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Old 6th Apr 2020, 11:56 am   #1
BulgingCap
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Default Triangular red LED

I have had no success in trying to find a source of triangular red LEDs.
In 1984 I built a pair of mono audio amps and, out of vanity, added a pair of 4mm equilateral triangle LEDs behind a piece of translucent red Lexan. They are mounted on a small PCB in the form of a stylised 'W' (my initial.)
They have never been bright enough so, during a refurb, I thought about replacing them with modern high-brightness types.
I have tried overdriving the existing LEDs but even at 35mA they are not very bright through the thin Lexan.
Any ideas on a source? RS etc don't seem to stock them anymore. I have found non-equilateral shapes, and pointers.
BC
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Old 6th Apr 2020, 12:12 pm   #2
Terry_VK5TM
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Default Re: Triangular red LED

https://au.mouser.com/ProductDetail/...vtXSoQNhz7o%3D

Still around Mouser part #696-SSL-LX3T453ID

Or Ebay - 20 for about 5 GBP roughly (I'm converting from Aussie dollar).

And if you really really need them and nobody else has them, Kingbright will custom make them for you. although I think you have to order a minimum of 1000.
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Old 6th Apr 2020, 3:09 pm   #3
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Default Re: Triangular red LED

Thanks for looking Terry, but I saw both of these: they are 'long by narrow' and not equilateral triangles.
It has just occurred to me that maybe I can get a flat 'giant LED' and mask the flat surface to create a 'W'.
I recall that when I originally attempted this 'vanity' feature (34 years ago!)I filed a flat top on a standard 5mm round LED, thinking that I could then file it to a triangle, but it did not work as the face did not illuminate but showed a near point source.
Maybe I should just change my name to a more convenient initial letter shape. Thanks anyway.
BC
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Old 6th Apr 2020, 4:00 pm   #4
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Default Re: Triangular red LED

@ BulgingCap,

You have a PM.

Regards,

Dave.
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Old 6th Apr 2020, 5:00 pm   #5
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Default Re: Triangular red LED

Just a suggestion, and more complicated, but what about overdriving them with pulses? You could peak-drive them to say 100mA with a 10% duty cycle and rely on the eye's persistence of vision to show them up as a lot brighter.
Might work...
-Jeremy
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Old 6th Apr 2020, 5:38 pm   #6
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Default Re: Triangular red LED

Overdriven LEDs get dimmer not brighter
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Old 6th Apr 2020, 7:00 pm   #7
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Smile Re: Triangular red LED

You might get away by carefully filing down some 10mm red LEDís as the actual LED chip and metalwork inside is fairly small compared to the size of the plastic case. There is quite a lot of material to be able to shape a triangular shape led. They are also cheap enough that if you did destroy one or two, you have only lost a few pence.

Christopher Capener
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Old 6th Apr 2020, 7:26 pm   #8
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Default Re: Triangular red LED

I guess these are the same as in Post #2?

https://www.esr.co.uk/components/opto-led5.htm
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Old 6th Apr 2020, 7:58 pm   #9
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Default Re: Triangular red LED

Quote:
Originally Posted by Julesomega View Post
Overdriven LEDs get dimmer not brighter
For pulsed DC, I thought there was an increase. But having now checked online, apparently that only held for early low-brightness LEDS.
Interesting!
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Old 6th Apr 2020, 8:38 pm   #10
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Default Re: Triangular red LED

Saw the top off and glue a new high brightness led on the stump? A SMT LED would stick on well. The new ones are extremely bright.
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Old 7th Apr 2020, 1:39 pm   #11
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Default Re: Triangular red LED

Julesomega and Paphonica- This seems correct from some tests that I have done today.
I repeated the experiment from 1984 where I filed a flat top on a domed standard red LED. I tried to take a pic but it did not really show the result. The light is just a red dot from the emission from the diode and does not illuminate the full surface.
The LEDs are just visible (off state) in one of the pics, behind the red Lexan. They do look as if they are not equilateral, but they are.
As I detailed to Amraduk in a PM- I have now disconnected the LEDs and will run the amps without an 'On' indicator. There is an indicator on the pre-amp and the amps are mains powered from the pre-amp on/off switch.
At some time I may fit one standard round LED in each amp.
MerlinMaxwell- I'm not sure what you envisage, but I could easily remove the small PCB that carries the pair of LEDs and replace the LEDs with any style, with suitable spacings.
Thanks all for the interest and info.
Regards, BC
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Old 7th Apr 2020, 1:51 pm   #12
BulgingCap
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Default Re: Triangular red LED

Yesnaby- They are. I am not sure what light output the diodes are that I have fitted at present; they probably came from Ambit or Maplin, or were rep's samples in the early 80s. The 'mcd' figures do not really mean anything to me. It seems from the data on the ESR site that the red ones have less light output than yellow or green but I'm not sure how that is perceived by the eye.
BC
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Old 8th Apr 2020, 1:02 am   #13
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Default Re: Triangular red LED

I have some 6mm round, flat difused top LED's. You could try being useful with a file. That may be an option. Yours if you want some.

Daniel.
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Old 8th Apr 2020, 9:31 am   #14
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Default Re: Triangular red LED

When i was experimenting a few years ago i had some success moulding araldite around leds. I got a large 5mm led that gave uniform output i.e. not a clear focused one. Roughed up the surface with wet and dry and made a moulds to the diamond shape i was after. I think i added some talc to the araldite to make it opaque. If i was doing it now i would probably try some smt devices. I just got a bunch of very bright ones with presoldered wires from China for my daughter's model trains. They seem to give light in a fairly nice distribution pattern
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Old 9th Apr 2020, 4:35 am   #15
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Default Re: Triangular red LED

Daniel and Dominic- thanks for that. I have experimented with a through-hole white LED which is so much brighter at half the current than the vintage red ones. I think I will install a pair side-by-side and fit a thin mask in front. As you can see from the pic I spent a lot of time 36 years ago trying to get this right! (it looks messy but that is old adhesive from some thin opaque tape that I used to stop light bleeding out the side into the translucent case sides.) I ground away the Lexan to try to reduce the attenuation of the translucent red.
I am ashamed to say that I was being paid whilst doing this in 1984. I won't detail the time spent trying to fit a small LED as an indent marker in a volume knob...
BC
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