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DC/DC 12v to 5v 2-3Amp supply

terrym2002uk

By terrym2002uk
in DIY Astronomer

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terrym2002uk

terrym2002uk

Posted
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Hi,

Not sure if this is the best group to ask in but I suspect so.

I need a 12v to 5v DC/DC supply preferably 2-3A output so I can power a D-Link USB hub from my power tank. Guess it should be regulated.

Anyone know where I can get one or as a last resort a circuit to build one?

I doubt the 6v output on the SW 17ha Power Tank would be suitable.

Many Thanks

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malc-c

malc-c

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Terry, Google comes up with a range of options from £13 ( E-PLENISH.com Online Catalogue, 9UUC.001.04,TomTom 9UUC.001.04 Auto Adapter,12 V DC, 5 V DC,2.10 A For GPS Navigator, Cellular Phone, iPad, iPod, iPhone, Portable DVD Player )

To a 100w converter for just under 1oo quid Car/air Adapter 12/24v Input - 5v/16v/19v Output.. | Ebuyer.com

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terrym2002uk

terrym2002uk

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Thanks Malc.

The first one could be a goer I think, with a hacked usb lead. The second option is way to expensive for my budget and is probably a bit over kill to power a usb hub.

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Reggie

Reggie

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A selection of suitable devices :)

5v 3a dc to dc converter | eBay

Something reasonble, not sure about that efficiency but it's better than the 96% the cheaper versions are claiming.

DC/DC Converter Regulator 12V Step down to 5V 3A 15W | eBay

This is more what you're looking for, something that is dedicated to 12v/5v conversion. Either that or build your own with something like a mrcrel 29300-5.0, it'll need a hetsink, 4 wires and not a great deal else :(

If you don't know what size the jack is on the usb hub, take it into maplins and get them to sort you one out.

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terrym2002uk

terrym2002uk

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Thanks for all the options.

The dedicated step down modules on ebay look the biz at a price that's right.

The efficiency will depend on whether they use switched or linear regulators and the line input voltage. Linear is very bad if your stepping down from 14.8v to something quite small like 5v, as the difference is thrown away as heat. It needs to be switched otherwise I'm just throwing away my power tank time.

3A should be ideal, as a usb port cant draw more than 500ma max, so 3A for 7 port hub is a good fit.

Hubs arriving today so will see what the connector size is.

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MG1

MG1

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WOW thanks for that!

Quite an intense chap...imagine what christmas must be like in his house! :(

One thing I'd like to know is if there is more or less noise with a switched over linear?

I was planning to make a stepdown to power my DSLR camera as well as the 5v for a USB hub, but I'm slightly worried about it as I'm pretty sure that the camera electronics are quite sensitive. Am I worrying too much, or is there some sort of filtering arrangement that would work with some form of switching regulator?

Is it okay to run two voltage regulators and would you run a common ground? :)

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themos

themos

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I don't really know how much noise you can expect but I suspect that switching ones suffer more. Having said that, if you google "low noise switching regulators" you'll find the same thing I did! They do exist. I thought that if we are getting our 12V from a powertank we just can't afford the losses of a linear regulator.

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terrym2002uk

terrym2002uk

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Took the easy option and ordered one of these:

DC/DC Converter 12V/24V Step down to 5V ? 3A 15W | eBay

Also ordered a similar 5A version which lives in its own little heat sink, as I can see these coming in handy!

I'll just mount on the tripod leg on a plate next to the hub with a connector and a fused lighter lead.

Its all environmentally sealed so something less to worry about.

and yes a very interesting vid.

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terrym2002uk

terrym2002uk

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It's the camera power supply voltage I'm more worried about. Don't want to fry my 5D!

I got the astronominiser dummy 12v battery pack adapter for the 500D as I wouldn't want to risk feeding it with one of my concoctions.

http://www.astronomiser.co.uk/canonpower.htm

As for any "power noise", I cant imagine there would be much running from a 12v DC battery source. Its not like being in a car where the alternator generates a shed loads of electrical interference..

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Reggie

Reggie

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I got the astronominiser dummy 12v battery pack adapter for the 500D as I wouldn't want to risk feeding it with one of my concoctions.

Astronomiser - Automated Astronomy and AstroImaging Solutions

As for any "power noise", I cant imagine there would be much running from a 12v DC battery source. Its not like being in a car where the alternator generates a shed loads of electrical interference..

I have one of astronomisers original ones for a 450d, the newer ones are much better having the regulator in an external box rather than inside the battery. I needed one for a 400d recently but I really couldn't justify the price given what I know now, so I built myself one using perspex and flat brass picture hooks :) It's connected to a nice adjustable ldo regulator, so I *know* exactly how much power is going into the camera :(
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