Replace tungsten with LEDs in LTM Peppers et.al.?

[videographer]

Hi all. Like just about everyone in the video production world, most of my portable tungsten lights are gathering dust and being replaced with LEDs of varying capability. But I haven't found any LED fresnels that can replace my LTM Pepper 200w and 400w units for anything resembling a reasonable price. I would really like to replace the tungsten bulbs with LEDs of similar capability. To that end, I have purchased raw COB LED units from a place called American Science and Surplus ( sciplus.com - it's a hoot) and a power supply from Mouser and got almost decent results. But it is just that - a science experiment. I'm not an EE, just a curious tinkerer.

Does anyone know of any actual replacements out there? I'd love to save these units! Thanks in advance -

 

[videographer]

Pictures of my experiments...

 

[FMEng]

That looks like a fun experiment with the old fresnel. There are very few retrofit LED bulbs for high power tungsten because of the engineering challenges. LEDs, like any semiconductor, are very sensitive to heat. Enough heatsink and fan to keep the LED happy has to fit in the same shape and size as the glass bulb, which is often impossible. The other challenge is the driver circuit fitting, although that could be done externally, in some cases. The LED array has to be optically compatible with the lens and reflector, meaning the the size, shape, and placement of the LED light source has to be similar to a filament. The color temperature and CRI also have to be right, especially for photography. That usually means mixing multiple LEDs of different phosphors, which makes the size challenges even harder. In the unlikely event that all of the engineering can be accomplished, it has to be profitable, which is hard to do with the small market for stage and studio bulbs.

ETC managed to do it with the Source 4WRD, but it replaces the whole burner assembly, and is far larger than an HPL bulb. There are some retros for automotive headlights, but that's a huge market, and the wattages are much lower. Optically, they are a major compromise, but they find a market because car hobbyists will buy anything, even if it means blinding the driver in the oncoming lane.

 

[ship]

Funny, back in like 1964 I believe in date.. people and retailers were all about doing the halogen upgrades to their Fresnels from the incandescent versions... I have one upgrade in the museum that I had at one point upgraded back to normal Fresnel, than had to find the parts to bring back to that "halogen upgrade" concept. This before the single ended halogen lamp came out, it was a dual ended 2.3/8" long version in about the same lesser wattages but halogen..

Amazing how at times, circular the technology is.

My assistant and I during the pandemic made a 1950's 8" Leko into a viable RGB with very proper output. Problem was we needed forced cooling, heat sinks and decoders. Too expensive for a prop light.

A long life version or upgrade of the BTH lamp would be a concept within the GLA line of lamps for economical for the Fresnel in easy to do but not cost effective to do given how many LED fixtures are replacing the Fresnel.

Don't know what is coming say long life lamp, or a better LED... but most of those "Upgraded" fixtures to a lesser wattage, no doubt went to the srap yard, or got re-converted to the single ended version. This was not cheap as you had to buy an entire new reflector/base carriage.

Wait, my advice. Save money for an upgrade to your system to LED fixtures, or a LED lamp upgrade.

 

[David Ashton]

I don't understand why you want to spend heaps of money to produce an inferior light, if you were running hundreds of hours then a power saving might be worth it or if you have very limited power you might need to but to get close to halogen quality light costs a serious amount of money.

 

[videographer]

I don't understand why you want to spend heaps of money to produce an inferior light, if you were running hundreds of hours then a power saving might be worth it or if you have very limited power you might need to but to get close to halogen quality light costs a serious amount of money.

But it's not (necessarily) inferior light. So many of the LEDs out there depend on an array of small individual lights - which brings up the unfortunate "thousand shadows" result. All I want is the nice, controllable edge and punch a single bulb produces thru a fresnel lens. What I don't want is the profligate electricity use and the waste heat. Not to mention that it's getting harder to find replacement bulbs.

 

[David Ashton]

Sorry but by definition a LED has an inferior light unless there's one with a CRI of 110 I don't know about and with the amount of energy to produce leds you need to use them a lot to get a return on greenhouse emissions unless your running on renewable power in which case it's even longer. I just get upset when schools I work in scrap a perfectly functional halogen rig and buy some led "pars" which are practically useless but everyone goes ga-ga over because they're LEDs it's like the emperors new clothes and then with all the channels they need it takes a computer style desk to operate and the average student doesn't have the time to learn it, so what was a simple lesson to work a manual desk to show how key, back and fill light works but now no-one bothers. Practically it's good business, we can make heaps on selling expensive gear, then more on providing operators, but it's not very good for the kids.

 

[JonCarter]

I agree with David Ashton. A (say) 30 classroom school's HVAC and light for (say) 10 hrs/day/40 weeks/year is going to FAR exceed the power used by the conventional (incandescent) lighting instruments used in the auditorium. Teach the kids how to LIGHT; not how to use a computer. Using the computer to make the light will come in time IF they know how to LIGHT.

 

[David Ashton]

wow I was expecting a chorus of "Luddite" and other derogatory comments.

 

[ship]

I was yesterday on a site survey for work at a 1984 church built Main stage theater. A 3/4 thrust space in the town I grew up in but never visited. Quoting out a hybred growing LED system. Over the stage where it's getting new rigging, LED's. In the house upgrading the perfectly fine S-4 Leko's to LED in lamp cap replacement as budget allows..

While I was in town at the church theater, they told me of the local high school I went to, now under major upgrade also... This is the second time since 1974's upgrade and re-build of the origional theater complex down to bull dozers got re-built!!!

While I was at that High School, I measured out and re-produced accurate drawings for extra class credit in Architectural Drafting class it's stage's actual dimensions. Also useful for show design. Yea... Back into even the 1970's my High School had a full drafting program. (Now I visit remote schools where grammer school and high school are combined... and with at best a Gymatorium, as opposed to even my Junior Highschool had a respectable Main Stage Theater..)

Must be nice to live in a city with so much money to filter down to it's next 20 year total upgrade in not just buying new lights... starting over I'm told. I grew up appairently with say the 2nd
1974 upgrade to the theater. Amazed at this theater I worked in was not modern enough - it had everything there that a Main Stage any school would make well use of.

Direct Fresnel replacement was less a question at the other local in town theater I went to. Remember I'm an old school type lighting person in the purpose of the Fresnel. Directly over my head in the home grid is also two 65Q Fresnels needing some attention for future donation.. A LED PAR fixture can do the work of a Fresnel in different way than a PAR in beam spread... LED PARs are less like a PAR can... not a Fresnel, but if lensesed right more like them than a classic PAR Can. Going LED lamp cap for incandescent Leko's we agree on also at this point. Dimmer changes, but that was the bulk part of the quote.

I love the look a Fresnel gives, but LED PAR's are not the PAR Can of yesterday... They are more... neither in output in combining both. The only thing missed about less fixtures to do the same thing.... is less fixtures to blend and cover with. In some ways that's a regression in lighting design I think.