How to make an emf Detector?

jpanhalt

Joined Jan 18, 2008
11,087
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upload_2016-10-22_18-36-26.png

Just get some colored heavy-weight paper, scissors,, and tape and glue. Connect it with a piece of string to your raspberry and then program the raspberry to flash an LED at irregular intervals. Alternatively, use Legos to make the detector. Same string will work with that too.

What do you really want to do and why? There are designs for very sensitive emf detectors, but the image in your link is probably not one.

John
 

Thread Starter

Deltafee

Joined May 22, 2015
35
Like this?
View attachment 114083

Just get some colored heavy-weight paper, scissors,, and tape and glue. Connect it with a piece of string to your raspberry and then program the raspberry to flash an LED at irregular intervals. Alternatively, use Legos to make the detector. Same string will work with that too.

What do you really want to do and why? There are designs for very sensitive emf detectors, but the image in your link is probably not one.

John
Thank you for that information but I was more talking about what DickCapples pointed to, I am looking not for ghost but emf leaks in a lab and instead of just buying a detector I wanted to learn how it works and build my own.

DickCappels, I am looking at the schematic and I have a NTE457 will this be okay to use instead of the 2N4117, they're datasheets appear to be similar.
here is the datasheet of the NTE457 http://www.farnell.com/datasheets/1924947.pdf?_ga=1.17465018.2015964549.1469828170 and the datasheet of the 2N4117 http://www.mouser.com/ds/2/676/InterFET_2N4117_19A r01 (2)-752976.pdf.

Also do I really need the neon lamp? Is the antenna connected to the 1 M ohm resistor in series with the jfet?
 

DickCappels

Joined Aug 21, 2008
10,152
It is very likely that the circuit will work just fine with nearly any N-Channel JFET, and given that there are no performance specifications, we can be assured that operation will not be out of spec :)

There are many detector circuits out there and there is a chance that there better circuits for your purpose.

What kind of emf leaks?
• What would be making leaking signal?
• Frequeny(/ies)
• Field strength levels
• Electric, magnetic or elector-magnetic (radio)?
 
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