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Trying to find right transistors to use for a project...sal2

Discussion in 'Electronic Basics' started by Guest, May 27, 2005.

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  1. Guest

    Guest Guest

    Trying to find right transistors to use for a project...sal2

    Greetings, All

    I would like to switch on and off 4 of my 4mW pen lasers on and off (in various ways)
    using my usb 6008 DAQ device
    however I don't have enough current/voltage to power my 4mW pen lasers from my
    usb-6008 DAQ device. Here are some Specs that I've measured from my device.
    The digital outputs on the DAQ device produce:
    5V, and 1mA (they have a 4.7k ohm resistor I can't get to inside)

    What I would like to do is connect my 4 digital outputs from my DAQ device to
    4 transistors that would switch the power on and off from a 5V dc Power supply.

    I'm having issues trying to figure out which Transistors I need. Can anyone give
    a little assistance.

    Also if you have any other suggestions I'm open to that also. I'm allways
    willing to learn something new.

    Note:(DAQ) is short for Data Aquisition)

  2. Bob Monsen

    Bob Monsen Guest

    You can use any NPN transistor, like a 2N2222A, or a 2N4401. Use a 1k
    resistor, and connect it from the base lead of the NPN transistor to
    your DAQ output device. Attach the emitter lead of the NPN to ground,
    and the collector lead to the - terminal of the laser device. You can
    find the datasheet of the transistor you've obtained online, which will
    show you which leads are which.

    If the laser device is designed to run off of 2 1.5V AAA cells, then
    you'll need to limit the current a bit. Thus, use a resistor from the +
    lead of the laser device to the 5V supply. I don't know how much current
    it uses, so you'll have to play with the resistors to get it right. I'd
    start off with a 1k resistor, and if it's too dim, go to 470, 220, 100,
    47, 22, 10 until it is bright enough.

    Make sure the ground is connected to the ground coming out of the DAQ
    device. The output should have two leads, a + and a - lead. Connect the
    - to the ground of the 5V power supply.
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