Hi,
I wanted to build a simple emf detector using an arduino, did some research and apparently it can be done using a wire as a probe and a 3M Ohm resistor. I'd like to make it as sensitive as possible and thought about using an amplifier but wasn't sure how to do this, does anybody have any advice? Or if you already know a circuit I could use could you direct me to the website or draw it for me please? Would be HUGELY appreciated 
Thank you
Using your favorite search engine, entering the words 'amplifier circuit diagram' will net you a whole lot of amplifier circut possibilities
Travers:
Hi,I wanted to build a simple emf detector using an arduino, did some research and apparently it can be done using a wire as a probe and a 3M Ohm resistor. I'd like to make it as sensitive as possible and thought about using an amplifier but wasn't sure how to do this, does anybody have any advice? Or if you already know a circuit I could use could you direct me to the website or draw it for me please? Would be HUGELY appreciated
Thank you
The longer your wire probe is, the more sensitive the detector is.
Paul
This may not be what you are looking for but...
During product development we would use a cheap** AM radio tuned off station at the low end of the scale (i.e. to any spot with no radio signal). We would use it like one might use a geiger counter. Ideally one should receive no "signal" from the device being tested.
** the cheaper the better.
BTW, I assume you were looking to measure noise (EMC, EMI). Technically EMF is "electromotive force" aka voltage.
JohnRob:
This may not be what you are looking for but...During product development we would use a cheap** AM radio tuned off station at the low end of the scale (i.e. to any spot with no radio signal). We would use it like one might use a geiger counter. Ideally one should receive no "signal" from the device being tested.
** the cheaper the better.
That only works if the EMF is fluctuating at a frequency around where ever the radio is tuned to. EMF is DC to light frequency.
Paul
That only works if the EMF is fluctuating at a frequency around where ever the radio is tuned to. EMF is DC to light frequency.
As it turns out pretty much all EMI sources have some sort of pulse of impulse waveshape. It is a good initial indicator of the level of EMI issues one is likely to find. At least for military and automotive requirements.
Again, I'm not sure this even applies to the OP's need / goal.
Also, I don't think anyone has related photon fluence (light) as an EMF.
This is why I say that there is no such thing as being too pedantic when it comes to electronics.
Travers, what frequency? Electric fields or magnetic fields? What is this for?
Are you attempting to measure electrical noise escaping/radiating from something you've built, or are you looking to DIY one of those EMF ie Electromagnetic Field Detectors favored by ghost hunters and people who think powerlines cause cancer?
Are you looking to build something that you can reasonably calibrate, or merely a qualitative measurement?
I think we are talking to ourselves, at least until the OP replies. I guess I have too much time on my hands.
Hi,
Thank you for your replies, Polymorph mentioned the EMF detectors favoured by ghost hunters, that's the kind of thing I'm looking into. Specifically something that could be calibrated to improve accuracy.
Travers:
Hi,
Thank you for your replies, Polymorph mentioned the EMF detectors favoured by ghost hunters, that's the kind of thing I'm looking into. Specifically something that could be calibrated to improve accuracy.
You cannot afford to have them calibrated.
Google for "field strength meter".
Paul
Thanks Paul, I'll start looking into the field strength meters
A field strength meter is something different, meant for electric field probing of RF fields, usually near a transmitting antenna.
Typically, a ghost hunter EMF meter is looking for low frequency magnetic fields. If also looking for electric fields, it will usually be much more sensitive than a garden variety Ham radio field strength meter.
You are usually just picking up powerline hum, anyway.