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gayan77's Achievements


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  1. Thanks MP & Audioguru for your comments. I think I have to change the power supply design. I might use a DC adapter (close to 9V DC output), because 1 hour battery life probably not enough. Also note that this is not a permanent on circuit. It is only used to test a temperature sensor (which made up with LM20) and get the temperature reading. It take only takes less than 30 seconds for each. And also I preferred a portable device so i can test pre-installed sensors without a AC wall socket. But doesn't matter, i will use a DC power adapter. Now it is little bit easier to draw the PCB when i remove the battery from the enclosure. With the battery i only can have a PCB size of 60mm x 55mm. Without battery it is 87mm x 55mm. I'll post the finished PCB layout if someone interested in building this project. OK i already got some tantalum capacitors 0.22uf/35V and 0.47uf/35V, i hope i can use these. I'll use .47 before 7805 and .22 on the output side of the 7805. please correct me if I'm wrong. Thank you all again, Gayan
  2. Hi MP, I got good news for you. spending more than four hours yesterday i finally managed to get the temperature reading on the display. As you said i played with the trimmer until i get a closer temperature reading and also i added another trimmer to the input as well. because i wanted to input 1.864V to the IN HI pin of the ICL7107 IC. That is the voltage for 0.0
  3. Hi MP, Thank you so much for the reply and i learned a lot from you in this project. I went through the following links to get some understanding about the scaling. Both links relates to two projects that list under the project section. http://www.electronics-lab.com/projects/test/014/index.html http://www.electronics-lab.com/projects/test/007/index.html Now could you please correct me if i'm wrong again. (1) If the input to the pins 30 & 31 (IN HI, IN LO) is between 0V-2V then i select the 2V scale. if it is between 0V-20V then scale is 20V. I hope i'm right so far. (2) output voltage from temperature sensor is between 1.160V to 1.864V. so it means the input to the ICL7107 is less than 2V. In that case i select 2V scale, right? (3) Now i want to display 0.0 on the display when it reads 1.864V and display 60.0 when it reads 1.160V. What i confused about is you said i can not display 60.0 on the display if i selected the 2V scale right? but the input is still under 2V. Or are there two scales for display and the input? Could you please kindly explain me about this part again? Thank you Gayan
  4. Why is that some of the segments of led display brighter than other segments? is that because i don't have two capacitors around the voltage regulator? if i do need filter capacitors what are the best values. When i serched internet i found a schematic with 100n capacitors, will that be ok for this?
  5. Ok here is my full schematic including the power supply part. so far i got all this built on a temporary copper strip board. Please let me know whether that LM7805 needs filter capacitors. I am using a standard 9V battery for this circuit. Thanks again MP for your support on this and yesterday i read all the articles related to ICL7107 posted in this website. most of them were voltmeter projects. still i can not figure out how to display 30.0 when it is actually reading 1.515V. Do i have to do anything with the Vref? Thank you, Gayan Temp_Display.pdf
  6. Hi MP, Thank you for the hint. First i must say, i am at very beginning level of electronics, so please excuse me if i can not understand even simple stuff :-[. i am building this circuit for two reasons. one is to check temperature sensors that made up with LM20 semiconductor and the other reason is to read the temperature from the sensor. So as i said to get some understanding of the circuit i built the test circuit that was on the ICL7107 data sheet. Couple of modifications added which you can see in the attached schematic. The scale i selected was 2V. This circuit works very well and it display the output voltage from the LM20. But i want to see the actual temperature instead of the voltage. so i need help modifying this to display the temperature. lowest temperature I'm going to measure is 0 Temp_Display.pdf
  7. Hello everyone! I am in the middle of building a circuit to display the ambient temperature using ICs LM20 and ICL7107 (maxim). In last couple of weeks
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