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question about solenoids — Parallax Forums

question about solenoids

ArchiverArchiver Posts: 46,084
edited 2003-10-22 01:55 in General Discussion
i'm trying to control two 24vdc .250mA solenoids. i am using a
TIP120 transistor, but i was told that when the solenoids
deactivate they create a reverse spike and that i need to use a
"snubber" to deal with this problem. my question is where can i
get a snubber? any help is appreciated, thanks.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-10-21 20:08
    The snubber is simply a diode connected across the solenoid coil. The cathode
    to the positive supply side of the coil, anode to the negative side of the
    coil.

    Ken

    i'm trying to control two 24vdc .250mA solenoids. i am using a
    TIP120 transistor, but i was told that when the solenoids
    deactivate they create a reverse spike and that i need to use a
    "snubber" to deal with this problem. my question is where can i
    get a snubber? any help is appreciated, thanks.


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-21 20:27
    I hope this won't end up getting too far off topic, but just for my own
    knowledge, is that considered a snubber or simply a transient suppressor? I
    always thought that snubbers were specifically designed to limit the rise
    and fall time of a signal across a current sensitive component (like a
    triac) for protection.

    just curious,

    d...

    >
    Original Message
    > From: smartdim@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=hKawTeKF7s6uk7h-5cEhUY3ZvOYXz9dxZye19H6cBC5DsUHcQVw9rGFt91b42R7zP3UAB5F-]smartdim@a...[/url
    > Sent: Tuesday, October 21, 2003 12:08 PM
    > To: basicstamps@yahoogroups.com
    > Subject: Re: [noparse][[/noparse]basicstamps] question about solenoids
    >
    >
    > The snubber is simply a diode connected across the solenoid coil.
    > The cathode
    > to the positive supply side of the coil, anode to the negative
    > side of the
    > coil.
    >
    > Ken
    >
    >
    > i'm trying to control two 24vdc .250mA solenoids. i am using a
    > TIP120 transistor, but i was told that when the solenoids
    > deactivate they create a reverse spike and that i need to use a
    > "snubber" to deal with this problem. my question is where can i
    > get a snubber? any help is appreciated, thanks.
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
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  • ArchiverArchiver Posts: 46,084
    edited 2003-10-21 20:50
    Just transient protection.....

    see

    http://www.maxim-ic.com/appnotes.cfm/appnote_number/848


    I hope this won't end up getting too far off topic, but just for my own
    knowledge, is that considered a snubber or simply a transient suppressor? I
    always thought that snubbers were specifically designed to limit the rise
    and fall time of a signal across a current sensitive component (like a
    triac) for protection.

    just curious,

    d...


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-22 01:55
    --- In basicstamps@yahoogroups.com, "jsteff74" <jsteff74@y...> wrote:
    > i'm trying to control two 24vdc .250mA solenoids. i am using a
    > TIP120 transistor, but i was told that when the solenoids
    > deactivate they create a reverse spike and that i need to use a
    > "snubber" to deal with this problem. my question is where can i
    > get a snubber? any help is appreciated, thanks.

    Check out the data sheet for the TIP120, it has an internal diode
    just for what you describe.

    http://www.onsemi.com/pub/Collateral/TIP120-D.PDF

    bottom of page 3

    Dave
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