Need schematic: 60-LED analog seconds-only clock Answered
I built a "barn-door" tracker to take photos of planets and stars so that they are tracked (i.e they appear as dots, not trails). See http://en.wikipedia.org/wiki/Barn_door_tracker if you want more info about trackers of this type.
My tracker can be seen in the first two photos here: http://www.tjimaging.com/ted/astro.htm
These devices depend upon the user manually turning a knob at exactly one rpm for as many as fifteen minutes. This is (very) tedious, but gets good results. The biggest difficulty is in keeping the proper rate of knob-turning. I use a stopwatch timer and have a pointer on the knob so I can manually match each second as it goes by. This has to be done in the *dark*, though, for obvious reasons! So there's an additional problem of lighting the dial and stopwatch.
My idea would be to affix a steady red LED to the end of the knob pointer and to use an analog clock consisting of 60 red LEDs arranged in a circle around the knob. Only one LED would be lit at a time, starting at 12 o'clock position, and advancing one LED at a time, clockwise, and keeping each LED lit for one second. This arrangement would let me simply match the knob's steady LED with the currently-lit one and thus makes manual matching of the "second hand" visually easy.
I expect a 555 timer circuit (powered by battery, not A/C, for portability) could handle this task, but I don't know enough about electronics to know for sure. I'd like to keep the cost lower than it would be if an Arduino-based circuit were used.
I've also never made a custom printed circuit board, but I'm game to try after building a successful breadboard.
I just need a schematic! Thanks, all.