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Posted: Thu Jul 03, 2008 12:02 pm
by brother361
vovka351 wrote:goose--get a wall socket and a diode. try not to kill yourself. :D
Starman--well, when there's salt in the water electrolysis seperates it into Sodium(OMG reactive metal) and chlorine(OMG poisonous gas)
ok but your not suppose to use salt BAKING SODA is what alot of people use

Posted: Thu Jul 03, 2008 12:15 pm
by goose_man
I'm currently using distilled water and baking soda, though I'm not using/measuring any specific concentration. Does anyone know the ideal concentration to use?

-goose_man

Posted: Thu Jul 03, 2008 12:16 pm
by brother361
i know 1 guy was using 1tablespoon to 1 gallon of water

Posted: Thu Jul 03, 2008 12:48 pm
by goose_man
brother361 wrote:i believe you could use the realy big flashlight batteries in parrell that might work im not sure how much they are but you could try
I have. I used three of them, but the output wasn't enough. I have an old cell phone charger thing that plugs into the wall socket and outputs 5.0 volts at 0.7 amps. Would this be safe to use? Could it cause a problem in my house?

-goose_man

Posted: Thu Jul 03, 2008 12:53 pm
by brother361
id imagine itd be safe but i realy dont know about it lol
some1else on here might be able to help you with that more then me

Posted: Thu Jul 03, 2008 1:21 pm
by goose_man
Okay, after consulting a friend, I tried the cell phone charger and I couldn't even see gas production. Very disapointing. I probably need a computer power supply. Any ideas on the wattage I should use?

-goose_man

Posted: Thu Jul 03, 2008 2:47 pm
by TurboSuper
A standard 3-prong mains outlet in a house can source 15A at 120VAC. At a low voltage, you could have well over 30 Amps, so no biggie there. The cell phone charger can't source nearly enough current for what you're trying to do.

Even a 250W power supply will be able to source enough current, since you're only using a single rail. If you want to get even simpler, just build a power supply out of a transformer, diodes, and a couple of capacitors. I'm pretty sure an electrolysis machine won't mind if the power has a slight ripple.

Oddly enough, I see full 500W power supplies that are cheaper than a single power transformer :roll:

Posted: Thu Jul 03, 2008 3:07 pm
by jimmy101
Electrolysis is pretty basic process. Do some reading on the web, all of this stuff has been written up a zillion times.

A few highlights;

1. You only need a couple volts. More volts doesn't help, in fact it hurts the process.

2. The current pushed through the cell controls the rate of gas generation. The more current the faster gas is generated.

3. The higher the salt (generic chemical term, not table salt) concentration the more current the cell will carry and the faster gas is generated. Generally, if you want very high current you use very high salt concentrations. A tablespoon per gallon is basically nothing. Try a 10% solution (300~400 grams salt / gallon water).

4. Various salts are used. Table salt (NaCl) is not good since it generates chlorine gas which is toxic. It does not generate any sodium metal since Na metal reacts instantly with water to create hydrogen. Indeed, hydrogen is formed at the electrode, not Na metal. Bicarbonate is often used and is cheap, available and non-toxic. Google for various other possibilities.

5. Current through the cell depends on the distance between the electrodes. You want them as close together as you can get them. Usually, there is a practical limit to how close they can be. Bubbles get stuck between the electrodes which stops the reaction.

6. Current through the cell depends on the surface area of the electrodes. You want as much area as you can possible get. Usually that means the electrodes are plates, not wires.

EDIT:
7. As a starting point figure you need at least a couple amps through the cell. Typical wall warts are only a couple hundred milliamps (if that much) so they are too wimpy. Figure you need at least 5~10 AMPS for a decent cell. A brand new AA battery will source nearly 10 AMPS for a very short period before it goes dead. A car battery charger is a possibility. It'll probably do at least a few tens of amps. Only problem is it's ~13.6V which is too high. To get the voltage down to where you want it you can just wire several electrolysis cells in series and let the cells do the voltage dropping.

8. Tens of amps at ~13V will knock you on your ass. The 120VAC power to a car battery charger will kill you.

9. Salt water + electronics don't play well togther.

Posted: Thu Jul 03, 2008 5:01 pm
by brother361
i just made a very simple one and the cell phone charger and it worked very well for what i thought

Posted: Thu Jul 03, 2008 6:53 pm
by goose_man
I just removed a 200 watt power supply from my old Gateway (Newton Power Supply NPS-200PB 88 A 200W). It says it can output 18 amps at 5 volts, so that should work. One problem - there is a lot of wires coming out of the power supply, and though I know a bit about electronics, I'm lost here (I don't really build / modify computers).

I would just chop some wires and use my voltmeter to find the wires I want through guess and check, but I don't think it can handle such a current. Any ideas?

-goose_man

Posted: Thu Jul 03, 2008 8:11 pm
by TurboSuper
Well, one thing you're going to realize, is that when you plug the power into the supply, it won't work!

There is a special pin that needs to be grounded on the large rectangular connector in order to start the PSU, google for a pinout and you'll find it.

Computer power supplies have 12V, 5V, and 3.3V outputs. The 3.3V ones are on the large rectangular connector, 5V and 12V can be found on the 4-pin MOLEX connectors, amongst other places.

And I'm confused at what you mean when you say your "voltmeter can't handle such current". A voltmeter is in the realm of a few megaohms, so I strongly doubt a computer power supply will fry it, or 99% of power supplies out there, for that matter :P

Posted: Thu Jul 03, 2008 8:42 pm
by rp181
in addition to putting that wire to ground, you have to load the 5v line with a resistor. I didnt once, and 2 transistors blew up ( violently).

A volt meter in current mode is a pretty much a short circuit, your supposed to put it in series with a load, it can fry.

Posted: Thu Jul 03, 2008 9:03 pm
by daxspudder
For the electrolytic process to be effective, you have to use De-Ionized water, which also would have no NaCl content, but needs an electrolyte(for best breakdown of the gasses from water... Have a pic of a simple diagram, but its bmp and i dont feel like changing it...

Posted: Thu Jul 03, 2008 10:28 pm
by brplatz
http://www.techwarelabs.com/guides/misc_mod/psumod/

halfway down the page it shows where you need to connect the "special pin"

No resistors are need, i have done this many times at my workplace which is a computer repair shop :D

Posted: Fri Jul 04, 2008 2:06 am
by goose_man
On the advice of a friend, I cut all the wires and connected all of the red wires (+5V) together to a single red wire output. I then connected all of the black wires (ground) together to a single black wire output. He didn't mention a special pin, but would you agree that according to that website, I could just reattach the one green wire to ground?