Hello everyone,

I need a transformer that outputs a around 9V 500mA AC. I don't have this transformer but I have one that outputs 9V 500mA DC. The transformer part is enclosed in a plastic cube.

Could I change the DC transformer to AC by taking out the diodes that I think are in the cube, will this work?

Will it still output 9V 500mA?

I would really appreciate some help.

thanks,

George L.

 

You just have to throw out the cirucit.This is how many wallwarts abre built.An cuble looking like an transformer and an circuit board that makes AC to DC(4 diodes and an cap)

__________________
Il give you shocking experience.

 

all transformers o/p AC
better to go for a new X--9v 500ma transformer

 

You first need to know EXACTLY what your circuit requires?, for a start does it have to be AC?, DC will often work just as well - it depends on the circuit inside the unit. Secondly, what voltage range will your unit work over? - unregulated wallwarts are extremely poorly regulated, a 9V DC one probably outputs 15V to a low load?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

hello,

I was going to use the AC transformer for a "experiment." I was going to wind a primary transformer coil and put in under a large sheet of aluminum and put the secondary transformer coil on top of it. The sheet is much larger than the coil. I think the secondary coil will still receive power anywhere on the sheet even if it is not near the primary coil. I don't know if it will work.

If it won't work, please tell me so I don't waist my time :wink:

It is just an experiment at this point so the voltage or current doesn't really matter, just something average will do. The AC transformer will pulse AC through the coil under the aluminum sheet.

(should I use a ferrous or nonferrous metal for the sheet)

please help.

thanks,

George L.

 

George - I'd avoid modifying the cube or wall wart for safety reasons.

Look around. Here in the US it's hard to tell if the wall wart has AC or DC output unless you look at the markings. I have 50 of them in my junk box - many are AC output. That would be the safest approach.

You might add a fuse in series with the secondary of the supply - at maybe 50% over the limit of the wall wart. It might help with the unintended short circuit.

If you must build your own take a look at a doorbell transformer. My concern would be with safety on the primary side - where the voltage can kill you.

__________________
stevez

 

A 9VDC wall wart has a bridge rectifier that reduces the AC peak voltage by 1.4V so the peak voltage is 10.4V. The RMS value of the 10.4V peak is only 7.4VAC at full load and much higher without much of a load.

__________________
Uncle $crooge

 

I don't know how well it might work?, but you need to wind the coil to match the output of your mains transformer - if it's too low then it will overload the transformer, if it's too high then it won't be working at it's best. Applying a load to the coil will also increase the current it takes from the mains transformer, so you should err on the high side (probably using LOT'S of windings).

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

thanks for the help everyone, I will try to find a transformer that outputs AC and use a secondary winding of a transformer I took apart a long time ago as the coil. I will post the results of my experiment...

not anytime soon, I do my experiments EXTRA SLOWWWWWW :lol:

thanks,

George L.

 

i don't think it will work as u expect.. the secondary will receive power when placed anyware..but the power o/p will decrease exponentialy