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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Fri 19, 2019 1:45 pm 
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Location: St. Louis, MO, USA
If you can cut this acolyte endlighten into small wedges and use green LEDs on their edges, could you make an acceptable substitute for a tuning eye tube?

Dennis


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Fri 19, 2019 3:49 pm 
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Dennis Banker wrote:
If you can cut this acolyte endlighten into small wedges and use green LEDs on their edges, could you make an acceptable substitute for a tuning eye tube?

Dennis

Cool idea, literally. Theoretically that could work, but the devil's in the details. A correctly sized tuning eye replacement would require either a laser cutter or good tooling and the patience of a watchmaker. The trick is to get sharp light cutoff at the edge of each pie piece, so the edges would have to be painted black, yet thin and precise enough to be invisible between the lighted sections. That might work better if only the bottom 7/8 of the edge was black so there's some bleed across the top surface. That might leave acceptable bleeding edge between light and dark. It would be tons easier to make a proof of concept piece 4-5 inches in diameter that can be viewed from several feet away.

On a cooking show there were some HUGE nixie tubes for the countdown timer, like 6 inches long. I couldn't believe nixies came that big so I looked them up. The art director stacked edge lit acrylic plates that each had a number etched on it and he placed them inside watch display domes. They were very convincing. I wondered how you could stack that many sheets. Turns out acrylic transmits more light that glass.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Sun 21, 2019 4:06 am 
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I've been wondering how easy it would be to make an edge lit LED panel that could emulate an EL panel. I had some 1/8" acrylic, both clear and white. First I drilled some test holes in the clear plastic using regular drill bits of different sizes. Those holes are visible on the right side of the pictures. Seeing how they did indeed reflect edge lit light, I decided to make a grid using a Dremel with a tiny router bit to drill the grid holes. None go further than halfway through the plastic. I taped a piece of perfboard on the clear acrylic to make a template and to keep from drilling too deep.

My drill and router bits are not made for plastic. The flutes get clogged, especially on the tiny router bit, resulting in unevenly drilled holes. Still you can see the promise in this approach, especially if one used a dedicated plastic bit. It would be easier to just get some proper Acrylite Endlighten, as no drilling would be necessary.

Either way, foil on the back side makes a big difference in the light output. Polishing the edges and using foil on the opposite edge also gets more output.

The white panel works best when it's separated from the clear panel by about 1/8-1/4 inch. Any more result in more even light, but unsuitably dimmer. I doubt that separating the diffuser would be necessary with proper end lighting plastic.

One characteristic of edge lighting that I've noticed both online and in this experiment is there's a hot spot right where the LED is. Then the light can be fairly even after that. Anyone who wants to use this approach would do well to oversize the panel and mask off the hot spot.

Alternatively, lifting the white panel on the end where the LED is will reduce the hot spot.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Mon 22, 2019 11:41 am 
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Cool


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Mon 22, 2019 5:00 pm 
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Quote:
My drill and router bits are not made for plastic. The flutes get clogged, especially on the tiny router bit, resulting in unevenly drilled holes. Still you can see the promise in this approach, especially if one used a dedicated plastic bit. It would be easier to just get some proper Acrylite Endlighten, as no drilling would be necessary.


Unfortunately, drilled holes have a lot of scratches that will scatter light and diffuse it. You might try polishing the drilled cavities with some fine abrasive powder.

Properly done, light should be conducted within the plastic and escape only at corners or cuts.

https://www.youtube.com/watch?v=nnXvK8qUEU8

Rich


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Mon 22, 2019 10:01 pm 
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Google "Sylvania 593", radioattic.com pictures of the dial face in the dark.

https://radioattic.com/itemshow.htm?radio=1000004

I gotta check the schemo to see how it's wired.

http://www.nostalgiaair.org/pagesbymode ... 021719.pdf

Looks like it takes DC ( Correction: That is AC, confusing the way it's drawn) thru two 12K resistors, but there is also a 3rd 12K and a variable 50K on the clock connection. Panelescent Control?

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Last edited by westcoastjohn on Jul Wed 24, 2019 3:58 am, edited 2 times in total.

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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 12:27 am 
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It runs on AC.

Perhaps that panel is a newer version that doesn't dim as fast or at all with use or maybe the panel was never used or lightly used.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 2:46 am 
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EDGE-LIT PANEL UPDATE: I studied RGB LEDs to see what would be involved in dialing in just the right color. That job can be done for just under $20. The following can be done under $2.00.

To simplify things, I used an acrylic cutting (scoring) tool to quickly scratch 24 parallel lines spaced 1/8 inch apart. One aqua blue LED lights this up.
The material is a clear plastic brochure holder. The LED is one of a package of five for $1.00. The scratches are free. The diffuser is a frosted polyethylene milk carton. Get the LEDs here: https://www.goldmine-elec-products.com/ ... ber=G18758

The photo below uses a piece of diffuser from a broken fluorescent light fixture. (I have trouble throwing potentially useful things away.) Images of two vacuum fluorescent display (VFD) clocks in our microwave and 70s clock radio are included for color reference. Another diffuser layer evens out the light more, but at the trade off of a thicker form factor and dimmer display. I expect that dedicated edge-lighting plastic would give a more even output, just not quite for $2.00.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 2:56 am 
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Very nice.

I think that before I do anything I should get the numbers on the dial repainted then try the dial on 120Vac just to see if it is bright enough.

Here's an older picture I found of mine with the panel lit on 120Vac, although it isn't quite as bright as the picture shows.

Image

Now if the original panel is bright enough or I get a replacement, perhaps I can design a circuit that turns the panel on only when it is dark enough in the room.

Here's a picture of an instrument cluster lit up by electroluminescent panels.

Image

I'm thinking that if I can find that color that would work.

I think I read somewhere that there may be some special paint used to repair the panels in those instrument clusters. so perhaps if that is true and I can find the paint I could repair mine or maybe I could find someone who repairs those in cars and see if they can repair mine.

Just found something on electroluminescent panels.

https://mds.marshall.edu/cgi/viewconten ... ontext=etd


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 3:40 am 
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Well the color is pretty close. Next question is how much space is behind the panel. The scratched surface edge lit LED panel would need at least 1/2" clearance all the way around.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 4:20 am 
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Unfortunately there is no space behind the panel.

I did find these guys.

http://jcauto.com/services/1

Sent them an email asking if they restore any electroluminescent panel or if they know anyone who does if they themselves only do panels on car instrument clusters.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 12:52 pm 
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Location: Powell River BC Canada
Sylvania promoted EL panels for many applications. Essentially they look like a capacitor.
If you try to energize them with any thing other than 120 Volts AC from the line cord
circuit , i.e, some inverter, they will radiate a buzz into the radio.

Somewhere I have a file with the original stuff Sylvania sent out. The applications were
supposed to be good for arena signs, etc.

Here is an experiment. Drive the panels from an audio amplifier stepped up with two
70 volt line transformers so that the high Z sides are in series, and able to deliver 120
volts over a range of sin frequencies.

You will find that as frequency increases you will drive more current through the panel,
yet maintain the 120 Vac rating. Scope this to be sure it doesn't clip.


But what I do remember is the this, at higher drive frequencies, the panel colour
gives the impression that it may have changed its hue.

Another thing, push it too hard, and it will burn a wee hole and be ruined.

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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 1:30 pm 
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I could try that experiment as I have an old 60 watt Bogen amp I put a small sinewave generator in along with a larger 70 volt transformer with a voltage select transformer from an AKAI reel to reel specifically for powering a Sansui record player that I could not otherwise get to run at the exact proper speed.

EDIT:

I heard back from that company and they said to send the panel in and they would see what if anything they could do with it.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 23, 2019 8:58 pm 
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A hand spectrometer is very handy for looking at light sources to determine
what they are. What things seem aren't always what they are.
Spectrum lines cant easily be hidden.

Who out there owns a DU ? https://www.youtube.com/watch?v=uaMhxG3mHrI

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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Wed 24, 2019 1:28 pm 
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I pulled the panel and the glow looks a lot like the color of the instrument panel I posted.

The plastic panel that is over the electroluminescent panel has a slight blue tint to it which possibly affects the color slightly.

I did try the panel on120Vac 60Hz where it drew just under 1mA.

At 200Hz it drew 2.2mA.

At 400Hz it drew around 1mA.

So it may be that they found the same material optimised for the 200Hz inverter used in cars worked well enough for home use.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Wed 24, 2019 3:38 pm 
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Tube Radio wrote:
I pulled the panel and the glow looks a lot like the color of the instrument panel I posted.

The plastic panel that is over the electroluminescent panel has a slight blue tint to it which possibly affects the color slightly.

I did try the panel on120Vac 60Hz where it drew just under 1mA.

At 200Hz it drew 2.2mA.

At 400Hz it drew around 1mA.

So it may be that they found the same material optimised for the 200Hz inverter used in cars worked well enough for home use.


Two questions:

1. In context of the paper your posted, were you able to tell any difference in color at the different frequencies?

2. How much brighter, if any, was it when it drew more current?


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Wed 24, 2019 5:28 pm 
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At 200Hz it was a little brighter.

Now at 200 volts which is what the electroluminescent panels used in some cars ran at, the panel was noticeably brighter.

Personally I feel they built them the same as they did for the cars and found the lower frequency and voltage produced a usable enough brightness.

Can't say I noticed much if any real color shift.

Didn't want to do too much testing on it as if I send the panel out to get it restored I figure they would want to see the panel light up.

Now if it is better to do so I can perhaps make a tiny 200Hz 200 volt inverter somehow then use a resistor to set the brightness provided said inverter won't interfere with the radio.

I could also just find the circuit used in the cars, duplicate it and install it in the box I used for the radio's power transformer as I have plenty of room there for an inverter. I have the area in the rear panel where the original power cord connector went so I could mount a jack there for the panel's power.

If 60 Hz will work (know it does, but don't know if 60Hz or 200Hz is best for the longevity of the panel) I can use a Triad N-68X isolation transformer either wired normal for 120Vac operation or wired reverse for 230 volts if 120Vac is not bright enough and just use a variable resistor to set the brightness.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Jul Tue 30, 2019 5:45 pm 
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I ordered some Acrylite Endlighten and diffuser panel. Endlighten is shown in the first photo with aluminum foil below it. It's about 3/16 " think. The next photo shows the appx . 1/8" thick diffuser panel over it, mechanically cropped with a ruler to hide the bright LED part. The LED was diffused with a piece of frosted tape. The light is just not spread evenly enough for prime time.

VERDICT:
Other than not having to drill holes, there's negligible benefit to using Acrylite for edge lighting on a single edge. In fact, drilling holes or scoring scratches, if it could be done accurately, has the advantage of putting light where you want it. The problem with edge lighting is the beam degradation. It could be mitigated with twin LEDs mounted on opposing sides; they would have to be just the right distance apart to make the light spread more evenly.

At this point I see no way of avoiding having relatively large areas of the panel rendered unusable where the LED is too bright. Perhaps precise hole drilling could remedy this.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Aug Sat 31, 2019 4:34 am 
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Weeks back I ordered the EM panel from Amazon. Took a long time to come from China. It's bright. It looks greener to the eye than to my camera.


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 Post subject: Re: Electroluminescent panel lighting
PostPosted: Aug Sat 31, 2019 6:18 am 
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Very nice.

This coming Thursday I'll send my panel off to see if they can do anything with it.

Think it's very similar to the panels used in a few cars back then so maybe they can do something with it.


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