[kinetic (Steve)]

I bought this Red LED Cherry light set a while back for dome
interior lighting. It works so well that it deserves a DIY write up.

It's a 200 bulb set that works with an 18v controller but I hacked it
apart and installed about half of the bulbs under my circular desk
in the dome. I also made a small bank to sit over the Bartel-Drive Laptop
keyboard as all of the Scope-Drive functions can be done by keystroke.
That's pretty hard in the dark, one wrong key and I can ruin a tracking/ GOTO etc.

Bulbs mounted under the desk are perfect because the bulbs are out of your eyeline
and the mood of the lighting is functional . I have it voltage adjustable and it's divided
into several circuits so I can switch banks on as I need them.
I run each bank on my general purpose dome 12V DC.

Pulling apart the set:

To try and work out how each leg of the multi loom wiring went was
too time consuming so I cut out 6 bulbs to start with which were
wired in daisy chain serial style.
The LEDS are white underneath the red plastic difuser.
LEDs typically need about 1.5v to give off light , all colours are slightly different.
A good current to drive them safely and not too brightly is between 10-20mA.
With 6 Bulbs this would need approximately 6x1.5v=9v to make the LEDs work.
BUT LEDS need current limiting because directly across 9v they would burnt out
almost instantly.
With a bit of a play on my Benchtop power supply and a few current limiting
resistors I confirmed that with 12V and a 470 ohm resistor across 6 serial bulbs,
the light level was perfect. Forward bias bulb current was between 1-5mA when
I adjusted the 12v. The LEDS extinguished at about 10 volts.

For the laptop keyboard bank I made it from a piece of 'AussiDuct' PVC ducting.
This one has two channels but single channel duct is fine.
I glued each bulb into small cuts made in the centre rib with a hot melt glue gun.
I soldered the 470 ohm resistor in one leg and connected it with some Fig 8 speaker
wire. I always make the black stripe of Fig 8 the negative as a rule.

I then made a lid for the duct with a cutout but there really is no need for a lid.
The only function of the lid was to cap the ends and stop light leaking out
sideways. Some gunmetal grey spray and it matched the laptop.
Stuck on with good double-sided tape to the laptop screen and it was all done!

Steve