LED choice for annunciators?

[Sean Nixon]

I'm planning on using 2 x 5mm LED's per annunciator on my overhead. Looking at buying LED's it appears the brighter they are, the narrower the viewing angle, and vice-versa.

I think I'd be better with brighter ones rather than those with a wider viewing angle. Has anyone any experience of this?

SN

[fordgt40]

Sean

If you go for "brighter" ones with a narrow field of view you tend to get round "hotspots" particularly on annunciators which have a lot of text ie the lettering is unevenly lit at the edges. Another key factor is the distance between the led and annunciator. If your leds are far enough away, then a narrow field of view is compensated to some extent by the distance, though with less light on the annunciator. Too close and you get "hotspots" again. Experimentation on your setup is the answer:)

After many failures I always use two wide angle flat top leds around 5000mcd each per annunciator

Regards

David

[Sean Nixon]

Thanks for sharing that David. I did see your response to Clive's problem after I posted this question.

I'm using Engravity's annunciators which come with an LED holder specifically designed for 5mm round LEDs. Using that also places the LED well into the annunciator, very close to the text, so I can envisgage the hotspots you mention with narrow angle, brighter LEDs.

It's interesting that you're talking as low as 5000mcd's for the square LED's. The round ones I'm looking at are around the 20000 mark.

I suppose it wouldn't be too difficult to modify or make new holders to suit square LEDs, like you say, it's time to experiment!

Thanks David.

Sean

[fordgt40]

Sean

These are the ones I used:-

http://cgi.ebay.co.uk/30x-5mm-Orange-Flat-Top-Wide-angle-LED-Free-Resistors-/120716319838?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1c1b40dc5e

The supplier is good and quick, also will send you whatever resistor values you want. My leds are within 4mm of the back face of the annunciators and work ok. Experiment and good luck :)

ps always sandpaper the back face of the annunciator to roughen the surface and improve light spread

Regards

David

[ian@737ng.co.uk]

hi sean.....
the led's David is referring to are not square. they are a 5mm round body, but they have a flat top which gives a
wider fiels of view.
have a look at these.........
http://cgi.ebay.co.uk/10-WHITE-FLAT-TOP-EXTRA-WIDE-5mm-led-leds-LEDS-FREE-RS-/190452951734?pt=UK_ConElec_LightingLEDsStrobes_RL&hash=item2c57e16ab6
you'd just need to choose the colours you want.
rgds

ian

[Sean Nixon]

Those ebay links have orange and yellow LED's. Would these be the equivalent of amber?

Thanks again guys.

[fordgt40]

Sean

Re colour it is a personal choice and very subjective. I should try both colours, from my purely personal perspective I found the yellow too "washed out" and went for orange. Doubtless others will say that orange is too "red"

It is whatever turns you on:)

Regards

David

[ian@737ng.co.uk]

hi sean.....
totally agree with David, my preference is orange also.
rgds

ian