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Wiring problem — Parallax Forums

Wiring problem

ArchiverArchiver Posts: 46,084
edited 2002-05-15 15:43 in General Discussion
I want the BS2 to trigger a DC12V application. At frist i thought
the answer was with relays but i later found i would have needed a
12V relay with a 1.8V pickup coil which i dont think exists.
However, i consulted one of my friends that knows a lot about
schematics and all that(hes 16 like me though so hes kind of an
unreliable source) and he said i should try using a resistor. He
explained to me that a resistor works just as a relay would. It is
triggered once it has attained a certain voltage going through it.
So, there would be a constant 12V supply going to the battery and
then when the BS2 triggers a pin to send voltage (1.8V i think) it
would take the 12V and add it to the 1.8V creating a voltage of 13.8
he said i should just by a transistor that would be trigger at
something like 13V...Is my friend correct? would this work? if not,
how can i make it work?

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-05-14 21:58
    This sounds wrong. First you need to define what level of current you want
    to control at 12vdc. Then when I know this I will design a ckt. schematic
    that will work for you. Skip

    Original Message
    From: compsci2522003 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ylOXswy9NZxBAkYi35T9iG3BJbzgbr_TD9Zass130JL7-Q_oNOfGc5M7PhueYzBTEsVk1V0RJgPDYp-_-XzStl0]waseemthedream@h...[/url
    Sent: Tuesday, May 14, 2002 1:23 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Wiring problem


    I want the BS2 to trigger a DC12V application. At frist i thought
    the answer was with relays but i later found i would have needed a
    12V relay with a 1.8V pickup coil which i dont think exists.
    However, i consulted one of my friends that knows a lot about
    schematics and all that(hes 16 like me though so hes kind of an
    unreliable source) and he said i should try using a resistor. He
    explained to me that a resistor works just as a relay would. It is
    triggered once it has attained a certain voltage going through it.
    So, there would be a constant 12V supply going to the battery and
    then when the BS2 triggers a pin to send voltage (1.8V i think) it
    would take the 12V and add it to the 1.8V creating a voltage of 13.8
    he said i should just by a transistor that would be trigger at
    something like 13V...Is my friend correct? would this work? if not,
    how can i make it work?


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  • ArchiverArchiver Posts: 46,084
    edited 2002-05-15 04:54
    in the original message i kept using the word resistor instead of
    transistor, how foolish of me. Perhaps, this post will make more
    sense now...And im still working on finding how many amps come out of
    12V car battery.
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-15 13:29
    It is not the voltage source that sets the current it is the resistance.
    Current is equal to the voltage divided by the resistance of the load.
    Example 12v / 12ohm load = 1amp of current. Skip

    Original Message
    From: compsci2522003 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Q2tqOlgTvDVNLWCasF5ti7GB2IjlvnDh4uiESrUTXuwisAwccd8fE0mAV5_-52Q35M5D1iPOPK0bHGwMQzyReaRBzRwJ]waseemthedream@h...[/url
    Sent: Tuesday, May 14, 2002 11:54 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: Wiring problem


    in the original message i kept using the word resistor instead of
    transistor, how foolish of me. Perhaps, this post will make more
    sense now...And im still working on finding how many amps come out of
    12V car battery.


    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/
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-15 14:28
    At 23:54 05/14/02, compsci2522003 wrote:
    >in the original message i kept using the word resistor instead of
    >transistor, how foolish of me. Perhaps, this post will make more
    >sense now...And im still working on finding how many amps come out of
    >12V car battery.

    The amount of current flowing from a car battery depends on the resistance
    of the circuit it flows through. It's governed by Ohm's law, I = E/R where
    I is current, E is voltage, and R is resistance.

    A car battery that is short circuited can deliver many hundreds of
    amps. Or, if connected properly to power your BS2 Basic Stamp will deliver
    perhaps 20 milliamps.

    It all depends on the resistance of the circuit.

    Jim H
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-15 15:43
    You might want to check out the Parallax web site, specifically the
    "Stamps In Class" section. They have provided all kinds of information
    about interfacing to the real world. Look especially at Industrial
    Control experiment #3. It has exactly what you need.

    http://www.stampsinclass.com/downloads/Ind Control/ic3.pdf


    --- In basicstamps@y..., "compsci2522003" <waseemthedream@h...> wrote:
    > I want the BS2 to trigger a DC12V application. At frist i thought
    > the answer was with relays but i later found i would have needed a
    > 12V relay with a 1.8V pickup coil which i dont think exists.
    > However, i consulted one of my friends that knows a lot about
    > schematics and all that(hes 16 like me though so hes kind of an
    > unreliable source) and he said i should try using a resistor. He
    > explained to me that a resistor works just as a relay would. It is
    > triggered once it has attained a certain voltage going through it.
    > So, there would be a constant 12V supply going to the battery and
    > then when the BS2 triggers a pin to send voltage (1.8V i think) it
    > would take the 12V and add it to the 1.8V creating a voltage of
    13.8
    > he said i should just by a transistor that would be trigger at
    > something like 13V...Is my friend correct? would this work? if not,
    > how can i make it work?
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