On Sat, 13 Oct 2007 10:00:07 +0100, Baron
wrote:

Don Kelly wrote:

"Chuck" wrote in message
newsOUPi.148422$Fc.93550@attbi_s21... Dimmer won't work when
connected to power inverter

I successfully tested an 18ft long section of rope lights (Hunter
brand) and a 3-stage touch dimmer in my house before taking out to
install it in my RV. After plugging it into my 12VDC to 110VAC
power inverter it just has one brightness level which is maximum
brightness. Once its on, I can't turn it off again without
unplugging it. I tried using a standard incandescent rotary dimmer
with the exact same results. Why is this happening?

Why does it work properly on 110V 60Hz household current but not
with the power inverter? Thanks. ----
The waveform from the inverter may not be appropriate to a device
which expects a sinusoidal or near sinusoidal wave. Your inverter
which is probably intended for resistive loads (or loads such as a
TV in which conversion to a different level or levels of DC takes
place) may not provide a true sine wave and possibly even gives a
square wave which makes the dimmer simply turn on fully no matter
how you set it.

--

Don Kelly
remove the X to answer
----------------------------

Yes this is the reason. The inverter outputs a square wave. You could
try reducing the 12 volts supply to say 10 and see if the change in
output is enough.

---
The change in output amplitude has nothing to do with it.

The reason it's not working is because the fast-rising edge of the
square wave output is defeating the intended purpose of the
phase-control circuitry. He

http://www.littelfuse.com/data/en/Ap...tes/AN1003.pdf


--
JF