The PWM (Pulse Width Modulator) DC Motor Controller is used for controlling amperage. Usually found in golf cars and RC cars, etc., they can also be used as part of your HHO system. It will regulate how much voltage is applied to the fuel cell and therefore control the amount of Hydrogen (bubbles) produced
How PWM Controllers work
PWM or pulse width modulation controller of a power or signal involves modulation of its duty cycle that conveys information over a communication channel and controls the intensity of power sent to a load. PWM controllers use a square wave where the pulse width is modulated that result in the deviation of the standard value of the waveform.
A PWM controller includes a standard current mode PWM and a Standard voltage mode PWM. But the advanced PWM covers the most common and high-tech SMPS applications. New PWM controllers that are manufactured nowadays enable smaller and lower cost power supply that delivers high efficiency starting from standby to full loading mode and thus reduces switching losses and minimizes EMI emissions.