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STEP DOWN TRANSFORMERS

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2/7/1998 8:14 AM
bob	STEP DOWN TRANSFORMERS My friend is moving to India for school where the AC power from the wall is 220 volts. His stereo, TV, and most importantly, his guitar amp do not have a 220 volt tap. Does anybody know of a website or book that describes how to make step down transformers? thanks, Bob

2/7/1998 8:33 PM

Step down autotransformers are cheap enough that it's not worth his time and effort, as well as accepting the safety exposure that is involved in his making or modifying his own. This is NOT a good bet. I know AC power transformers backwards and forwards, and I'd never contemplate making my own stepdown. If you're having trouble finding one, send me email and I'll help.

Any good mail order house (Mouser Electronics included) will have a number of selections of stepdown autotransformers (that is what he needs) to do this. Note - the wall socket power MAY be 50 Hz, not 60HZ, so he needs to be sure that the stereo, TV and amp can work on 120VAC 50Hz. Many can, some can't; the most likely problem is the amp.

2/8/1998 9:48 PM

I used to live in Pakistan about 15 years ago, so I may be able to help you out. There are three types of power transformers he may wish to purchase. The first are tiny "wall wart" types. These are inexpensive, low wattage types, for use with small appliances (radio's, etc...). Radio Shack used to sell these, but you'll have to check to make sure.

The second type is a regular bulky, heavy type that you see in tube amps etc... These are expensive, and can be used for higher power appliances such as TV's, high-powered amps etc... If he does buy these, make sure they are protected by some type of fuse! I have see two of them blow ($300+ US), from a broken appliance being connected to them. If you consider that in the US an average circit breaker will take about 1800W of power before it blows, the transformer will only be able to handle a fraction of this, and may be damaged if the load is drawing large amounts of current. As for TV's, as far as I know, India uses the PAL system instead of the NTSC type used here. This means that his TV may only be useful to play video tapes from his NTSC VCR. I would suggest sellings these items and purchasing multi-format versions overseas. You can rent tapes (English) over there, and there are English stations availiable in many places. If possible I would suggest a stop over in Singapor as it is duty free and electonics are dirt cheap, or at least they were when I visited.

The third type, I'm not too familiar with. These are extreamly costly power supplies that convert the 240V 50Hz to 120V 60Hz. I sure could have used one over there. At the time I had a TI 99/4A computer, and more often then not, it would crash after several hours of programming. Since the tape(cassette) it used for perminant storage was really slow, I rarely backed up and lost quite a bit of software.

Anyway, this is getting a little of topic, so if your freind would like some more info you can email me directly.

GVB

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