stan2004 posted:
So here we have what would happen in a typical engineering company back in the day. An engineering design review subjects the schematic to the peanut gallery (other engineers) who weigh in and must "sign off" before PCB layout.
The problem with using the 123 is the thresholds are not calibrated. This being in contrast to the comparator design showed earlier. In principle the 123 chip is specified to trigger anywhere between 1.35V and 3.15V … a fairly wide range. Within one chip, the two halves of the 123 will trigger at the same levels just from how the device is manufactured. But the thresholds can vary between two chips. This makes the 4 level detector (using two 123 chips) problematic and would probably not pass a design-review in a corporate environment. But we're talking hobby DIY so I'll grin and bear it.
Exactly why I went with a trimpot instead of a fixed R-div
