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Using Mosfet to drive solenoid... — Parallax Forums

Using Mosfet to drive solenoid...

ArchiverArchiver Posts: 46,084
edited 2002-10-04 01:41 in General Discussion
Greetings,

I would like to know if anyone has experience using mosfets to drive
large current loads. What I would like to do is to use the logic
level output of the stamp to drive an optoisolator and then have the
output of the opto drive the gate of the mosfet.

The mosfet would then engage the solenoid on the starter motor of a
small gasoline engine. The mosfet is rated at 15 amps and typically
the solenoid draws only 2-3 amps. I would be using separate power
supplies as well, eliminating having to tie the grounds together.

I also would like to drive an electric clutch directly from the
mosfet. The clutch draws 7 amps and I would have thermal & fuse
protection in case of a stall. The clutch would be engaged sometimes
for up to an hour- will this reduce the life of the mosfet? I have
this problem worked out using mosfets to drive on board relays, but I
would like to go all solid state.

Thanks in advance,
Tim

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-10-03 16:23
    I know it's off the subject, but you mentioned an electric clutch. Where
    could I find an electric clutch for a gas engine? I have an upcoming
    project that may require one.

    Thanks,

    Rich
    Original Message
    From: ohiotim2 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xKMnuzBD7ymDPT63ONMrim2pVX_yrw5OVG9ZTV4ZUvipzPHaYeNdoJZzPXI1rcwnBDRSDjS8ZrnIElcqWI0]tweaver@i...[/url
    Sent: Thursday, October 03, 2002 9:06 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Using Mosfet to drive solenoid...

    Greetings,

    I would like to know if anyone has experience using mosfets to drive
    large current loads. What I would like to do is to use the logic
    level output of the stamp to drive an optoisolator and then have the
    output of the opto drive the gate of the mosfet.

    The mosfet would then engage the solenoid on the starter motor of a
    small gasoline engine. The mosfet is rated at 15 amps and typically
    the solenoid draws only 2-3 amps. I would be using separate power
    supplies as well, eliminating having to tie the grounds together.

    I also would like to drive an electric clutch directly from the
    mosfet. The clutch draws 7 amps and I would have thermal & fuse
    protection in case of a stall. The clutch would be engaged sometimes
    for up to an hour- will this reduce the life of the mosfet? I have
    this problem worked out using mosfets to drive on board relays, but I
    would like to go all solid state.

    Thanks in advance,
    Tim


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  • ArchiverArchiver Posts: 46,084
    edited 2002-10-03 17:36
    Tim, check out a IRL520n from digikey. You can drive this straight from the
    stamp. Handles about 9 amps.I use them a lot and they are good for driving 12
    volt loads from the stamp.
    http://www.irf.com/product-info/datasheets/data/irl520.pdf

    Original Message
    From: ohiotim2
    To: basicstamps@yahoogroups.com
    Sent: Thursday, October 03, 2002 7:06 AM
    Subject: [noparse][[/noparse]basicstamps] Using Mosfet to drive solenoid...


    Greetings,

    I would like to know if anyone has experience using mosfets to drive
    large current loads. What I would like to do is to use the logic
    level output of the stamp to drive an optoisolator and then have the
    output of the opto drive the gate of the mosfet.

    The mosfet would then engage the solenoid on the starter motor of a
    small gasoline engine. The mosfet is rated at 15 amps and typically
    the solenoid draws only 2-3 amps. I would be using separate power
    supplies as well, eliminating having to tie the grounds together.

    I also would like to drive an electric clutch directly from the
    mosfet. The clutch draws 7 amps and I would have thermal & fuse
    protection in case of a stall. The clutch would be engaged sometimes
    for up to an hour- will this reduce the life of the mosfet? I have
    this problem worked out using mosfets to drive on board relays, but I
    would like to go all solid state.

    Thanks in advance,
    Tim


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject and Body
    of the message will be ignored.


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    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-10-04 01:41
    Auto air conditioning compressors use electric
    clutches that handle similar power levels and
    duty cycles.

    rehards, Jack

    Richard Brull wrote:
    >
    > I know it's off the subject, but you mentioned an electric clutch. Where
    > could I find an electric clutch for a gas engine? I have an upcoming
    > project that may require one.
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