Hello Mr. Rusell, Thanks for the reply and offer of your help. Thats was kind of you. I have posted the webpage link in my previous mail. >>Have you looked at the signals with an oscilloscope? Yes I did. The signals were quite disturbed and I wasn't able to infer anything out of it. >>If you short circuit the probe connections at the connection to your circuit what does the display do? If I shortcircuit the probe, the display shows 0mV. >>If you arrange for a fixed known voltage into the PIV what happens? My display shows more or less the equivalent value of the known voltage. Sairam ________________________________ From: Russell McMahon To: Microcontroller discussion list - Public. Sent: Sat, March 20, 2010 6:18:06 PM Subject: Re: PIC ORP problem > I constructed a PIC ORP(Oxidation Reduction Potential) interface using the help of Mr.Marcel Du Champ from this list. I am facing a problem with signal noise. The LCD display is showing a value close to 200mV when I dip it in a solution of potential of 200mV (say 203 to 207mV). When I remove my probe out of the solution, I see that my display is indicating all possible values between 0 and 900mV before returning to 0mV. /> Have you looked at the signals with an oscilloscope? If you short cicruit the prpobe cvonnections at the probe does the display still read randomly? If you short circuit the probe connections at the connection to your circuit what does the display do? If you arrange for a fixed known voltage into the PIV what happens? What is the probe impedance / resistance? Do yuou have acapacitor connected across the probe terminals. Seeing your circuit would be REALLY useful. You need to keep any circuit ssent to well under 40 kB to be sure they dont get discarded. On a website as PDF / JPG / GIF / PNG / ... is usally better. If you have no website access, if you email it to me I will put it on a website for you. R I don't want my probe to pick up noises from the environment. It is also displaying some junk characters before returning to zero. How am I supposed to eliminate such erratic behavior? > > I am planning to actuate a relay using the displayed voltage. I am worried whether any devices would be actuated due to such erratic behavior. > > > Sairam > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist