Grounding 12V help

Discussion in 'General Electronics Chat' started by TehDawg, Apr 18, 2011.

  1. TehDawg

    Thread Starter New Member

    Feb 4, 2011
    8
    0
    Good day forum!Sorry for spaming the site with basic questions, but I wanted some solid answers :D
    Im building a small project, running a motor with a 12VDC

    (http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0435942)

    Now the thing is that the supply only provides the input, but where must I ground my PCB & motor? Can i ground it to the case or a mounting screw? Where must i find my 0V without electrocuting myself or others?

    Thanks in advance !

    Regards

    TehDawg :p
     
  2. mbxs3

    Active Member

    Oct 14, 2009
    141
    3
    Your link doesn't work. Can you provide pics of the equipment you will be using? More pics will yield more information.
     
  3. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    You will have to give more detail of exactly what you are doing in order for anyone to provide good detailed advise. You say you want to run a motor with a 12 volt, A 12 volt battery or wall powered supply???
     
  4. TehDawg

    Thread Starter New Member

    Feb 4, 2011
    8
    0
    Weird, the link works my side. Go to "http://www.rs-components.com/index.html" and search the following:
    RS Stock No. 435-942
    PSU,ac/dc adaptor,90-264Vac I/P,single O/P,12Vdc.

    Its a wall powered supply, which goes through the above mentioned adaptor.
    The adaptor has a 2.1x5.5mm Center Positive Standard output connector. Im not familier with these connectors @all! Does that connector yield a ground aswell?

    Below is the link for the datasheet for the adaptor.
    http://docs-europe.electrocomponents.com/webdocs/0b16/0900766b80b162ee.pdf

    Please let me know if you need more information to help me out!

    Thanks a million for the replies and patience :StayatHomeElectronics & mbxs3!!

    Regards
     
  5. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    Since the power that is supplied to the device only uses two prongs, ie. hot and neutral, it does not provide a true ground. A center positive output connector will usually just be -v on the outside and +v on the inside or center, where the difference between -v and +v is your 12 volts.

    You can most likely ground the outside -v connection of the supply to a true ground, i.e. a grounded case, chassis of some sort. The +v should still read +12V with respect to -v.
     
  6. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    Normal convention puts the negative side of the power supply as ground but that is not firmly cast in stone. For example there might be a current sensing resistor in the negative side of a circuit. In that case ground might be on either side of that resistor. In the good old days some automobiles had a positive ground.

    What is "R 198.8" in terms of US dollars?
     
  7. TehDawg

    Thread Starter New Member

    Feb 4, 2011
    8
    0
  8. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    You will be fine if you connect the GND point on your circuit to the chassis ground provided that your 24 volt supply is isolated from the mains power through a transformer.
    You will not be fine if you use the 7812 voltage regulator as shown in the circuit and you use a 12 volt power supply. The regulator requires about 2 volts of headroom to work, therefor the supply voltage must be higher than 14 volts.
     
  9. TehDawg

    Thread Starter New Member

    Feb 4, 2011
    8
    0
    The supply will be provided directly from the adaptor mentioned in the previous posts. So it should be isolated inside with a transformer of sorts :D
     
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