I have another issue now. When I connected the 0-20V of a DC RPS, my output was stable and the values didn't change frequently. Now, I connected the output of the sensor to the display. When there is no output voltage, the value of the display keeps changing frequently. i.e 0.01, -0.01, 0.3 etc and this seems to be highly fluctuating. I am told that the quality of the components used in the meter is low. I checked the same output from the sensor using a multimeter. The value seems to be relatively stable. When the sensor is idle, the output voltage is 0.16V and when the output is maximum, the output is 5.01 V. I read the ICL7107 datasheet and I came to know that the ADC reacts to the reverse current from the LEDs and grounding the digital and the analog signals is necessary. I am going to try grounding the display's ground and my sensors ground to the body of the enclosure. Is there any suggestion you may have? Can I try adding a filter to the input? I cannot offer my customer a display which is unreliable. Your help is highly appreciated. Thanks in advance. Regards, Sairam >Message: 43 >Date: Fri, 4 Dec 2009 09:54:16 -0500 >From: "Richard Seriani" >Subject: Re: [EE] Problem with PM129B 31/2 Digital Panel meter >To: "Microcontroller discussion list - Public." >Message-ID: <3E3DEACB241E4D96A53BD819D9DBE84F@RICHARD> >Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original >Sairam, >Congratulations! >It is always a good feeling when we finally make something work the way we >want it to. >Keep learning. >Richard >Perpetual Student ----- Original Message ----- From: "Research Faraday" To: Sent: Friday, December 04, 2009 4:12 AM Subject: Re: [EE] Problem with PM129B 31/2 Digital Panel meter > Dear Mr. Richard Seriani, > I thank you for your help. The display is working. I > added an external voltage divider circuit. > > Thank you very much. > > > Sairam > > > Message: 25 > Date: Wed, 2 Dec 2009 08:00:23 -0500 > From: "Richard Seriani" > Subject: Re: [EE] Problem with PM129B 31/2 Digital Panel meter > To: "Microcontroller discussion list - Public." > Message-ID: <12FD431D95204F9CA91D6AE8B57633A7@RICHARD> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > "There is a variable resistor "105" available in the back side of the > display. I assumed it was meant for calibration of the display voltage and > I > tried adjusting it." > "Is there a possibility that the calibration is wrong. I noticed an > information in the website saying that if needed, we must add proper > voltage > dividers and decimal point wire jumper. I don't have an idea what they > meant > by this information." > > The second link you provided contains this information. No need to > "assume". > The fact that this is a 200mV full-scale display means that, if you want > to > measure voltages higer than that, you need a voltage divider. The chart in > the datasheet is pretty clear on the values you need. For 20V full-scale, > use an input voltage divider made up of a 100K resistor and a 9.9M > resistor. > Look at the relationship between those values and the relationship between > the 200mV and 20V full-scale you are trying to achieve. > > You may want to do a search on DC voltmeters so you can see how input > voltage selection is usually accomplished. That may help. > > Good luck. > > Richard > > > > > > ----- Original Message ----- > From: "Research Faraday" > To: > Sent: Wednesday, December 02, 2009 12:40 AM > Subject: [EE] Problem with PM129B 31/2 Digital Panel meter > > >> Dear All, >> I am trying to display my sensor's output voltage to the PM129B >> 31/2 Digit LED Digital Panel Meter. >> >> The display information is available at the following link: >> >> http://store.kysanelectronics.com/servlet/-strse-68458/PM129B/Detail >> >> The data sheet of the display is available at this link: >> >> http://www.circuitspecialists.com/images/PM-129A&Bspecs.pdf >> >> The display uses a ICL7107 IC which has A/D conversion and display >> utilities. >> http://www.intersil.com/data/fn/fn3082.pdf >> >> The problem I am facing is that I am not able to read the output voltage >> using the display. The voltage uses a 5V power supply. I have set the >> display's voltage range to be 0-20V. >> >> When I switch on the power supply to the display, it shows that "0.00". >> So, >> I concluded that the display is in good condition. >> >> Now, when I tried giving a 12V to the analog input pins, to test the >> display, it is displaying the character 1 and a dot. When I cut off the >> signal voltage, I see that the value indicated is gradually reducing to >> zero. I also noticed that it seems to decrease from some random higher >> value. For example, while decreasing, it shows values like this 16.36, >> 12.00 >> and so on until it shows zero. >> >> There is a variable resistor "105" available in the back side of the >> display. I assumed it was meant for calibration of the display voltage >> and >> I >> tried adjusting it. There were no changes and it was showing the same >> character 1 when I provided the input voltage. In order to double check >> this, I tried giving a signal using a 1.5V battery. It seems to show the >> same character 1. >> >> Is there a possibility that the calibration is wrong. I noticed an >> information in the website saying that if needed, we must add proper >> voltage >> dividers and decimal point wire jumper. I don't have an idea what they >> meant >> by this information. >> >> Any help in this regard, would be appreciated. >> >> Thanks in advance. >> >> Regards, >> 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