#garfield Logs

Oct 10 2022

07:22 AM aandrew: Rue_mohr: having some trouble understanding what you’re doing here: https://twitter.com/ruenahcmohr/status/1579411396076646400?s=21&t=qqjQnqdScA_aA1CwNyoqXw
01:27 PM rue_mohr: its a user interface, a cheap replacement for an optical encoder
01:27 PM rue_mohr: so
01:27 PM rue_mohr: the idea is that you want as much signal in both directions as you can get
01:28 PM rue_mohr: and you want to be free of electrical noise
01:28 PM rue_mohr: so,
01:28 PM rue_mohr: the motor leads sit between two adc channels, so that you can diff them to ditch noise
01:31 PM rue_mohr: and the resistors hold the two signals so that the average is 1/2 vref
07:22 PM aandrew: I understood the concept, interesting idea on the differentializing
07:22 PM aandrew: I thought there was maybe a neat trick being played with the four 1k resistors; I noticed the 1/2vref but wondered if the 10k to ADC1 from midpoint and 10k to ADC2 from midpoint was doing something unusual
09:16 PM rue_mohr: just to center up the signal, you want both adcs to hit limit at the same time
09:16 PM rue_mohr: my vref was 5V, so :)
10:36 PM rue_mohr: ok, so I had a buddy visit that I have not seen in ages, great to see him again. didn't get anything done tho
11:24 PM rue_mohr: https://whynot.fail/factory/making-pcbs-at-home-milling-the-first-layer/