12 v dc power supply

cuda.340, Apr 4, 3:20am
i want to supply 12 v dc to a car stereo amp in a party area with 230 v ac. whats the best way to do this!
74nova, Apr 4, 3:22am
A couple of big batteries and a bloody good charger.
skin1235, Apr 4, 3:25am
a 70 or 95 amp alt hooked to the rotary hoe, feeding a big battery
cuda.340, Apr 4, 3:25am
umm yeah, i'm thinking cheap, reliable & compact.
kingfisher21, Apr 4, 3:36am
Old alternator hooked up to a push bike, get the missus to pedal hard out all night :-)
skin1235, Apr 4, 3:40am
then be thinking 50 amps continuous for as long as the party continues

and thats going to negate the cheap part

don't know if hire centers do a big 240/12v tranny

seriously though the alt from an old mitsi sigma ( 70 or 90 amp),( has built in reg and rectifier) on a bracket in front of the rotary hoe and feed a battery that you're feeding the system from ) all you gotta do is keep filling the tank - oh and have a rotary hoe too I guess, all thats missing is the compact, reliable depends on how fast you can run with the fuel can
mm12345, Apr 4, 3:42am
Well the suggestion you got above for using a good battery and a damned good charger is about as cheap and compact as it's going to get.

Edit - read your last post, and for 50 amps 12v over a long period, you're basically stuffed.
But a question is why!50A/12v is only 600 watts input probably 400w output (only if you can run low very impedance speakers), and with typicallow efficiency car stereo gear, probably better just to use a domestic hifi or better borrow a small PA system.
skin1235, Apr 4, 3:46am
but it's going to take one humungous charger to deliver 30-50 amp continuous
mm12345, Apr 4, 3:49am
Yep.Hire a PA, or use a seriously grunty home hifi instead.Save a lot of grief.
cuda.340, Apr 4, 4:03am
dudes, this is low budget sh!t i'm wanting. i've fitted up some Marine omni directional speakers, i have a car amp of 200 watts to drive them, i'm just wanting the cheapest 12v dc power supply that'll keep the amp running while while we suick back the coldies. i'm going to hook up my phone to supply the sounds. i can wire up a 230v ac to 12 v dc inverter, battery charger whatever to be the power supply. i'm not hiring/renting nothing. sheesh!
taipan4, Apr 4, 4:11am
old stick welder & pick up some heavy diodes & some capacitors to smooth out DC ripple & a big ole truck battery, & check voltage before hooking up.4 diodes in a bridge network.
skin1235, Apr 4, 4:12am
if you have a 240/12v inverter handy then sure, wire it in, honestly, it will work, you only have problems if you undersupply, the inverter will supply what 80 to 100 amps ( think aboutload rate, 100 at 10% means you'll cook the inverter - 50 at 95% means you won't)
I would caution though, put a battery in the audio feed circuit, it helps smooth out the feed saves frying you head unit/amp etc
skin1235, Apr 4, 4:13am
works too, but most were 24V, great for starting trucks and bulldozers, no diodes needed , they were and are all DC voltage
mm12345, Apr 4, 4:17am
Well 200 watts and 600 watts is a big difference.Assume 66% efficiency and the 200 watt amp is only drawing 300W max, and probably averaging less than 1/2 that.So get a big battery, connect a 15A charger to it, and it'll probably be fine.
skin1235, Apr 4, 4:20am
agreed, and if the charger cannot hack it, clip it onto mums shopping trolley, leave that idling out the back for an hour or two
matthew_129, Apr 4, 7:17am
Cheapest/easiest way is a computer power supply, about $50 new. Short the correct pins together on the main ATX plug and it will start up then the yellow wires are all 12v positive and the black ones are your negative. Red ones are 5v. Just be wary that thier pretty low amperage. They will run a head unit and some small amps but dont expect to be driving a sub with it (well at least at any big volume)
tonyrockyhorror, Apr 4, 8:46am
Yep. Just check the label on the side and it'll tell you what it can supply on the +12VDC.
bitsy_boffin, Apr 4, 4:52pm
PC power supply is a good idea, plentiful, if you look around you should be able to find an old AT one which runs without any bridging, for close to nothing.

Couldn't you combine all the 12v linestoo!Limit would be per line wouldn't it!
tonyrockyhorror, Apr 4, 5:02pm
The rated delivery is for the whole unit but you wouldn't need ALL the +12VDC wires to get the capacity. Just a few, depending on what the unit itself can deliver. If it was 25A, 5 wires would be enough on each +12VDC and earth.
studio1, Apr 4, 11:39pm
There was a guy from down south selling a 70 amp 12 volt power supply on here for a few weeks in a row recently. That is EXACTLY what you need. It was used to power a car audio comparator in its previous life.
cuda.340, Apr 5, 1:27am
ok guys i've sorted it. i went to a laptop reconditioning outlet, bought a power supply lead with box in the middle. it was rated 5 amps & 60 watts. it's been running at 1/2 volume all arvo & sounds great. nothing got hot & the sound wasn't distorted. i'm happy. cost me $8.