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I'm new to electronics and I'm trying to design some circuits and blocks on my own.

I'm making a block to measure temperature in a range between 2ºC and 50ºC, by using the sensor LM35. I have set the circuit (which is pretty basic) in a Protoboard and it works. However, I'm wondering if there is any way to maximize the resolution (currently, I obtain a resolution of 0.1mV). I am using a ISO TECH IDM 203 multimeter (which is 3 3/4 digits).

I thought that this could be done with an amplifier. But my knowledge of amplifiers is not very good.

Is this feasible? And any idea on how to start to do it (or what OpAmp block should I use)?

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A x10 amplifier will give you 1mV/deg, a x100 will give 10mV/deg. The latter is better suited to the range of voltages you may want to read. The former will give you the decimal point in the right place if you are reading on a mV range.

The op-amp block that will be simplest to use for your application is a non-inverting op-amp. Search and there will be more than you can shake a stick at. For instance https://en.wikipedia.org/wiki/Operational_amplifier_applications#Non-inverting_amplifier

If you want to know which particular amplifier to use, then the choice is more down to what's available in your local supplier, than what's the perfect one to use.

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Google images are your friend: -

http://www.electro-tech-online.com/attachments/amp-jpg.34774/

The gain of the op-amp is 1+ R1/R2 so if you want a gain of 10 choose R1/R2 = 9. The op-amp needs to be good at working down to 0V (both inputs and outputs) maybe something like this: -

enter image description here

The circuit above has a gain of 5.022.

Regarding resolution the basic output from the LM35 is 10mV / degC so you can currently get a resolution of 0.1 degC with your setup. Given that the basic accuracy is only 1 degC for this part, having more gain doesn't give you more accuracy.

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