Moisture detector

[WCE4]

Looking for a circuit that can detect moisture using one probe wire and ground as a return path with a sensitivity of 4k to 100k I have been playing with a 555 IC and using a Pic micro using PicBasic but having problem with the sensitivity. Any help would be appreciated

Thanks WCE4

[Chris Smith]

Under or over sensitive?<p>I found the 555 to be able to be set off at the wave of my hand, and tone down to any lower level.

[WCE4]

Chris Smith
Thanks for the reply.I am Having a under sensitive problem.

[Chris Smith]

Play with all your external components, "under" was never a problem? <p>Adjustable components, is best, and plug in caps will save on time. Its been 20 years but as I said, a wave of the hand near the two pins up to 18 inches away, worked quite well. Ill see if I still have the drawings? Morph between the touch sensor and the water sensor for best results.

[WCE4]

Chris <p>Maybe I am going about this the wrong way this how I have the circuit wired.

Pin 1 to Ground
Pin 2 to 6 with a 0.1 uf cap. going to ground
Pin 6 to a 150k res. to pin 3
Pin 6 to a 390 ohm res. to a 0.22 uf cap.to probe
Pin 8 to 4 to +5v dc
Pin 7 to a PIC16f84

[Chris Smith]

I sent you a "touch switch" which is how I did mine back then. Compare the two? <p>I'll look it up also.<p>Just looked and their different. <p>"Two" is the touch input. <p>Let me know if you got the email?<p>[ September 20, 2003: Message edited by: Chris Smith ]</p>

[WCE4]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Chris Smith:
I sent you a "touch switch" which is how I did mine back then. Compare the two? <p>I'll look it up also.<p>Just looked and their different. <p>"Two" is the touch input. <p>Let me know if you got the email?<p>[ September 20, 2003: Message edited by: Chris Smith ]<hr></blockquote><p>Thanks for the Dwg. I will need to try this circuit out the two things that may be a concern here is over sensitivity and the probe excitation, which I was told it, should be AC ?