HHO generator?

[psycix]

goose--get a wall socket and a diode. try not to kill yourself.
Starman--well, when there's salt in the water electrolysis seperates it into Sodium(OMG reactive metal) and chlorine(OMG poisonous gas)

Goose, just try to get an PSU from an old pc.

vovka, if you electrolyze liquid salt (no water involved) you get elemental sodium and chlorine gas. If you electrolyze water with salt in it, you get hydrogen and chlorine, but no elemental sodium! In fact, the sodium just stays as it is (Na+) and the Cl- gets replaced by OH-, result: a NaOH solution.
If you electrolyze water without salt but with baking soda or NaOH or some other non-reacting electrolyte, you will get hydrogen and oxygen, and thats what you want

[goose_man]

Okay, I hooked up my power supply (red wires = +5V output) and connected the green wire to ground. When I plug in the power supply, the fan on it moves slightly but does not spin. The voltmeter read around 5 volts then began to drop quickly, then continued to go down slower and slower. I'm lost so any suggestions would be great.

-goose_man

[jimmy101]

Most PC power supplies require a load on the outputs. Typically 10% or so of the rated output.

No load on the output = no output voltage, or at least, the output voltage is nowhere near the spec for the supply.

A cheap and simple load is just a 120V light bulb. Fiddle with the wattage rating of the bulb until the power supply's output voltage is stable. A 100 watt 120VAC bulb is a ~150 Ohm, 100 watt resistor.

You can also use high wattage, low resistance, power resistors but they are more expensive and much harder to get than a standard 120VAC light bulb + socket.

turbosuper said "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"
The problem is the "volt meter" generally means a meter that will read both voltage (volts) and current (amps). Many simple (cheap) voltmeters in the amp ranges will only handle an amp or less (good meters will handle tens of amps). Like someone said, to measure current the voltmeter is set to an amp range and wired in series with the circuit. It presents a very small resistance to the circuit, typically only a few ohms. A generic pc power supply will easily fry many typical "volt meters" in their current measuring mode. Heck, an AA battery may well fry a cheap "volt meter" in the current measurment mode. Fresh AA battery ~10 Amp, cheap meter current range ~0.25 Amp.

[psycix]

Most cheap "multimeter's" (volt meters only meter voltage!) can only measure up to 200mA.
When buying a new one, I made sure it handled like 20A if needed.

[TurboSuper]

Yeah, sorry, I thought by "voltmeter" he specifically meant one that measures voltage. I'm used to the multi-function ones being called "multimeters", or D(A)MMs for short.

[rp181]

Rewind a MOT (microwave oven transformer). Hack away the secondary, wind ~5-10 Turns of really thinck wire (thick as you can fit) and use it. It gives a couple hundred amps, people use it for spotwelders.

[goose_man]

I hooked up a 75 watt light bulb to the output of my power source, and the fan went on, although the bulb didn't light. When it stops raining I'm going to test my electrolysis machine with it.

-goose_man

[SNDM]

Oh dear, I spent an entire chemistry lesson breathing inb Chlorine, it was fun and I like the smell.

Oh dear.

Maybe I should have listened to my teacher, friends and the world on this one.

[jimmy101]

I hooked up a 75 watt light bulb to the output of my power source, and the fan went on, although the bulb didn't light. When it stops raining I'm going to test my electrolysis machine with it.

-goose_man

Sounds good. The light isn't lit up because the voltage is too low. You might be able to see a dim glow in the dark.

What does you VOM

(Volt Ohm Meter, the most common type of meter, usually also measures up to ~0.25Amp current, most new ones are digital and are usually called DVMs {digital volt meters} even though they also measure current, resistance, capacitance, time, diode drops, continuity...)

say the output voltage(s) are?

[goose_man]

After some more tests/tinkering with the power supply, I have come to the conclusion that it is not working properly. I am now using a Radio Shack plug-in transformer box that outputs 6 volts at 300mA (I had it lying around). It produces better output than the 6 volt batteries, but I definately still need even more power, so I might go check the store to see if anything catches my eye.

I will also be rebuilding the electrolysis machine. I went to the local welding supply store and asked for graphite rods. I now see that they are copper-coated, which presents a problem. Maybe I could use the center/core of a "lead pencil"?

-goose_man

[DYI]

Maybe I could use the center/core of a "lead pencil"?

Or you could just buy graphite rods...

Why not use a 12V lead-acid battery for the power supply, and wire 3 or 4 cells in series? Not particulary high tech, but it's worked for me.

We used 3" x 6" stainless steel plates for electrodes, and we got it to the point that the water was forming a thick froth and making an audible gurgling noise. This was with only one cell. We used sodium hydroxide at a concentration of about 10M for an electrolyte to avoid boiling the water with the several hundred amp output current of the battery.

Not very precise or well thought out, but it worked, so it can't be too hard.

[jimmy101]

DYI is correct, you can order graphite rods for pretty cheap from McMaster, part #7979A13, pack of ten 1/4" diameter by 12" long rods for $5.70.

Sheet metal actually works better than the carbon rods, the rods just have too small a surface area for decent gas production. With NaOH (from drain cleaner for example) as the electrolyte almost any grade of steel sheet can be used as the electrodes, even galvanized flashing used by roofers. The metal won't last forever (like the graphite will) but it should last longer than your interest in the electrolysis cell.

A couple electrolysis cells in series powered by a car battery charger (perhaps set to it's slow charge rate) works well.

Here's how I built a very small setup to show to grade schoolers.

Edit: One of the best home-brew electrolysis rigs I've seen is Dean's The page doesn't have many details since the author is worried about ssomeone killing themselves.

[psycix]

Remember not to use hot glue, since it may melt away when the cell heats up. I've had that and a strong NaOH solution covered my desk.

Also, I once used graphite rods out of Zinc-carbon batteries.
Note that almost any form of carbon rod might fk up since the bubbles generated in small cavities break them open and the pieces of the rod break off.