My cheap LED tripod markers
Ever been to a star party and worried about someone tripping over your power or laptop cables? Maybe you'd like to wander around a little, and you need to mark your scope and cables so people don't trip or bump into your $10,000 investment? These little boxes can be made for under $5 each, and will run for months on 2 AA batteries.
Parts list :
I used Radio Shack parts, any similar parts will do, just vary
"AA" battery holder #270-408
SPST toggle switch #275-624
Blinking red LED #276-398 (2.8v 12ma 500mcd)
I started by removing the screw in the battery holder, then pulling the two wires back inside the case. There's two strain relief posts inside the case that can be removed by twisting them with a pair of needle nose pliers. Cut the wires to a length of 2" and strip/tin the ends. On the opposite cover, drill two holes 3/16" diameter between the center screw hole and the outside edge of the battery case. I just used an exacto knife, since the plastic is quite soft.
Insert the LED on the negative side hole, and attach the switch on the positive side. The LED can be super-glued into the opening. Once the superglue is dry, bend the negative (shorter) lead on the LED around the screw hole, and to one side of the switch.
Solder the lead to the switch. Solder the red (+) power lead from the battery pack to the other side of the switch, and solder the black (-) wire to the remaining leg of the LED. I clipped this leg so that it would be a little shorter. Insert two AA batteries and reassemble the battery pack.
I know a resistor should be used in this simple circuit, however, these LED's have been working fine for over a year now without any current damage. I've always said, if it works let it be. I use these more when I take my kids camping. I put one on each leg of the tripod, and that way the kids and any visitors stay clear of the tripod. The output is quite small and very unobtrusive, but still bright enough for people to see.
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