CyberGene Yes, that is possible somehow but it would require additional electronics, maybe on-site ADC conversion and whatnot. Honestly I forgot about everything.
IIRC, you v2 idea was to get away from the potentiometers providing a reference voltage for the comparators and instead use a DAC to provide that value in a digital/programmable way. That will work in the same was as your current design, just that the "turning" can and does happen in software rather than with a screwdriver, and as such it can be programmed according to an automatic-to-execute logic rather than manual process.
CyberGene I've looked into a lot of sensors and solutions, especially other sensors by Vichay. Honestly, the dumbest reason I've selected the CNY70 was that it's bulky which meant it would work perfectly to create a L-shaped sensor board above the hammers
Yes, I remember one post in which you had not even settled yet for an optical sensor! In any case, thanks for explaining this part of your selection process.
vagfilm I maintain my suspicion (nothing more than a hunch...) that ADC-like continuous detection of hammer/key/damper position is an unnecessary level of detail that will only add latency and complex iterations to the code.
If you could have a perfect mechanics and a perfect electronics I'd agree with you. However that ADC level of details will tell you many things (especially in calibration, but not only) that a simple comparator would not. For example, if your comparator detects several triggers in a row, what does it mean? Player vibrating the key? Background flickering light? Electrical noise? Hard to tell. I would expect a few edge cases creating problems like the infamous NU1 "loud note". With an ADC you have the additional information which can help debug these edge cases, if you need to, and plus you could do the same thing as with a DAC (digital threshold selection, which is important e.g. for temperature drift compensation).
Regarding latency, I am not sure if you are talking about the latency of the ADC conversion or the latency of the data analysis. I think both can be kept under control, especially if one uses the right parts (i.e. not the one with which I started this thread, which is obviously too slow).
vagfilm I would suggest that you think through your proposal of looking at the damper position. I
Yeah, I am calling "dampers" but the sensors will be simply looking at the keys. The actual damper action of this grand (and I believe of any grand) is too bulky and too heavy to install and stay within my desired size and weight of the instrument, so I am building a prototype "simulated damper" action which you'll learn about in a couple of weeks (spoiler alert: that "infinite pivot" message of mine is an important detail of this simulated damper action).
vagfilm can only serve as an annoying devil's advocate, and raise food for thought
That's useful and appreciated. In fact I was expecting you chiming in http://forum.pianoworld.com/ubbthreads.php/topics/3175226/sanding-hammers-weird-question.html (sorry guys had to go there, since there are no technicians here) -- also: thanks for this cool video, I had seen similar ones, but not this one
@Del Vento You need an assistant of some sort ……
Drew-r Be this as it may, you need an assistant
Are you offering again to be one? For a problem assembling the lyre, I need to flip the cabinet upside down (or disassemble too many things which might be better, but more time consuming and tedious). I was thinking of recruiting my daughter for that, but if you offer, I'll be happy to take you. Don't think that "online" will work though…
I have many, many other tasks that need to be done. Woodworking is almost complete (only a hinge remains to be finalized, and that nasty upside-down lyre business). I have other "mechanics" e.g. that simulated damper action (and more). And electronics e.g. going through the list I mentioned earlier in this post and see if there is one with programmable I2C address, and if so what is its sampling rate; then testing the two sensors I know are potential candidates and any third for that list; finding a similar list from other vendors…. And firmware. And software. And more. So if you are offering again to be my assistance, let me know what best interest you and you are good at doing, and I'll gladly recruit you again 😀 Many of these things are more "information" (i.e. trying X and see if it works as imagined or if problems arise), so unlike the "flipping the cabinet" can be easily done remotely.