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New to circuit implementation help!

  1. Jan 29, 2007 #1
    To preface this: I decided to ask this over the internet where my reputation with my professors for not asking such stupid questions is not at stake :smile:

    Ok here is my issue: I have been charged with the task of using 5V logic to turn on/off a high power CMOS transistor, which will supply around 4.5A to a device (automotive application). I have my transistor, which is of TO-220 design and will do the things I wish, but my problem is that I have been using a breadboard for the 5V logic because it's cheap and easy, but obviously you can't pass 4.5A through a breadboard, so my question is what should I do to connect everything together?

    I understand this is a stupid question for someone who is charged with such a task, but I am trying to learn before I do something stupid. Can I simply walk down to a home improvement store, buy an appropriate insulated length of wire and some connection sockets, and connect a wire to one pin of my power transistor and the other end to my device's appropriate cable and have everything work? I tried to search for how to wire something with this much power involved, but I have had no luck. I am currently perusing howstuffworks. Please take pity on my soul, I have done entirely theory up to this point and am sorely lacking in practical implementation :cry:

    Ah and PS: This is for a side project while going to school so I could do a little learning on my own.
    Last edited by a moderator: Jan 29, 2007
  2. jcsd
  3. Jan 29, 2007 #2


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    Staff: Mentor

    You are correct that your plug-in breadboard has a maximum size AWG wire that it will handle -- probably something like 22AWG or so. For anything bigger, just solder up some flying wires to the components off of the breadboard.

    Is the TTL drive enough to turn on and off the CMOS transistor directly, or do you need another low-power discrete transistor in between? Either way, keep the high current conductors off the breadboard, and also be sure to calculate whether you need a heat sink for the CMOS power transistor.

    Not a stupid question at all, vsage.
  4. Jan 30, 2007 #3


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    Science Advisor
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    "Not a stupid question at all, vsage." And the hardware part is the real fun.
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