I'm thrilled to announce that I believe we've found a fantastic solution to the problem of trying to replace the blacklight in certain models of flip clocks (Panasonic RC-7264 and the Copal Model 705L for example).
With Surface Mount Technology, continued improvements in LED technology and the development of "LED Drivers" (AC to DC transformers) specifically designed for LEDs, we've now reached a point that replacing the blacklight in flip clocks is economical while delivering great results.
If you're wondering, yes, I am excited about this. For a reasonable cost (including shipping) of under $20.00 I was able to replace the blacklight in my Copal 705L. (see the parts list at bottom).
The "contant current driver" provides just the right amout of steady 12V DC to power the strip of LEDs cut from a length of the weatherproof 12V LED Tape Light. These things are amazing. A length of this tape (you can buy multiples of this for other applications) has 30 LEDs. You can actually cut this tape every third LED (the tape is well marked). It was nice that the length shipped to FlipClockFans Studeos already had the leads soldiered to the tape. A 3 LED piece provides plenty of evenly spaced black light to make the Copal 705L look like it did back in the day!
The LED driver is an inch and 1/2 square about 3/4 inch deep. A 3 LED length of tape measures 2 inches. It's very convenient the the tape comes with peel-and-stick adhesive backing. I was able to press the tape right into the well that held the vintage black light bulb.
Parts List (Superbrightleds.com)
LD-CU3512-01: 350mA Constant Current LED Driver - 1 Watt LED Driver $5.95
SWFLS-UV30-WHT: Outdoor LED Strip Lights - Weatherproof 12V LED Tape Light Side Emittin - 59 Lumens/ft - UV-BlackLight $11.95
After 15% promotional discount and shipping, total cost: $18.70
To comment and see a video of the process see the forum post