Finding Parts

Discussion in 'The Projects Forum' started by Sun1, Jul 16, 2011.

  1. Sun1

    Thread Starter New Member

    Jul 16, 2011
    Hello Everyone,

    I consider myself only a novice when it comes to electronics... I can dissect most consumer electronics and figure out how they work; however I am having issues getting over the learning curve when it comes to designing things.

    My scenario is simple: I am using pulse width modulation to control a 12V/2.5A motor from a transistor. The transistor will turn the motor on and off as well as adjust speed based on the pulse. I need it to be able to be controlled from my microcontroller(thus, 10ma on the base.)

    For the life of me though, I can not find out how to select a transistor. There are so many different variations.... none of which allow 2.5A to be controlled by 10ma. How do professionals go about designing circuits and picking parts?

    Thank you for your time.
  2. Wendy


    Mar 24, 2008
    If you're power supply is 12VDC you could use a MOSFET. They don't use current, they use voltage. The catch is you need a driver for the MOSFET, since it is like charging and discharging a large capacitance at the gate (think 0.1µF).

    LEDs, 555s, Flashers, and Light Chasers
    Chapter 10

    Not the most comprehensive source, but it will get you started.