Dropping voltage on 12v battery

[Tcoil]

Hi, I.m looking to drop the voltage of a 12v die hard to 9, 7.5 and 5 volts safely handling 2 amps. What's the best way to go with least amount of drain in the battery from the voltage dropping circuit.

[sawreyrw]

What you want to do would be easy to do with (properly rated) linear regulators, but they are relatively inefficient. If you really need minimum battery current, you need to use a buck type switch mode power supply.

[!]

9, 7.5, and 5V seem like unusually low voltages, do the amps really need this low a voltage? If so it is as sawreyrw wrote, either linear (voltage loss * current) regulator drop or switching buck circuit to reach a pulsed average voltage.

The former is much easier and less expensive to build. The latter you will probably HAVE to build yourself as it is very unlikely you'll find a SMPS with those 3 particular outputs. Maybe using more than one PSU with adjustable outputs would work, but simple/small/low-current SMPS for this application to keep cost, size and time within reason, would tend to have relatively poor/noisy output for an audio amp.

Back to the original question, do the amps really need this low? The 9V and 7.5V especially, both seem odd as many ICs, capacitors, etc that can handle 7.5V to 9V, can handle ~ 12.6V battery ok. 5V, I wonder if it's a digital IC with lower current so it's less power loss to use a linear regulator for that?

A bit more detail about the project might help.

[DigitalJunkie]

Originally Posted by !

9, 7.5, and 5V seem like unusually low voltages, do the amps really need this low a voltage?

I think he means 2 amperes,as opposed to 2 amplifiers.

My suggestion,switchmode buck regulators.

[!]

^ haha, yes

[Tcoil]

Well, my project is for remote camping. I have to rely on solar power and batteries. I have accessories that require different voltages. My audio equipment runs on 12v but my recorder runs on 3 volts and other devices run 6 and 9. I was lookig for the most efficient circuit to conserve battery power. I want to get away from inverting dc to ac

[Tcoil]

yes, amperes of current but I'm also rumming 2 amplifiers. My 12 v stereo and my 12 v guitar amp. Any good circuits out there?

[!]

Here are some ready to use, might not be worth the bother to build your own for time, space and durability reasons when camping. I found it searching ebay for Switching Regulator (including in description), there were some other hits in the third link you might browse through too but most were for lower current.

Step-Down switching DC converter 90W 2.5-12.6V variable | eBay

This one barely makes the cut at 2A rating, or you could treat it as an example circuit to clone with help from the respective chip datasheet LM2596S DC-DC Step Down Adjustable Power Supply Module | eBay

switching regulator | eBay

However these may not have very clean output, I wouldn't try to power an analog audio amp circuit with them.

[auplater]

might be cheaper and easier to just by separate rechargeables... wally world has 3 cell pb/sulfate cells in the standard 6V package for not a lot of money.

http://www.google.com/search?q=lead+...w=1152&bih=656

http://www.google.com/products/catal...=0CIYBEPMCMAA#

With a little effort, you could probably find other similar voltage range batteries to suit, then build a simple switch box to give you 2/4/6/8/10/12/whatever with little or no loss...

just a thought...

John L.