My new stacking controller

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Rylee Isitt
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My new stacking controller

Post by Rylee Isitt »

I thought some of you might be interested in a project that has eaten up most of my waking life for the last several weeks.

I wanted something more professional looking, compact, and versatile than my old LEGO stacking controller (which you can see here - it's the red box with switches on it).

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The controller is somewhat similar in design to my previous, using an Arduino micro-controller and custom circuitry. But it differs in using an IR receiver for control, a 8-bit shift register to keep internal wiring to a minimum, and an additional reed relay to better support the half-press (focus/expose) mode of the camera. The shift register and lack of big, space-hogging buttons and switches allowed this all to fit in a reasonably compact enclosure.

The little red thing on the bottom right is the IR receiver. The use of IR allows completely hands-off operation of the system, keeping vibrations down. I'm using a very inexpensive keychain remote purchase from SparkFun, but it can work with other remotes as well. Programmable/universal remotes used for entertainment centers aren't very easy to work with since they use multiple protocols depending on the button pushed, so I'm sticking with remotes intended to control a single device.

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Here you can see the ports for the shutter release cable and the cable that connects to the stepper motor. It's easy to program using the USB connection - you just need the proper drivers and software available from the Arduino website.

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The new design should work for any camera that has a three conductor port for a shutter release (definitely works for all Canon DSLR cameras that I have gotten my hands on). This is done using two reed relays (one for half press, one for full press) that complete a circuit over a three-conductor cable in any possible configuration. The configuration is set with DIP switches. The switch positions you see in the above photo are for Canon DSLRs. The DIP switches can be accessed without having to take the controller apart, through a happy-circumstance panel that can be pried off on the top.

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This is the internals of the unit. The custom-made board on the right is a two-level stack (I had to make it two levels to get it to fit in that little space) with the stepper controller, shift register, relays, and DIP switches on it. It acts as an intermediary between the Arduino, camera, and stepper motor. The Arduino also controls the LCD and receives input from the IR receiver directly.

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A better look at the custom circuitry.

I am still programming the last of the stacking features and am planning to write a build article, with schematics and a step-by-step how-to for building a similar (or identical, if you want) unit. Mind you, this does require a moderate level of experience with both soldering, electronics troubleshooting, and programming - as well as the tools and parts. So there's a definite money and time investment here. But if you already have the tools and experience, the parts are pretty cheap.

In addition to stacking, it can do anything requiring control of a camera shutter and motor (as long as you can program it!). My plans are to add timelapse support including the movement of a rotation platform, as well as the ability to control a barn-door equatorial mount for long exposure astrophotography. For those purposes I'd power it with an external battery pack.

Thanks for looking! Once the build article is done, I'll post a link if there is interest - that might take a while, though!

johan
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Post by johan »

Super impressive - I considered this but decided I just didn't have the electronics skills! Good for you =)
My extreme-macro.co.uk site, a learning site. Your comments and input there would be gratefully appreciated.

Rylee Isitt
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Post by Rylee Isitt »

johan,

Thanks!

Two years ago, I didn't have much of any electronics skills to speak of. I had fiddled with Radio Shack electronics kits as a kid, and even took a high school course (none of my stuff ended up working), but even "fiddling" is probably a generous term for what I did.

When I bought my soldering station a few years back, the first thing I did was burn the tip out because I didn't know it had to be kept tinned. Then I destroyed a $12 voltage regulator chip because I pulled out the storage capacitors while it was in operation.

My first project a few years back was making a remote shutter release. It's just a switch mounted into a film canister that connects to a shutter release cable. But it let me practice my soldering.

My second project was a voltage regulator for 20 watts of solar panels. It only has a small number of components, so it was a good intro project.

From there I worked my way up - building a lightning trigger for my camera and then finally the first and second incarnation of the stacking controller. Discovering the Arduino micro-controller was a huge revelation for me. It makes things much easier than you'd think. Controlling an LCD for example, or deciphering IR signals from a remote - these things sound difficult, but the LCD screen might as well be an array of LEDs - it's that easy to operate. It's just a shift register that controls an array of pixels. The IR receiver has a built in chip to convert the pulses from the remote to binary, so all you have to do is watch the stream for a specific signal that corresponds to button x. Someone even made an Arduino library for the SparkFun remote. If you use the library it's even easier.

For this project my biggest fear was directly soldering ICs to the PCB. I'd always used sockets before, not wanting to overheat and damage the chips. But once you have a few projects under your belt and you keep the iron tip properly tinned, you can solder very quickly, so the chips don't get damaged at all.

The point of this story is that almost anyone can do this, given a few years to practice!

pierre
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Post by pierre »

Impressive piece of work !
Regards

Pierre

Pau
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Post by Pau »

Great project!
I wish someone will make it available at a reasonable price, because my electronic skills are zero :cry:
Pau

g4lab
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Post by g4lab »

Just as an encouragement to any and all forum members to go ahead and jump in if your are inclined to I would make the following recommendations.

One of the tricks to soldering is (as mentioned ) to keep the tip clean.
Also size your iron and tip properly for the job at hand. If you can manage it and you are in the USA buy a Weller soldering iron rather than a noname or radio shack. The tips last longer. Use rosin flux cored solder , never acid core.

I started playing with electronics when stuff was still built with vacuum tubes.
I have to laugh when I think of my twelve or thirteen year old self playing with 400 volt plate supplies. My guardian angel was on duty and I never got a shock until I was in my thirties. (that one was 700+ volts and was a doozy but fortunately just on my hand. Vacuum Tube Audio )

When transistors came out they tried to terrorize us about heat sinking the leads while soldering . The same is mentioned in conjunction with integrated circuits. But I can't ever recall cooking a semiconductor. So just Do It!

Building something yourself and having it work is a wonderful experience IMHO. I congratulate Rylee on this project and look forward to seeing the build project. I have not made the leap to microcontrollers, in spite of having been tempted for a long time.

Rylee Isitt
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Post by Rylee Isitt »

Thanks everyone for the kind words!

I agree with g4lab, Weller stuff is good. They are actually quite a popular brand, so in many cases you can find accessories in even small hardware stores. I can get spare tips, tip tinner, and polishing bars from my small town's local hardware store, which is nice.

I recently tried out a smaller tip and found that I get less sloppy solder connections, but for some reason the tip is more stubborn so far as becoming oxidized really easily. Larger surface area to volume ratio perhaps?

ChrisR
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Post by ChrisR »

for some reason the tip is more stubborn so far as becoming oxidized really easily.
Small ones tend to need a thermostat control or they overheat (& oxidise) when you aren't using them and overcool when you are.

Rylee Isitt
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Post by Rylee Isitt »

ChrisR,

Hmm, I do use a soldering station that seems to keep a fairly constant temp. I set it to 600 degrees (F) for most work. It has a digital readout and this seldom goes above 610 degrees, usually peaking right after removing it from a heat sink such as a large metal part or a container of tip tinner.

g4lab
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Post by g4lab »

A thermostatically controlled iron is great. You should also become obsessive compulsive about cleaning the tip. Many soldering tips are iron plated and once the plating oxidizes all the way through the tip becomes more trouble than it is worth. This is a bit counter intuitive since they are made of copper or high copper brass.

I like to have liquid and paste rosin flux handy because if you hit the tip with that it really lasts longer. And the sponge tip cleaners , kept wet with water, allow you to wipe the tip after and maybe before each joint depending on how long in between. And always tin the tip before you turn the iron off so as it cools it has a nice thick coating of fresh unoxidized solder to freeze on the tip. And if you go 15 minutes without doing a joint, wipe it and tin it again. Solder is much cheaper than tips. You can really make them last a long time.

If you are going to to any serious amount of work , sizing gets important.
Too big an iron can't solder the small connections on chips. Hobbyists are even doing surface mount stuff now but that is an innovation I have resisted so far. I have a bunch of irons including 20 watt fine tips and a 400 watt plumbers iron and everything in between.

ChrisR
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Post by ChrisR »

+1 on having a tin of rosin flux handy. (I'd written simlar things but nodded off and gone to bed without posting...)

If you have a normal tip-down stand for the iron, make sure the tip has solder on it when you rest it still switched on, between solderings. That'll help prevent oxidation of the tip.

You can weave a small mat of "solder wick" which is copper stranded braid soaked in flux. It's useful for occasional wiping the tip harder than a sponge, without abrading it.

Back the day it was routine to put surface mount components on manually, with solder paste. Transistors especially, cos they're more keen to blow (and have well spaced contacts!).

Rylee Isitt
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Post by Rylee Isitt »

I've seen some video by some very skilled folks doing surface mount soldering with regular everyday soldering irons. The technique they use for soldering on chips with many pins seems like it would make for a lot of cold joints, but I guess not? They just put a huge bead of solder on the iron and then quickly wipe it along the perimeter of the chip. And then use a heat gun with a narrow nozzle to get it all apart again.

I've been tempted, but there's one thing keeping me away: you have to work with etched PCBs. I just really like my stripboard. It's cheap and you don't need to etch anything!

g4lab
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Post by g4lab »

There are lots of tricks out there. The one you just mentioned does not sound like one I would want to learn.

When they manufacture circuit boards there is a technique called wave soldering. I machine melts a large quantity of solder and pumps it into a wave which is elevated slightly above the surface of a solder lake.

The circuit board is slid over this on tracks after all the parts are mounted and fluxed(and anti fluxed too). If I had not seen this with my own eyes I would not have believed it.

Lots of fine pitch big chips like CPUs are soldered with hot air. You need a special "hair dryer tip" for each and every style of chip on the board as well as a high precision XY table (with Z for the hot air gun) and work out the process, of temp and timing and so forth. This is one of several reasons why
much modern electronic and digital equipment is simply unrepairable. You have to have that special tip for the hot air gun and the tip could be $200. The rework station five to ten thousand. Easier overall just to replace the whole board.

It is extremely frustrating when you have a , say $4,000 spectrophotometer and its about eight years old and still looks like it was bought yesterday. All its functions are on one single $1,000 board. So the choice is buy a new board or a whole new instrument. Of course such construction DID make the instrument affordable in the first place.

Rylee Isitt
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Post by Rylee Isitt »

g4lab,

Yeah, I had a GPS which stopped working. Knowing some people might have had the tools to repair it, I put it on a freebie shelf with a sign saying it wasn't working. It disappeared within hours, but who knows if the person who took it wanted to repair it or just gut it of useful parts. Probably the latter, I guess. And recently my Lenovo T61 laptop fell victim to a known defect with the GPU, but a recall was never issued. Basically the traces inside the GPU stopped making electrical contact. The easiest way to fix it would be to replace the entire system board, at a cost greater than working, used laptops were selling for. The hard way would be to replace the GPU chip, but then you'd be replacing it with a used chip of the same model (requiring a rework station), so it too might stop working not long after.

On the other hand, there seems to be a reemergence of the DIY culture. I remember once listening to either a TED talk or some sort of science-related podcast where the speaker was lamenting about how young people weren't building things anymore. Just recently I listed to a TED talk celebrating how the opposite was beginning to happen. Enterprises like Sparkfun and Arduino are turning entire assembled boards into modular, versatile devices that are almost being perceived as single components. So perhaps we're not so far off from being able to build that spectrophotometer ourselves, from modular boards that can be swapped out if they are damaged. Then there's this emergence of desktop 3d printers which is still very much in its infancy, but getting more useful by the day. Soon they might be useful for building precision load-bearing components.

When that day comes, I suspect surface mount work will become much easier and affordable just because the tools will be more commonplace.

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