Woah, slow your roll there a bit.... I'm simply responding to your comments about measuring inductance and capacitance.
From what you're saying now it sounds like there's way more to it than measuring capacitance.
How often would you expect to add more water? From the perspective of a layman I'd have thought that a signal generator could be adjusted to generate different frequencies, so unless the calculation of the required frequency is insanely complex it would seem like recalculating wouldn't be an enormous deal. But then I'm not an expert in these circuits, so maybe I'm way off the mark.
Measuring Capacitance, Inductance and Resistance is not a problem. As you mentioned earlier, these can be done with most cheap multi meters. Once you know these values, the formula for resonance in an RLC circuit is easy to calculate.
In normal RLC circuits, where the values for these are fixed, it is simple. You know the values, you use the formula to figure out resonance, and viola, you can create a resonant RLC circuit if you have a signal generator able to tune to the exact frequency that produces resonance for the circuit.
What makes this different is that the Capacitance is variable with the quality of water used, and the idea that (my guess here) when the electrons are torn off the water molecule and form HHO, the capacitance will change again(as water declines and gas is captured), requiring re-calibrating for resonance. This may take milliseconds, seconds, or longer. I simply don't know. If short periods, it's basically a waste of time, unless you have a circuit (different to the RLC circuit) measuring resonance in real time and adjusting the frequency in real time to keep it at the resonant frequency to keep producing gas on demand.
There are circuits available out there that claim to do all these things - the basic RLC circuit, and the frequency sweeper to adjust for the variables of the capacitance with change of water/change of capacitance due to water being extracted in the form of HHO and used. They are beyond my budget.
A signal generator that can produce sine, saw, square etc waves at various frequencies is within my budget, but it's still a piece of equipment I have to buy for basically one project, a project I have no personal experience works, and a waste of $$ unless I delve further into electronics as a hobby with other projects.