See.
Now Martin has never understood this the myriad times it's been explained before so I doubt he will this time but we are not concerned about what he understands here so much as we concerned with trying to prevent kingschiff from making a buying decision he may regret. Limiting discussion to the MW101 and MW102 let's start with the cost difference. $11. So you have to decide whether ATC is worth $11. To my way of thinking it is but ATC isn't, in this case, what the $11 is really buying you. It is a digital rather than an analogue meter. You cannot build an analogue meter with ATC. That's why the MW101 has three potentiometers. The user manually adjusts the gain and offsets of analogue amplifiers. The output of the amplifiers goes to a digital voltmeter. In the MW102 the amplifier is fixed. The gain and offset adjustments are done in a microcomputer which does them arithmetically based on the temperature it measures. The user is relieved of the necessity to record temperature, look up the buffer pH in the tables, adjust the temperature gain knob (which in this case of the MW101 has bizarre tic spacing) and adjust the slope and offset pots. In the digital implementation it's all done automatically. The buffer tables are stored in the instrument (MW102). You can do a cal with buffers at different temperatures and measure samples at a different temperature still. Not that we recommend that you do that and Martin will argue that if we use good practice the corrections are so small it doesn't matter and he is right about that. That's why I say that your additional $11 investment is justified more by the digital implementation than by the actual ATC.
Now there are those that will argue (mostly for the sake of argument I think as the question is, by now, pretty thoroughly settled) that digital designs are in no way superior to analogue and that you are wasting you $11 on components you don't need (I think I remember Martin advancing this argument at one point). These guys are happy listening to their AM radios and vinyl record collections. But if they are happy, then who are we to burst their bubbles? To decide for yourself whether analogue is superior to digital compare some other analogue pH meters to the digital ones. Remember that you can't buy a digital meter without ATC. The algorithm that computes the displayed pH (it's in the Sticky here on pH meter calibration) requires calibration coefficients. The meter needs to know temperature to calculate those. The problem you will have in making the suggested comparison is that other than $10 cheap Chinese knockoffs (don't be tempted by those though there are people who will argue that they are just as good as an MW102) you are going to be hard pressed to find an analogue pH meter today. Milwaukee has retained the MW101 and I guess people are still buying it or they wouldn't continue it but people who understand how pH meters work are not going to chose it when the marginal cost of the digital equivalent is only $11 more.
There are other manufacturers in the near $100 price range that make meters as good or better than the MW102. They are, of course, all digital and all, thus, have ATC. If you buy a modern meter you are getting ATC whether you appreciate its virtues or not!
Now Martin has never understood this the myriad times it's been explained before so I doubt he will this time but we are not concerned about what he understands here so much as we concerned with trying to prevent kingschiff from making a buying decision he may regret. Limiting discussion to the MW101 and MW102 let's start with the cost difference. $11. So you have to decide whether ATC is worth $11. To my way of thinking it is but ATC isn't, in this case, what the $11 is really buying you. It is a digital rather than an analogue meter. You cannot build an analogue meter with ATC. That's why the MW101 has three potentiometers. The user manually adjusts the gain and offsets of analogue amplifiers. The output of the amplifiers goes to a digital voltmeter. In the MW102 the amplifier is fixed. The gain and offset adjustments are done in a microcomputer which does them arithmetically based on the temperature it measures. The user is relieved of the necessity to record temperature, look up the buffer pH in the tables, adjust the temperature gain knob (which in this case of the MW101 has bizarre tic spacing) and adjust the slope and offset pots. In the digital implementation it's all done automatically. The buffer tables are stored in the instrument (MW102). You can do a cal with buffers at different temperatures and measure samples at a different temperature still. Not that we recommend that you do that and Martin will argue that if we use good practice the corrections are so small it doesn't matter and he is right about that. That's why I say that your additional $11 investment is justified more by the digital implementation than by the actual ATC.
Now there are those that will argue (mostly for the sake of argument I think as the question is, by now, pretty thoroughly settled) that digital designs are in no way superior to analogue and that you are wasting you $11 on components you don't need (I think I remember Martin advancing this argument at one point). These guys are happy listening to their AM radios and vinyl record collections. But if they are happy, then who are we to burst their bubbles? To decide for yourself whether analogue is superior to digital compare some other analogue pH meters to the digital ones. Remember that you can't buy a digital meter without ATC. The algorithm that computes the displayed pH (it's in the Sticky here on pH meter calibration) requires calibration coefficients. The meter needs to know temperature to calculate those. The problem you will have in making the suggested comparison is that other than $10 cheap Chinese knockoffs (don't be tempted by those though there are people who will argue that they are just as good as an MW102) you are going to be hard pressed to find an analogue pH meter today. Milwaukee has retained the MW101 and I guess people are still buying it or they wouldn't continue it but people who understand how pH meters work are not going to chose it when the marginal cost of the digital equivalent is only $11 more.
There are other manufacturers in the near $100 price range that make meters as good or better than the MW102. They are, of course, all digital and all, thus, have ATC. If you buy a modern meter you are getting ATC whether you appreciate its virtues or not!
