24v to 12v project guidelines

[stj]

Re: 24v to 12v project guidelines

No, he'd definitely not be willing to pay too much for it, plus the idea is to make one

Out of curiosity nonetheless: what's the one you've got like ? Is it homemade or is it commercial ?

it's a comercial unit made by ASTEC from a london bus!!

[mariushm]

Re: 24v to 12v project guidelines

You could just buy a second 230v..240v -> 24v AC transformer and wire it the other way, so you'd get 230v -ish into a mains socket ... then use a regular 12v laptop adapter or wall wart or something to produce 12v.


if it's 24v AC being sent ...


Bridge rectifier, 35v or higher rated capacitor to smooth out the voltage
then just buy a dc-dc converter to produce 12v :

Links : http://uk.farnell.com/c/power-line-p...-dc-converters

non-isolated dc-dc converters : link

isolated dc-dc converters (min 12w , that support at least 36v input voltage or more) : link

[Dannyx]

Re: 24v to 12v project guidelines

if the guy wants to cover the postage, i have a 24 to 12v convertor designed to power radio's in buses or trucks.

if your going to make one, you need a switching buck regulator.

No, he'd definitely not be willing to pay too much for it, plus the idea is to make one

Out of curiosity nonetheless: what's the one you've got like ? Is it homemade or is it commercial ?

[stj]

Re: 24v to 12v project guidelines

if the guy wants to cover the postage, i have a 24 to 12v convertor designed to power radio's in buses or trucks.

if your going to make one, you need a switching buck regulator.

[Dannyx]

Good day folks. A friend of mine recently asked me, thereby giving me a "mental challenge", to come up with a solution for converting a 24v supply from a crappy old transformer to a 12v supply which he'd use to power a car headunit he intends to install in his basement. To clarify, where I live, many apartment blocks don't have a mains supply running into their basement due to safety regulations regarding electric hazards caused by floods from leaky pipes or water used for putting out potential fires, so instead there's a beefy 24v transformer somewhere at the top levels feeding some crappy bulbs down there for light only and that's it, so if there ever IS water down there, the supply is isolated and harmless to those who might be standing in it.

The idea is to tap into the 24v bus, put a rectifier on it and regulate it to run a headunit...from what I understand, the headunit in question is a junker he got from a friend, so we're not talking amps and 1000w subs here

Come to think of it, many headunits run perfectly fine on 24v as well, since they're designed for use on trucks or vehicles which operate on 24v, so technically no conversion should be done at all, but without first seeing the thing I can't know for sure. Even then, I'm thinking of all the spikes going on on the mains side which would translate to possible overvoltage on the secondary as well, so I need at least some minimal regulation.

Obviously a switching regulator would be best suited for maximum efficiency, but that's a bit overkill and hard to design, especially since it would probably cost more than the headunit itself and would have to be fairly beefy, since automotive equipment tends to draw quite some amps (again, this is a number I haven't got at the moment, since I haven't seen the thing he's trying to power, but I WILL tomorrow hopefully....some rusty hunk of junk he found at the wreckers from what I understand )

I HAVE simulated a linear regulator one using an op-amp and basic feedback and it works (in theory at least), though it's going to be highly inefficient, because it would have to shed 12v (24v-12v) and even at 1-2 amps, we're still talking 12-24w for the pass element. Cooling and pricing becomes an issue at this point - again, would probably outweigh the radio itself. What would you use ? Thoughts ? Ideas ? A battery radio or a phone, I know what you'll say, but that's not the point of the discussion