It is vitally important to get some form of amp meter. If you don't know what kind of power you are using, you will blow up your power supply every time. Brand doesn't really matter. You can spend as little as $20 for a good clamp on amp meter. Well worth it for testing.
For a power supply, I use a deep cycle marine battery with a 75 amp booster/charger. Since I design my HHO generators to only pull 20 amps, this combination works great.
In case you are not familiar with the concept... there are two ways to limit your current draw. 1) reduce the amount of electrolyte mixed with water. 2) use a PWM.
The first method is obviously the cheapest.
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Some days I get the sinking feeling that Orwell was an optimist!