Hi there to you all, Just have a query regarding the above transformer,I'm thinking of setting up a car Stereo in my sons bedroom, and in the stereo theres a 15amp blade fuse, does this mean that in order to run this stereo from the mains I have to use a 12 volt dc 15 amp transformer? Also I havnt been able to source one from anywhere! Does anyone know where one of these can be obtained from if this is the case? Many thanks

 

hi,
A transformer supplies alternating current 'ac', you require a 12V 'dc' direct current power supply. The 15amp fuse is not an indication of the current requirement of the radio, I would expect it to be about 5 to 10 amps 'dc'.

The way to check the radio, would be to connect it to a 12v car battery [also the speakers attached to the radio] and measure the current into the radio using a ammeter.

Does this help?

 

A 12V car battery is 13.8V, not 12V.

__________________
Uncle $crooge

 

Cheers for that i will check it out

 

You need a mains 13.8V power supply.

Maplin sells them up to 10A, if it's enought for you.
http://www.maplin.co.uk/module.aspx?...o=231&doy=11m7

If you want 15A then I'm sure other places like RS Components and Farnell but you have to place and order, you can't just turn up and buy it.

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Its 13.8V when its fully charged, it quickly falls to 12V,, its rated at 2V/cell * 6 = 12V

I suggest you look at this link.

http://en.wikipedia.org/wiki/Lead-acid_battery

 

13.8V when charged in standby mode, and they always charged in standby mode. Your stereo is both safe when supplied with 12V or 13.8V DC.

 

Most car radios are rated with a 14.4V power supply.
Most people listen to their car radio with the engine running and charging the battery at 13.8V.

__________________
Uncle $crooge

 

No one's disputing this statement.

Many people also listen to their car radios with the engine switched off, that one of the reasons
your ingition key has those intermediate positions so the auxiliary devices can be operated.

As 'blatman' says the radio is designed to work safely with a 12V or 13.8V supply.

As 'hero' suggests I would also buy a 13.8V psu.

BUT a lead acid cell is still a nominally rated at 2V/cell, which gives a nominal voltage of 12V for a lead acid car battery,
not 13.8V which you suggested.

 

The spec says that the stereo allowance is 11v-14v.Cheers for the advice fellas

 

Then its output power per channel at clipping (low distortion) into 4 ohms is about 17W RMS with a 14V supply and only 9.4W with 11V for its supply.

__________________
Uncle $crooge

 

How many channels?

If it's 8hm: per channel, each channel takes 3.5A so four channels would require 14A plus any biasing current what's required for the microcontroller and any illumination.

But that's only the peak requirement at full volume, I don't know what peak current of the 10A Craplin power supply is but it'll be fin providing you don't play it too loud.

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