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displaying data on seven segment displays

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nvinod_13

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icl7107 + themprature + lm35

hi
i've got to do a mini project titled "instrumentation amplifier and display device"
so i've decided on a block diagram which has
1)temperature sensor
2)instrumentation amplifier
3)a/d converter
4)seven segment display
i've decided to use a temperature sensor maybe kty10 or lm 35.

what do i actually place on it to measure the temperature?

i've designed an instrumentation amplifier.now i need to convert it to digital and display.but i dont know how to interface all these.even if i were to display somethin then it wud be a voltage value.how do i bring about a relation between the temperature sensed and the voltage reading.
also i dont understand a thing about using an led driver before connecting to on led display.i believe icl7107 does a/d conversion and has in built led drivers but there is a diagram in the data sheet which says that there needs to be a latch and a seven segment encoder before icl7101 is connected to the led display.

please help with any suggestions.
 

IanP

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display icl7101

Have a look at the picture below. It show "digital section" of the ICL7107. As you can see latches are already build-in. If your display can operate with segment sinking current of 8mA you don't need anything .. otherwise you will need to connect drivers, such as 7407 or similar ..

As far as the temperature sensor is concerned, the LM35 outputs 10mV/degree, so all what a pre-amplifier (in your case you will need to modify your instrumentation amplifier) shoud do is to "scale" the voltage from the LM35 in such a way that the input of the ICL7107 will "see" 0-200mV (in data sheet you can find input configuration of the ICL7107 for 200mV full scale) for, say, 0-200°C, what means that each mV --> 1°C ..
If you need 0.1°C resolution you can re-configure input of the ICL to 0-2000mV and re-scale the output from LM35 accordingly ..

Regards,
IanP
 

    nvinod_13

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nvinod_13

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temperature sensor with icl7107

tanks ianp
does that mean that i've to look for data sheets of seven segment display ic's which can support segment sinking current of 8ma?pl give me the link or the ic no if u come 2 know of it.n how do i have to modify the design of the instrumentation amplifier?
 

IanP

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icl7107+lm35

Small 7-segment LED common-anode display will comfortably run of 8mA and you can drive them directly from the ICL7107 pins ..
Here are some examples (they are rated for 10mA, but 8mA will be enough):
http://www.purdyelectronics.com/products/opto/ledredgreensegment.cfm

Assuming that the ICL7107 will be in its basic configuration (0 -200mV), the LM35 temperature sensor's output should divided by 10 using 2 resistors (voltage divider), or your instrumentation amplifier (if you have to use it) should have gain of 0.1 ..
Here is an interesting link with some useful tips on the LM35 temperature sensor:
http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Sensors/TempLM35.html

Regards,
IanP
 

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