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Minimal build circuit help

Discussion in 'General Electronics Discussion' started by bodies, Mar 26, 2013.

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  1. bodies

    bodies

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    Mar 26, 2013
    Hi everyone,

    I am a network security engineer / pentester in South Carolina. I am trying to build an arduino project in a minimal form. The build calls for an atmega328 running with 16Mhz I don't see why this is necessary an would like to swap the atmega for an attiny85. I am a novice with electrical engineering having only gotten my arduino uno a few months ago and started messing with this stuff, I figured I would come here and ask for a more seasoned viewpoint. any advice would be great

    The article I am trying to replicate is available here: http://blog.spiderlabs.com/2012/10/pentesting-hotels-with-pens.html

    in the comments some users shared my same thoughts on the attiny minmal build but others had more questions on the schematics. could someone view the diagram at see if/what it will take to run on an attiny85 with a 6v a11 battery?
     
  2. bodies

    bodies

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    Mar 26, 2013
    I specifically would like some help understanding how the zener diode is relevant in its position on the schematic. I know they are used as a rough voltage regulator but is is even being used in its current position on the diagram? more importantly would it be necessary if i am using a 6v a11 battery as the power source?
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The zener diode clamps the supply voltage to 3.3V. It seems wasteful to use a 12V battery and a 3.3V zener.

    The zener also helps protect the device if the battery is inserted around he wrong way.

    Remember that a 6V battery may have a voltage higher than 6V when new (4 AA batteries will give you anything up to 6.8V when fresh.)

    The operating voltage for an ATMega328 extends only to 5.5V, so 6V is too high, and 6.8 is worse. You could probably get away with a 5V zener.

    There may be other reasons for a 3v3 Vcc though.
     
  4. bodies

    bodies

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    Mar 26, 2013
  5. BobK

    BobK

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    Jan 5, 2010
    I would suggest that you not try to use this to break into hotel rooms.

    Bob
     
  6. bodies

    bodies

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    Mar 26, 2013
    As I previously stated I work as a security analyst and pentester, this would be for work related use. I will be under contract with the building owner prior to ever using this tool or any of the other tools my company owns. I have only resorted to building this because none of our vendors have heard of or carry a similar item.
     
  7. BobK

    BobK

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    Jan 5, 2010
    Okay, I suppose. What is a pentester?

    Bob
     
  8. bodies

    bodies

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    Mar 26, 2013
    I click bunches of pens! haha! -jk

    Pentester is short for penetration tester, someone who is hired to test security systems. In my case I test network security (ex. firewalls, routers, servers, that sort of thing) and occasionally a client will require an onsite audit of their physical security as well as security policies and procedures, thus the need for physical entry devices such as lock picks and the device I am trying to build.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Bodies, just to make things clear, if you have trouble getting this to work, we're not going to help. I'm happy with generic power supply stuff, but at a high level (we're not going to hold your hand).

    I'm sure you understand.
     
  10. bodies

    bodies

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    Mar 26, 2013
    I don't expect to be spoon fed answers and schematics sorry if I have come off that way. but i did expect some help... as it is posted in the "circuit help" category.
     
    Last edited: Mar 27, 2013
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,418
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    Jan 21, 2010
    No, we'll generally spoon feed people, but not to build things that are morally, legally, or ethically dubious.
     
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