What all do PWMs do?

[Tremorfalcon]

I know they adjust the frequency of the power being sent to the cell.
I know they can limit the amount of power going to the cell.
I know they help reduce heat because of the above two items.

However, I've seen things such as "a PWM with voltage stepping from 1kdc up to 20kvdc pulsed anywhere from 10khz to 45khz. "

Do PWMs also act like an ignition coil does and increase the voltage from a low 12volts to as high as 20kilovolts?

I'd like to know because the cell I am an designing is currently planned to use only 6 plates, due to having 12volts powering it. If a PWM could even up the voltage to 50Volts DC I'd be happy becuase then I could run as high as 20 plates instead of the lowly six. I am looking at an amp draw of 30 amps. So, would a PWM make it possible to up the voltage to at least 50 volts and still run as high as 30 amps?

[mytoyotasucks]

that would be a good idea, i was wondering that myself, cause my 2nd cell puts out .5 LPM at 12V and 18 Amps, but at 24V and 15 amps it puts out .65 LPM.

So i am looking at different V's to see what is better and make a PWM with a voltage jump, still testing more V's though.

[ridelong]

A pwm does not boost voltage in any way.

The pwm can only turn on and off like a switch. The more on time, the more average current. The more off time, the less average current.

The pwm can never draw more current than applying straight battery voltage, only less.

They are great for preventing overheating.

[Tremorfalcon]

When building a PWM you use a MOSFET transistor. You want it to be able to hold at least 30amps for hydrogen generator experimentation.

However I was wondering. Does the voltage rating of the transistor matter? A cars alternator puts out aroudn 14.5volts, so anything at least 15volts should be fine right? I dont need to get one of those crazy 400V rated ones?

[Tremorfalcon]

I plan on building this PWM
http://www.rmcybernetics.com/project...controller.htm

PWMs can adjust the frequency and can adjust the pulse width and they are also used for limiting the amount of amps to the device.

What part of this PWM actually limits the amps? The schematic uses a 10Amp transistor, however I want the PWM to limit the current to 30amps. How would I go about limiting the current to 30amps? Would I have to get a 30amp transistor? Or could I get a 50amp transistor and somehow adjust it to limit the amps to 30?

[Q-Hack!]

I plan on building this PWM
http://www.rmcybernetics.com/project...controller.htm

PWMs can adjust the frequency and can adjust the pulse width and they are also used for limiting the amount of amps to the device.

What part of this PWM actually limits the amps? The schematic uses a 10Amp transistor, however I want the PWM to limit the current to 30amps. How would I go about limiting the current to 30amps? Would I have to get a 30amp transistor? Or could I get a 50amp transistor and somehow adjust it to limit the amps to 30?

These are the most common type you see on the web. The LM555 timing chip sets up a frequency that is adjustable by VR1. This frequency is fed into the LM393 comparator chip which is used to turn on and off the IRF740 MOSFET. The MOSFET is what pulses the current fed to the generator. The more the MOSFET is turned on, the more current applied to the generator.