Hi all,
Forgive the OT (and my ignorance of how electricity works), but I
couldn't seem to readily locate the answer to a question I have regarding
electricity usage. I have several gadgets (flashlight, cordless
screwdriver, etc..) that are rechargeable and the directions to these
products state that once the product is fully charged I don't have to unplug
it. The question I have is if there is no more electricity being used, then
why does the AC-to-DC converter remain warm (very warm)? Doesn't the
presence of heat indicate an electrical discharge/action is taking place?
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The gadget probably has a small transformer to convert the 110AC house
current to a lower voltage. The way transformers work is to run
AC current through one side of the transformer. This induces a current
in the other side. The electrical engineers who design the thing
know how to set up the coils on both sides so the proper voltage is
created. The current in the second side is rectified to DC current
to charge the batteries. Once the batteries are charged they resist
further charging and little, if any current goes through them, but there
still is some current which goes through the first side of the transformer.
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This same question bothers me about my SRS sub-woofer...it has an
auto-on feature, so that the amp is supposed to turn off if no music signal
is present (after some elapsed time period), however, the heat sinks on the
back of the sub-woofer are still fairly warm even if it's not been used for
several days.
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There is probably a sensor circuit which detects when a music signal
is present. This has to remain on all the time even though the amp
does not. As long as power is going through it, it will be warm.
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TIA to anyone with the patience (and time) that can explain this to
me (in oh, let's say, 3rd grade level knowledge). :-)
Ray Shahan
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Not being an electrical wizard, I will be glad to have someone with
more experience explain this better.
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