I would like to build a small project for hobby, and in this I will have to buy some instrumentation amp and op amp.
My question is there are million and million different op amps in the world, how do I choose the one that fits me, amongst all the products from all possible manufacturers please?
(like any website which is essential to browse which helps to narrow down the choices)
It all depends on your design and the final project. For example, you may want to amplify a signal that has a frequency around 1MHz, in this case you have to go for wideband Op-Amp. Another example, you may want to compare to signals to each other, in this case you need a comparator not an amplifier.
I mean, there are many design aspects you should concern while selecting the components.
If you give us more details about your project, may be we can help.
In my design, I will need an instrumentation amplifier to read a signal from a human being, I have seen some others design and they use amp like INA114, INA118 or INA333, so I dun know which one is better. I just need one with high CMRR, and seems like they all have this property.
So how should I choose? are there any better one in fact?
I have already read them, each of them only have a small variation to me, so in terms of Input Offset (+/-), Input Offset Drift(+/-) and Input Bias Current (+/-), how do I judge the performance of the component please? Is it the lower of these values, the better the component it is please?
Yes, the lower the parameters you mention, the better the performance. So, I think the INA333 if the best of these three. However, the best is not always available and cheap. In the end, it's a compromise.
If I do find something interesting it National Semiconductor and Analog Devices, the thing I have to do for choosing a device between these manufacturers, is it to compare their parametric?
Is it a good idea in general to have all the devices/components used on a board are manufactured by one single manufacturer? or mixing of let say TI and AD isn't really a matter?
Most major manufacturers have some kind of parametric selection tool on their websites for their own products but for comparison between brands you're usually on your own. Mixing brands on a board makes no difference.
For a small project, it sometimes makes sense to buy all your parts from one supplier to save on shipping but the good suppliers carry multiple brands.