Car radio powered on 12VAC?

[bad_idea]

I have a car radio in my garage powering my stereo. I had a computer power supply providing 12 VDC to the car radio, but it failed (after 3 years). I found a low voltage lighting transformer at the ReStore for $6 and grabbed it. I didn't realize it was AC until I got it home. Will the car radio work right on 12 VAC? Thanks guys.

Here is a picture of the stereo just for grins. Since this picture I have run the RCA outputs from the car stereo to a home stereo receiver, better sound quality.

 

[G_P]

No. Needs to be 12v DC.

Grab a $3 bridge rectifier from radio shack and attach it to the output of the 12v AC transformer.

 

[bad_idea]

Tell me more. Please explain further. How does a bridge rectifier work? I understand AC power switches directions from + to - (60) times per second while DC flows from + to -. I am sure there is more to it than that, but that's about the gist right? Does the bridge rectifier act as a check valve stopping the power from switching back and forth?

 

[ForceFed70]

I really doubt your radio will be happy with a rectified 12VAC input. That is about as dirty of a power source that you could feed it.

I suppose it's worth a try, but I'd just find a new PC power supply to use. Should be able to find one for free and same amount of work to get wired up.

Voltage provided by a rectified AC signal looks like the attached picture

 

[Elvenhome21]

just use an old computer power supply. cheap easy and you can use it for other things as well.
http://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/

 

[pedrodagr8]

Computer power supply is easiest, though for most old ones you need a lightbulb on the 5V line otherwise they won't start up propetly.

To use this one, you need a bridge rectifier as some others mentioned and some filtering caps, a couple of 2200uF 25V caps should work well enough. Without the filtering caps, the device likely won't work because of how the voltage is not constant.

 

[ForceFed70]

Computer power supply is easiest, though for most old ones you need a lightbulb on the 5V line otherwise they won't start up propetly.

It's not that you need a lightbulb, it's that you need a load. It's hard on the PS to be turned on without a load.

In his application, the stereo is the load - so the lightbulb can be skipped so long as the stereo is always on when the PS is on.

 

[pedrodagr8]

It's not that you need a lightbulb, it's that you need a load. It's hard on the PS to be turned on without a load.

In his application, the stereo is the load - so the lightbulb can be skipped so long as the stereo is always on when the PS is on.

You missed what I was saying. I said the 5V rail. You are right in that it doesn't have to be a light bulb but it does have to be a load and on the 5V rail. Light bulbs are dirt cheap and work. That's why I suggested it.

Why the 5V rail? Because most cheaper designs are group related and need a minimum load on each of the rails. If you only load the 12V rail, this enters a situation called cross-loading and things can go out of wack really quick. Voltages of up to 16 or as low as 6 on the 12v rail are not unheard of due to cross loading.

Sent from my LGLS990 using Tapatalk

 

[Kevin C]

I would look at buying a low cost 12V switching supply from off of E Bay or find another spare used unit. New they can be had for under $10, used.... Often for free. The time, cost and effort to regulate and filter an AC supply makes it hard to justify.

http://www.ebay.com/itm/12V-5A-Power-Supply-Adapter-w-US-Cable-for-3528-5050-RGB-LED-Strip-String-Light-/370986811881?pt=US_Lighting_Parts_and_Accessories&hash=item56608981e9

Something like this should work. I have at least five similar units in the closet that I keep as spares for this kind of project.

Also, since most charging systems put out a voltage above 12 V (13.5-14.4), its not a problem to use a 14V supply . In fact, the amplifiers may work a bit better.

http://www.ebay.com/itm/AC-DC-Adapter-For-14V-5A-LCD-Monitors-TV-Switch-Power-Supply-Mains-Charger-PSU-/400339671118?pt=US_Monitor_Power_Supplies&hash=item5d361a984e

Switching supplies tend to have a bit more noise and might require a line filter. So far, the ones I have used have been fine.

 

[dowmace]

Honestly you don't need a bridge rectifier the radio won't be that sensitive. Just put a large diode on what would be the positive leg of the circuit. 10 cent fix

 

[bad_idea]

I got the radio figured out. I used a switched power supply from some old electronic item I had. The radio sounds much better than it did w/ the dying pc power supply.