One further point, are we discussing an actual transformer, either
ferro or torroid cored? These will be quite heavy, about the weight of
a house brick. The other possibility is a switch mode type, which ought
to work at a much higher frequency than the 50Hz mains frequency. If a
badly designed SMPSU, then it might give rise to the effect you are
reporting. An SMPSU would be relatively light in weight.
It depends what you call series. With the 3 lamps in series they would
each receive about 4v each (12v/3 = 4v) and would be very dim, so no.
On Tue, 30 Dec 2003 22:47:45 GMT, Harry Bloomfield wrote:
The image in the link previously posted looks like an electronic
transformer aka a SMPS. Add in the 10 min delay then I suspect they
are overheating and shutting down/becoming unstable.
Check the specification of the transformer, is it capable of driving 3
x 50W lamps. Yes, they maths is OK but practice is another matter...
It would also be fairly important that each transformer only feeds 3
lamps. The two transformer outputs are best completely isolated from
Dave. pam is missing e-mail
Clutching at straws here but....you are running from two
smpsu/transformer things. If you disconnect one then does the
other continue to flicker in the same manner ?
I wonder if what you are seeing is some kind of beat frequency
as the frequency of the 'transformer' output drifts as it warms up.
They could start of very close to being in phase with each other then
drift at different rates.
I'll admit it seems unlikely, but you never know.
I have three in-cupboard 20w LV halogen lights in my kitchen. The two
connected to one electronic transformer (SMPSU) don't flicker; the third
one, connected to its own transformer, does. The flicker is a random
changing in brightness.
Swapping the transformers and bulbs over didn't cure it; the flicker
stayed with the lone fitting and I put it down to the transformer being
under-loaded and not regulating properly. Since it's only in-cupboard
lighting, I haven't let the flicker worry me; it would be very
irritating if it were in general room illumination though.
A. Top posters.
Q. What's the most annoying thing on Usenet?
Took out one of the lamps from each set and the flicker stops. So although
the transformer is rated at 150W and the lamps at 50W each. The transfomer
can't cope with three lamps.
Thanks for everybodies help,
On Wed, 31 Dec 2003 11:45:27 +0000, Bill Gardener wrote:
You might get away with replacing the 50W with 35W.
IME there is a required derating for electronic 12V supplies of 30%.
The figure is 0% for low tech Xformers, which can still be dimmed with the
right type of dimmer.
Ed Sirett - Property maintainer and registered gas fitter.
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