One problem with old things is they can be hard to keep working. I had this fluorescent tube lamp from the 80's with a fantastic large magnifying lens but it's really inconvenient to replace the bulbs. My solution was to replace the scary old transformer with a DC converter and LEDs.
LEDs are 3.3v and were purchased on E-Bay and came pre-reflowed onto a thermal substrate. I would recommend getting them this way unless you have a way of doing it yourself. With high output LEDs you need some way of cooling them which I discuss in a later step.
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Step 1: Clean Up Your Lamp
Remove any old wiring and connectors.
I kept the power outlet extension since it was really convenient for connecting power to boards and other things.
It isn't necessary but I wanted to improve the look so I completely took apart the lamp to clean off the rust and repaint it.
Step 2: Painting (completely Optional)
I picked up a can each of oil-rubbed bronze spray for the body and chrome for the reflective inner surface. The reflective layer was designed for a fluorescent bulb and thus was a solid piece but I will mount the LEDs to the solid metal hood. I made a template to position the LEDs and cut out holes of an appropriate size for the lenses.
The LEDs I will be using are 3.3V each and need a heat sink to keep cool during long periods of use. These ultra bright, high output LEDs are great but are nothing like the through-hole types most hobbyists are used to using.
To do this cooling I will make use of the large metal lamp hood and affix them to it with a thermal paste. This paste is a silicone base but cures incredibly strong and has been designed specifically to allow heat transfer. When painting the hood I masked off the areas where the LEDs would be in contact so they would have good contact with bare metal.
Step 3: Choosing Your Power
I had a "broken" wall wart DC supply that was an appropriate voltage. It was outputting 15V with a supply of 1000mA. Gracefully wielding cutting blades, wire cutters and pliers (brute force twisting, snipping and tearing) I made my way into the sealed case to expose the transformer.
Once removed from the plastic case the wires can be easily desoldered but before doing anymore work I just needed to test the fit of the core inside the lamp base. This core is also far lighter than the circuitry that made up the high voltage supply for the fluorescent tube which proved a bit of a problem later on when trying to set it up on a table.
Step 4: Test Wiring
Checking the brightness on the LEDs with the DC converter and making sure it works before installation.
Step 5: Putting It All Together
There isn't much to this step other than making sure you put things together in the right order they were taken apart. For instance I had waited a few weeks between painting and putting back together and had forgotten how the springs attached. Good thing I had some notes for reference.
Be careful to measure your lamp cord thickness as mine was almost too thick to fit through the lamp hood. It was a bit tighter than I was expecting and would have chosen a smaller gauge if I had checked everything first.
The LEDs came with some lenses and those just pop into the holes. I used a little JB Weld on the back to secure them. They're also not necessary to make this project work but can improve the brightness on the surface bu helping to focus the light.
Step 6: Enjoy the View
Some of the things I would have changed:
Adjust weight (add weight) so the base could better support the lamp hood. I'm thinking of attaching it to an old weight lifting disk and felting the bottom.
Making the lenses adjustable so I can tilt them if necessary when working on things much closer to the lens. As it is when I get down to small parts like surface mount the lights are far enough apart that they no longer over lap entirely. Not an issues but just a flaw that could be improved upon.
Thanks for reading.