Atco Possum Electronic tranny redux

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I recently installed a bunch of these in my home and was pleased with the
much lower heat production, compared to the old iron trannies. I was
prompted to replace them, whilst doing some work in the ceiling and, after
touching one of the old trannies, was horrified at how hot they got. Anyway,
here's my measurements on the new vs. the old trannies (it also explains why
the lights seen somewhat brighter than the old):

All measurments performed at 240 VAC.

Old tranny:
Output Voltage: 11.4 VAC
Power consumption:  64.7 watts

New tranny:
Output Voltage: 12.8 Volts
Power consumption: 56.4 Watts


A good thing. Dunno about the lifespan of the lamps, given the higher input
Volts though.

Some more nice things about the Crompton kits, which use the Possum
trannies:

Silicon leads for the lamps.
A nice gimbal mount
The lamps have a glass cover.
I like the cord clamping on the Possum trannies. A clever design.

The biggest win, however, has been the replacement of the 120 Watt lamps in
the bathrooms, with some Phillips 23 Watt compact fluoros (the ones with the
curly tubes). VERY impressive light output, with almost identical spectra to
the old incandescent. Highly reccommended. 8 Bucks each from Bunnings.


--
Trevor Wilson
www.rageaudio.com.au




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Re: Atco Possum Electronic tranny redux

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Ok, take out a CRO and have a look at the output voltage of the Possum.
Fairly ugly compared to the nice sinusoidal waveform of the old iron cores.
The voltage you measured would not be accurate, as I think from memory, the
rated output voltage of most ET's is about 11.6V thereabouts. If you have a
higher voltage you will have a shorter lifespan on those dichroics.

Of course if you have them dimmed all the time then that's a different
matter.

Another thing. A device needs to reach a temperature of 200 deg C. to start
a fire when placed next to timber. I think, again from memory, that 60 deg
C. becomes too hot to touch. This could, I assume, give one false reasoning.

Cheers.






Re: Atco Possum Electronic tranny redux

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I need a nice clean sine wave for light bulbs too.

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Re: Atco Possum Electronic tranny redux

"Trevor Wilson"

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** How did you measure this?

The output of a  " Possum" is a 100Hz, amplitude modulated, 45kHz squarish
wave.

Harmonics out to 500 kHz.

Evil.





........  Phil









Re: Atco Possum Electronic tranny redux

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**A 'True RMS' meter.

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**Yup. Very efficient though.


--
Trevor Wilson
www.rageaudio.com.au



--

Re: Atco Possum Electronic tranny redux

"Trevor Wilson"

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  **   LOL.

     Like they are all the same ....





.........   Phil






Re: Atco Possum Electronic tranny redux
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They are if you use a real RMS meter, eg HP3400A thermal RMS voltmeter
or a Fluke 8920 (IIRC)

Cheers
Terry

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