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My first "inclination" is to have separate return paths for Tx and Rx coils, i.e 2 ground returns. But as with all things having to do with EMI and grounding, it's 20% inspiration and 80% perspiration......
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i've been experimenting with a couple of HH versions and have been using the 'audio' grounding techniques that I was taught as a lad.
this doco ( fig 10.7 on page 3 ) has a drawing showing current flow and earth paths. you'll also need to find some info on shielding technuques to add to this knowledge.
my idea is that the coil is just like an extra component of the metal detector but it has a high level signal ( tx ) and a low level signal ( rx ) located at the end of a cable. and i treat the shield on the cable in the same way as i'd treat the electrostatic shield on a coil. my earth common point is as close to the detector electronics as is practical.Comment
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Originally posted by greybeard View Posti've been experimenting with a couple of HH versions and have been using the 'audio' grounding techniques that I was taught as a lad.
this doco ( fig 10.7 on page 3 ) has a drawing showing current flow and earth paths. you'll also need to find some info on shielding technuques to add to this knowledge.
my idea is that the coil is just like an extra component of the metal detector but it has a high level signal ( tx ) and a low level signal ( rx ) located at the end of a cable. and i treat the shield on the cable in the same way as i'd treat the electrostatic shield on a coil. my earth common point is as close to the detector electronics as is practical.
Thanks..
That seems to be my conclusion by arriving there the hard way.
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