DMX Dimmer Ghosting

[HilcrRWise]

I have a Transcension UP-2 single channel dimmer we have connected a string of 100 x G40 1W bulbs to (we just want to turn these either fully on or fully off, no dimming required).  These turn on fine however when the DMX intensity for these is turned fully down to 0 they still imit a low level of light.  I believe this is termed ghosting and can be resolved by adding a 'ghost load'.  I understand this is usually done by adding another lantern to the channel (which we can do as the UP-2 has two IEC outputs on it), however we don't really want to add another light source to this channel, is there another way to add this ghost load?  Alternatively we could add a 650W lantern and completely close the barn doors so there would be minimal light leakage, however is this likely to cause the lantern to overheat and blow the bulb?

Thanks

[Dave m]

I always called it a dummy load.
The light can be anywhere. Often under the stage or behind something to hide any light.

 

[mnorwood]

You've stated that you wish the lamps either On or Off with no dimming. Does the ghosting occur if you put the device into "switch mode" as per the instructions in the manual? (Assuming it's not already in that mode...)

[richardash1981]

An electric heater (one without a fan) will work as a non-glowing load - obviously, unless you choose a halogen type which glows! Harder to find a low wattage one however, and you still need to think about fire risk like you would with a spare lantern.

[sunray]

3 hours ago, HilcrRWise said:

I have a Transcension UP-2 single channel dimmer we have connected a string of 100 x G40 1W bulbs to (we just want to turn these either fully on or fully off, no dimming required).  These turn on fine however when the DMX intensity for these is turned fully down to 0 they still imit a low level of light.  I believe this is termed ghosting and can be resolved by adding a 'ghost load'.  I understand this is usually done by adding another lantern to the channel (which we can do as the UP-2 has two IEC outputs on it), however we don't really want to add another light source to this channel, is there another way to add this ghost load?  Alternatively we could add a 650W lantern and completely close the barn doors so there would be minimal light leakage, however is this likely to cause the lantern to overheat and blow the bulb?

Thanks

Would it not make sense to use something with a switched output 

QTX DP4 4 Channel DMX Dimmer Pack | eBay 

3 Channel 5A DMX512 Controlled Relay Switch DIY Kits Converter DMX Dimmer Relay | eBay

rather than mess about with some big light hidden away somewhere?

[indyld]

Check you are using it in switch mode and not dimmer mode. In future, when actually using it as a dimmer make sure there is no stored level set at the pack or some kind of preheat set up.  

 

[sandall]

10 hours ago, richardash1981 said:

An electric heater (one without a fan) will work as a non-glowing load - obviously, unless you choose a halogen type which glows! Harder to find a low wattage one however, and you still need to think about fire risk like you would with a spare lantern.

Towel rail? 250 & 500W.

[alistermorton]

Even something as simple as a tubular heater like this one from CPC might be enough load.

[timsabre]

Most dimmer packs even when set to "switch mode" will still exhibit this problem. It is because of current leakage through the RF suppression circuit, this is a tiny current but enough to light an LED.  If you are powering something with a DC supply like fairy lights, it can pulse on and off as the current charges up the caps in the PSU circuit.

The only way to avoid it, other than the suggested dummy load, is to use a relay pack (that definitely uses real relays and not "solid state relays" which are just triacs again).

[HilcrRWise]

Switch mode didn't make a difference so I ended up connecting a 500W lantern which I hid behind a blackout curtain and added a dark coloured gel so light bleed isn't as obvious.

Thanks

[dbuckley]

Interesting - you've got 100w of (I assume) incandescent lamps, and still getting glowworms.  I usually use a 60w lamp as a ghost load...

[timsabre]

2 minutes ago, dbuckley said:

Interesting - you've got 100w of (I assume) incandescent lamps, and still getting glowworms.  I usually use a 60w lamp as a ghost load...

He said 100x 1W G40 lamps, this is the classic LED festoon from China. Incandescent G40's are usually 15W or 25W.

[dbuckley]

Roger that; LED would explain it.  Bloody modern technology!

 

 

[adam2]

a very simple possible cure would be to replace a couple of the 1 watt LED lamps with incandescent lamps, whilst one lamp would probably do, two gives redundancy against one lamp failing.

 Use of a lantern using hundreds of watts is rather wasteful, esp at todays electricity prices.

Or as already suggested, an incandescent 60 watt lamp somewhere out of sight.

[James Remo]

Maybe overkill for your situation but I keep a couple of etc coloursource relays in the warehouse for use in situations where I need a relay - mostly mirror balls and led practicals. They came to me second hand for a bargain price and work flawlessly. Great form factor.