120 to 12 volt transformer at 20 Khz


Old 12-29-04, 04:46 PM
terrance phil
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Question 120 to 12 volt transformer at 20 Khz

My question is: Why do many manufacturers of small lighting transformers (70 watt) convert to 20kHz at 12 volt output instead of using a 60 Hz transformer? Does it have to do with the ability to use halogen lamps or perhaps a size reduction method to keep the transformer smaller ?
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Old 12-30-04, 09:13 AM
Join Date: Aug 2004
Location: USA
Posts: 539
The answer is pretty

much what you've already guessed, the higher the frequency, the lighter and smaller the transformer can be. It's also possible that this isn't a "transformer" at all, but the inductor for a switching power supply.

Hope this helps!
Old 12-30-04, 11:21 AM
Join Date: Jan 2002
Location: Chicago
Posts: 1,915
A transformer doesn't change the frequency... only the voltage. What you porbably have is a switching power supply. The idea is simple, the higher the rectified frequency is the easier it is to filter the ripple voltage and the better (closer to real DC) the output voltage is.

Plus, switching mode power supplies are much smaller and cheaper compared to "regular" power supplies using transformers.

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