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Setting off an EMF meter

MRC_Hans said:
Yes, you can connect a relay to buzz (disconnect itself). For someone like me, that would be the solution; I have plenty of relays lying about, and circuitry experience. However, for someone with no parts on stock and no soldering iron, something off the shelf is the thing.
And those buzzing relays tend to make quite a bit of acoustic noise too, which would sort of give away the whole thing.
Hans
ETA: If those things are triggered by dimmers, it is no wonder people find ghosts all over the place. :nope:
Click to expand...

We used them at work to test new products. They were known as "Clackers".
One of the collage interns did a engineering paper on them with spectrum tests.
They are in effect a low frequency spark-gap transmitter and generate a whole lot of interference and a whole lot of (audible) noise.

What budget EMF meters are available?
 
This gadget appears to be popular with "ghost hunters". It looks like it's basically an AC magnetic field detector with a quoted frequency response of 30- 20,000 Hz. It should respond to fields at the common power-line frequencies of 60 Hz (North America) and 50 Hz ( most of the rest of the world).

I would suggest a nice big flat coil, like the loop antennas sometimes found in old AM radio receivers but with a diameter of a couple of feet or so, connected to a transformer delivering 12 VAC or thereabouts ( a "filament transformer" as we old geeks used to call them) with a series resistor to limit the current to a safe value for the transformer secondary (say an amp or so). Hide the coil under the floor and use a remote like the BSR X-10 system to turn the power to the transformer on and off as desired.

It would probably be a good idea to get ahold of one of the meters to test and tweak your rig to goose up the woos reliably.
 
ktesibios said:
This gadget appears to be popular with "ghost hunters". It looks like it's basically an AC magnetic field detector with a quoted frequency response of 30- 20,000 Hz. It should respond to fields at the common power-line frequencies of 60 Hz (North America) and 50 Hz ( most of the rest of the world).
Click to expand...

Ahh, that primitive!

Then this-

I would suggest a nice big flat coil, like the loop antennas sometimes found in old AM radio receivers but with a diameter of a couple of feet or so, connected to a transformer delivering 12 VAC or thereabouts ( a "filament transformer" as we old geeks used to call them) with a series resistor to limit the current to a safe value for the transformer secondary (say an amp or so). Hide the coil under the floor and use a remote like the BSR X-10 system to turn the power to the transformer on and off as desired.
Click to expand...

Should work just nicely. For a bit more overtones, you could connect a diode in series with the coil.

It would probably be a good idea to get ahold of one of the meters to test and tweak your rig to goose up the woos reliably.
Click to expand...

Absolutely.

Hans
 
Why not just fake it completely? Get a cheap remote control toy and remove the power supply, receiver, and servos from the toy and put them in a box. Make the servos move a meter, or activate a motor to vibrate, or just use the non-servo remote switching circuits to turn lights or a buzzer on and off.

Or, tell the player that instead of an EMF meter, he or she has an innate psychic sensitivity to EMF. To simulate this, buy a remote controlled vibrator from a sex toy site, and tell the player to wear it in -- um -- an appropriate location. Use the remote when you want to make his or her "spidey sense" tingle.

ETA -- Oh, I missed a sentence in the OP. You've already acquired a real EMF meter so that's why you want to trigger it that way. Never mind.

Respectfully,
Myriad
 
Myriad said:
Why not just fake it completely? Get a cheap remote control toy and remove the power supply, receiver, and servos from the toy and put them in a box. Make the servos move a meter, or activate a motor to vibrate, or just use the non-servo remote switching circuits to turn lights or a buzzer on and off.

Or, tell the player that instead of an EMF meter, he or she has an innate psychic sensitivity to EMF. To simulate this, buy a remote controlled vibrator from a sex toy site, and tell the player to wear it in -- um -- an appropriate location. Use the remote when you want to make his or her "spidey sense" tingle.

ETA -- Oh, I missed a sentence in the OP. You've already acquired a real EMF meter so that's why you want to trigger it that way. Never mind.

Respectfully,
Myriad
Click to expand...
Still, Myriad's suggestion makes sense (as they usually do). Take the EMF meter, take out the electronics, insert the receiver from a radio controlled toy, connect the meter to the receiver output (have an engineer help you, if you can't do this yourself), and PRESTO! At the push of a button, you can have ghosts wherever and whenever you want.

Hans
 
Thanks chaps. Reminds me of a funny story - it was during the screening of a Most Haunted Live, and phil boy (a good mate) was on screen picking up an anomalous EMF reading. I immediately realised what it was - the fridge, every time the engine cut in - woot, woot. I managed to text him, and when he was next off camera he was immediately clued ina nd said "ah iot's the fridge!". He would have worked it out anyway, he was far from dumb - phil was always the one who paid attention to technical stuff. One of the hassles of being a mere researcher was I was often a hundred miles away from the events, and just watching them on TV like everyone else! :)

And thanks to everyone who gave suggestions. Our first game is May 22nd, I'll let you all know how it goes! :)

cj x
 
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