[SignalOne] Meter Backlight

[jerry]

So - in order to put this CX7A back in its case, I really want to get
a backlight on the meter.  I bought 8 little skinny lightbulbs from
"Electronic Goldmine".

   Unfortunately, I cannot find the baggie with the 8 skinny lightbulbs 
:(.
I looked in all the sensible places;  Now I guess I have to move to the 
not-sensible
places, and that will take a LONG time.  Might be more efficient to just 
buy
more skinny lightbulbs :).

   In the meantime, I started looking at LEDs.  There's not much space on 
top
of the meter.  But SMD LEDs are really small.

   Then I remembered... I had acquired some "Bowerful" LEDs to restore 
the backlight
on an Alinco DR-1200T.  That radio has multiple "grain of wheat" bulbs, 
and they
ALWAYS burn out.  The Bowerful LEDs are made for dollhouses.  They are 
SMD LEDs with
leads soldered on.

https://www.amazon.com/25pcs-Pre-soldered-Micro-Wired-Muti-Resistor/dp/B07P8PMCCS

   The two lugs on top of the meter supply +5V.  How would two LEDs in 
series work off
that?  I tried it.  The full turnon voltage of these LEDs is 2.7V.  Two 
of them in series
light dimly off 5V with no series resistor.

   So I made up a little piece of perfboard;  1" long by 3/8" wide.  
Stuck two of the LEDs
in it, wired them up in series, laid a piece of Kapton tape across the 
top, and soldered
them to the meter.

   It works.  But not too impressive.  Basically, a little Hitler 
mustache of white light
at the top of the meter.

   I'm going to see if I can sneak in a second series string with the 
leds further
apart.

                  - Jerry, KF6VB