95 VAC to 120 VAC Treshold Detector

[Lostgallifreyan]

Franc Zabkar <fzabkar@iinternode.on.net> wrote in
news:1ngvt2p0mh0kn4je162vk89ufv977jk0sg@4ax.com:

On Tue, 20 Feb 2007 16:36:39 GMT, "Dr. Phibes" <none@your.biz> put
finger to keyboard and composed:

It seems to me that your controller is the problem though since it
doesn't really switch off. Is there any way to modify that ?

Yes, it's definitely the problem. It's a DMX light controller, very
commonly used for stage light controlling. Definitely not made to
drive LED lights.

I don't know anything about this subject so I did some reading:
http://en.wikipedia.org/wiki/Digital_Multiplex

It seems that your controller uses RS-485 to send a digital value to
an intelligent dimmer. If the output of this dimmer is merely chopping
the AC by means of a TRIAC, then the idea of a 95VAC threshold makes
no sense.

Good point. Also, LED's have a largely constant forward voltage drop, so
it's not the voltage that must be controlled, but the current.

 

[Dr. Phibes]

You need to wire the LEDs in anti-parallel, otherwise they will only
light during each alternate half cycle.

I have a full wave bridge rectifier as the first component of this circuit.

Also, it does seem like the controller needs to "see" a load out there. I
plugged a regular stage light in the DMX controller along with one of my LED
lights in paralell on the same DMX outlet, and both the stage light and LED
light click on and off like they should. So it's now clear to me that the
DMX is looking for the same type of load to function like it should.

Which sucks, because the entire point of me making the LED lamps was to save
on power consumption, as well as other perks that LEDs have to offer.