Dichroic Lights & Toroidal TF's

Hey all! i'd like to know what the differences are between specific toroidal transformers for dichroic lights, and just any old toroid. I want to drive a rail of 3 dichroic lights (upto 50W ea.) so im gonna get a

150VA TF, but would the regulation of said "any-old" TF be so poor as to blow all the lamps if one failed? im not planning on dimming etc.

Also, how much stress would it place on the 150VA TF to only drive one, say

20W bulb. thanks any advice would be greatly appreciated! cheers scott :)

snipped-for-privacy@ntlworld.com

Reply to
Scott Hill
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in article 9mBqb.1934$ snipped-for-privacy@newsfep3-gui.server.ntli.net, Scott Hill at snipped-for-privacy@ntlworld.com wrote on 11/6/03 4:06 PM:

This seems like a strange question to me.

First, I do not know what you mean by dichroic lights. Do you literally mean two colors? In one light? How are these lights constructed and how do they work? It seems to me that if you specify what is required to make the lights work, you would not have to specify the transformers. Just provide what the lights need in any way you can.

Bill

Reply to
Repeating Decimal

12V halogen reflector lamps -- reflectors are usually dichroic, reflecting visible light but allowing infra-red to pass straight through so the beam doesn't contain so much heat, but the fitting has to cope with the heat being dumped into it instead.
Reply to
Andrew Gabriel

In article , snipped-for-privacy@ntlworld.com mentioned...

Don't worry about that, be concerned if you use a 150W transformer for three 50W lights. Loading the transformer to its full rated capacity is going to cause it to get hot, which will shorten its life. Use a

200W 0or more transformer so that it will not be running at its maximum.
Reply to
Watson A.Name - "Watt Sun, Dark Remover

You got it in one. Regulation, 12V lamp is rated to 12V +/- 5% . Too much and lamp life goes down the pan, too little and brightness and colour are wrong.

No stress on the transfomer, lot of stess on the lamp.

If its a wire or rail system use wound transformers, if it`s individual lights use electronic transformers, RFI is to graet to use these on long conductor schemes.

Adam

Reply to
Adam Aglionby

Two main areas that may be of concern: 1. regulation - these lamps are very supply sensitive (eg see GE website for data) and are designed to run within +/- 5% (max) of nominal to get decent life and output performance.

  1. Safety - remember this must be SELV et al. Are you sure your transformer is up to it.
Reply to
R.Lewis

In message , Repeating Decimal writes

Dichroic's or "dichroic lights" are terms used to describe the generic MR16 (and others) type of lamps that use a dichroic glass reflector to project visible light forwards but pass the infra red component back through the rear of the lamp.

The question regarding the use of a single 50W lamp on a 150VA transformer is perfectly valid, since the low load will lead to a higher voltage due to the regulation of the transformer.

With torroidal transformers the regulation % tends to be quite low which is good, but if the voltage measured at the lamp is measured and found to be too high, a cheat is to maybe use a slightly longer cable to introduce a bit of voltage drop between the transformer and lamp. If the voltage supplied to the lamp is lower than 12V then the light output will reduce quite significantly while the lamp life will also increase significantly. A good compromise between lamp intensity and life is

11.5V
Reply to
Clive Mitchell

I do not believe these lamps are substantially more sensitive to voltage variation (on a percent basis) than any other incandescent lamp. The problem is that with a low voltage system it is much more likely that the voltage at the lamp terminals will be a bit too high or too low.

Reply to
Victor Roberts

in article $ypTwtDb$Br$ snipped-for-privacy@emanator.demon.co.uk, Clive Mitchell at snipped-for-privacy@emanator.demon.co.uk wrote on 11/7/03 2:42 PM:

As this thread developed, I began to realize that dichroic really meant dicrhroic in the sense that there were filters present thar reflected and transmited unlike colors. The complication is that dichroism has little to do with the generation of light but much to do with heat transfer and effective color temperature. To keep things simple, the dichroism should have been kept separate from electrical characteristics.

Bill

Reply to
Repeating Decimal

In article , Repeating Decimal writes

We are really talking about low voltage lighting and possibly lighting within a ceiling . I am in favour of torroidal transformers rather than electronic transformers. There are now torroid transformers that fit into the hole made for the lights, one torroid/light . I did the wrong thing! fitted 150W electronic transformers to drive 5

20W 12 V "dichroics" The volts drop from transformer to furthest light even with "correct" wiring is significant and more important, the em radiation in the medium wave and long wave blot out all radios in the room. The electronic transformers dissipate 20% or so of the energy so they warm up and overheat in a confined space. Don't place them near any of the lights as the extra heating from the lights exacerbate the problem.
Reply to
ddwyer

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