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Need help in designing switching/chopping circuit

Discussion in 'General Electronics Discussion' started by j37prakash, Jul 15, 2011.

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  1. j37prakash

    j37prakash

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    Jul 15, 2011
    I am in need of designing and constructing a switching / chopping circuit to switch a power supply of around 100V dc at the rate of about 250Hz and the Load is a purely Inductive load. The load is nothing but a buzzing coil to switch on and off reed switches at 250Hz frequency. The current through the coil will be around 3A. It currently runs on an old bulky transformer but the system must be replaced with a solid-state controller. Kindly suggest me if I should deploy SCRs, MOSFETs, or any other device. Please provide me your valuable suggestions and ideas or send me links to any such solutions or references. Thanks a lot in advance for your kind help.

    Regards,
    j37prakash
     
  2. daddles

    daddles

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    3
    Jun 10, 2011
    My first response would be to replace the reed switches with MOSFETs. But you need to communicate the present design by giving a schematic and include the relevant currents, voltages, and timing. Include information on any loads too.
     
  3. BobK

    BobK

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    1,686
    Jan 5, 2010
    3A at 100V to operate a reed switch?

    Bob
     
  4. j37prakash

    j37prakash

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    Jul 15, 2011
    No Bob, I want to buzz the reed switches soon after production so that the flexibility of the reeds and the operation speed of the switches decrease. This is necessary for making the reed switches more suitable for various complicated customer applications. I put around a 1000 switches inside the coil and operate them all more than 2 million times.
     
  5. j37prakash

    j37prakash

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    0
    Jul 15, 2011
    Dear Daddles, thanks for your response. I do not use the reed switch for switching, but I am making the design to buzz the reed switches after production. Please advise me if I should go in for Mosfets, SCRs or any other device ?
    Currently it is being done by passing a heavy pulsed current through the primary winding of a huge transformer whose secondary drives the coil. It obviously radiates a lot of heat and wears out easily. That's why I wanted to switch over to the solid state model.
     
  6. duke37

    duke37

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    768
    Jan 9, 2011
    An interesting problem!
    To get an idea of what is required, it would be necessary to know the inductance of the coil you wish to drive.
    Why does the transformer radiate a lot of heat and wear out? If it passes the same current when driven by solid state devices then it will get just as hot.
    Should the pulsed current be unipolar or bipolar?
    Can the design of the coil be improved by modifying the magnetic path so reducing the necessary current?
     
  7. BobK

    BobK

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    1,686
    Jan 5, 2010
    Okay, that was far from clear in the OP. Now it makes a lot more sense.

    Bob
     
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