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A series power supply problem

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Offline natapongw

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A series power supply problem
« on: 09 / April / 2011, 00:25:33 »
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Hi everybody,

I have some problem with external power supply for A480,A540,A570is. All 3 cameras have same problem.
I make 1.5 A 3.0-3.3 V adjustable power supply but can't work all. When switch on they show "Change battery" only.

I try to use AA battery and it's work. When I move this 2 battery for power source of external battery I found same problem. They show only "Change battery"

Is my problem come from DC jack or anything ?

Thank you very much for all answer  :)
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Offline fudgey

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Re: A series power supply problem
« Reply #1 on: 09 / April / 2011, 02:32:00 »
Possible causes:
  • Too long wires and/or bad connectors causing high resistance -> voltage drop during current peaks -> low battery detection
  • 1.5 A may not be enough, Canon's power supply is about 3 A AFAIK (at least the one I use is and it has worked flawlessly)
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Offline thepanoguy

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Re: A series power supply problem
« Reply #2 on: 09 / April / 2011, 03:04:38 »
Designing a reliable power supply is an art. If your heatsink is too small for the current draw or if the current draw is too high for the regulator, the regulator will overheat and internally shut down.

Unless you possess the right test equipment, you would be better off purchasing a commercially made power supply. Most commercial power supplies use switching circuits which contain undervoltage, overvoltage and short circuit protection and they are more reliable than a home made linear regulator power supply.

You don't state your application. I would ask the guys on this site for application advice, what power supply they use and what brand they would recommend.
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Offline NewbieToobie

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Re: A series power supply problem
« Reply #3 on: 10 / April / 2011, 17:24:42 »
You need to know the exact voltage and amps required for an external power supply. For example, my camera uses 4 AA cells. This is only 4.8-6.2v. Yet the external DC-In plug requires 7.4v DC at 2.0 Amps. I found I can power it okay at 6.5V DC through the DC-In plug, but it will sometimes shut-off if the power-draw is too high on some camera operations.

Check your owner's manual for the camera specifications, or go to Canon's site and find the external-power adapter and read the specs on that. Then you'll know what voltage and amps are required.
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Offline fusionstream

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Re: A series power supply problem
« Reply #4 on: 31 / May / 2011, 11:58:26 »
I'm currently building a 18650 li-ion based power supply and after significant searching, I finally came across an article here (I went one big round, more than twice) which said that the canon powershot A series actually requires something more along the lines of 3.6 volts (but the poster said although he had read the 3.6V thing somewhere, he had no problems with 3.5V). I've built a number power supply configs on my breadboard and can confirm that 3.5V is your minimum threshold. Anything below that and you will have problems even operating the damn thing. This is in spite of there being a clear 3.15V marking on the device.

If you're building an SMPS based power supply, wire up a multimeter in parallel and in series for voltage and current readings respectively. Watch the meter as you turn on your camera in play vs rec mode, when zooming in or out, saving a picture, taking a picture, flash, etc.

I've got a working prototype ready and am waiting on higher quality parts (to finalise the design - which is simple) and... for red/black electrical wire. After all this time and of all things to be short on, it's the damn wire. lol.

Some other notes on the voltages. My Canon powershots, at the very least, (A540 and A1100IS) are extremely sensitive to the input voltage.

At 3.48, the camera has problems turning on completely or will turn on fully and then display the "Change Battery" message when performing high current tasks.

That being said, with my latest design, using an LM2592-adj, the voltages go down as low as 3.4 during some operations but still works. This is in contrast with previous designs. Still trying to figure this out.

And your power supply should be able to supply 1A.

Hope it helps.
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Offline fudgey

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Re: A series power supply problem
« Reply #5 on: 31 / May / 2011, 13:14:57 »
My a570 (also marked 3,15V) works fine at above, say, 2.5 V from the DC jack. But the power supply needs to be able to supply current without a delay (an insufficiently good SMPS will droop with transient loads and thin/long wires will ruin it too). Also, 1 A may not be enough.
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Offline thepanoguy

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Re: A series power supply problem
« Reply #6 on: 01 / June / 2011, 00:08:30 »
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