Sciencemadness Discussion Board

Spark in a test tube...

craynerd - 25-10-2006 at 14:00

Hi guys,

I know this seems a rather trivial request in comparison to the majority of high tech. posts you get on here but I’m desperate.

I went to a science and tech. museum today and they had this cool contraption. You turned a wheel, generating electricity, supplying electricity to electrodes in dil. sulphuric acid. This electrolysis produced H2 and 02, you then proceeded to press a button which caused a spark to ignite the mixture and shoot a rocket into the air. This was micro scale, don’t get any big ideas, it was all very simple.

Anyway, my point is I want to try and replicate something similar. I can generate electricity for the electrolysis and then can even collect the gases in a test tube. The bit I am struggling with is actually producing a spark safely to ignite the mixture. What’s the easiest way to produce a spark at low voltage? The best method I have so far is sending a low voltage down some iron wool, but its a poor method since it needs replacing each time.

Any ideas?


cray

Waffles - 25-10-2006 at 14:16

In many barbeques, self-lighting propane torches…any device that ignites open flame (your gas stove likely has something similar, though not with the button) they have a button (usually red) to ignite it.
What happens, is when you press the button, you flex a piezoelectric crystal, and it snaps back to its original position, and a charge is generated.

Basically, take any of the above apart. Get the button, it should just be its own little plastic cylinder with the button on one end and a wire coming off the other end. Test this for yourself: cut the wire (or use as-is), press the button, and a spark comes off the end. Shock yourself, shock other people (people will tire quickly of this and the clicky noise of the button), make little sparks against metal things- and for your purpose, use to ignite rockets :). Talk about 'water-powered'…

mericad193724 - 25-10-2006 at 14:45

Yep, Waffler gave you the easiest way. Most Barbecue Grill lighters cost about $10 dollars new, just buy one of those cheap Cigarette lighters that have a clicking mechanism to ignite the flame instead of the thing you role to generate sparks. The one you press has a Piezo device...it will only cost you a few dollars.

Take a look here for something similar:

http://sci-toys.com/scitoys/scitoys/echem/echem.html#bomb - The device generates H2 and O2 gas and ignites them shooting water out of tubes. Modify it to shoot whatever you want.

Good Luck

Mericad

craynerd - 25-10-2006 at 15:12

Brilliant, thanks guys. I know exactly what you mean, we use to take them out of lighters as kids and go around shocking each other with them lol ! :P Never even gave them a thought!

Brilliant, i`ll let you know how it goes!

Cray

Waffles - 25-10-2006 at 15:43

Quote:
Originally posted by mericad193724
Yep, Waffler gave you the easiest way. Most Barbecue Grill lighters cost about $10 dollars new, just buy one of those cheap Cigarette lighters that have a clicking mechanism to ignite the flame instead of the thing you role to generate sparks. The one you press has a Piezo device...it will only cost you a few dollars.


Heh, the only problem with one of the lighter ones is that- there is no wire. At least with the self-lighting propane torch, you have a couple inches of wire between ignition and your fingers…

mericad193724 - 25-10-2006 at 16:47

There is usually only one wire, if there is none just solder one on! You can just add a length of wire to the sparking wire on the Pizo if it is too short. They are dirt cheap...look in a trash can if you are really dirt poor :P . Notice there is only one wire since it is an electrostatic discharge.

[Edited on 26-10-2006 by mericad193724]