I really need to learn how to build this circuit, but I don't undetrstand it! They said that it is supposed to be easily understood and even a beinginer could do it, but I really don't get it and was wondering if anyone could help me with it and give me better step-by-step directions? Please and thank you! or if you know where i can buy one, that is even better. I need to make one that can control the output of a car battery for a hydrogen engine for a science project. Thank you!
This is the diagram they give me for a control circuit.

http://keelynet.com/energy/waterfuela.htm

 

Don't feel bad about not understanding the circuit. It is part of a scam. We have had numerous people come here looking to get circuits like that one working, and all without success.

As a safety note - applying electricity to water will result in hydrolysis - the water will be broken into its oxygen and hydrogen components. Michael Faraday established how the process works back in 1820. The problem is that the junk that the scammers make available mix the gasses. The mixture is explosive and quite dangerous. Any spark can set it off.

The oxyhydrogen mix is also not healthy for an internal combustion engine to try to run on. Most setups only provide a small fraction of the fuel the engine needs, and so is negligible in the effect. But the mix is explosive, and will beat an engine to death in a short time.

This is not a good science project - the premise is based on fraudlent claims.