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Posts posted by slackjack

  1. Hey all,

    I just started my website using google pages. Its a collection of ebooks, video lectures, and projects that cover the areas of physics, math, electrical/electronic engineering. Do check it out: http://linuxfreak87.googlepages.com/ Its a great resource if youre a college student.

    --thank you.

  2. The trick is to have that transistor permanently either fully on, or fully off, so that its I x V is always near zero.

    So youre trying to minimize power dissipation. So now I must ask how would you choose whether to leave the transistor fully on or off?

    The design is more complex, of course. Does this interest you enough to have me draw one up, test it and post it?

    Yes, that would great.

  3. So, for these examples, choose a transistor that can handle 160mA, 1W.

    Is this parameter known as PDmax?

    The power disspipated by Q2 peaks about half way between fully off and fully on, when it has 6V across it.

    I dont really understand why this is so. Also why did you use half the max current?
  4. This all has little to do with voltage across the LEDs, and is more about controlling the current the through them.

    It makes sense now. Thanks for youre help  :)

    btw, I noticed that you used some dashed lines in the schematic (LED section). Does this mean that I can have as many LEDs without changing component values?
  5. Thanks for the replies guys. I've got another question about the circuit that Cabwood  drew. Can the circuit be made with only one transistor? Also why wont the LEDS come on just like that, I mean the way I see it the anode is currently more positive than the cathode - shouldnt this cause the LEDs to light up wihtout any variations in brightness?

    Set up a LED flasher that flashes the LEDs at 1000hz.

    Hey Theatronics , do you by any chance have an example that I can look at (that may also include the PWM circuit)?
  6. Hey Cabwood, thanks for youre reply. But you said that the voltage linearly drops across the collector of Q2, do we really need to have the transistor in there. Couldnt this be accomplised by just the charging and discharging action of the capacitor? Also I dont understand the need for a dralington pair.

    thanks again

  7. Hey all,

    I want to make an LED dimmer, that has about 5 LEDs hooked up to a 12VDC supply.  They should gradually  approach their (near) max brightness. But I want this to be done with user intervention. I just close the switch and the brightness increases (and also the opposite must happen when I open the switch). Can this be done by a capacitor whose charging time is controlled by a resistor? Please tell me the several ways of doing this.

    --thank you.

  8. I'll be using TubroC++ for my programs. Is it this project you are referring to Ante?

    Theatronics, thanks for the walkthrough, it very much appreciated. But I have decided to use the parallel port as a start becuase I have several books on it  ;D Do you have any tips on using the parallel port, mayb some experiments?

    thanks again guys.

  9. Career Opportunities
    Graduates of this program may begin their careers in a variety of entry-level positions in various fields involving electronics engineering technology and computer engineering technology such as technician, electronics technician, field service representative, salesperson and computer technician.

    To find out about more jobs opportunities with your degree, you can seek help from your guidance counselor at ITT Tech. It wont hurt to pay the department a visit before classes start and chat with someone.

    I was wondering what type of pay would I be looking at as starting pay?

    nanop  link:
  10. You can download electronics for dummies here:


    Check out our electronic resources section for links to tons of other books. We also have the The Art of Electronics which is very good.


  11. which software, what are you going to control or get data from, how many channels do you need, analogue or digital or both?

    Well for now I'm going to use windows xp (mayb later I'll worry about interfacing with linux). Ante can you please elaborate on "software". For now I plan to control, but later I will be using sensors hooked up to the computer. I dont understand what is meant by "channels". I guess (talking about the sensor part) ill measure some entity with analog signals then ill have to convert it to digital signals so the computer can understand it.  But before I jump that far ahead ill worry about the LEDs and LCD display  ;D

    The Voltages can be converted using a MAX232 chip (Digikey part Number:MAX232ACPE-ND)
    This allows you to deal with simple 5V single supply systems.

    This 5v you are talking about. Does it apply to the volatge from or to the serial port? What is the typical output volatge from the serial port or is it variable?

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