Morris, Nick- Thanks for comments.
The displays I have are in a GR 1123 syncronometer. I need to replace a few
lamps and get one of the counter decade dividers operating properly
again.(That WILL be a challenge!) I was aware from my own experiments and
those of others in similar LED replacement situations that the directional
properties are a significant disadvantage sometimes. Someone suggested
sanding the whole surface of the lens so it becomes 'non-clear' and more of
a distributed source but I've not attempted that as yet, mainly as it seems
too difficult given the small sizes involved, so I don't know if it would
improve things at all. A very small sand blaster, using very small
abrasives, operating similarly to the old spark plug cleaners might work- it
needs more thought, as you can no doubt tell!
Cheers
DaveB, NZ
----- Original Message -----
From: "Morris Odell" <[email protected]>
To: <[email protected]>
Sent: Monday, May 19, 2014 9:25 PM
Subject: Re: [neonixie-l] About this type edge lit display.
Hi all,
A few years ago I built a 6 digit clock using those indicators. They are
multiplexed and the clock looks terrific. Mine uses 12V flange based
bulbs.
The downside is that the bulbs don't last all that long when multiplexed
at
the theoretically correct voltage of 12 * sqrt(6) = 30 V (approx). Those
little bulbs are not easy to find. The local professional suppliers (RS or
Farnell) have them but you need to buy 100 at a time. I have had some
success substituting LEDs as the quality and colour of high intensity warm
white LEDs have improved. Once I run out of my last purchase of 100 bulbs
which should be in about a year at the current rate, I'll install them. It
won't look quite the same but them's the breaks.
Substituting LEDs is not straightforward. The issue with LEDs is that the
light intensity is maximal in one direction while a small hot filament
quasi-isotropically radiates in all directions. The bulb housings are like
an integrating sphere with a slit where the edge of the perspex picks up
the light. If the LED radiating direction does not coincide with the slit
you lose a lot of it so even with very bright 5 mm LEDS the display looks
dim compared to when a bulb is used. Recently I picked up a batch of warm
white LEDs which have short bodies thus allowing more of the light to be
bounced around inside the integrating housing and they are not too bad.
I've got quite a collection now of unsuitable high intensity white LEDs!
Morris
On Monday, 19 May 2014 09:37:22 UTC+10, Dave Brown wrote:
Yes-those KGM displays are really quite interesting.
Has anyone come up with an LED replacement for the bulbs in them?
DaveB,
Christchurch, NZ
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