using an an isolator for stuff using the same power supply.

Discussion in 'General Electronics Chat' started by Gibson486, Mar 18, 2015.

  1. Gibson486

    Thread Starter Member

    Jul 20, 2012
    199
    12
    Would it be over kill to use a receiving isolator (such as for RS232...ADM3251) for devices that run on the same power supply? For example, if I have a computer, everything would be powered off the same supply. However, there would be different boards with in the computer and they need to talk to each other. One would simply think that you would just hook all the grounds together, however, what if there are multiple ground points with in each board. For RS232, you have the ground in the cable that connects to the motherboard, but you also have the ground on the same board that connects to the power supply. Would this potentially create a ground loop since some boards would have multiple paths to ground?

    Thanks!
     
  2. PlasmaT

    Member

    Feb 19, 2015
    40
    6
    Have you considered an optocoupler for this?
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    the grounds in pc's are all common. the only time the grounds may be not common with the motherboard is for boards that are internaly islolated input and output boards, which have their own isolation built in. like rs232 boards, which onoly isolate ground for noise problems.
     
  4. Gibson486

    Thread Starter Member

    Jul 20, 2012
    199
    12
    But what if we made another board in the PC that talks to it via serial? There are multiple paths to ground ... isn't this bad? I added a pic to hopefully clear things up.

    http://postimg.org/image/xarbpsreb/
     
  5. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,903
    2,155
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    and rs422 and o0ther internal serial communications does not refference ground anyway, it is two wire with each 180 degrees out of phase. differential pair serial is normally used to reduce noise and cross talk. anything coming into he board from outside should be isolated to reduce noise and possablility of static surges getting into the computer.
     
    Last edited: Mar 19, 2015
Loading...