Trailing Edge Dimmer

[boswell]

We would like to change our auditorium lighting to PAR38LED, We have found suitable lamps (Viribright Par38) but can't find a Trailing edge dimmer that will accept 0-10v Control signal at a sensible cost, minimum spec would be 1 channel 500w (or 3x200w) with 0-10 control input.

I have confirmed with Viribright that they don't like leading edge.

I've found one unit that will do the job but it's 3x10A and costs £1k1 !!:o

any suggestions please for a supplier in the UK

[Jivemaster]

chat with XTBA.co.uk and see whether they have a 0 - 10 to DMX converter. Also chat with Artistic Licence, http://www.milinst.co.uk/ and look at the Velleman offerings through Maplin and the like.

http://www.xtba.co.uk/products/analogue-merge Will do a sensible job of converting an analogue signal to DMX BUT £650+ may not help your budget.

 

Consider using a separate controller for house lights There does seem to be a six slider unit available from pro and disco shops originally at sub £100.

[Brian]

Have a look at an MK K1402M.

[boswell]

Thanks for that Brian, never thought of looking at MK !! Asked for a price

 

Thanks also to Jivemaster

[David A]

Just bear in mind that the leds will not dim smoothly, they will cut in and out at the bottom end, I suggest you test one to confirm you can live with them.

[timsabre]

Just bear in mind that the leds will not dim smoothly, they will cut in and out at the bottom end, I suggest you test one to confirm you can live with them.

 

Indeed, I would suggest (if it is not too late) looking at using DC-powered LED fixtures with separate DMX controlled driver packs. This is the only way to get good dimming. It would involve a change of the light fitting and some extra wiring though.

[Pat]

To find that dimmer on a small price will be very hard.

 

But you can bend DMX input signal to 0-10V.

http://www.dmx4all.de

If it goes the other way around just ask them.

[boswell]

Have a look at an MK K1402M.

Ordered one to try £130+Vat

Thanks

[David A]

• Base: E26
• Beam Spread: 270
• Bulb Type: Dimmable Par38
• Color Temperature Kelvin: 4000K
• CRI: 80
• Lumens: 1300
• Shape: Par38
• Watts: 18
• they will be very fluoro looking with that colour, the CRI is not very good, they will not dim uniformally and will switch on and off at different points and they are expensive.
• Should I be wrong then let be know as it will be the first time that LEDS have been usable as theatre houselights and I will buy some

[boswell]

• Base: E26
• Beam Spread: 270
• Bulb Type: Dimmable Par38
• Color Temperature Kelvin: 4000K
• CRI: 80
• Lumens: 1300
• Shape: Par38
• Watts: 18
• they will be very fluoro looking with that colour, the CRI is not very good, they will not dim uniformally and will switch on and off at different points and they are expensive.
• Should I be wrong then let be know as it will be the first time that LEDS have been usable as theatre houselights and I will buy some

Part number 73488

Fitting E27

Wattage: 18W

~Halogen 90W

Input Voltage: 220-240V AC

Frequency: 50-60Hz

Power Factor: >0.8

Beam Angle: 90^o

Life Expectancy: 25000 Hrs L₇₀

Colour: Warm white

Colour Temperature: 2800K

Output Lumens: 1100lm

Dimmable: Yes

CRI Ra >80

Certification: CE, RoHS

LEDs: 2034 Blue GaN Chimei

Proof Class: IP20

Dimensions: ∅120 x 135mm

Warranty: 3 years

 

£14.50 each for 25 off, (+VAT)

 

 

I've got 2 and I'll try them on the MK trailing edge dimmer

[rossmck]

Should I be wrong then let be know as it will be the first time that LEDS have been usable as theatre houselights and I will buy some

Not quite the first time, but a very different budget ;)

 

 

http://www.etnow.com/news/features/2003/stageapollo/index.htm

 

Impressive back in 2003 though.

 

I've used some (budget) LED fixtures ( Chauvet COLORado Batten 72 Tour, Showtec CYC 2000 and Chauvet COLORado range ) as houselights in temporary spaces (bouncing them off white vaulted ceilings mainly) quite successfully, again far more expensive than a straightforward LED replacement of a traditional lamp, but not quite on par with the fixtures used at the Apollo Victoria ;)

 

 

[timsabre]

Not quite the first time, but a very different budget ;)

http://www.etnow.com...pollo/index.htm

Impressive back in 2003 though.

I've used some (budget) LED fixtures ( Chauvet COLORado Batten 72 Tour, Showtec CYC 2000 and Chauvet COLORado range ) as houselights in temporary spaces (bouncing them off white vaulted ceilings mainly) quite successfully, again far more expensive than a straightforward LED replacement of a traditional lamp, but not quite on par with the fixtures used at the Apollo Victoria ;)

 

That's different though, that is using DMX controlled fixtures.

Here we are talking about using "dimmable" LED mains lamps. Which usually are not as bright as the halogen equivalent and are not very dimmable.

[David A]

A dimmerable led, without a separate power supply would logically be impossible because the electronics need volts to power them which of course is not there on a dimmer at 0v add to that the zener effect of any diode and I fail to see how a plug in unit can ever work and even making them consistent between units and different ages would logically be a bridge too far.But I hope to be proven wrong as the advantages would be great.

[Brian]

There are now chips around which claim to dim LEDs down to 1% and which are controlled by a dimmed mains feed of most flavours. These are specifically designed for retrofit LED lamps.

 

Example.

 

I've got a step-up smpsu chip here on the bench which will start at just 0.9v.

[Tomo]

Very interesting, but I have to ask - 1% of what?

 

Power consumed by the LEDs? Lumen output? Perceived brightness? Input, Output, RMS or peak voltage/current?

- All of these are different.

 

I also wonder about the dimming curve, as if it's anything like the DALI curve you won't like it.

 

It may not be a fundamentally insoluble problem, however nobody has yet even come close to meeting theatrical requirements in a two-wire LED (or florry) yet.

 

- Not really a surprise, as Domestic/Office usage is pretty much solved and that is a much bigger market.