Possible to up Amperage of a 12V 500mA wall wart?

[steinklatre]

I am building a radio from a car stereo and want to use a wall wart I have on hand that is rated for 120VAC 60Hz 12W 0.1A to 12VDC 500mA to a higher Amperage rating which I have to figure out for the radio. Is this possible? If so any directions?

Ideally id put the wall wart guts in the radio and a standard plug to the wall.

 

[OLIVE2222]

Hi Steinklatre, 500mA seems not enough for a car stereo. Are they any indication on the car stereo, or a fuse in the supply line to estimate the needed current ? If not can you carefully connect it to a car battery and measure this current?
Olivier

 

[steinklatre]

Olivier I didn't even think about the fuse! It has a mini 10Amp one. So that being said is there any way to change the guts of the wall wart to 10Amps?

 

[jackorocko]

Olivier I didn't even think about the fuse! It has a mini 10Amp one. So that being said is there any way to change the guts of the wall wart to 10Amps?

Most wall warts are not made to be taken apart without destroying the outer case. They are normally fused together. I also don't think you will be able to replace a wall warts components to get 10A unless you replace every component. So why not just make your own linear power supply?

 

[OLIVE2222]

10 amps is a super maximum, rated for full audio power. Anyway you probably still need something in th 5 amps range which don't exist in the wall wart style. You must go for supplies like used for CB transceiver. sadly it's not a financial viable option, as "decent" stereo should be available for around 50$

Olivier

 

[steinklatre]

Yeah I knew I would destroy the case but I wanted to put the guts inside the radio anyways. See my logic was. The 12v transformer ine the wall wart is the most inportant part so it must be other components after that giving me the 500mA's so if I change those ill get 10A. I knew it couldn't be that easy! I will google linear power supply but what is the benefit?

 

[OLIVE2222]

No in power supplies all component are dimensioned for the rated power, none can be reused to go to 10A from 0.5A
a linear power is the easier to build (doesn't mean cheap)
Olivier

 

[steinklatre]

Ok I am following you! My father in law just recommended I plug the radio into a car battery and see exactly what its drawing and then figure out what I am requireing for power and then to figure out the power supply. He agrees it may be cost prohibitive.

 

[OLIVE2222]

connect it (with the loudspeakers) and measure the amps is a good suggestion !

 

[davenn]

See my logic was. The 12v transformer ine the wall wart is the most inportant part so it must be other components after that giving me the 500mA's so if I change those ill get 10A. I knew it couldn't be that easy! I will google linear power supply but what is the benefit?

A 10A capable transformer is going to be several times larger than a complete 500mA plugpack. So you cant just swap the transformer.
yes try measuring the current drain of the stereo when operating across a car battery
WHAT is the rated power ooutput of the stereo in watts ? it should be written on it

10W, 20W or 50W or what ever per channel

from that you would be able to work out what current is needed to power it.

Dave

 

[BobK]

http://www.amazon.com/Wagan-Amp-12V-Power-Adapter/dp/B000P7O5DG

$14.95. You could not build one for less than this.

Bob

 

[steinklatre]

I am waiting on my multimeter should have it in the mail tomarrow. Anyways thats what I am looking for plans online for! But I will find out for sure what its drawing and go from there! The overall build is for a plexiglass desktop radio for work with some cool internal LED lighting. Opposed to junking the ole stereo.

 

[davenn]

Again...

Does the stereo have how many watts per channel writted on it ?

D

 

[steinklatre]

Oh sorry. No it doesnt. It does have the model number so I can look it up. I am at work so I will do it later today.

Thanks for your help

 

[steinklatre]

http://www.crutchfield.com/S-Mej7kdqS8BA/p_130DEH1700/Pioneer-DEH-1700.html#details-tab

Looks like 20watts.

 

[jackorocko]

So peak output is 45W.

45/12=3.75

So you will need a PSU to output 12V at <= ~4A max to run the head unit.

 

[steinklatre]

Is it possible to find a wallwart capable of this or make one?

 

[(*steve*)]

Is it possible to find a wallwart capable of this or make one?

See BobK's advice at the top of this page.

 

[Resqueline]

I don't want to complicate matters, but just for the record; that's 20W rms output per channel into 4 ohm speakers - at full tilt - and there are 4 channels.
That translates to 26W input per channel, or about 2A per channel = 8A in total if running all 4 channels. Add to this the idle current for the stereo and you get ~10A.
That's the theoretical maximum draw, but in practice 5A is more than enough and you'll not be able to hear the difference in maximum available loudness.
Also, if you'll be running only two channels you should be completely safe with 5A.
500mA might not be enough to cover even the base (idle) current draw of these "modern" radios.
For the old "twist-tune" radio-cassette players 500mA would have been enough to play quite loud though.

 

[davelectronic]

Like was suggested by BobK the unit in his post is a high powered version of a wall wart, only difference is there more powerful and there is a lead to plug it in, the other end still sports a trailing line plug. The units are very efficient , and not bad value for money.