PHilgeman
That is how the rest of us do it. You can wrap a number of turns around the end of a pencil to go sniffing with. You will find that transformer's have two strongest radiating sides and emit two distinct peaks in a wave form, though you will need a scope to see them. You will also find that steel chassis have a "creep" zone down each fold in the metal. This creep zone can and will re-radiate the EMF, always right at your low level most sensitive circuit. Some kind of law.
In solution thoughts for your problem, know that EMF is infinite in reach and can only be steered by strongly permeable materials (nickel, mu metal), pushed to one side by impermeable materials (0.060 thick fully annealed CRS), contained within a box or excluded from another box. Otherwise it is everywhere all of the time.
I actually have calibrated coils I use for absolute strength numbers with a VTVM. A digital volt meter will give you some relative numbers and a small coil will allow close in sniffing. The pencil will keep you alive. Use a cheap meter and coated transformer coil wire.
Bud
That is how the rest of us do it. You can wrap a number of turns around the end of a pencil to go sniffing with. You will find that transformer's have two strongest radiating sides and emit two distinct peaks in a wave form, though you will need a scope to see them. You will also find that steel chassis have a "creep" zone down each fold in the metal. This creep zone can and will re-radiate the EMF, always right at your low level most sensitive circuit. Some kind of law.
In solution thoughts for your problem, know that EMF is infinite in reach and can only be steered by strongly permeable materials (nickel, mu metal), pushed to one side by impermeable materials (0.060 thick fully annealed CRS), contained within a box or excluded from another box. Otherwise it is everywhere all of the time.
I actually have calibrated coils I use for absolute strength numbers with a VTVM. A digital volt meter will give you some relative numbers and a small coil will allow close in sniffing. The pencil will keep you alive. Use a cheap meter and coated transformer coil wire.
Bud
got a busted 3.5" floppy? the head will read magnetic currents very nicely.
I bet if you search the Linear Technologies website you'll come up with a nice "sniffer"
ps -- you will also need a precision rectifier. here's one which appeared in EDN:
http://www.tech-diy.com/precision_rectifier.gif --
I bet if you search the Linear Technologies website you'll come up with a nice "sniffer"
ps -- you will also need a precision rectifier. here's one which appeared in EDN:
http://www.tech-diy.com/precision_rectifier.gif --
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