using a 110volt charger in Europe, through have bridge application

Hi,

Can anybody help me on this one?

I bought a dewalt charger for 18volts in the states and want to use it here in the netherlands on 220. I know the easiest is using a step down transformer, but can I also take out three diodes from the bridge rectifier, changing the full bridge into a halve bride? I read it would give me halve the voltage after smoothing, but I'm not sure.

total power needed (max) is 54VA

Any help or elaboration would be appriciated. Thanks Patrick

First look carefully at the charger and see if it in fact will accept 240 V. Some will.

In general, if you take diodes out of a bridge, you get either no output at all, or the same peak voltage as before with more time between the peaks.

Unfortunatlly it is only rated at 110v...

if I take out two blue ones from this picture:

It should still function. will it then (if the ac supplied voltage is

This won't work.

Graham

No. The peak voltage will remain the same and there will be twice as much time between the peaks. If the capacitor is large enough there will be no change in the output voltage.

Can anybody help me on this one?

The AC supply transformer will go up in smoke immediately you connect it to

A little problem called "magnetic saturation".

....... Phil

You might try a lamp dimmer set at 50%. It would be a good idea to add a

Paul

"Paul E. Schoen" .

....... Phil

Only if that dimmer is a variable transformer, like a Variac.

Triac and SCR type phase control can be used to control transformer primary voltage to regulate secondary voltage of bridge rectifier DC supplies. Many high current DC power supplies use this system. It is generally not recommended to use ordinary dimmers on inductive loads, especially motors, but I think battery chargers have a mostly resistive input characteristic and should work OK. It might be a good idea to add a snubber to reduce inductive transients, but otherwise I don't see any problem. The properly sized fuse should protect the transformer in case the triac shorts.

Paul

No, it will not function. It will smoke. The transformer is rated for 110V. If you put 220V across the primary, you will let the magic smoke out of the primary.

Don't do it - buy the adapter, or look for a charger that's designed for

Good Luck! Rich

No, it's not that easy. Buy another charger such as DW9180-220 (confirm compatibility). Or use an inexpensive autotransformer, which will also convert the plug for you.

Best regards, Spehro Pefhany

The main problem you will have is that the transformer will burn out very soon after you plug it in. The transformer is designed for 110V and will saturate and burn out with 220V.

Without changing the transformer, anything you do to the diodes is a waste of time.

You can buy a 220V to 110V transformer from a hobby electronics shop, and that's what you should probably do, unless you can get a replacement charger for the drill that is designed for 220V.

Chris

"Paul E. Schoen F****it "

PISS OFF !

........ Phil

Check page 9 for a 220 to 110 VAC circuit using a triac.

Granted that a cheap light dimmer circuit may not be optimized for this type of load, but I think it's worth a try, if proper precautions are taken. A simple RC snubber should take care of transients. Otherwise perhaps a fan motor control may be better.

Paul

"Paul E. Schoen = Asinine F****it From Hell "

Got ZERO to with a transformer based PSU.

you PITA BLOODY IDIOT .

....... Phil

As a point of interest, stMicro has an evaluation board for an AC/AC chopper, which is essentially an electronic Variac or Powerstat, and suitable for inductive and regenerative loads such as a motor:

They also have a simple triac circuit for a 220 to 110 VAC converter, which would be an interesting project for your application:

This article has good information about the potential problems of using triacs for an application such as this. The website has a wealth of other good articles.

Unless you are able to understand the reasons why your original idea would not work, I would suggest you go the safe route and get an autotransformer type voltage converter, or purchase the correct charger for your mains supply. Lack of knowledge and inadequate precautions can be a deadly combination when experimenting with line voltage devices.

Paul

"Paul E. Schoen = Asinine F****it From Hell "

Got ZERO to with a transformer based PSU.

you PITA BLOODY IDIOT .

....... Phil

"Paul E. Schoen Asinine F****ng IDIOT " "

F****IT !!

YOU have no comprehension of such devices.

PISS OFF !!!!!!!!!!!!

........ Phil