principle. 3 pins. Low, Wiper, High. Wired identically. Just bigger.

And so...
The faceplate exists. 
The box exists.
The first half of controls are wired and ready to be connected to power, ground, and respective wiper pins.
I have half of a functioning controller.
I can consider this project at 40% to 50% complete. 

Because this part I wanted to do. I wasn't scared of doing it whatsoever. I'll be honest, I was putting off something that had me concerned for the longest time...

How the hell do you wire all of these buttons AND make them light up?

Until next time everyone! Thanks for reading, thank you for your patience, and thank you as always for all your kind words.

You want to know what the matrix is? The matrix is...

Monday, July 30, 2012

Apollo 13: Writing on Hold!!!

I didn't post anything on Thursday, and I regret to inform everyone that nothing can be posted this week due to some time constraints.

This is 100% due to preparing for the Evanston Mini Maker Faire which I'll be presenting the Apollo 13 mixer at! I'll be taking plenty of pictures and recording whatever video I can! You can check out the Maker Faire at or if you are in the Chicago land area see the device for yourself.

I continue to receive lots of emails and I know many of you are still interested in this project - rest assured I will finish these posts. If it is insanely important, if you are starting it yourself, if you have questions please email me, I'm here to help!.....just not this week. I'm really booked.


I'll continue writing, but I am really focused on shooting a 2nd video showing the thing in action and far less of a "here's what the buttons do" video. I've received enough requests for one that it certainly merits a video response. Thank you to everyone for all the continued support and kind words.

After an extended absence, the project continues at...

Tuesday, July 24, 2012

Apollo 13: The Case

Thank you Home Depot for this lovely sheet metal.

After figuring out the faceplate and all the parts I was going to use, I feel as though I very jokingly said "Well this should be easy NOW." But much like the faceplate, cutting it, designing it, and doing everything required to make it come into being - I found myself in a similar position with the box.

The Maven has an inherit tilt to (genius might I add) and it's all covered by those two fancy aesthetic choices preventing a clear view of how it possible assembles on the sides. When I first approached the problem of box design the problem that kept going through my head was "Either it's cut from a single peice and folded in such a way that it perfectly closes OR I cut it from three separate pieces." I'm sure the first choice is valid but I went with the second one for a few reasons.

1. I don't have access to a machine brake, I'm going to have to hand bend. That is going to be rough for my girl scout figure.

2. I don't nearly trust my measuring enough to accommodate for error with my hand bend of the metal.

3. I need something that is technically the easiest thing to re-produce if I wanted other people to do this. Even if it involved someone just hanging metal on a ledge and pounding it down with a hammer.

I purchased I believe a 24" by 24" sheet of 16 gauge steel from Home Depot. It comes coated in a layer of oil to prevent rust (this wasn't stainless steel) and has a decent thickness and weight to it. Perfect for adding some weight to this device. But walking out of the store with this giant sheet of metal in my hands, grinning with what was eventually going to happen I still arrived back at - " do I cut this stuff?"

Angle grinder! Perfect! That's what I'll use! Right? that didn't work out so well. I don't know what I'm doing. All I know is this 2 inch cut took me like 30 minutes to do. It looks jacked up and oh right I've never used an angle grinder before. Better start over with some mineral oil, and a bandsaw.

Talk about an infinitely cleaner cut. Minus the damage on the right hand side. I guess I'll use the angle grinder to smooth that out? I have no idea, but I do know this flat sheet of metal is getting slide into this bending brake and getting bent.

If you are looking closely at the last picture here, you maybe wondering "Uhh, that doesn't fit. Sure you could bend the top and bottom but the width it's all off." To that I remind you, it was a 24" by 24" sheet.

Since I had never done anything like this before, I made my measurements for the 1/8" plastic faceplate and used the excess as my test bends/cuts/excess. Which is to say there is an extra shell/box/case for the board laying around. Just not as wide.

If you look closely at the above picture, you'll see the "mini" version of the box/case/shell resting inside the actual size one here. Additionally, the faceplate is going to have to rest/mount on something. Thus, i got some really thin sheet metal (still steel) to clamp down into a vice and hammer into right angles with.

Blue line is as you may have guessed, where the bend was made in the vice. However since this much thinner than 16ga steel, my bend could be far more perfect than the box used with the hand bending brake.

Above you can see the bent steel just resting between the top edge of the box and the faceplate. Eventually, i drilled into both of these parts and fastened them together.

Faceplate length + bend length 
total length of box.
I don't want to neglect the measurements on this post. The faceplate length (which is 17")  plus the bottom lip of the case (1.25") and top of the case (4") make up where to make the bends. Obviously, this part is open to interpretation and your own work. To me this just looked like the right degree of bend/tilt to the original Maven. Something tells me I'm probably 1" off when it comes to the back of the mixer. But i rather error on the positive side. After all I plan what if I want to build this thing out more? I mean the original Maven has some serious analog power.

Using a drill press I drilled two holes into the back of this (MIDI IN and MIDI OUT), since it was already bent, it was somewhat awkwardly positioned on the bench. I went with the closest diameter I could find to the plugs and filed what I needed too by hand.

Continuing on my drill press spree (I've never used one, wow are these things great) I began mounting the front and back lips to the case. This is what the faceplate will rest on and screw into eventually. The other thing I did between the original bend and more work, is scratch the absolute hell out of the case intentionally. Using a steel wool pad, I brushed all over this thing to remove whatever rust was starting to form and more importantly give the primer something to stick too. The primer I used was Flat Gray Rustoleum. Three coats over three days.

 I can not convey the level of excitement I felt when I put this on top of the box and it rested in place.

The Sides.
Since I decided not to build a box that would fold into itself, I'd cut the sides separately. This was done by simply laying the case on it's side against excess 16 gauge sheet metal and tracing it. Yeah. Tracing it. I error on the side of caution make sure that when I cut I'd have plenty of excess to cut and angle grind down. Even still, I'll need more steel right angles to hold the case together. Fortunately, those are insanely easy to make with the vice and a hammer.

After I made them, I drilled four holes into them and firmly pressed the case/sides together and with a marker dotted the holes. Walked over to the drill press, hoped for the best and drilled into the sides but more importantly - my completely so far good looking case. Fortunately - SUCCESS!

Is there an engineer crying yet?

Hiatus is over and the writing continues at...

This wraps another post...
As always I welcome comments, emails, instant messages, skype calls, tweets, facebook requests...and whatever means of communication you prefer. The goal again is to make this easy for anyone of any skill level to understand and replicate. Thank you once again and as always for reading, I look forward to the next post to continue to discuss this more in depth.

Thursday, July 19, 2012

Apollo 13: Faceplate Design and Acquiring Parts

Apollo 13, attempting to be cool and not succeeding at it picture.

With the two big questions out of the way, the next most popular one is "If you had to pick one part of the project, which one was the hardest?" My answer thus far hasn't changed, "As a guy who has never done something like this? All of it."

The parts list, like many parts of this project was crucial in helping recreate the experience and look of the fabled controller in question. The problem is they were based on the unknown dimensions of a oddly shaped box. But the following picture changed all of that for me.

In the above picture, we see the Maven pictured between an Apple laptop and Pioneer DJM800 mixer. What's more, a front facing pic helped reveal an onboard analog sound output, there are headphones plugged into this thing! More importantly, the jack is tilted downwards. All in all this was great, because I knew a quick google search would yield and the exact WxDxH dimensions of 12.6 x 15.0 x 4.3 - perfect. I now have a relative size to begin basing this off of, judging by the first photo it was clear the device was larger, and accounting for the tilt I estimated the faceplate of the Maven to be 13.1 x 17 inches (width x height). But let's be honest, not everything is perfect the first time around...

So in the week I gave myself to learn AutoCad with my 30 day trial, I managed to produce 3 different versions within 4 days. The very first drawing is the furthest one on the right (hence the v1.0 mark beneath it). You can see that i originally drew a very wide looking mixer and approximate sizes of all the various functions on it. Version 2 i got a bit better with my measurements, and realized i could tighten things up significantly. Additionally there is a significant design change that occured, between version 1 and 2 you'll notice the majority of the potionmeters (knobs) shift their positioning so the pins beneath the board are facing different directions. This was done to avoid any wires bumping into the side of the eventual box, other inputs, and make wiring slightly easier. But I could probably could go tighter, version 3 introduces even more accurate measurements on my behalf and a more compressed design. But you know what helps? Calipers.

Which i have no problem admitting, didn't know what they were until this project. For those equally unaware, its just a measuring instrument that lets you make very insanely fine measurements - perfect for taking the width of a knob, button, or length of a fader.

Version 4 introduced two things - layering and Mitch. Mitch for all intents and purposes helped me refine version 3 into version 4. He showed me layering and the importance of it. Now I am personally a huge Photoshop person, so the value of layering instantly clicked with me, more than anything I just didn't know how to do it in AutoCad. But that was solved relatively fast with him. For the sake of explaining the color coding, all RED lines represent what you see on the faceplate, the holes, the slits, etc. The BLUE lines represent the actual size of the object resting behind the board. The YELLOW lines are merely notation for the sake of alignment and seeing individual channels clearly AND also show a relative size of the knob/fader. This is the first version where I realized these dimensions of 13.1 x 17 were going to be the final dimensions I was going with. This version was cut on 1/8" plastic, the following are ALL the pictures of that process.

Hurray!!! It exists! Kind of! But i felt a minor success none the less. However the second I started mounting parts I realized one thing (go look at version 4 cad again)....go ahead I'll wait.

Doo da dooo....

Find it? Well if you didn't thats ok, the 8 knobs and 8 buttons featured along the right side of the mixer had the knobs oriented in such a way that the pins for them were pointing towards the box edge. I knew this was a wiring issue not worth going through. Version 5 (The Final Design) was created, and last minute changes were made.

This is the final faceplate. Holes for mounting, and turned the knobs to face away from the edges.

If you notice anything about this design and the final product I have is that I left ample space for text. I haven't given up yet! Also some of you may notice a tiny red notch on all the knobs, that's the place for what's known as the "key" of a knob. If you scroll down and look at the photo of the knob, you'll see a very tiny peice of metal jutting up from the side of the knob. Apart from screwing the washer/nut to attach these knobs to the board, the key ensures the knob doesn't turn in place.

Some of you may also be wondering (as did I when this started) - how the hell do I drill holes for the faders? How do you make that measurement - calipers! You can measure the distance! Or you could look up the physical parts schematic sheets as they offer the measurements for you, but I found more satisfaction in doing this myself.

Now I didn't return to make the final cut for another month, I just need to order some kind of metal and I still hadn't decided on it at that point in time. I figured I'll worry about it later, I was more concerned with the the next challege - acquiring parts and wiring it all together.

The Parts List
Now some of you maybe asking "You designed the faceplate without parts?" No the parts were done in tandem with the above steps (it was a really rough week learning CAD and speccing out parts!) as I kept looking for parts I kept refining the design. So I had the relative dimensions based of off another mixer in that above photo. The question was how could I determine the relative size of the inputs on the board? Fortunately I discovered this photo.

This was the photo that sealed the deal. Seeing Sasha's arm positioned next to the device said a LOT about the size of the mixer, it's components, and it clearly showed off the extreme tilt of this box! Sure his arm is bent at the elbow, but that was easy to accommodate for. Which helped me arrive at the following...

Large Faders (i wanted linear, but i could only get them in logarithmic). These are mounted directly to the faceplate.

Short Faders (these are mounted to perf board from Radio Shack, I didn't use copper perf board. Just the simple stuff.)

Knobs - These can be found anywhere, it is a 10kOhm Linear potentiometer. It also goes by b10k. Common short hand for "linear" is a preceding B before the resistance value. If you see A it implies the fader is "logarithmic" - I suggest ebay. They are uber cheap. Outside of the resistance value, the two dimensions below help contribute the a very minimal fader. (these are mounted directly to the faceplate)

For anyone who doesn't know what it means to have a linear or logarithmic fader - let me save you the technical verbiage, research, and some time. 
If you have a linear fader, you have a 1 to 1 mapping. If the physical fader is positioned in the middle, you will see it positioned in the middle in software. In fact wherever you see the physical fader lies you will see it identically placed in software. 

If you have a logarithmic fader, you don't have a 1 to 1 mapping. You have an implicit curve hard defined within the fader. Better yet, let's imagine it as a crossfader with two hard defined curves. Bottom to middle is a very wide/long/open curve - it takes a huge push to get even a little volume. But the middle to top? A very sharp/fast curve. The tiniest push is a huge shift in the volume.

I somehow had some no name faders laying around (after 2 months of research I discovered there were knockoff Alps faders and thus aren't manufactured anywhere), and just so happened to find faders that were the exact specification of those. Why was this important? I forgot to tell you, I designed the CAD file around those original no name faders! Faders I thought I could purchase again! I was wrong. Talk about 4 days of hell racing to find a fader with nearly identical dimensions. Ugh, never again. BUT! The large faders I found were the ones that are listed above. The Apollo 13 features 7 logarithmic channel faders (channels 1-6, plus master volume) and 2 linear faders (master BPM and the crossfader). Doing this you can quickly slap a fader to kill volume to a channel, and you don't have to do it all the way down. Just hit about the middle and it'll be dead. But the master BPM and crossfaders absolutely had to have a linear fader. Just a bit of a personal preference.

Sweet! But, wait...the buttons. The Buttons! THE FREAKING BUTTONS THAT LIGHT UP! TELL ME ABOUT THOSE!
I spent an absolute stupid amount of time trying to find the identical buttons used in the Maven. My only conclusion is they are custom made, because I can't find this kind of design anywhere...

This is one of the most close up shots I've ever found of the device, and it really highlights the size and design of those LED push buttons. That and the font that was custom designed, which you'll notice I recreated...

I digress.

The buttons! Ok, so after a lot of searching. A lot of phone calls. Hundreds of quotes. Using a bunch of musical gear and contacting major manufactures of dj equipment, I purchased these...

The LP15R1 by E-Switch

These little beauties are FAN.FREAKING.TASTIC. They are insanely bright and the best part? Come in all the colors you need to build a Maven. Green. Red. Blue.


Now I made the purchase from Newark/Element14, however I absolutely must emphasize these things vary wildly in price and I completely lucked out of purchasing them when they were selling these things for $2.66 a piece. The price has changed since then and I advise everyone to absolutely search the hell out of these things before buying. But they snap into perf board ever so nicely with those 4 gold...fangs? I'm going to call them that. Fangs. There I said it. Fangs.

I had to build 6 of these little boards (obviously) as these are all the green buttons that represent the clips that will be launched in the 6x6 matrix. Emphasis on matrix. These are wired in matrix. But i'll get to that in later posts.

I'm sighing all over again just looking at this photo.

So there you have it everyone, those four parts make up this entire board. This entire MIDI Board. They are either mounted directly to the faceplate or perfboard that then mounts to the faceplate via Nylon Standoffs. If you are wondering what the white pegs jutting out from the perf board are called, they are nylon standoffs that...well do just that, help something stand off from the surface. Here's a link! I used 3/4" nylon stand offs in this project for all perf mounted inputs. Which to summarize, all perf board requiring standoffs were any LED Pushbutton or any short fader used.

Alright so maybe it's five parts because of the standoffs.
Wait, six I forgot about the perf board.

Until next time!
This wraps the first of many more posts to come outlining the design, my thought process, and all things Apollo 13 so you can build your very own. I encourage comments, questions, emails, skype phone calls, you name it - i want to make this fun and easy for everyone. I also hope these posts are living up to what the people who are following this project expect these posts to be.

I think I'm going to shoot for Tuesdays and Thursdays 7-8pm central time to post new articles. I'll try to step it up if i can, but I'm confident I can at least keep that promise of twice a week. More importantly this post introduces another thing people are itching for - downloads. So, let the downloads begin.

Continue the story at...