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How to use the MOSFET Power Board

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  • How to use the MOSFET Power Board



    Pins 1 and 2 are connected together, and need to be supplied with the same voltage as what you are switching. Pin #4 controls the MOSFET on the left when grounded, and pin #3 controls the MOSFET on the right when grounded.

    The Fusion Brain works with switched grounds. So when you connect the FB to the MOSFET board, connect the + side to the "bottom" pin and the - side to the "top" pin. The drains of the MOSFET are on the outside bottom 4 pins, and the sources are the middle two.

    For best operation, the sources should be tied to ground, (it needs to be the same ground as the Fusion Brain). Then your load gets power normally, and the ground of your load is connected to the drain pin on the MOSFET. So when the Fusion Brain turns on an output, the pin is grounded, and the MOSFET allows current to flow through the power source, to the load, to the MOSFET, and to ground completing the circuit and turning on the load.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  • #2
    Thanks for the info. I'm gathering bits for my HVAC and now I'm changing my mind again on blower control. If I understand this correctly, this board can PWM two motors independently? Can I steal a picture from your website and post here with mark-ups for the electron challenged?

    Comment


    • #3
      Yup, you can switch two loads fast and continuously like PWM with these boards.

      If you want to mark up a picture, go for it
      Fusion Brain Version 6 Released!
      1.9in x 2.9in -- 47mm x 73mm
      30 Digital Outputs -- Directly drive a relay
      15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
      Buy now in the MP3Car.com Store

      Comment


      • #4
        Possible Manual Section

        This is my best guess off the information here, hopefully 2k1Toaster will review it and give official approval or blacklist

        Designed for use in a larger collection (but def. needs aesthetic improvements! I'm open to suggestions/edits )

        EDIT: Oh, just remembered there's no technical data included!! Doh! Good to inform the user as to max voltage, amperage, etc. I'll be adding that in soon (but if there are/not errors it'd be nice to know, I *really* don't want to lead someone astray and break their hardware trying to be helpful...)

        EDIT 2: Started to add technical data, changed AC information, added (amateur) background

        EDIT 3: Removed background (just too much, both visually and for smooth scrolling), still need technical data (2k1? )
        Attached Files
        Last edited by UniqelyCommon; 02-10-2011, 03:42 AM. Reason: removed background

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        • #5
          Doing some research, do NOT use the MOSFET board for AC loads!!! Ignore that diagram!

          Comment


          • #6
            As a graphic designer and not a EE, diagrams and sample files are really really appreciated (hint-2k1).

            Thanks for posting this.

            GadgetBandit

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            • #7
              Originally posted by UniqelyCommon View Post
              Doing some research, do NOT use the MOSFET board for AC loads!!! Ignore that diagram!
              OUCH!

              Could be solved with larger Vds (only 100V), but I would argue to stay away from domestic/mains/wall AC etc - that get's way too litigious! (And you'll need Vds > 400V anyhow....)
              (Though I presume you have the right creep distances - eg for >400V etc???)

              It's better to have the FB or FETs control a mains/AC rated relay "wired in accordance with YOUR local laws & regulations...." with every required protective caveat you did & didn't think of....

              Better still....
              "WARNING: Not for AC use!" (Except LVAC where permitted...)

              Comment


              • #8
                "wired in accordance with YOUR local laws & regulations...."

                My granddad used to say "Just keep a fire extinguisher handy."

                GadgetBandit

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                • #9
                  Originally posted by GadgetBandit View Post
                  As a graphic designer and not a EE, diagrams and sample files are really really appreciated....
                  Thanks for posting this.
                  No problem, just compiling what little I know hopefully its correct
                  (For what its worth, as an EE/ME student and not a graphic designer, its hard for me to make pretty diagrams or backgrounds )

                  Originally posted by GadgetBandit View Post
                  My granddad used to say "Just keep a fire extinguisher handy."
                  Love it, going to use it!

                  Originally posted by OldSpark View Post
                  Could be solved with larger Vds (only 100V), but I would argue to stay away from domestic/mains/wall AC etc - that get's way too litigious! (And you'll need Vds > 400V anyhow....)
                  Yeah, but a pity as that's what I'm going for Now I'm looking at TRIACs and all sort of EE hoodwinkery that's (at best) a few semesters ahead of me

                  This thread seems to be the most promising of those I've found for dimming a 120VAC supply. Not designed for PWM though, sadly...
                  Last edited by UniqelyCommon; 02-10-2011, 05:22 AM. Reason: possible 120VAC solution?

                  Comment


                  • #10
                    Originally posted by GadgetBandit View Post
                    "wired in accordance with YOUR local laws & regulations...."
                    My granddad used to say "Just keep a fire extinguisher handy."
                    A fire extinguisher is usesless.
                    A spade is better - it both digs the hole to dump the torso, and can disperse any flame retardant.


                    Originally posted by UniqelyCommon View Post
                    This thread seems to be the most promising of those I've found for dimming a 120VAC supply. Not designed for PWM though, sadly...
                    The same opto-TRIAC (or two SCRs) circuit is used for phase control which is PWM (where "on" occurs after a phase delay and stays on until next zero crossing).
                    Or for less interference & depending on the load, it could remove full half-cylces - eg, for 1/120th dim; off for a full half cycle, on for the rest; or for 1/2 dim: on every 2nd full cycle etc (to balance +ve & -ve to avoid dc offsets).

                    Not that either of the above use uPC or PIC PWM functionality per se - it is usually easier calculating the required phase or cycles and turning the optocoupler on as appropriate.


                    Or use a suitably rated MOSFET or IGBT, but isolate with an optocoupler etc for safety's sake.

                    Comment


                    • #11
                      "It's like he's trying to speak to me, I know it. Look, you're really cute, but I can't understand what you're saying. Say the first thing again." -Marlin, Finding Nemo

                      Comment


                      • #12
                        The first bit is simple. It's not fire, it's fatal.
                        The danger is not smoke and flames, but the death of someone.
                        (Connect the FB to an AC supply and if somebody dies.... I don't think I need say more. But now that I have, FB have little choice....)


                        The second part explains methods of dimming AC circuits. Simple & ancient. Used for tungstens, fluoros, motors etc.
                        Seek and ye shall find.

                        Comment


                        • #13
                          Originally posted by OldSpark View Post
                          The same opto-TRIAC (or two SCRs) circuit is used for phase control which is PWM (where "on" occurs after a phase delay and stays on until next zero crossing)
                          Oh, I was thinking of controlled by PWM, my bad. Heh, helps to ask the right question, eh?

                          Comment


                          • #14
                            Well you'd use the same opto or equivalent for PWMing of AC...

                            But since once triggered, SCRs/TRIACs are ON until zero current (ie, zero crossing), it's not like you can turn them off as with PWM. FETs, IGBTs, transistors etc - yes, cool for PWM.


                            But SCR/TRIAC "phase control" is like PWM.
                            VIZ: A self regulating PWM circuit - eg, and SMPS. If the PWM triggered SCRs instead of FETs, the output voltage would swing higher than desired, hence the next trigger would be delayed to compensate.
                            That might not be a problem if hi-frequency, but SCRs etc are usually only suitable a few kHz (I think).


                            But as I wrote, despite PWM similarities, it's easier NOT using the Brain's or PIC's PWM output for such circuits.


                            I may have confused readers that weren't aware of the three distinct things I was discussing - using any output to control a 110-240VAC device (isolation is required); using an opto-coupler to isolate and control anything (SCR; MOSFET); using PWM to vary output... an SCR-controlled lamp is a form of PWM (look at its current) despite its controller emitting fixed-width pulses - ie, phase control where ON = phase (a short pulse from the controller) and OFF is the next zero-crossing.

                            But I did want to highlight that sometimes a dimmer etc does not require the PWM output....

                            Comment


                            • #15
                              question nick...

                              would i be able to use this in conjunction with my car's PCM to drive a Coil On Plug setup, using the PCM's ignition triggers to trigger the power board? car uses constant +12v, 2 switched grounds, which is exactly what your power board handles...

                              lemme know, if you jump on msn anytime soon that would be cool too...
                              Planning: [|||||||||-] 90%
                              Purchased: [|||||||||/] 99%
                              Installation: [|||||||||-] 90% (when is anyone's project ever REALLY done...)

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