DIYbanter - View Single Post - Range clock

Rod Speed

wrote
(Don Klipstein) wrote
wrote
wrote
Jeff wrote
wrote

I think he is seriously over estimating the power usage of a
clock chip and LCD display. 1 Watt would be more like it.
5 Watts would be about right for an old mechanical stove clock.

You are, of course, neglecting the power supply losses.
Non switching regulators typically throw away half or
more of the power. The trend is away from them.

Well, we do seem to be arguing the number of angels dancing on pinheads. ;-)

Not really. Transformers draw significant power even when there is
no demand upon them. They just turn it into heat rather than work.

Plug in a wall wart with no load on it and measure the temperature
and current draw after an hour. That's a very tiny transformer.

If you remove one tube form a two tube florescent light fixture with an
old fashioned transformer, it hardly changes power consumption at all.

On that last point, I find that the power consumption changes a lot.

The change is less when the ballast is one of those "pseudoparallel"
electronic ones rated to power more than one quantity of tubes, and
the remaining tube(s) get increased power when one tube is removed.
But the overall power consumption still goes down when one tube is removed.

My point was that the power consumption is not cut in
half by removing one of the tubes. If you turn on a two
tube fixture with NO tubes in it, it will draw power as well.

Nope, it doesnt with the traditional ballast that fools like you dont realise isnt a transformer.