earth tester

every body ! kindly ;show me the way that I can design my own earth
tester,I need to a circuit diagram.

 

** So you want an electronic soil analyser ?

These Google Groupies are such a hoot.




........... Phil

 

Test for what?

Continuity?
Static discharge safe limits?
Salinity?

RL

 

thanks . to measure soil resistivity.

 

thanks . to measure soil resistivity.

 

Perhaps the references on this page may be useful:
http://www.leminstruments.com/grounding_tutorial/html/start.shtml

 

How far down into the soil do you want to be able to see?

Do you want a profile or just a single value?

Is your local mains frequency 50Hz or 60Hz?


I'll assume 60Hz


(1) Make a good 30Hz square wave that is isolated from any other earthing.
This needs to be about 25V and able to output several amps.

(2) Make a synchronous detector circuit. Followed by a filter that cuts
off at about 0.5Hz.

(3) Sync the detector (2) to the generator (1) via an opto isolator.


(4) Drive large spikes (1cm Dia 20cm long) into the soil like this

ASCII Art:

---I--- ---V---
! ! ! !
V V V V
--------------------------------------
Soil


(5) Measure the voltage you get for some known current and apply a
"geometry factor" to get the resistivity.

 

Whether or not he's on earth. ;-)

 

Immunity to excessive heating?