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Thread: PWM vs CCPWM

  1. #11
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    Quote Originally Posted by wikitjuggla View Post
    Can you tell me what the benefit of frequency control is? think i'm just gonna leave that part out, which frequency should i use, the 490hz pin or the 980hz pin?
    There is no benefit from dynamically controlling the frequency (as far as I can tell) and I'm not a believer of this "magic resonance" that some speak of, but there is plenty of benefit from dynamically controlling duty cycle. I use pin 3 with my Nano and this library https://code.google.com/p/arduino-pw...uency-library/.

    During initial install, you want to be able to adjust the frequency to the optimal setting for the reactor you have built. Size, shape, plate gap will partially determine what that final number is. I actually go about it in a course manor once the reactor is at normal operating temps (~95 - 100*F):

    1) From 1 Hz, make course frequency adjustments (1 KHz at a time) upwards until amp draw ceases to increase
    2) One a course number is defined, then move on to fine tuning (100 Hz decrements/increments)

    By doing this, I determined that the correct frequency for my reactor is approximately 16,500 Hz and I could probably continue to do more fine tuning. No magic here though

    Interesting side note:

    It seems that the larger the reactor plate dimensions, the lower the optimum pulsing frequency. The smaller the reactor plate dimensions, the higher the optimum pulsing frequency.
    Last edited by Stevo; 12-18-2013 at 07:34 PM. Reason: add note

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    I'm way too much of a noob at arduino for that kind of complexity. I'm still trying to figure out how to implement millis() into a sketch so I can use the same arduino that will be controlling my PWM to also control my headlights and make them turn on/off automatically and stay on for 2 minutes after I turn off the car at night

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    it looks like no one has explane to you wat you want
    the normal pwm was made to control electric motors, and this motors has the same amperes all the time. when you use it on a drycell you now that electrolize makes the water get hot, and hot water is more conductive, so you will have to make adjusts all the time if want to keep the AMPS at certain point. wit the ccpwm you donīt have this problem, you adjust to an AMP you want and if the water getīs hoter you will have all the time the same AMPs even if you raise the voltage.
    this is very important to new cars that donīt want big variation on the gas production because of the CPUīs they use.

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    Thank you for that answer. Well those ccpwm units cost about 70-150 plus, let's say 150-200 for a homemade dry cell unit. Does the gas money saved justify $350? Once the water has reached the temp you want it at, shouldn't the pwm amps level off? Probably not reasonable for short trips to the store but still would work for long trips
    Last edited by wikitjuggla; 01-12-2014 at 10:50 AM.

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    Is Arduinio really all that necessary for a basic, adjustable PWM? Surely you can make one with adjustable frequency & mark space (pulse width/duty cycle, whatever) with a simple 555 (or double 555 or 556) circuit & some powerful MOSFETs (or even old fashioned transistors, FETs, IGBTs or IGTs)??? It appears to me that using Arduino for a basic PWM is just making things unnecessarily complicated, but that's only my view of it. Not being well versed on Arduino I can only say it as I see it.

    I haven't got into Arduino yet myself as my workshop is more mechanical than electronics based. Until I get a bigger workshop I am stuck with the basic stuff (I'm not even printing my own PCBs yet, still using veroboard). I would be interested to know what the advantages are.

    I'm also interested in the difference between basic PWMs & Constant Current devices. I am thinking about making a large cell for my workshop to use with a blow torch & maybe a cutting torch. I plan to use my modern TIG/MMA welder which is an inverter based DC power supply with current variable from 10-150 amps. I'm guessing this is a constant current machine? (as MMA & TIG welding call for CC, whereas MIG welding needs constant voltage). I still don't know enough about the differences between these power supplies though, surely constant voltage would be useful in an HHO cell, to maintain the ultimate "volts per cell" figure?
    Last edited by nutgone; 01-18-2014 at 12:28 PM.

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    Simply stated a CCPWM automatically controls the duty cycle to maintain a given amp draw. As a reactor heats up the resistance of the electrolyte is lowered allowing more amps to flow if not controlled. A PWM requires you to adjust the duty cycle manually to maintain a given amp draw. The advantage of the CCPWM is you can set it and forget it. It is the best way to go if you are going to use a PWM at all.
    "Democracy is two wolves and a lamb deciding what to have for dinner. Liberty is a well-armed lamb."

    ONE Liter per minute per 10 amps which just isn't possible Ha Ha .

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    Thanks for clearing that up. Unfortunately my funds are very limited, so until the Chinese start producing CCPWMs for peanuts I'm stuck with the normal, old fashioned PWM.

    I guess, in use, you just set the old fashioned PWM to the amp draw you want when the cell is up to working temperature & leave it there. I don't envisage having to constantly make adjustments to it. Of course a CC device would be better & give you more constant cell output.

    Are there any circuit diagrams out there (not including Arduino) for CCPWMs using common (easy to obtain) components??? I have had a look but most CC supplies are or LED drivers, which require a fraction of the current we are after.

  8. #18
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    Quote Originally Posted by nutgone View Post
    Is Arduinio really all that necessary for a basic, adjustable PWM?
    Manual adjustment? No

    Constant Current? No

    Dynamic duty cycle/frequency control based external sensor input or OBD data from the computer? Yes


    Quote Originally Posted by nutgone View Post
    It appears to me that using Arduino for a basic PWM is just making things unnecessarily complicated, but that's only my view of it. Not being well versed on Arduino I can only say it as I see it.
    That depends on what you are trying to achieve. Was pretty simple for me and I am not a certified EE.

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