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Posts posted by slackjack

  1. Hey guys,

    I'm now wanting to interface circuits to the PC. Whether if its for data acquisition, control systems or just to light up a few LEDs or LCD display, it just comes down to interfacing. My question is what interface (port) should I use on the computer - serial port, parallel port or USB port? And can you please say why I should use that.

    --thank you  :)

  2. The 7447 is the BCD to 7 segment decoder. What you have to do is feed the output (binary) into the 7447. Consider the following:

    Here you can see four inputs - A,B,C,D (the input will of course be the output from your calculator. The outputs a - g, will go to the respective pins of your 7 seg display.
    This one 7 seg will be able to display 10 states (0 - 9) hence thats why we have 4 binary inputs (1111 base 2 is 9 base 10). Here is an example of the pin playout:


  3. Hi misha14,

    I think you indirectly answered what decoupling means. It used to block dc signals i.e. it prevents the mixture of the ac and dc signals. In order to do this we can use a capacitor, which btw has an infinite resistance for dc, therefore it blocks it and lets the ac signal through.

    It can be placed in series with the source (that needs amplifying) or at the output of each stage for a multi-stage amplifier.

  4. Thanks for the unlocker tool Kasamiko. But sad to say that it does not work, yes the rename feature of it does not work on my desktop.
    An error pops up saying "Cannot rename file: Cannot read from source file or disk".

    Logan, the reason for  it being renamed is becuase these are all file names reverved for the system. Trying any of these will also result in "New Folder".

    CON, AUX, COM1, COM2, COM3, COM4, LPT1, LPT2, LPT3, PRN, NUL  ;)

  5. Thats a neat little trick Ante. But it does not work on my desktop (from win explorer). It works for other folders and files that are not located on my desktop though. I know that it is trying to rename because I hear a beep that usually sounds when a user tries to do something that windows wont allow. One way I can solve my problem is by moving the folder or file in question to another part of my drive and rename it but this gets highly inconvenient. It seems that the permissions on my desktop are messed up, any idea on how to change this?


  6. Hi rigdoctor99  ;D

    I guess I forgot to mention that there is no rename option in the properties of the folder. In the attributes section of the folder, read-only seems to be automatically selected everytime I make a new folder. Unchecking it and applying the changes does nothing.

  7. Thanks for the input logan. I'm currently trying to make the transition from whatever theory I know to practical applications. But unfortunately its not going as smooth as I thought it would. Mayb I just need to work on a few more projects. I plan on doing this extensively during the summer vacation.


  8. I will be graduating in 2 yrs with a bachelors degree in computer engineering. I want to know whats the best way to prepare for the "real world". What should I start doing from now to best prepare myself for post-college jobs. I want to avoid receiving a blow in the face.

    Any advice would be great.

    --thank you  :)

  9. I plan on using comparators instead to indicate voltage levels. For now I experiment with 3 different voltages - 5V, 12V, and 25V. I plan on using the LM741 general purpose operational amplifer. I have a problem with this circuit though:

    V1 is used to represent the reference voltage (connected to the non inverting input). I set up a voltage divider so that each 741 has its own reference voltage. V2 is used to represent the output voltage from the power supply. V3 supplies +-Vcc to both comparators (and is also the voltage source for the LEDs). The forward voltage drop for the LED is 1.8V and activates at 2mA. I calculated that the current limiting resistors should be 3600 ohms.

    What did I forget to add to this circuit (or connected wrongly) because it does not work?


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