P
Paul Hovnanian P.E.
Guest
Don Klipstein wrote:
mains voltage when the option is finding someplace to dump all that I^2R
heat.
Some budget designs demand absolute minimum parts counts. A bridge
rectifier can count as one, but wall warts might be out of the question.
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Paul Hovnanian mailto
aul@Hovnanian.com
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If Mama Cass had just split that ham sandwich with Karen Carpenter,
they'd both be alive today.
Or capacitor. This is an often used technique for powering an LED fromIn article <48FCC4ED.B207D5E@hovnanian.com>, Paul Hovnanian P.E. wrote:
ehsjr wrote:
[snip]
A simple approach may be best for you. An LED needs to have
the current limited to a (relatively wide) range, and needs
to be protected against reverse voltage. Placing a diode in
antiparallel with the LED accomplishes the latter.
Or another LED wired the other way around for 2X the light.
What I like to do is use a bridge rectifier to have both halves of the
AC cycle bcoming DC for the LED. A bridge rectifier will protect the LED
from reverse voltage while also never giving the LED reverse voltage.
Put the resistor upstream from the bridge rectifier, so that the
resistor limits current if the bridge rectifier shorts. And 400 volt
bridge rectifiers are cheap.
mains voltage when the option is finding someplace to dump all that I^2R
heat.
Some budget designs demand absolute minimum parts counts. A bridge
rectifier can count as one, but wall warts might be out of the question.
--
Paul Hovnanian mailto
------------------------------------------------------------------
If Mama Cass had just split that ham sandwich with Karen Carpenter,
they'd both be alive today.