Friday, 3 July 2015

Making an Illuminated Inspection Lens From Junk

I recently removed a large lens assembly from an old rear-projection television.  It is an excellent magnifier with a wide field of view.  It would make a GREAT pcb inspection magnifier except that it is a bit too heavy and big to be handheld.  And there's a bigger problem.  It's too dark.  Read more to learn how I turned it into a great tool.
First I added some stilts from old standoffs.  Slide your PCB (or whatever else) underneath and enjoy handsfree magnification!  Now to deal with the fact that it's too dark.  Here's what we're dealing with.

The only light that gets is in from the bottom sides, which isn't much.  So I ordered a 12V white LED ringlight from - it's intended for cars.  There are many, many options out there and all of them are only a few bucks each.

Turns out it fits perfectly on the bottom!  A bit of glue, and it's done.

A quick test shows how much better it performs with a light source.  Check it out now!

The only thing left is to attach a battery and toggle switch so I don't need to plug anything in.  I used a spare 3S (11.1V) li-po battery intended for RC hobby aircraft that was left over from teaching myself to fly.  The switch is just a push-on, push-off from the junk box.

Some spare velcro strap does all that's needed to hold things securely.  (The wing nut slider is for small focus adjustments, by the way.)

Now it's handsfree, rechargeable, and wireless.  Works great!

 One thing that doesn't really come across is how big the field of view is through this lens.  You can "pan around" a surprising amount just by moving your head around.  I've tried to demonstrate this with the following animation - this is all just by moving the camera.  Everything else is sitting put.