Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: HotBluePlates on March 01, 2012, 09:53:27 pm
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Has anyone built an amp with a light up control panel?
I'd like to incorporate one in my current build. I'm aware of the old light-up Ampeg logos, where engraving on clear plexi is lit by light applied to the edge of the plexi.
What I'm interested to know is if light applied to the back surface, say at one end of the panel, will transmit through the plexi the same way. The goal is to have a solid-color panel, with lettering engraved through to the clear substrate. I'd like to use LED lighting due to choice of colors, and the d.c. operation. What I don't know is if an LED shining on the back surface of the plexi will transmit through, and light up the engraving, the way applying light to the edge of the plexi will. The LED location and narrow angle of light means that my chance to get it shining on the actual edge of the plexi is unlikely.
Anyone know for sure?
I have a couple back-up plans, including:
- using incandescent light (but would prefer not to)
- shining the LED on the back edge, but chiseling a ~45 degree angle on the point of incidence to (hopefully) refract the light and transmit through the plexi to the lettering.
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(http://www.pacificcable.com/images/Fiber-Optic-Diagram.png)
Cladding is optional. (Mostly for cross-talk in adjacent cables.)
Note "Acceptance Cone".
http://www.pacificcable.com/Fiber-Optic-Tutorial.html (http://www.pacificcable.com/Fiber-Optic-Tutorial.html)
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So you probably already figured, but the LED likely needs to be mounted at a 90-degree angle to the panel.
Judging by the acceptance cone, and the fact that most LED's seem to have a very narrow viewing angle (for bright ones, and those mounted in a holder of some kind), that seems to make beveling the surface the LED shines on mandatory.
Also judging from the acceptance cone, a bevel less than 45-degrees seems better. 0-degree reference for what I'm describing would be the plexi panel surface closest to the LED, and perpendicular to it. Of course, if I can angle the LED to be more on the plane of the panel, I see that would help. Looks like I'll need to fashion a non-standard bracket...
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is this what you're look at doing, maybe something similar?
http://www.mouser.com/Optoelectronics/LED-Indication/LED-Light-Pipes/_/N-76e3p/ (http://www.mouser.com/Optoelectronics/LED-Indication/LED-Light-Pipes/_/N-76e3p/)
--DL
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Try this:
Get the LEDs, sanding paper, and sand the LED's lens till it is nice and fuzzy white.
This way, it will spread the light better through the plexiglass, as well as hold the LED better to it. I've see this being used a lot by case modders.
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I've put some thought into this myself, but have yet to implement any of it.
Here's what I'm thinking I might do soon. Mount one of the led strips like are shown on this page of the Mouser catalog:
http://www.mouser.com/catalog/catalogUSD/645/138.pdf (http://www.mouser.com/catalog/catalogUSD/645/138.pdf)
To the edge of the front panel piece of the cab - the way I build 'em is shown here:
http://i41.tinypic.com/15oe060.jpg (http://i41.tinypic.com/15oe060.jpg)
When the chassis is mounted in the cab, the front of the faceplate will sit flush with the front edge of that board, so the LED strip mounted on the edge of that board would shine down across the top of the faceplate. There is another front panel mounted on top of this as can be seen in the following picture (this is the state of the amps today - still workin on them)
http://i42.tinypic.com/erfps4.jpg (http://i42.tinypic.com/erfps4.jpg)
That front piece that the LEDs would be mounted to is only 1/2" ply in the picture shown, but 3/4" might be better for mounting the LED strip. Next Mouser order I plan to get an LED strip or two and experiment.
Please keep us posted, I'm interested to see what you come up with.
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How about some pots that light up?
My distributor over here carries them and they have caught my eye.
Might be a good alternative.
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Back-lit knobs WOULD be pretty cool looking.
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How about some pots that light up?
They're cool, but not the right style for this amp. I'm building a Standel, with a few modern touches, but I think the lit knobs would be too out-of-character. Instead, I've got some old-style rose-colored and cream-colored chicken head knobs to audition.
Actually, I think DL hit it on the head...
is this what you're look at doing, maybe something similar?
http://www.mouser.com/Optoelectronics/LED-Indication/LED-Light-Pipes/_/N-76e3p/ (http://www.mouser.com/Optoelectronics/LED-Indication/LED-Light-Pipes/_/N-76e3p/)
--DL
I don't think the light-pipes are where it's at for me, however, the right-angle LED mounts used to supply the light to the light pipes looks perfect! I can stuff them with whichever color works for me; looks like the only thing I'd need to do is cut a small rectangular opening in the panel, and position the mount in the opening. I'll have to eyeball the specs for those, and figure the best way to mount those holders in place.
And since a pic is worth a thousand words, I'm going to do something similar to the pic below, however, I don't want to use incandescent bulbs, and I think blue lighting would look slick against a gold-colored panel.
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That amp's no darn good. Only goes up to "9".
So your plastic is smack against the wood? Even so, you can get LEDs slimmer than any plastic which will take stage use.
Long ago there was a series of rectangular 0.2"(?) wide and <0.1" high so they could stack on 0.1" centers for bar-graphs. Since I can't imagine using less than 0.09" Plexi, seems like edge-lighting is possible. As I say, this is older stuff; might not have been produced since Blue LEDs came on the scene.
(http://ca.mouser.com/images/kingbright/lrg/wp513hdt.jpg)
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As you can see here the led for illumination of plexyglass surface aren't on the back of the panel
they are mounted on the side of the panel and engage the thikness of the surface
Lavagna Luminosa a LED - Scrivibile Cancellabile - 7 colori (http://www.youtube.com/watch?v=X4AWQxefOoY#noexternalembed)
Lavagna Led (http://www.youtube.com/watch?v=ljMu6Z9hrg0#)
to mount led strips on the side of a panel you can use an aluminium profile, something like this, only you must find a profile with proper thikness (hope you can understand what I mean, I'm not able to explain better)
may be that for this use you must use an "U" profile not planned for led montage
http://www.ebay.it/itm/6-Eloxierte-LED-Aluminium-Profile-zur-Auswahl-Alu-Profile-Aluprofil-f-LED-Strip-/250988453356?pt=DE_Haus_Garten_Lampen_Licht_Leuchten&var=&hash=item80146ceaf2 (http://www.ebay.it/itm/6-Eloxierte-LED-Aluminium-Profile-zur-Auswahl-Alu-Profile-Aluprofil-f-LED-Strip-/250988453356?pt=DE_Haus_Garten_Lampen_Licht_Leuchten&var=&hash=item80146ceaf2)
Kagliostro
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I've played around a bit with this and haven't come up with what I desire.
But her'es what I know.
You need to light from the sides.
Use acrylic, not poly carbonate or lexan.
you need a bezel to hide the edges and led's
minimum thickness I've found to work is 1/8. use 3mm leds.
drill into the edge best you can to mount the led
use water clear led.
glue the led in with weldon 16 acrylic cement
sand all other edges to a very smooth finish, polished is best. paint edges white or silver with white over it (reflects more light into the board.
Play around with it, cheap to experiment.
OH and also wide dispersal led's.
light from both sides top and bottom. the engraving can leave shadows, ymmv.
Ray
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That amp's no darn good. Only goes up to "9".
So your plastic is smack against the wood? Even so, you can get LEDs slimmer than any plastic which will take stage use.
:laugh: Yeah, I'm going to position "1" and "9" at slightly different angles than seen on the example; the original has those in the spots I see as "0" and "10". Regardless, a Standel isn't the kind of amp to crank to 11... :icon_biggrin:
The likely thickness of the plexi panel will be ~1/16" and the chassis itself is another 1/16". Since the plan is chassis under plexi under wood cabinet, the available opening to set the LED in will be about .125". Worst case, I can recess the wood somewhat where it meets the plastic panel to gain additional clearance.
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you need a bezel to hide the edges and led's
In this case, the cabinet is the "bezel". The opening for the control panel is less than 12" where the LEDs will be mounted, but the chassis is 14" long.
The original amp drilled 2 big holes through the chassis and faceplate, and inserted the typical #47 lamps in the openings. Since these opening were hidden by the cabinet, you only saw the effect of the lighting.
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How about a routed groove in the cabinet
The LED's get mounted in the grooves on a strip of drilled plexi that forces them to align correctly
The face panel edge bumps up against the LED panel
The LED panel could be much thicker than the face panel
You could drill holes and glue in regular round super bright LED's
I have ground down the round tips on LED's to make them flush with the panel surface
I did it on my bench belt sander
There is plenty of meat of the tips of round LED's
Of course this would require routing the wood before it is assembled
I would think that along the top front edge shining down would work and you don't need to route the cabinet for that
You could make a test led panel and press it up against the edge of a faceplate to see how it works first
I stock these super bright LED's and have used them for lots of different projects
(http://www.hoffmanamps.com/MyStore/catalog/images/IMG_6130.jpg)
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Here's a little experiment I did today
I engraved some text into an old piece of clear plexi
I glued 3 high output white led's into a piece of clear plexi
Then I ground down all 3 LED tips flush with the plexi surface
I hooked the LED's up to a battery for this test
I shot a video in the dark showing how you can just bump the LED strip up against the edge of a piece of plexi and light it up
I move the LED panel up and down to show the different levels of light as you move the center of the LED's across the center of the plexi text panel
Here's some still shots of the experiment and a video
LED Panel test (http://www.youtube.com/watch?v=XkzG2aV-jEc#)
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So it's been a minute since I asked the question. Thanks to all who offered ideas, and especially Stingray for providing some material for experimentation.
Ultimately, I found I had the wrong idea on how Standel did the control panel. I thought it was a colored panel engraved from the front surface to a clear substrate. Really, it is a clear panel that's engraved in reverse from the back surface, and the chassis is painted to provide the background coloring.
But I've got the clear panel made and engraved, and the LED lighting sorted out. It lights up beautifully!
I might not have looked everywhere I could, but I seemed to only find superbright blue LEDs in a round 5mm package. The acrylic panel came out to 1/8" thick. So I filed the round ends of the LEDs flat to butt against the acrylic, and also filed two opposing sides to get the LED down to a flat 1/8" thickness. The filing left the surfaces a milky white.
I arranged 6 LEDs to light from one end, wiring them in parallel using the the LEDs' own leads with some insulation off of 22ga wire to prevent shorts. 22ga wire is attached to the last LED, which runs into the chassis through a small hole, with the LEDs' dropping resistor inside the amp chassis.
In the end, the simplest way to mount the LEDs seemed best: The panel is fixed by the pots, so the flat ends of the LEDs are pressed against the panel's edge. The top and bootom of the LEDs will be held in place by the cabinet surface and chassis, since the panel edge is not exposed by the cabinet control cutout. Some thick rubber splicing tape is built up and applied to the chassis on the back end of the LEDs to keep them positioned.
The 6 LEDs are in an array less than 2" long, which might be overkill. But it seems to work well and give the desired intensity to the lettering.
Pics to follow in a few days when I get a chance to take and post them!
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Looking forward to seeing the pics!
If you didn't want to take the time/effort to file down LEDs, or if the space were even more limited, I wonder if using a single, high-power LED and distributing the light via optical fiber would work well. I first came upon this idea in the form of distributing a camera flash as in the attached image. The fibers probably could be cemented straight to the acrylic, and they could fit into very small spaces indeed.
Just another idea to throw into the mix. :icon_biggrin:
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That's pretty hot!
The suggestions offered up were great, and would be the way to go for something beyond a one-off for personal use. But there was just going to be more work than necessary shoe-horning the various methods into limited preamp chassis space. That or too many items that would require more precise fitting than the method I used, which gives more opportunity for a problem.
In the end, what I went with was very simple and effective.