need reastat help


Old 04-08-01, 11:50 AM
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I need to build a variable power supply sense no one i can find sells them where i live. the smallest reastat i found was 140 volts and all i need is a 0-8 volt variable power supply my question is when i put the 12 volt transformer in the mix do i put it power cord then the transformer then the reastat, or do i put the power cord then the reastate then the transformer, or doesn't that make a difference. any help is greatly appriciated
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Old 04-08-01, 12:59 PM
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Is this a DC or AC variable power supply that you need ? and what is its purpose ?
this is a 1.4 to 45 v dc power supply schematic.

If an AC power supply, I would have the reostat on the load side (12v side) and also fused on the load side (before the reostat). Putting it on the line side will drop the output of the transformer but may change the characterisitics of the rated amp output , the transformer is rated for a certain amp load on its output, and you change its input votage and thus inductance this could change its output capacity. I think it would be best to keep the transformer running on its orginal rated input voltage.

Old 04-09-01, 12:59 PM
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If this is those low voltage lights everyone wants to install under kitchen cabinets then you may want to check your manufacturer's instructions. Most of these low voltage lights and transformer are approved to have a normal dimmer installed in place or the wall switch dimming both the low voltage lights and the transformer. Just confirm it with your instructions coming with those low voltage lights.

Good Luck

Old 04-09-01, 05:27 PM
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That is a good point, I assumed it was just a personal electrical/electronic project.

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