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#59684 12/13/05 12:58 PM
Joined: Jul 2002
Posts: 717
M
Member
Try Google searching for a company called Moose. They were great for cheap power supplies. Also if you have an ADI store in your area, go there and they have just what you are looking for in stock.

#59685 12/13/05 01:28 PM
Joined: Aug 2001
Posts: 7,520
P
Member
What do you actually want to run on the 12V DC? That will determine just how well the output needs to be regulated, what sort of ripple voltage would be acceptable, and so on.

#59686 12/13/05 09:24 PM
Joined: Apr 2002
Posts: 197
T
triple Offline OP
Member
Without delving into the entire project, I am looking to power a car stereo (and possibly a small DC motor).

#59687 12/14/05 12:30 AM
Joined: Oct 2003
Posts: 156
D
Member
Being a former RF engineer and avid amateur radio operator, there lots of way to get to the point where you want. Since you mentioned car radios, and dc motors, how about a car battery and float charger?

Any ham fest or ham web site has tons of 12 (actually 13.6) power supplies up to 50-amps for dirt cheap.

#59688 12/14/05 12:36 AM
Joined: Nov 2005
Posts: 827
Likes: 1
J
Member
triple: Without delving into the entire project, I am looking to power a car stereo (and possibly a small DC motor).

Maybe I'm being old fashioned, but it was usually preferable to use linear supplies, as opposed to switchers, in audio applications. Ripple voltages and possible radiated noise from the switcher can have nasty effects in your audio path. (Like high freq. buzz). And you are probably really wanting a 13.5 VDC for your car stereo to get the most out of your final. It is probably wise to take your motor drive off of your input filter network via a separate path so that your amplifier supply and motor supply are isolated.
Joe

#59689 12/14/05 11:19 PM
Joined: Apr 2002
Posts: 197
T
triple Offline OP
Member
1) A battery is out of the question since weight is an issue.

2) I've changed my plan and a 12vdc motor will no longer be used. Thus, the car radio will be the only load.

#59690 12/15/05 01:01 AM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
Still hard to beat a $5 PC supply for simplicity in the development stage. If you want to refine it to some special purpose $50 supply when you get past the prototype go for it.


Greg Fretwell
#59691 12/15/05 11:10 AM
Joined: Apr 2003
Posts: 60
C
Member
Odd sounding device... weight is an issue in a device that uses household voltage?
Why am I picturing a walkman personal radio with a power cord?

#59692 12/15/05 12:31 PM
Joined: Mar 2005
Posts: 1,213
S
Member
Using a computer power supply to power 12V devices is common, especially among computer efficianados with high-currenet 12V devices. Be aware of two things:

ATX power supplies will NOT work out-of-the-box. They are designed to be switched from the motherboard, so you will have to manually modify the motherboard cable with some simple circuitry to "trick" the PSU into believing the motherboard has instructed to turn it on. Older AT power supplies do not have this feature and always supply power when they're turned on.

Also note that most power supplies are designed to provide power to a computer as a whole, with typical balanced power on 5V, 12V, and other supplied voltages; if you leave all the lines unloaded and load the 12V side down, some will not work at all and others may give varying results (eg, 14V or 10V output, something like that.) It's hit or miss; DIY hobbysts don't sweat soldering a resistor on a 5V wire to balance the load and if you're just jerry-rigging an old car radio, this could be the way to go, but I wouldn't do this for something critical.

Considering how many of these things are sitting "free" on junk piles of old computers, it's very tempting, isn't it?

[This message has been edited by SteveFehr (edited 12-15-2005).]

[This message has been edited by SteveFehr (edited 12-15-2005).]

#59693 12/15/05 01:44 PM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
ATX supply, you ground the green wire from pin 14 to start it. AT supplies are either on with the switch or (IBM Aptiva and similar) you tie the black and white wire together on the 3 wire connector. A paper clip in the connector holes works.
Dell ATX supplies have a different pin out but the green wire is still "start".
These things have internal overload protection that shuts them down so it is hard to blow one up. Some will shut down if the load changes suddenly.


Greg Fretwell
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