LED Footlights

[Shez]

I'm currently looking at a project to construct some clamshell style footlights. The mechanics are in hand but I'm in two minds about the electrics and would appreciate some advice from anyone who's been there or somewhere similar recently.

 

Option 1 - mains.

Conventional 240v LED dimmable lamps with a DMX dimmer that will do a good job of dimming smoothly to zero. Something like a SunDial Quad although that's rather more than I'd like to spend! T'internet is full of a £30 DIN rail mounted "DMX302" but I don't have high expectations of performance there! I'd like at least three channels for cheesy chases.

 

Option 2 - ELV.

DMX LED drivers from someone like LTech but I'm stuck with the "bulbs". Maybe I just don't know the right terminology to search with but I can't find much in the way of "driverless" "bulbs". The form factor isn't critical as it'll be masked within the clamshells but it would be nice to have something vaguely bulb-like. I completely understand why it wouldn't be sensible to manufacture a 24v lamp with a base normally used for 240v but that would make the assembly so much easier! I've seen a couple of items intended for use on houseboats but not dimmable.

 

I'd prefer to go with Option 2 for the relative ease of dimming and the absence of mains from under people's feet. It's just the light sources that I'm stuck with. Any suggestions? Ideally "bulb" form factor, with a base that allows it to be unplugged for transport, 5-10W, dimmable with commonly available DMX LED dimmers, self contained so no need for external heat-sinks, colour temp below 3200K.

Other approaches also welcome, along with some education on terminology as I seem to be lacking the vocabulary for this one!

[adam2]

12 volt and 24 volt LED bulbs are readily available with standard E27 or B22 caps, they are widely used in buses, yachts, off grid homes, and where mains voltage is prohibited or unwise. Most types are can not be dimmed.

 

Last year I used these in footlights for a basic outdoor stage. Did not attempt dimming but simply a choice of light levels by selective switching. Coloured lamps exist but are rare.

 

"onsolar" offer a range of ELV LED Lamps. One style has two switch selectable output settings. 0.5 watts or 2.5 watts. Use of these lamps would give several brightness settings.

 

VERY LOW=alternate lamps lit at 0.5 watts

LOW= all lamps lit at 0.5 watts

MEDIUM=Alternate lamps lit at 2.5 watts.

FULL= all lamps lit at 2.5 watts.

 

Higher wattage lamps such as 24 volt, 6 watt exist but are not suitable for dimming.

Edited July 12, 2021 by adam2

[J Pearce]

Unless the bulbs are on show behind the clamshells then release yourself from 'bulbs' and the options become much wider. I've done it using 12V G4 capsule lamps. Either halogen via a transformer, or LED via a driver. They're not super bright though, so depends how much punch you need out of them.

A 12V MR16 would give you a bit more punch (and directiivity) if you can derive a suitable way to make it stand up (back end of a PAR16 and ignore the nose?)

[gyro_gearloose]

If the lamps won't be visible, how about making up a flat plate covered in LED tape? You could use RGB or white tape, and there are plenty of low voltage LED DMX-able drivers out there.

[sunray]

Unless the bulbs are on show behind the clamshells then release yourself from 'bulbs' and the options become much wider. I've done it using 12V G4 capsule lamps. Either halogen via a transformer, or LED via a driver. They're not super bright though, so depends how much punch you need out of them.

A 12V MR16 would give you a bit more punch (and directiivity) if you can derive a suitable way to make it stand up (back end of a PAR16 and ignore the nose?)

We did a sketch where prisoners of war created a show, part of it was making the footlights out of coffee tins and candles. For the 'show scene' footlights were placed upstage of the tabs and pointed out to the audience as part of the script. However the dummy tins were mounted on a wooden batten with angled back edge containing 2 rows of warmwhite LED tape in many 300mm or so sections, with each a simple 555 astable with tiny off times to give the impression of flickering.

In other words the light doesn't have to come from the clamshells.Will small LED floodlights fit in the clamshells? https://www.ebay.co....h0AAOSw79JgPLUR

Edited July 12, 2021 by sunray

[Junior8]

There are plenty of low voltage lightbulb shape lamps available if you want that form factor. It would be a help to me understand your needs if you said whether you wanted the Clamshells to look like the genuine article light-wise or whether you have another aim.

[Shez]

"onsolar" offer a range of ELV LED Lamps. One style has two switch selectable output settings. 0.5 watts or 2.5 watts. Use of these lamps would give several brightness settings.

I'm very much hoping to be able to dim. I haven't completely ruled out tungsten (the aesthetic I'd really like) but LED would seem sensible for many reasons.

 

 

A 12V MR16 would give you a bit more punch (and directiivity) if you can derive a suitable way to make it stand up (back end of a PAR16 and ignore the nose?)

This might be the way to go. Keeping it all 12V is a big plus. In an unrelated thread I saw a suggestion of SORAA lamps being a very good choice for tungsten replacement and good dimming, albeit at a price. DMX 12V CV dimmers are a thing and I'm led to believe that they'll drive such 12V LEDs which removes the need for transformers too. You're absolutely right that mounting will be the biggest issue though! Might have to experiment with some diffussion too as 36^o seems to be about as wide as they go which may be a tiny bit less wide than ideal.

 

 

If the lamps won't be visible, how about making up a flat plate covered in LED tape? You could use RGB or white tape, and there are plenty of low voltage LED DMX-able drivers out there.

That's an interesting idea! With pixel tape I could control each shell independently very easily and just daisy chain power & control. Although I'm really looking for a tungsten aesthetic, the possibility of RGB certainly opens things up a bit.

 

 

Will small LED floodlights fit in the clamshells? https://www.ebay.co....h0AAOSw79JgPLUR

I don't have one in front of me to check dimensions right now but I suspect it might be a squeeze. Also mains & non-dim which is less ideal.

 

 

It would be a help to me understand your needs if you said whether you wanted the Clamshells to look like the genuine article light-wise or whether you have another aim.

The shows they'll be used for have quite a vintage aesthetic so I'm aiming for something reasonably authentic looking from the audience perspective. I think how they look on the performer side is less important as long as the light output is warm and smooth. I suspect most in the audience won't have seen the genuine article in use so there may be an element of hitting an expectation rather than being completely authentic.

[Junior8]

The shows they'll be used for have quite a vintage aesthetic so I'm aiming for something reasonably authentic looking from the audience perspective. I think how they look on the performer side is less important as long as the light output is warm and smooth. I suspect most in the audience won't have seen the genuine article in use so there may be an element of hitting an expectation rather than being completely authentic.

 

As Mike Green so simply put it - to make the sound effect of a tray of china being dropped take a tray of china and drop it

So in the same spirit - Brass batten lampholder, 240v 60-100w GLS Clear.

Yes I know it's not LED but it is simple and it will do what you seem to want - simply. If you want easy dimming and control it seems to me to be the most convenient way.

Edited July 13, 2021 by Junior8

[timsabre]

Most 12V LED lamps (including MR16s) won't dim, or won't dim very well, even supposedly "dimmable" types, due to the internal driver electronics. Edited July 13, 2021 by timsabre

[Shez]

So in the same spirit - Brass batten lampholder, 240v 60-100w GLS Clear.

That option certainly isn't off the table! I'd prefer to keep mains and glass away from people's feet if possible but I agree it wins on light quality and simplicity.

 

 

Most 12V LED lamps (including MR16s) won't dim, or won't dim very well, even supposedly "dimmable" types, due to the internal driver electronics.

This is exactly where I'm struggling to find concrete information. What exactly is inside these bulbs - and what's the difference between a dimmable and non-dimmable one? I've also considered a bare COB - no built-in driver to cause issues so I can pick/design a dimming circuit that works properly.

[sunray]

Will small LED floodlights fit in the clamshells? https://www.ebay.co....h0AAOSw79JgPLUR

I don't have one in front of me to check dimensions right now but I suspect it might be a squeeze. Also mains & non-dim which is less ideal.

 

 

The ones I linked to are 12v-24V and for size the same width as a passport: https://photos.google.com/u/1/album/AF1QipMQvwTveON-V9XRKVjruUS7sGSdvRZZQbl2Ukcl/photo/AF1QipO54zRLBTc4GAahSALZfEteuaCq7YH_3tOBkH4w

The driver (for what it's worth) is very easily bypassed to run on an external dimmable driver.

 

[Junior8]

The truth is that even suppliers of so-called dimmable LED lamps are cagey about whether they will actually dim satisfactorilly in many cases.

[Shez]

The ones I linked to are 12v-24V and for size the same width as a passport: https://photos.google.com/u/1/album/AF1QipMQvwTveON-V9XRKVjruUS7sGSdvRZZQbl2Ukcl/photo/AF1QipO54zRLBTc4GAahSALZfEteuaCq7YH_3tOBkH4w

The driver (for what it's worth) is very easily bypassed to run on an external dimmable driver.

Ah, that's interesting then. Something with a built-in bracket would certainly help with mounting! Skipping the existing driver would also be good.

 

 

The truth is that even suppliers of so-called dimmable LED lamps are cagey about whether they will actually dim satisfactorilly in many cases.

I'm aiming for PWM dimming as I think conventional phase control will always be a non-starter for LEDs. I've just been browsing Big Clive's Youtube channel; he has a nice tear-down of a 12V filament E27 bulb that simply has a resistor inside - no driver, and dims well to zero. Ebay suggests that all of China is out of stock of the 12V version at the moment but I'm sure there'll be some somewhere! That would be a very nice looking solution if I can find stock.

[J Pearce]

I've had no issue finding G4 capsules that are resistor driven, and dim on a LED tape style driver quite well (as well as LED tape does). I've been able to find MR16s of similar basis, but it was harder.

[adam2]

I have just experimented and found that ELV LED bulbs CAN be dimmed but not by any standard type of dimmer.

 

I have some LED lamps intended for DC supply from 10 volts up to 30 volts. They give full light output down to about 11 volts, dim slightly at 10 volts and dim smoothly on lower voltages, going out at about 8 volts. So possible but not very convenient.