Universal Fluorescent Dimmer for Non-Dimmable Ballast.

[Ravenvalor]

Hello,

Does anyone know of a fluorescent dimmer that will dim a regular non dimmable F32T8 ballast?

I am pretty sure the answer will be negative but since I only delve into this topic about once a year I miss a-lot of the new dimming technology news.

Thank You,

 

[gar]

130628-0731 EDT

A normal fluorescent bulb requires heating or high field electron emission from the electrode at the bulb end. Once started a normal fluorescent bulb effectively heats the emitters by the current flow thru the bulb. If you lower the bulb intensity by lowering the current thru the bulb, then the emitter temperature drops. A normal ballast provides no means to separately heat the emitters.

A dimmable ballast provides a separate means to heat the filaments.

If I bring a fluorescent tube into a field that will excite the gas in the tube without electron emission from the tube end electrodes, then the light output can be adjusted by that field intensity. Once a long time ago I gave a demonstration of the field pattern of a 2 meter beam antenna by moving a fluorescent tube in the field of the antenna and showing the bulb intensity variation (no connected wires).

.

 

[Ravenvalor]

Hello gar,

Thanks for the lesson in fluorescent light bulbs. Your demonstration reminds me alot of the demonstrations that I do with my Tesla Coil and a fluorescent bulb.


The customer is concerned about the quality of the light with the dimming of fluorescent lamps. I have to admit that my experience with fluorescent dimming systems have led me not to impressed with the light quality. Anyones thoughts on light quality would be appreciated.

Thanks,

 

[suemarkp]

Maybe they aren't here yet, but I searched dimmable LED F32T8 and only found non-dimmable units. If you can find dimmable T8 or T12 LED tubes, then you can install those. They don't use the ballast at all -- just 120V or 277V to the LED tube pins (so you have to rewire the tombstones and bypass the ballast).

 

[suemarkp]

Found one that's 6000K: http://www.eledlights.com/product-info.php?Dimmable-T8-4Foot-LED-Tube-pid23.html
and one that 4000K or 5000K: http://www.eledlights.com/product-info.php?T8-4Ft-LED-Tube-UL-DLC-Dimmable-pid41.html

This will work with a standard 120V wall dimmer intended for CF/LED/Incandescent use.

How nice these look when dimmed I don't know. Do you want to spend the money to find out (and will they want to drop $40 - $50 per tube to replace?

 

[gadfly56]

Many years ago when I was doing theatrical lighting, I found by accident that if you have an incandescent lamp in the same circuit as the fluorescents, you can dim the fluorescents with a standard SCR-type dimmer. I would guess that any kind of resistive dummy load might do.

 

[Ravenvalor]

If it does not say Philips or Sylvania on the lamp I will not risk it. Thanks for the help though.

 

[Ravenvalor]

Many years ago when I was doing theatrical lighting, I found by accident that if you have an incandescent lamp in the same circuit as the fluorescents, you can dim the fluorescents with a standard SCR-type dimmer. I would guess that any kind of resistive dummy load might do.

I will try that some day, thanks.

 

[gar]

130629-1035 EDT

With a standard rapid start fluorescent and sine wave voltage excitation there is only a small change in light output with a 80 to 120 V change in input. Below about 80 V the light goes out and won't restart by simply turning the Variac back to 120. It is necessary to have the quick change from 0 to 120 from switching to to reinitiate light output. Minimum start voltage was about 110 V. Also with the old rapid start ballast with which I ran the test I could not start new low mercury content bulbs.

Changing to a phase shift dimmer control with some resistive shunt it is possible to obtain a change in light output. The control and range are poor and not stable. Yes dimming, in a generic sense, in this case is possible, but not really useful. Good electron emission is necessary to get effective operation.

Incandescents are the nicest for dimming.

.

 

[GoldDigger]

130629-1035 EDT
Incandescents are the nicest for dimming.

Although LED fixtures specifically made for dimming (so that the power regulation function of the LED driver does not just try to cancel out changes in input voltage) can work nicely too.
The best would be LEDs with a separate 0-10 volt control input. That would give you flicker-free and smooth dimming. You should even find that combinations of fixtures from different manufacturers dim in parallel when using a control voltage signal.