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Floating Pin on Transformer Unused Center Tap

Discussion in 'General Electronics Discussion' started by edmundsj, Mar 25, 2015.

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  1. edmundsj

    edmundsj

    13
    1
    Feb 22, 2015
    Hello,

    So I am using transformer to step-up voltage in a very simple circuit. It's a met-23 22.4:1 step-down transformer and I have attached the datasheet below. However, I have no use for the center tap on the primary coil and I'm not sure where to put it. This part will be soldered onto a PCB soon, and I was wondering if I should clip the pin and leave it floating, ground it, or apply a certain voltage across it? I am using a 9V battery as the power source to step up the pulse voltages to around 250V+ when no load is attached. I'm somewhat uncertain what the function of the center tap is, and I don't know if grounding it or applying some other constant voltage would affect its performance. I have tested it with the center tap floating, and it worked as I wanted it to. Thank you.
     
  2. davenn

    davenn Moderator

    13,589
    1,872
    Sep 5, 2009
    I have deleted your pdf file, it really screwed up my browser and I'm not risking trying to open it again
    or risk other people also having problems

    give a link to the datasheet
    but if it's a normal centre-tapped secondary, just leave it disconnected ... don't ground or anything

    Dave
     
  3. edmundsj

    edmundsj

    13
    1
    Feb 22, 2015
  4. davenn

    davenn Moderator

    13,589
    1,872
    Sep 5, 2009
    WOWOWOW DO NOT PUT POWER ONTO IT !!!!

    That's an audio transformer NOT a power transformer
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    Lets start at the start and describe your whole project
    ALL the details any circuits you are working from etc :)

    Dave
     
  6. edmundsj

    edmundsj

    13
    1
    Feb 22, 2015
    Okay, here are the project details: I'm build a Functional Electrical Stimulation (FES) System to be used on healthy individuals studying the effect of distributing electrical stimulation on muscle fatigue. The design I currently have uses a MOSFET to switch a 9V battery through the transformer below, and steps up the voltage to about 250V+ without a load attached, and with a load that resembles human leg tissue (A 500K resistor in parallel with a 133pF capacitor). With the load attached, the voltage measured on the primary coil maxes out at about 150V or 70V depending on the mood of my circuit. The waveform sent through the transformer is an 80 microsecond pulse at a rate of anywhere from 5-30Hz. Hope that clears some stuff up. The reason I used an audio transformer is that my device was reverse-engineered from a commercial FES device, where they also used an audio transformer of similar characteristics. Hope this clears stuff up.
     
    Last edited: Mar 25, 2015
  7. davenn

    davenn Moderator

    13,589
    1,872
    Sep 5, 2009
    sorry, this is highly dangerous and threads like this are always locked for everyone's
    health and legal safety
    I suggest you find a mentor that can work beside you ( not via the net) and check everything you are doing

    regards
    Dave
     
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