Quote from: stephenafreter on June 30, 2010, 09:00:56 AM
...I'll first use magnesium ribbon with a file to make small quantities of powder for testing.

@Stephenafreter
Be very careful with magnesium powder, it will ignite even with just a small spark. I've had it light on me a few times. Other than that sounds interesting, I'd like to know how it turns out. Keep us posted and keep up the good work.

@Jeanna,
Great job on your tests with the electrolytes. I was very surprised to see that the magnesium sulphate hardly damaged the ribbon compared to the salt. This is very interesting. Thank you for the good work, I think you may be on to something.

-Pete

Hi, I find that a graphite electrode is a very important advantage compared to others because according to the excellent potential chart linked by Pirate, http://www.thelenchannel.com/1galv.php, it has the highest positive potential AND it is not corroded during the reaction !!

It's even higher potential than gold or platinum 

The challenge it to make a hollow graphite electrode of large diameter (20-30 mm, 1") that is strong enough and can be re-used, by changing the external magnesium ribbon when it's exhausted.

I suppose that graphite pencil manufactures use pressure to put their graphite mix in form. I am looking for a way to do without the need of a press. Thanks if you can help to find the way.

Quick update, good voltage reading with the graphite grease electrode, but not enough power for the joule thief. So far I got much less power that around the 8mm diameter graphite pencil ...
Tomorrow should try with wax + graphite.

Edit: Measured resistance between 2 points of the graphite pencil is only around 20 Ohm, while on the graphite grease it's around 15k Ohm, that explains why there is not much power out ... the electric resistance is too high.
I'd better look for a conductive binder element, like a water gel ... any suggestion ?

The binder doesn't need to be conductive. You just have to add enough graphite.
You could use acrylic paint or epoxy. Just use as much graphite powder as possible and it should have a low resistance.

BTW. 10 USD for 150g of graphite powder seems a little high. I got 150g for 3 euro at my local hardware store.

Quote from: tishatang on June 30, 2010, 02:39:57 AM
Hi all

I just discovered this link about  (electrostatic) air batteries made 100 years ago! 

http://amasci.com/emotor/duluc.html

Look at this
http://en.wikipedia.org/wiki/Oxford_Electric_Bell

The thing has been continuously working for 170 years now and it will probably keep going for few hundred years.
No one really knows what's inside but I guess it's probably zinc foil, paper and manganese dioxide. The paper might have been soaked in zinc sulfate solution and then dried.