Stepping-up Voltage

^^^^^^^

Buy a 12V battery. :-)

But seriously, if the app notes and suggested circuits in the data sheet give you what you want, then go for it. At worst, it will be a very interesting learning experminet. :-)

Good Luck! Rich

Fair point .. :) this is still an option, but there are several good reasons why using my large supply of 7.2V 6AH batteries would be a major advantage ... I'm basically looking to power an LCD screen and wireless transmitter (both 12v and relatively small current users). Another audio transmitter is 3V, so ideally I'd want a 12V and 3V output-- but obviously going up to 12 is more difficult than stepping down to 3V!

These are used and charged almost daily, so moving away from charging

Unless I can get any other advice/suggestions, I think I'll get that component and give it a shot.

Cheers! Kris

I copied this from the link you provided. Notice this...

Output currents up to 3A are possible with this device, from a wide range of input voltages (35V to 40V). Output voltages up to 60V can be developed...

epicedium wrote:

Cheers for noticing that OMU, but below that description it says-

Q) The description states an input voltage range of "35V to 40V" while the data sheet provided says "3.5V to 40V" - I''m guessing the product description is wrong? - Lloyd Williams A) yes its an error in the description.

--

i.e., minimum input is 3.5V, not 35! Why they haven't ammended this I have no idea,,,

This image shows it as part of a simple circuit:-

Old Mac User wrote:

you need a DC to DC converter ....many available ...gewgle "DC/DC converter"

connect two in series. many 12V devices will work from 14.4v too.

other than that, you could try a boost converter.

Bye. Jasen

I had actually ruled out running them in series, mainly due to the weight, but if I could run both the Camera *and* peripherals off the two batteries than that would actually be fine ...

How stable would it be to do the following? i.e., would it be safe enough to run the sensitive equipment off ...

- Two 7.2V batteries connected in series

- Camera connected in parallel with One of the batteries (being fed

- The two batteries (14.4V) ran though a resistor & zener diode to give me a regulated 12V output.

Sorry if this seems simplistic, but that's why I'm posting in basic electronics ; )

many many thanks,

Kris

jasen wrote:

How about two 7.2 V batteries in series with about four diodes to drop the voltage about 4 x 0.5 volts?

epicedium wrote:

Kris has a good idea with putting two batteries in series and adding series diodes, although I'd think 3 diodes in series (e.g. 1N5401s) would be better -- your voltage drop at a couple of amps will be close to 0.8V to 1V each. Radio Shack sells them as their Catalog #:

Either that, or if youu're very concerned about getting an accurate voltage over load conditions, you could simply put a low voltage regulator between the 14.4V source and your load to get a well-regulated 12V for a wide range of load conditions. A good choice would be the LM1084IT-12. It uses only 5mA(typ) quiescent current, can crank up to 5A, and is available in the TO-220 package. Just add a heat sink, two 10uF tantalum caps, and a 500 ohm load resistor if minimum current is a problem, and you're good to go.

The diodes have the advantage here in one important way -- they don't use any current when there's no load.

Good luck Chris

Please bottom-post.

That said, it sounds like your setup should work fine, with the caveat that the bottom battery will need to be charged more often than the top one, because of the additional current draw from the camera.

Good Luck! Rich

If you need exactly 12 volts a LM7812 is generally preferable to a resistor and zener as it wastes less energy.

Bye. Jasen

Thanks everyone, advice has been v v helpful!

I've measured the batteries and they actually range from 8.37 to 6.05v, so the peak of 16.74v is probably too high to bring down with diodes (well, unless I have loads of them).

I'm thinking that I'm going to try two approaches-- the zener/resistor approach (maybe with a transistor to help regulate further), and with a cheap IC regulator... I'd like to see how both work, and what kind of efficiency I get.

thanks aga> > > I had actually ruled out running them in series, mainly due to the