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I've been having bad luck for years with rechargeable batteries which keep dying or don't hold charge for longer than a few minutes, or the charger for them stops working, and it's gotten to the point where I've spent 4 times more money on the batteries and chargers than the camera's own price. So I want to try something new − using 5v USB portable battery packs instead of the 2 AA rechargeable batteries. The camera has a plug hole for a wall socket 3v adapter (label on the bottom of the camera says 3.15v⎓) but that is not a mobile solution. But this hole can be used more easily than the AA battery contacts behind their protective cover.

I have basic soldering skills, but not enough knowledge about electronic components to figure out for myself what to use to make a circuit to do what I want. If you can post a complete noob-friendly answer, that's be wonderful. If you can point me at some starting places, that'd be great too.

An important thing to know about the expected power output of the circuit: apparently, standard non-rechargeable batteries will never work with a photo camera, as it will say "replace batteries" with any brand new pair fresh from the store. They don't seem to support enough output to power the camera's lens motor.

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  • \$\begingroup\$ If you're planning to use the "plug hole for a wall socket 3v adapter", then wouldn't you want to convert your USB 5V into 3V rather than 2.4V? \$\endgroup\$ – brhans Jun 5 '17 at 18:32
  • \$\begingroup\$ I suppose the camera will accept both voltages and in-between, but 3.15v is the maximum it's safely rated for. \$\endgroup\$ – user1306322 Jun 5 '17 at 18:33
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    \$\begingroup\$ use a step-down converter. They can be bought or designed easily. However, you're asking for a complete design, and doing that is off-topic here :) Your starting-point question is fine (if a bit too broad), so: yeah, step-down converters. www.ti.com, on the front page there's a supply designer, input: 5V, output 3V, current: as much as your camera needs, (maybe you need to choose the "mobile WEBENCH" on the next page, the regular one still needs macromedia Flash in 2017...), then pick "simplest solution". \$\endgroup\$ – Marcus Müller Jun 5 '17 at 18:34
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    \$\begingroup\$ to pick up on @jonk's question: I've not really seen AA batteries even in lower end consumer cameras for a couple of years – lithium batteries have become so cheap and reliable that most manufacturers just abandon the AA NiMH/NiCd battery type (because they have high self-discharge, deteriorate etc, as you've noticed in extreme). So, if you were a friend coming to me asking whether to build something out of a let's say $15 USB power bank, and some unknown cost for a step-down converter, or to just get a new camera: Probably the latter. Especially for point&click, there's been progress. \$\endgroup\$ – Marcus Müller Jun 5 '17 at 18:47
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    \$\begingroup\$ @user1306322 Okay. Thanks. Since you want "simple," and assuming you keep this beast, it's probably best that you get a complete DC-DC module (non-isolated, though it doesn't really matter in your case.) Mouser and Digikey both sell these. (Though perhaps not for exactly 2.4 V.) You can also get step downs, with multi-turn variable voltage pots, for about a dollar or two on ebay. \$\endgroup\$ – jonk Jun 5 '17 at 20:29
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Here you go, here is an easy to use package with 3-pins where you only need to add the input and output capacitors.

https://www.digikey.com/product-detail/en/microchip-technology/MCP1826S-3002E-AB/MCP1826S-3002E-AB-ND/1635993

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You don't mention any current requirements, but presumably you could use something like this as long as the camera's current draw is low enough...

https://www.digikey.com/product-detail/en/texas-instruments/TPS79328YEQEVM/296-19008-ND/863830

Or you could at least use it as instructions for how to solder together your own similar circuit. If you can get by with a simple linear regulator like what's on that board (you could get a similar one in a different package that's easier to work with), often you only need to add input/output capacitors and wire things correctly.

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