GEO Phone

[Davey C Sr]

I chase Ghosts!!!! I'm looking for a kit or a simple idea, to make a geo phone! It measures vibrations,or movement! I would use it for tables and beds. To See if there really are moving.......... And body have any Ideas??? I know that they make a kit but are not selling it now...It ran around $29.00. So I will have to build one! I need any help possible.

 

[Sceadwian]

Come on over here, I'll turn you into a ghost so you don't have to look so hard for them =P
Sorry, I absolutely detest ghost hunters. However the curiosity about the physical world is a good thing. The most basic form of a geophone you could use is simply to clamp an electret mic module to the back end of a hollow single ended tube (like a cup) The air cavity inside the cup acts as a resonant chamber for low frequency noises which makes it easier for the mic to hear them.

 

[Davey C Sr]

I respect your opinion! I don't necessarily hunt them! I try to disprove them or debunk them! Sometimes you can't! Thank you for your input. Will this pick up movement say on a bed or table? There is a kit on market but have been unable to find it!

Thanks Again

 

[Sceadwian]

Coupling the microphone to a resonant cavity will help it pick up vibrations but you'll still need vibrations to detect. So it won't detect if the table/bed is levitated, but if a lateral force is applied that causes the legs to drag across the floor invariably some kind of acoustic signature will be left. Shield the microphone elements back with hot glue or embedding it in cork will help prevent it from picking up noises from the air so more of the signal you reieve is vibrations from the chamber. You can try different sizes/shapes of cups as well as each one is going to have a specific resonant frequency(s)

 

[Davey C Sr]

Thank You. I will give it a whirl! I wouldn't want to check a bed if it levitated.
I appreciate your responses!!!! Thanks again

 

[Externet]

There is a geophones chapter here :

INFILTEC: How to Build an Inexpensive Seismometer - make seismograph kit

 

[Davey C Sr]

This is great!!!!! I can use this real well !!!! I'm going to use your idea also. But I can make both and use both....
Thank You Again. And if you see Casper the friendly Ghost tell him "BOO" LOL
Thanks Again