I've always been fascinated by LEDs.
The first one I got to play with was a red TI "TIL209" bought via a friend who had a RS account. It was horribly-expensive [a day's wages before-tax&national-insurance!] so I was _very_ diligent about getting the polarity right and fitting a higher-than-usual series resistor [820 Ohms] before turning out the lights and flicking the switch to apply 9V from a Pp3.
It really was an "and then there was light!" moment.
Shortly afterwards, I acquired - again at some cost - one of the first 7-segment LEDs made by Monsanto, the MAN3A
http://www.decadecounter.com/vta/art...w.php?item=364
nicknamed "The Claw" because of its packaging. I hooked this up to a suitable TTL chipset for counter/decoder/driver and - loand behold - I could get it to cycle through 0-9 and ABCDEF by pressing a button to increment the counter!
At that point I was convinced that this really was the way ahead - a year later I'd designed my first 'commercial' piece of equipment that used an ultrasonic transducer and four 7-seg LEDs - it was used to assess the thickness of the back-fat on pigs in a slaughterhouse, and sold a few hundred - at over £1000 each!
What are your LED memories??