Cheap and Easy PSU for Canon EOS

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About: I'm an Italian freelance structural engineer, graphic designer and photographer, and I'm teaching physics in Waldorf high-schools. I always investigate electronics, robotics and science in general, I'm a pas...

I think lot of guys here on Instructables know how much satisfaction is obtained building a gadget entirely by ourselves, but... sometimes it could be a clever solution opting for some nice and ready accessory. I think this is one of these cases.
I recently had the need to have a power supply for my Canon DSLR, an EOS 40D, to make some timelapse. For this pourpose I've bought an LM2596S step-down adjustable power supply module from eBay, it's very cheap, efficient, compact, and (I hope) safe... and it fits exactly inside my exhausted lithium battery case. And this instructable could be handy adapted for almost any digital camera battery, the only requirement is that the case contains the power supply module.

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Step 1: Intro

The new psu is intended to work with a wall-plug transformer the same as with any DC power source between 9 and 35V, as a car battery or almost any wall-plug psu. This could be very handy in case of timelapses, gigapan shots, or long movies.

Step 2: What's Inside?

I've made the same modifications on two batteries, because both of them were exhausted. They weren't Canon batteries, indeed the original ones are almost ethernal.
You have to cut/crack the plastic casing all around the perimeter, because it's glued verty sturdy. Inside you'll find two 18490 Li-ion batteries, which are very rare to find to replace.

Step 3: Keep the Shells

Separate the battery parts unsoldering the battery contacts, and clead the case edges with a cutter, they should fit each other so we'll glue them at the end.
Maybe you wish to keep the protection circuit as replacement...

Step 4: Drill the Hole

Now take misures of the aperture which you find on your Canon. It's a little rubber door which you can bend to let the wire pass through. I've found that in battery-grip the aperture is in a different position, but if you're powering the camera by an external powersource probably you don't need the battery-grip. So I've opted for the in-camera wire position.
Drill an hole in that position and file it or cut it untill it becomes of the same shape of the wire. I've also added some heat-shrinking tubes to toughen up the cable extremity.

Step 5: Glue the Circuit

Check that the circuit fits in the battery case, I've had to file a corner to make place for the cable.
I've insulated the two unused contacts, and also added a piece of tape to not let the pcb touch them.
Then I've used a double-tape to lock the circuit in place. I've added another layer of tape over the one you see in the pictures.
You can then begin to solder the wires on input and output terminals.

Step 6: Solder It

You can see the glued pcb in place. You can now connect a power source to the cable ends, maybe 12 or 24 volts work good. With a multimeter misure the output voltage and turn the potentiometer until you'll obtain an (almost) exact voltage of 7.4V. 

Step 7: Label It

Now you can add the DC input range on a label behind the battery, together with output voltage and plug's polarity scheme. I've printed some coloured labels so you can cut them and glue into the shape of the previous one.

Step 8: The Socket

As female socket you could buy one of those nice ones which already have a cable connected. I've used a different type, and I had to solder the wires on them. Then I've enclosed them into some heat-shrinking tubes to obtain a better look.
[UPDATE] You can now see the detail of the cable coming out from the rubber cover near the battery door.

Step 9: Done!

Check another time that everything works good, let the power connected for a few time, try different input voltage, bend the cable, flex it, pull it, also chew it if you dare... it's better to get a shock now than to find your three months timelapse failed because of a bad soldering! Obviously I'm fooling with you, always pay attention to high current sources as car batteries, they're very dangerous!
Everything is ready, it's time to glue the shells pair, maybe with two elements glue, and try your new power adapter!

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    44 Discussions

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    ju1234

    6 months ago

    Hello all,

    I know it is an old link but in case some one can help, please respond.

    I did not see this link before I made my device. But here is the problem I am running into. Advise:

    For my EOS 40D, The original battery is rated at 7.4 volt. The body of the camera at bottom says 8.1 volt. The original dummy battery and ac converter that is sold by Canon for this camera is 8.1v 2Amp. So I am assuming a 2Amp 8.1 volt power supply should be adequate to run this camera. OK, so I made my dummy battery. Inserted it in the camera. Checked it out with multimeter that the connections are correct. Then I have powered it with many different sources with the same result.

    I used a step down converter which is rated at 3amp to reduce voltage down to up to 8.4v (I am afraid i might burn the camera if I go over that) and used power from DC 12volt 7amp lead battery or 19v laptop battery or AC converter, they all give me same result. The camera sees the battery displaying an empty battery flashing sign in display but will not power the camera up. I even used an 18650 power pack (8.4v 8amp) directly (no step down) to the dummy battery. Same result. AC wall converter with 8.4v 2amp DC output directly, same result.

    What am I doing wrong? thanks for the help.

    4 replies
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    andrea biffiju1234

    Reply 6 months ago

    It's strange... my only supposing is that your psu doesn't really give 3A, but less than that when there is a load.

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    ju1234andrea biffi

    Reply 6 months ago

    Sorry, forgot to mention, my dummy battery is empty shell, no voltage step-down or step up inside it like in this instructable. The step down I used was outside. I can measure the correct voltage at the dummy battery terminals when outside the camera.

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    ju1234andrea biffi

    Reply 6 months ago

    Thank you for answering. Like I said the problem is same when I use direct output as well. I used 110v wall converter which is 8.4 volt DC 2.1 amp and is originally for Sony camera and works with it. Hooking up that directly to the dummy battery without any voltage converter does same thing. I took out some 18650 batteries from a spare laptop battery. I have 2s 2banks (2 parallel X 2 series = 8.4v and I am sure it is more than 4Amp because the laptop charger is rated at 3.5amp). I connected those directly without any protection circuit or any thing else and still got same flashing empty battery icon. My multi-meter measures only up to 250ma so cannot actually test it.

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    Mohammed AliA1

    3 years ago

    Hi there,thanks .i've done it but please help me I had problem err99 please shooting is not possible. Please turn off the camera or remove the battery" ? ?

    1 reply
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    TimotiusR

    3 years ago

    i know this instructables is kinda old but im curious if i can use dc-dc step up instead of a step down module. i want to connect it to a powerbank with 5v output.

    the modules looks like this:

    HTB1bLk8KVXXXXXlXFXXq6xXFXXXP.jpg
    2 replies
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    andrea biffiTimotiusR

    Reply 3 years ago

    yes you probably can, if it supplies enough current :-)

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    TimotiusRandrea biffi

    Reply 3 years ago

    how much current does it need? btw thanks for the reply

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    darklylit

    3 years ago

    I recently cracked an AC adapter dummy battery and was surprised how little was inside: just a jack, two capacitors and the contacts connected to a PC board. Would you have any idea how to determine what these type of capacitors these are and their values? They're so tiny and don't seem to have any markings on them. I'm not very electronics-savvy, so if anyone might be able to give me an idea of what their values might be, or if I could substitute something else for them, I would appreciate it. Thanks a lot.

    IMG_9185.JPGIMG_9186.JPG
    1 reply
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    MOs7DBSVdarklylit

    Reply 3 years ago

    The reason this adaptor is so tiny, is that all the electronics andrea_biffi put into the battery casing are located in the wall adapter of your battery AC adapter.

    You can measure the capacitance of the capacitors using what is called an LCR-meter. It not only measures capacitance (C), but also inductance (L), resistance (R).

    The capacitors are bypass capacitors, to filter any noise, that got coupled into the cable between the wall adapter and the dummy battery. They also compensate the inductance of that wire in case of sudden changes in the current.

    My guess is, that the smaller capacitor is 100nF and the larger capacitor is in the range of 1 - 10 uF. The exact values probably don't matter much. Common capacitors of this type can deviate from their labelled value by -20% to +80%(!).

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    vexedart

    3 years ago

    This was a great post. Used it as a building block for creating my own PSU with a few modifications. Ended up casting my own hollow battery shell in resin you can view some of the pictures here.

    http://www.vexedart.com/dslr_battery_diy_power_supply_resin_cast.html

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    mcvapes

    4 years ago on Introduction

    Thank you so much for the guide. I was just looking into using this exact converter. However, I am concerned about the heat. According to the spec sheet for the LM2596S, a heatsink should be used when over 10W. The stock batteries are rated for 7.4V at 2A. Unfortunately, I don't have the tools to measure how much power the camera uses. Have you ever checked for heat build-up in the battery enclosure after prolonged use? I

    1 reply
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    andrea biffimcvapes

    Reply 4 years ago on Introduction

    I doubt the camera has a peak of more than 10w. Batteries are so powerful to last many hours. I never checked the heat, but I used for time lapses so there is a certain interval between pictures and certainly enough time to heat down.

    Video mode on new cameras could be different, but you can always check if the psu is hot after some minutes of video.

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    meanpc

    6 years ago on Step 9

    Nice job! Would be nice if Canon included a DC input from the factory, wouldn't it? Especially since we are using them for video a lot now, which burns a ton of battery.
    Can you show the camera with your battery installed? I would like to see how you have the wire routed.

    3 replies
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    andrea biffimeanpc

    Reply 6 years ago on Introduction

    Yes I'll take the picture soon. Canon always wants to sell more accessories, see also timelapse features or flash transmitter... :-(

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    archp2008andrea biffi

    Reply 5 years ago on Introduction

    If you don't want to risk burned fingers you can order something that works like this for the Canon T2i on Ebay for around 10 bucks. http://www.ebay.ca/itm/180659453326?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649. If you have a larger capacity 7.4 volt power source (e.g. old canon camcorder battery) the dummy battery part of the above adapter can always be cut off and used instead of the AC adapter.

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    andrea biffiarchp2008

    Reply 5 years ago on Introduction

    Thanks for your advice, I've been using my DIY PSU with success for last seven months with not a pinkie burned ;-)
    My power source is 220VAC or 12VDC, this last connected directly to my dummy battery.

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    tvm777

    6 years ago on Introduction

    Its a good solution, i have a 550D, same solution for it??
    wich module did you use? i find this one cheap:
    http://www.ebay.com/itm/LM2596S-DC-DC-Step-Down-Adjustable-Power-Supply-Module-zl-20120129-002-/170855921526?pt=LH_DefaultDomain_100&hash=item27c7ce7776&vxp=mtr