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Transister Array — Parallax Forums

Transister Array

ArchiverArchiver Posts: 46,084
edited 2003-07-22 20:02 in General Discussion
I got the ULN2803A Transistor Array chip to attach to the BS2 out pins. This is
reduce the current used from the BS2 to activate a couple of relays that need
more than the 40mA max driven from the stamp.
Question: Can I hook it up directly to the BS2 as I think it would act just like
a transistor to suppliment the extra power needed to trigger a relay? or is
there another method I should use, like resistors or caps...
Anyone has used this, before I fry my BS2.... thanks a million....


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[noparse][[/noparse]Non-text portions of this message have been removed]

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 17:14
    You definitely need a series resistor between
    the BS2 pin and the Darlington base pin.

    The Darlington means the BS2 doesn't have
    to provide much current -- but you'll still
    need the series resistor to limit the
    actual current out of the BS2. The
    Darlington does not limit current into its
    base, normally.

    You may need a protection diode
    across the relay coil (some come with it).

    --- In basicstamps@yahoogroups.com, BASIL MAKHOUL <basilflorida@y...>
    wrote:
    > I got the ULN2803A Transistor Array chip to attach to the BS2 out
    pins. This is reduce the current used from the BS2 to activate a
    couple of relays that need more than the 40mA max driven from the
    stamp.
    > Question: Can I hook it up directly to the BS2 as I think it would
    act just like a transistor to suppliment the extra power needed to
    trigger a relay? or is there another method I should use, like
    resistors or caps...
    > Anyone has used this, before I fry my BS2.... thanks a million....
    >
    >
    >
    > Do you Yahoo!?
    > SBC Yahoo! DSL - Now only $29.95 per month!
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 17:23
    You can connect directly as the ULN2803 includes a built-in base
    resistor (2.7k) that will limit the current between the Stamp pin and
    the input.

    Let me take this moment to remind everyone that it's very easy to find
    tech docs on common parts like this and it is always a good idea to
    download and review them before moving forward with your project. Just
    use your favorite search engine (I'm a big fan of Google) and you will
    likely get the information you need in moments instead of waiting for
    list members to respond.

    -- Jon Williams
    -- Parallax


    Original Message
    From: BASIL MAKHOUL [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=1Hk5WDEDrw2c1-P7uABIQ_aQ672AiYfzzXHnLhC9gOVOcPVAIo5Eboj2vfaPV3QERHtdJEz56f5_eDBsXGg]basilflorida@y...[/url
    Sent: Monday, July 21, 2003 10:09 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Transister Array


    I got the ULN2803A Transistor Array chip to attach to the BS2 out pins.
    This is reduce the current used from the BS2 to activate a couple of
    relays that need more than the 40mA max driven from the stamp.
    Question: Can I hook it up directly to the BS2 as I think it would act
    just like a transistor to suppliment the extra power needed to trigger a
    relay? or is there another method I should use, like resistors or
    caps...
    Anyone has used this, before I fry my BS2.... thanks a million....


    Do you Yahoo!?
    SBC Yahoo! DSL - Now only $29.95 per month!

    [noparse][[/noparse]Non-text portions of this message have been removed]


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  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 17:26
    DOH! Well, I'm embarrassed. My Bad.

    --- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
    wrote:
    > You can connect directly as the ULN2803 includes a built-in base
    > resistor (2.7k) that will limit the current between the Stamp pin
    and
    > the input.
    >
    > Let me take this moment to remind everyone that it's very easy to
    find
    > tech docs on common parts like this and it is always a good idea to
    > download and review them before moving forward with your project.
    Just
    > use your favorite search engine (I'm a big fan of Google) and you
    will
    > likely get the information you need in moments instead of waiting
    for
    > list members to respond.
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    Original Message
    > From: BASIL MAKHOUL [noparse][[/noparse]mailto:basilflorida@y...]
    > Sent: Monday, July 21, 2003 10:09 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] Transister Array
    >
    >
    > I got the ULN2803A Transistor Array chip to attach to the BS2 out
    pins.
    > This is reduce the current used from the BS2 to activate a couple of
    > relays that need more than the 40mA max driven from the stamp.
    > Question: Can I hook it up directly to the BS2 as I think it would
    act
    > just like a transistor to suppliment the extra power needed to
    trigger a
    > relay? or is there another method I should use, like resistors or
    > caps...
    > Anyone has used this, before I fry my BS2.... thanks a million....
    >
    >
    >
    > Do you Yahoo!?
    > SBC Yahoo! DSL - Now only $29.95 per month!
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > 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.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
    > This message has been scanned by WebShield. Please report SPAM to
    > abuse@p...
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 17:47
    Datasheets are your friend for sure.

    So when is the BS3 coming out [noparse]:)[/noparse]

    Rob


    Original Message
    From: "Jon Williams" <jwilliams@p...>
    To: <basicstamps@yahoogroups.com>
    Sent: Tuesday, July 22, 2003 12:23 PM
    Subject: RE: [noparse][[/noparse]basicstamps] Transister Array


    > You can connect directly as the ULN2803 includes a built-in base
    > resistor (2.7k) that will limit the current between the Stamp pin and
    > the input.
    >
    > Let me take this moment to remind everyone that it's very easy to find
    > tech docs on common parts like this and it is always a good idea to
    > download and review them before moving forward with your project. Just
    > use your favorite search engine (I'm a big fan of Google) and you will
    > likely get the information you need in moments instead of waiting for
    > list members to respond.
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    Original Message
    > From: BASIL MAKHOUL [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qVe7VhZ8D6v7XF88VWOb63s0-JA_4zsS1dZ4VnRRFShib1p4HHb8yUXQw6sP3D83hNfChb3Jqyyj8F0J8FNnIQ]basilflorida@y...[/url
    > Sent: Monday, July 21, 2003 10:09 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] Transister Array
    >
    >
    > I got the ULN2803A Transistor Array chip to attach to the BS2 out pins.
    > This is reduce the current used from the BS2 to activate a couple of
    > relays that need more than the 40mA max driven from the stamp.
    > Question: Can I hook it up directly to the BS2 as I think it would act
    > just like a transistor to suppliment the extra power needed to trigger a
    > relay? or is there another method I should use, like resistors or
    > caps...
    > Anyone has used this, before I fry my BS2.... thanks a million....
    >
    >
    >
    > Do you Yahoo!?
    > SBC Yahoo! DSL - Now only $29.95 per month!
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > 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.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
    > This message has been scanned by WebShield. Please report SPAM to
    > abuse@p....
    >
    >
    >
    >
    > 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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    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 18:48
    When it's ready! ;-)

    -- Jon Williams
    -- Parallax

    Original Message
    From: Robert Staph [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=fa_dAU9lavTgfh6qyyqlNhMyhZpyez7_t3sU0sVGpAKKsgsqTuTSnD_4L3tTgXPtqlYOQEU3P_q3hWBllw]rstaph@a...[/url
    Sent: Tuesday, July 22, 2003 11:48 AM
    To: basicstamps@yahoogroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] Transister Array


    Datasheets are your friend for sure.

    So when is the BS3 coming out [noparse]:)[/noparse]

    Rob


    Original Message
    From: "Jon Williams" <jwilliams@p...>
    To: <basicstamps@yahoogroups.com>
    Sent: Tuesday, July 22, 2003 12:23 PM
    Subject: RE: [noparse][[/noparse]basicstamps] Transister Array


    > You can connect directly as the ULN2803 includes a built-in base
    > resistor (2.7k) that will limit the current between the Stamp pin and
    > the input.
    >
    > Let me take this moment to remind everyone that it's very easy to find

    > tech docs on common parts like this and it is always a good idea to
    > download and review them before moving forward with your project.
    > Just use your favorite search engine (I'm a big fan of Google) and you

    > will likely get the information you need in moments instead of waiting

    > for list members to respond.
    >
    > -- Jon Williams
    > -- Parallax
    >
    >
    >
    Original Message
    > From: BASIL MAKHOUL [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=nY5TQS2ipZoHHuQV9UE-efF09u5WjQiolU0vXIx0OOdyE6aGUSlZFKqY1xWdwDqVU_2jnG5p-OCyIB4-BvNe]basilflorida@y...[/url
    > Sent: Monday, July 21, 2003 10:09 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] Transister Array
    >
    >
    > I got the ULN2803A Transistor Array chip to attach to the BS2 out
    > pins. This is reduce the current used from the BS2 to activate a
    > couple of relays that need more than the 40mA max driven from the
    > stamp.
    > Question: Can I hook it up directly to the BS2 as I think it would act
    > just like a transistor to suppliment the extra power needed to trigger
    a
    > relay? or is there another method I should use, like resistors or
    > caps...
    > Anyone has used this, before I fry my BS2.... thanks a million....
    >
    >
    >
    > Do you Yahoo!?
    > SBC Yahoo! DSL - Now only $29.95 per month!
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > 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.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
    > This message has been scanned by WebShield. Please report SPAM to
    > abuse@p....
    >
    >
    >
    >
    > 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.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
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  • ArchiverArchiver Posts: 46,084
    edited 2003-07-22 20:02
    > > Let me take this moment to remind everyone that it's very easy to find
    >
    > > tech docs on common parts like this and it is always a good idea to
    > > download and review them before moving forward with your project.
    > > Just use your favorite search engine (I'm a big fan of Google) and you
    >
    > > will likely get the information you need in moments instead of waiting
    >
    > > for list members to respond.
    > >
    > > -- Jon Williams
    > > -- Parallax

    Another excellent online resource for locating device datasheets is
    http://www.digikey.com
    Just enter the part # into the search box, locate and download the datasheet in
    .PDF format.

    Regards,

    -Bruce
    tech@r...
    http://www.rentron.com
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