Matt the Teckie Posted January 16, 2009 Share Posted January 16, 2009 Hi chaps, I've got an unusual question for you electical big-brains. I'm trying to evaluate the effectiveness for some hum cancelling equipment but I don't have a site that exhibits the problem. Does anyone know how we could artificially create a ground loop in a workshop environment? If not, does anyone have a site in the NorthWest (Preston or Manchester area) that suffers hum bars? Hope you can help. Matt Link to comment Share on other sites More sharing options...
james.wilson Posted January 16, 2009 Share Posted January 16, 2009 only way would be with fancy psu's id say and have the negs at different potential and link them via the camera coax braid. ie (using 12v example that would need to be ac and 230v etc) psu1 running at +20v for pos and +8v for neg psu2 running at 12v for pos and 0v for neg. that way 8v and a fair bit of current would flow down the coax. i think you need a real site.... i have a few down here is it helps lol securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
ian.cant Posted January 16, 2009 Share Posted January 16, 2009 Easy way is to stick a dvr in one bulding with a coaxial link to another on a seperate mains supply for a monitor. That should do it! Link to comment Share on other sites More sharing options...
james.wilson Posted January 16, 2009 Share Posted January 16, 2009 only if the earth it at different potential. securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
luggsey Posted January 16, 2009 Share Posted January 16, 2009 only if the earth it at different potential. You did mean the neutral? ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum Link to comment Share on other sites More sharing options...
james.wilson Posted January 16, 2009 Share Posted January 16, 2009 i didnt no. should i? i take it your talking about unbalanced phases and the star point moving relative to earth? i take it we are talking 'ground' loops here and not neutral loops? securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
breff Posted January 17, 2009 Share Posted January 17, 2009 What about earthing a camera with a badly installed earth rod? The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not) Link to comment Share on other sites More sharing options...
luggsey Posted January 17, 2009 Share Posted January 17, 2009 i didnt no. should i?i take it your talking about unbalanced phases and the star point moving relative to earth? i take it we are talking 'ground' loops here and not neutral loops? No, if two buildings earths are at different potential that in it's self won't make a 'ground loop' because the current should have no path to earth within the building unless there is a neutral earth fault. If the two buildings have different neutral potentials then (remember this is mains, ground is neutral here not earth) the neutrals difference in potential will set up the ground loop, current from one installation flowing through another is a ground loop. The fact that many buildings have neutral and earth bonded at the intake changes nothing, it is the potentials of the neutrals that could cause a problem on mains systems, potential differences between earths is a dangerous electrical fault, which is why no equipment with class one earth should be powered from a supply outside the equipotential zone it falls within. I hope that makes sense, gets a bit involved otherwise! ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum Link to comment Share on other sites More sharing options...
hpotter Posted January 17, 2009 Share Posted January 17, 2009 Its mains we're talking isnt it? Glad you cleared that up luggsey You can get a ground loop on a PCB (usually is if both anologue & digital chips on same board). Link to comment Share on other sites More sharing options...
luggsey Posted January 17, 2009 Share Posted January 17, 2009 Its mains we're talking isnt it? Glad you cleared that up luggsey You can get a ground loop on a PCB (usually is if both anologue & digital chips on same board). Why did you mention chips! Now I got the munchies... Dohhhh! ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum Link to comment Share on other sites More sharing options...
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