My first post. I need help, guidance, direction. I want to build a PWM board for 12 or 24 volts DC at 50 amp's. adjustable from 20 to 30 khz. I have read some of the post but not find any thing that can handle the 50 amp's. I will be using it for electrolysis.

Thanks

George

 

Greetings! And welcome to AAC!

I've moved your post into its own thread, where it will draw more responses.

Please refrain from "hijacking" existing threads with tangent or off-topic questions. You can create new threads for new questions using the "New Thread" button on the upper left of the page.

Have you made a parametric search at the International Rectifier site? They have a number of devices that can handle that current.

This sounds like another hydroxy power idea - you might find this thread interesting: http://forum.allaboutcircuits.com/showthread.php?t=14695.

 

...And what is the 20 to 30 Khz about , what has do with anything ?

 

Electrolysis, a continuous process, is supposed to be somehow enhanced by applying a frequency that makes the water molecules come apart due to a resonance effect. Depending of which claim you read, the frequency is somewhere between 3 and 143,400 Hz.

The observed effect is: no current, no electrolysis. PWM just slows it down proportional to the off time.

 

I thank you for your help in moving my post. I did not mean any harm, I will be more careful where I place a post. I thank you for the thread also.

I did not want to get started on the foot. I look forward to learn or the guidance in what AAC has to offer.

Thanks Again
George

 

Hi George. Welcome to the Forums.

I was trying to help another fellow with a similar project in the other thread that Beenthere linked to. However, he really didn't want to switch from the LM324 opamp, so he's mighty limited in the frequency range that he can run.

Were you going to try finding a particular frequency? Or are you mainly interested in just regulating the current flow through your cell?

What kind of cell did you build or buy?

If it's the type that has alternating + and - plates in one container, you'll probably get somewhere between 1.5v to 2.3v or so drop across the cell using the 'brute force' or straight regulated current method. Without a switched inductor, using PWM will reduce your average current flow through the cell, but you'll also reduce the amount of gas generated. Without current, gas generation stops. With too much current, instead of generating more gas, you heat up the electrolyte solution.

 

I made my cell out of 12" sq. SS plates with 12" OD X 10"ID X 1/2" thick pvc plate. I wanted to isolated each water cell. I have 9 isolated water cells in the one unit. I have tabs on each plate so I can arrange each SS plate as +-+- or +N-N+N- or what ever works. I also am trying SS wool between each SS plate. I maybe way off but I'm trying different things to get the most production with the least amount of currant.

How would one control just the current?

Again thanks for the help.

George

 

I also am trying SS wool between each SS plate.

I am curios: what is your mechanism for preventing the wool from touching the plate? I've found wool to be ever so random and wandering.

 

In five cells I have thin sheets of Nylon woven mesh and in four I have polypropylene woven mesh.

I just trying different materials and ideas to make HHO.

Thanks Again
George

 

Are you trying to use less current than that predicted by the Faraday equations for hydrolysis?

Is there some rationale to expect a difference between nylon and polypropylene when used as separators in your hydrolysis cell?

John

 

HHO is cool/useful no doubt, but you aren't trying to improve fuel efficiency etc are you? I've seen alot of that lately, but its just a losing battle.. The process in 'intrinsically' inefficient.. You could get more work out of a battery directly than you can combusting the products..

 

By using nylon/poly insulators between the plates, it seems you're effectively decreasing the surface area of the plates. As gas flows out towards the top, the electrolyte rushing in from the bottom and sides will tend to pull your insulation layers tight against the plates due to venturi effect.

Frankly, the introduction of SS wool between two plates of different polarities capable of high current in an explosive atmosphere - scares me.

Take a SMALL piece of regular fine steel wool, put it on a fireproof surface such as a ceramic tile or brick, and apply a current across it. Notice how it bursts into flame.

Steel has about 10x the resistance of copper wire. SS has about 53x the resistance of copper wire. If your SS wool manages to make contact with both plates of opposing polarities, and the wool is not immersed in electrolyte, there will be a very loud "BANG" heard as the H2O2 ignites and blows your cell apart.

If the wool remains immersed in electrolyte during such a short, it will act as an electrolyte solution heater.

 

I'm not trying to break Faraday's equations just trying to be as efficient as possible. The two plastic's I'm testing witch one is more durable.

I had a PWM board from Jaycar that said it could handle 40 amp's. It lasted about 5 minutes. Should I be looking for a circuit to control just current?

Is there a simple circuit I can build to control current?

Thanks
George

 

I do'nt want to blow it up so I'll take the wool and plastic out. THANK YOU!

I know I am another one of them nuts trying to improve fuel efficiency with HHO. I have started it I want to finish it. What ever the results maybe.
Thanks for all of the input.

George

 

Nylon is less stable in many electrolytes than polypropylene. Scan down to the bottom of the list. Maybe that will help.

John