Illuminated Telrad Overlay

[arrayschism]

Hello all,

I have seen the idea of printing out a set of star maps and using a telrad circle printed on acetate for the ad hoc finding of objects in the sky - a little like a map and compass for terrestrial route finding. I thought that it would be more useful to somehow have a telrad overlay combined with a red light - that got me thinking on how to build something to do both jobs at once.

I did some googling about to see if there was such a product but could not find anything at all out there, so I've decided to have a go at something myself.

I did think about having a torch on some sort of flexible 'goose neck' above the overlay; then I thought, why actually illuminate the overlay?

There is a way of getting inscriptions to light up on thick clear acetate (say about 6mm), by illuminating the acetate from the edge (does that make sense?) - it's how a lot of shop signs are made these days I believe...

Anyway, I've build a 2 LED torch circuit, and my plan is to get some telrad circles engraved on some thick acetate, and drill the LEDs into one edge of the acetate to make a lighted overlay.

Once I get it completed, I'll post some details here, in case anyone else is interested