LED light from a penny

[corky]

Forgive me if this has been asked and answered. I just came in from a scout meeting where a guy had an LED flashlight made from a penny. It looked like the penny was sawed in half edgewise. The diode's wires disappeared inside the penny. The penny was surrounded by a piece of corrugated cardboard. When you squeezed the penny, the LED lit (very bright I might add). It was the topic of much discussion but no one knew how to make one. This one was made as a gift for him so he didn't know how it was made. Anyone know how I can learn to make one of these?

 

[Icebreak]

corky -

Welcome to CandlePowerForums.

Interesting post. I'm going to sit back and watch your thread. Good one!

 

[INRETECH]

There must have been another metal inside of it

You can get electricity from putting together disemular (bad spelling) metals and applying an acid

 

[James S]

modern pennies are disimilar metals. I think they are zinc inside? Can you make a battery out of zinc and copper? I think perhaps you can, perhaps the cardboard was soaked in lemon juice or something?

when you say edgewise do you mean it was separated down the middle leaving 2 penny sized pieces half as thick?

fun

 

[tiktok 22]

Hi Guys,

I have heard of people using a nickel, a penny, and a piece of tissue soaked in a salt-water solution. Just keep stacking them in this manner and you have a crude battery....I think.

 

[corky]

Gee... This question was tougher than I thought. You guys are way off (so far). There was no liquid involved whatsoever. We figured that the battery was copper/zinc bimetal, as newer pennies do have a zinc core. He has had this for 5 years and it still works like a charm. We couldn't take it apart without destroying it, so I'll describe it the best I can. The penny looked as though it was sawed in half lengthwise (edgewise). The middle of the penny was puckered out, so something was jammed into it to force a pocket to form between the two halves. Then, there appeared to be a semi-circle cut into the penny along the top of Lincoln's head. One wire of the diode went into this semi-circle slot and disappeared into the penny. The other wire of the diode you couldn't see, so I assume it went into the core from another place. The cardboard was a disc the size of a half dollar. There was a penny sized hole cut into the center, but not all the way through, so if you looked at it from the backside you could not see the penny. The LED's wires went in from the side through the channels made from the corrugation, so the light itself extended outside the periphery of the cardboard disk. When you squeezed the penny, (evidently forcing something to contact something else in the penny's core) it made the light shine. And it was very bright, more than enough to read a map in the dark.

I very much want to make one of these for a survical kit. I've seen one on the net made from a film cannister and a 9 volt battery, but this is much larger than I want.

Anyone?

 

[Lurker]

Is there any chance that there is a watch battery hidden in there somewhere? Maybe beneath the penny hidden by the cardboard. Or do you think there is some kind of chemical reaction that depends on the penny itsself and something else such as maybe the fingers that are pressing it?

It's an interesting question. At first I thought the penny itsself was emitting light, but based on your further description, that's not right.

 

[Entropy]

Either there's a watch battery hidden in there somewhere, or it's a thermocouple.

Most likely the former - Thermocouples don't provide that much power. Not enough to light an LED.

 

[corky]

Update:

I just treated a patient (I'm a doctor) who's an electrical engineer. He thinks that there are two coins (probably a nickel is used but also could be an old zinc penny from the 40's). The penny is bent to make a pocket. The two coins are separated by blotter paper soaked in an electrolyte solution or they may have used an electrolyte paste. Then the outside edges are sealed with hot glue. This is essentially a battery. The one lead from the diode goes into the slot cut in Lincoln's head. The second lead probable follows the channel in the cardboard along the underside of the second coin. He thinks a perforation is made in the channel so when you squeeze the penny that lead touches the second coin and completes the circuit. Then when you release, the corrugation creates a springlike effect that pulls the lead away from contact with the second coin. His advice was to go to an automotive store and buy one on a keychain for a buck. Probably good advice.

 

[webley445]

Here's a design I came up with this wekend. Take a small binder clip and clamp two 3v CR 2016 or CR 1616 batteries in the jaws. Then clamp the led in there too. Only thing there is no on/off but it works. Or maybe try the 9v setup on my web site [click link below].

There are also many inexpensive mini lights like this out there in the retail market. Ranging anywhere from $5-15. I would suggest a Photon II because it has a switch with constant on.

 

[Anarchocap]

Yeah, I'll take a Photon II please. Why make life so complicated? And there sure is hell isn't much copper, if any, in today's pennies. If there is any, I am sure it is just a plated top coat.

 

[kimgkimg]

I think another question is, "How to you 'saw' a penny in half edge-wise?"

 

[McGizmo]

Kimgkimg,

If it were me, I'd opt for the EXPENSIVE route and file or machine the heads off one penny and the tails of another. That's my 2 cents worth!

- Don

 

[B@rt]

 

[Max]

I'm totally convinced there is a watch battery in there. No way a simple coin sandwich is going to provide enough juice to brightly light an LED.

 

[Marked]

Turn two pennys on a lathe and cut out the center of the two. Add "coin" cell. Some way to insialate and swich on.

 

[franken2]

how about a gold dollar sized light with mr gransee on one side mr johnson on the other?

 

[James S]

You can definitely make a battery from pennies and zinc slugs, or in this case the penny and it's internal zinc. From what I can see by visiting high school physics websites talking about building a pile this way it seems you can expect to get half a volt from each cell. That is not enough to run the LED, but if you put 4 of them together they say you can light a regular red LED.

If the penny is really sliced into 2 disks (can't imagine how you would do that, very fine bandsaw?) then it would count as 2 cells, and if it was also cut in half then you could get 4 cells out of it, so it's certainly possible.

I'd ask him made as a gift from whom and follow up from there

 

[Harrkev]

Originally posted by corky:
I very much want to make one of these for a survical kit.

<font size="2" face="Verdana, Arial">I don't think that I would trust a "penny battery" in a survival kit (or even a "survical" kit). A Photon would be a much better choice, much easier than sawing a penny, and probably more reliable.

 

[INRETECH]

A Photon is just one of those things "must have" for Survival kit - I have always had one on my keychain since they first came out with it

I once purchased 20 of them and gave them out as Christmas Presents, they have a lot of neat stories about how the little lights "saved the day" on their website