My sister would like to use a light on the end of a string, and I was wondering how that could be made. I was thinking of putting a bright LED, and resistor, and some hook-up wire in a clear, plastic ball or even in some Saran Wrap with a battery to power the circuit. This may be completely implausible, I don't know.
9V battery + ------- 1k ohm RESISTOR ---- LED ---- 9V battery -
Wrap it in saran wrap, and you have a light on a string... ;)
The long lead coming out of the LED should connect to the resistor, not the - side of the battery. The resistor doesn't care.
You can get LEDs and resistors at radio shack, frys, or online at
Regards, Bob Monsen
atwww.goldmine-elec.com,www.digikey.com,www.mouser.com,www.futurlec.com,www.arrow.com, etc.
Wait, how do you connect the battery then? Negative terminal-wire- resistor-LED-wire-positive?
Or would one lead of the LED go to the resistor and the other lead to the battery? Also, how do you hook-up a lead or wire to a battery? I am really new at this.
Hook it up like this. I hope this is clear enough.
1K resistor .-----------. ___ long lead of LED | | +-|___|----------------------+ | +||-+ | __ |9V battery | +--------| \\ LED | -||------+ | ) '-----------' | +-----|__/ +--------------------------+ shorter lead of LED(view in fixed text or courier)
(created by AACircuit v1.28.6 beta 04/19/05
Allen
When I was in College one of the guys in the dorm hung a bare 60 watt incandescent light bulb, 120Volts, from the concrete ceiling of his room on a piece of string. The bulb would just hang there lit, fully bright, but looking at it you couldn't figure out how it was powered. It was a great conversation piece and kept a lot of people guessing. A bare bulb just hanging there on a sting without a socket or apparent wires burning away, it was great.
What he had done is twisted some very thin magnet wire, like 36 Ga. into the string and soldered the ends to the bulb base where the string was tied. The wires went up the string then across the concrete ceiling hidden in the natural cracks and roughness of the painted concrete. The string was taped to the ceiling. You could not see the wires without climbing up and very closely inspecting the situation. The wires came down one wall to a wall plug where other stuff was plugged in concealing the termination.
I wouldn't recommend this as it could be a fire hazard but it sure would be a hell of a lot more impressive than an LED. It takes a clever artistic person to weave and conceal the thin wires. If not carefully done it would be a dead giveaway if wires can be seen. If you try it be sure to never leave this kind of thing plugged in unattended.
Is it safe?
36 ga wire has 418 ohms/1000 ft. Your friend's display probably used 6 feet of wire. That is about 2.5 ohms. A 60W bulb uses 500mA at 120VAC, so your friend was dissipating about 5/8 of a watt in the wire. Enough to get it toasty, but probably not enough to start a fire. However, it exceeds the maximum current allowed by the American wire gauge guys by 1400%...!When the bulb first turns on, it'll be alot more power, but only for a second or so. Just don't hold the wire when you turn it on or you'll get burned.
Regards, Bob Monsen
away,
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I don't know if it was 36 Ga. or not, it might have been 34. In any case, a watt or two, even 5 watts dissipated in a few feet of wire won't get the wire hot. There is too much air all around that length wire for any appreciable temperature rise. Is it safe? Hell no! I don't think I'd be showing it to any electrical code inspectors or UL types. It's a dorm room or party trick, not to be left unattended. It is probably no more dangerous than a candle, however.
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