I am attempting to create a high voltage signal when the voltage from a sensor I am using drops below a certain threshold, which will be between .05 and .1 Volts. I was trying to use an LM741 op amp to do this, but I could not get it to work as a comparator for these small voltages. Can anyone recommend a component or suggest a way to get an LM741 to work for comparing such small voltages?
Comparator: What is appropriate for comparing ranges of about 50-100 mVs? Can I use an LM741 op amp
comparatoroperational-amplifier
Best Answer
The allowable input voltage range for a 741 is 2 volts inside the power rails. This means that on a +/-15V supply, the inputs will still adequately function from -13V to +13V.
If you are trying to tempt performance from a 741 with a grounded negative rail then don't expect the inputs to function lower than 2V above ground and worst case 3V.
Let's look at a few other things too.
My advice is this - don't use it - pick a better device - even the LM324's inputs encompass the neg rail. My general purpose work-horse op-amp is the AD8605 because it's not at all like the 741 and comes in single, dual and quad packages.