#robotics Logs

Feb 23 2021

12:35 AM rue_mohr: -- feb 22
06:30 AM system123454321: Any suggestion for variable resistor (potentiometer) made from sht and stick that teenagers could build themselves during robotic class? Will be used for experiments with DC motor, and accuracy is irrelevant.
06:30 AM polprog: paperclip and a soft pencil trace on paper?
06:31 AM polprog: probably too much resistance for a DC motor, but it would make a nice voltage divider to show on a dmm
06:53 AM system123454321: I need that it stays after adjusted.
06:55 AM system123454321: But it give me idea to use lego for mechanical part, and pencil trace for conductivity part. Going to try it.
08:56 AM polprog: not a bad idea
08:56 AM polprog: ive made a nice mechanical pushbutton with lego, click pen spring and some aluminum foil
09:20 AM rue_mohr: the answer is that a wound wire pot is good for motor level power
09:20 AM rue_mohr: Nichrome wire is a good target
09:21 AM rue_mohr: I'd go for a linear pot, they can be made larger
09:21 AM rue_mohr: er, resistor
09:21 AM rue_mohr: hair dryers have good wire in them for that
09:22 AM rue_mohr: needs to be straightened
09:22 AM rue_mohr: but they also contain mica plates, which make a good base for a resistor
09:22 AM rue_mohr: fromer
09:26 AM rue_mohr: at some point this morning the cat came up on the bed and walked on me to ask if he could have space to curl up
09:27 AM rue_mohr: another less than 6 hr night
11:26 AM polprog: what did the cat say?
11:26 AM veverak: welp
11:26 AM veverak: finally got the "pos pid -> vel pid" thingy
12:55 PM system123454321: some pencil rods work, but none of them work when on paper :(
12:56 PM mrdata_: heh
12:57 PM mrdata_: i seem to hear, often enough, 'well it works on paper'
12:58 PM mrdata_: pencil traces, on paper, if you look closely, are not continuous
12:58 PM mrdata_: the paper is flexible, the graphite isnt
12:59 PM mrdata_: paper is not perfectly smooth
12:59 PM mrdata_: thicker lines might help
12:59 PM mrdata_: sandwiching the paper between a couple glass sheets might help
12:59 PM mrdata_: adding an electrolyte might help
01:00 PM system123454321: ikea pencils conduct too good for single, maybe 3-5 in sequence could provide enough resistance
01:00 PM mrdata_: but home made potentiometers are usually resistance wire
01:02 PM mrdata_: often, you have a counter-rotating pair of coils that cross over so they dont add inductance, and an electrode that you press against and slide along the coil
07:33 PM rue_mohr: <rue_mohr> the answer is that a wound wire pot is good for motor level power
07:33 PM rue_mohr: <rue_mohr> Nichrome wire is a good target
07:33 PM rue_mohr: <rue_mohr> I'd go for a linear pot, they can be made larger
07:33 PM rue_mohr: <rue_mohr> er, resistor
07:33 PM rue_mohr: <rue_mohr> hair dryers have good wire in them for that
07:33 PM rue_mohr: <rue_mohr> needs to be straightened
07:33 PM rue_mohr: <rue_mohr> but they also contain mica plates, which make a good base for a resistor
07:33 PM rue_mohr: <rue_mohr> fromer
09:52 PM rue_mohr: egrep nfsd_\(read\|write\) /sys/kernel/debug/tracing/available_events > /sys/kernel/debug/tracing/set_event
09:52 PM rue_mohr: Then send the READ from the client, and cat /sys/kernel/debug/tracing/trace_pipe on the server again?