#garfield Logs

Apr 21 2020

12:00 AM rue_mohr: drat, I want to try that chopper amp too
02:06 AM polprog: oh yeah
02:07 AM zhanx: rue_mohr, up?
02:07 AM zhanx: sup polprog
02:07 AM polprog: lets make a pop quiz that starts when the class starts and ends when the class ends.. just what i need, you to tell me about maxwells eqns while i work out an impedance problem
02:07 AM polprog: not much
02:07 AM zhanx: gonna make an ANT bot with 24 9g servos for the legs and a pan tilt camera on it
02:08 AM zhanx: playing with openscad for the design
02:08 AM polprog: just having physics classes today
02:08 AM zhanx: i want it to be palm sized
02:08 AM polprog: sounds cool.. ill probably drill the adapters today
02:12 AM polprog: maybe i could throw the other PCB into a tinning bath
02:13 AM polprog: i have some tinning agent
02:14 AM zhanx: you mean flux?
02:14 AM polprog: no
02:14 AM zhanx: ?
02:14 AM polprog: sec.. let me find the safety datasheet
02:17 AM polprog: https://termopasty.pl/wp-content/uploads/2019/06/preparat-do-bezpradowego-cynowania-miedzi-2.jpg
02:19 AM polprog: tin (ii) chloride
02:19 AM polprog: nasty stuff
02:19 AM zhanx: i can read about 1/2 that, but enough to know i don't have it
02:19 AM polprog: "Stannous chloride"
02:21 AM polprog: https://www.fishersci.com/shop/msdsproxy?productName=AC196980025
02:21 AM polprog: i havent seen anyone do that so im curious how it works
03:24 AM polprog: rue_mohr: are we doing SCR/UJT oscillators again :v?
03:16 PM rue_mohr: its comming down
03:21 PM Tom_L: the roof?
03:41 PM rue_mohr: price on colour laser printers
04:34 PM polprog: the roof is on fire
04:34 PM polprog: https://twitter.com/polprogpl/status/1252711712698089472
05:06 PM aandrew: rue_mohr: kind of cheating, but UCC12050 or ISOW7841?
06:14 PM rue_shop1: I'v done it :/
06:14 PM rue_shop1: I'v made an opto isolator oscillator
06:14 PM rue_shop1: SO wrong...
06:16 PM rue_shop1: almost 6v p-p output from 12V!
06:39 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Cube/Cube_small.jpg
06:39 PM Tom_L: they just keep getting smaller
06:40 PM rue_mohr: oof
06:40 PM rue_mohr: the brass cuts nice.
06:40 PM Tom_L: yeah i like machining brass
06:41 PM rue_mohr: ok, well, hmm
06:41 PM Tom_L: soooo bored
06:41 PM rue_mohr: I didn't expect the opto-isolator osc to work
06:41 PM rue_mohr: little dazed now
06:41 PM Tom_L: i could probably go one smaller but i'm not
06:42 PM Tom_L: heh work on the first try?
06:43 PM rue_mohr: NOPE
06:43 PM aandrew: Tom_L: Im assuming you're milling the top face, manually selecting the next face "up" and continuing?
06:43 PM Tom_L: cnc but yes
06:43 PM rue_mohr: I tried a backup idea, and started to see some bumps, realized that it was operating as a phase delay osc and corrected the circuit
06:43 PM aandrew: yes, but CNC is 3 axis
06:43 PM rue_mohr: then added some voltage drop to make the output larger
06:43 PM aandrew: rue_mohr: nice
06:45 PM aandrew: oop looks like mouser didn't completely fuck me
06:45 PM rue_mohr: heh
06:45 PM aandrew: took them 24h to ship but I got tracking info just now (along with a digikey order i placed this afternoon)
06:45 PM rue_mohr: I had a really bad experience with them and never used them since
06:46 PM rue_mohr: dk cheats
06:46 PM aandrew: we'll see. both are fedex international coming from the US, mouser from TX and digikey from ND
06:46 PM Tom_L: huh, i've always had good luck with both of them
06:46 PM rue_mohr: they have a time machine that sends orders before their made
06:46 PM aandrew: I have historically had *shit* luck with mouser (extra paperwork holding up shipments, shipments that took weeks, etc.) but the last order was shipped in < 24h and this one in 24h
06:47 PM aandrew: but it's not here yet so we'll see
06:47 PM aandrew: I very very very very very rarely order from mouser because of their past performance
06:47 PM rue_mohr: ok, I have two more oscillators I wanted to try, and this opto one gave me a new idea
06:47 PM aandrew: what'd digikey ship time like for you way up where you are?
06:48 PM aandrew: I won't ask Tom_L, I know digikey shipping in the US is *awful*
06:48 PM rue_mohr: we have had next day
06:48 PM rue_mohr: which nobody can even do from vancouver
06:48 PM aandrew: I'm over 99% next day with digikey, have had maybe 3 orders in my entire 20+y lifetime of using them not be next day
06:49 PM rue_mohr: most things are + a day to get *here*
06:49 PM rue_mohr: so a week is usually 8 days
06:49 PM rue_mohr: there was a holdup with parts once, they phoned and appologized
06:49 PM aandrew: rue_mohr: are you truly "locked" where you are? The older guy I was talking to at your place said something like there are no roads to get you down to vancouver, the ferry's the only way
06:49 PM rue_mohr: it was just a stock order
06:49 PM aandrew: yeah digikey shipping is amazing in canada
06:50 PM aandrew: blows my mind that it's not the same in the US
06:50 PM aandrew: it's not even *close*
06:50 PM rue_mohr: the tracking info said the ferry took 5 minutes
06:50 PM aandrew: haha
06:50 PM aandrew: turboferry
06:50 PM rue_mohr: so we know a time machine is involved
06:51 PM aandrew: it is a pretty ferry ride, although I can see that becoming tedious
06:51 PM rue_mohr: yep
06:51 PM aandrew: how often do you have to get on to the "mainland" in your daily life
06:51 PM rue_mohr: hah
06:51 PM rue_mohr: maybe once a year
06:51 PM aandrew: oh wow really
06:51 PM aandrew: that's way less than I expected
06:52 PM rue_mohr: ok, ok, I need to keep going, getting stuck in my chair
06:53 PM aandrew: haha
06:53 PM aandrew: I need to be stuck in my chair, gonna lose the one contract if I don't get my ass in gear
07:00 PM zhanx: ok servo's ordered
07:33 PM aandrew: fuck yeah, hitting the zone
07:34 PM aandrew: got some Opiuo rocking on teh youtubes (Opiuo X Syzygy Orchestra, not what you think)
07:34 PM aandrew: C++ is kinda sorta almost making sense to me
07:37 PM aandrew: this music just fucked up enough to make C++ make sense
07:54 PM rue_mohr: hah
08:27 PM * Tom_L puts a thumbtack in rue_mohr's chair
08:28 PM aandrew: I admire your ability to get up and away from the computer and actually work on something
08:30 PM rue_mohr: heh, I just woke up from dozing off
08:31 PM Tom_L: you should be good to go for the long haul then
08:36 PM rue_mohr: I dont think I can beat the 555 circuit for the 12->24V booster
09:27 PM aandrew: I'm watching Dara O Briain - incredible irish comedian
09:27 PM rue_mohr: I got some 2N5089 from china
09:27 PM rue_mohr: INSANE high gain
09:27 PM rue_mohr: like 1000+
09:28 PM aandrew: rue_mohr: wow that was fast
09:29 PM rue_mohr: dunno, their waaaay back on my orders list
09:30 PM rue_mohr: those aren't the same ones you had in your circuit, are they?
09:30 PM aandrew: well it's only been like 2 weeks I think
09:30 PM aandrew: I think so which is why I said that was fast
09:30 PM rue_mohr: hmm
09:30 PM aandrew: yep
09:30 PM aandrew: 2N5087/89
09:30 PM rue_mohr: hmm
09:32 PM aandrew: highly recommend this comedian, I generally don't like them
09:32 PM aandrew: there's a difference between "smart" funny and stupid funny
09:32 PM aandrew: this guy is definitely the former
09:33 PM aandrew: he pulls in all kinds of shit from the audience and does his bit but mixes their stuff in too, quite fun
09:35 PM rue_mohr: :)
09:37 PM aandrew: https://www.youtube.com/watch?v=m7TSv_8O56w&list=LLhdv0U0JEgnq6Q0HSpEAGGQ&index=1122
09:37 PM aandrew: I just watched that part (I am watching the entire thing, but that specific part just came up
09:49 PM zhanx: https://imgur.com/a/MDThk3x
09:50 PM zhanx: i dont like the feet really
09:53 PM zhanx: thoughts?
09:55 PM aandrew: what is ti?
09:56 PM zhanx: quadruped tiny bot
09:57 PM zhanx: leaving room to grow on it also for dof
09:59 PM aandrew: crazy, what is the modelling program?
09:59 PM zhanx: openscad
10:00 PM aandrew: wow so you have a program to describe that
10:00 PM zhanx: its easier for me that way
10:00 PM Tom_L: not me
10:00 PM Tom_L: looks good
10:00 PM Tom_L: i dislike openscad
10:01 PM zhanx: i might redo the shoulder joints to add in bearings on the bottoms of the servo
10:13 PM aandrew: ok dumb questio
10:13 PM aandrew: question
10:13 PM aandrew: if I have a copper tube (think 1/4" copper tube) and kinked it to form a crude expansion valve
10:14 PM aandrew: if I pushed compressed air through it would I get a cooling effect from the expansion and ran fans over the tube?
10:14 PM zhanx: yes
10:14 PM zhanx: not greatest but it would cool some, can you use a fluid with it also?
10:15 PM Tom_L: aandrew, what are you making?
10:16 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Assembly/spindle_cooler/Cooler3.jpg
10:16 PM Tom_L: that worked wonders for keeping that motor cool
10:16 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Assembly/spindle_cooler/Cooler5.jpg
10:16 PM Tom_L: fishtank pump
10:17 PM Tom_L: for air, it would be best to have fins like your AC unit
10:17 PM aandrew: Tom_L: this is part of the oxygen concentrator
10:17 PM aandrew: bascially trying to dry the air before it hits the molecular sieve
10:18 PM Tom_L: mmm
10:18 PM aandrew: I mean it's not bad here now, 31% right now
10:18 PM aandrew: I could just run it through the dessicant beads
10:19 PM Tom_L: those would periodically have to be changed or dried
10:19 PM aandrew: yeah
10:19 PM aandrew: that's why I want to avoid it
10:19 PM aandrew: but a cooling tube and a simple separator needs to be drained too
10:20 PM aandrew: that cooler you have looks like some of hte hot water heat recovery systems I've seen on wastewater pipes
10:20 PM aandrew: never understood that
10:20 PM Tom_L: btw, if you ever bend a coil like that fill it with liquid and pinch the ends off. it won't kink
10:20 PM aandrew: right, the fluid protects the pipe
10:20 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Mill_Steel/Assembly/spindle_cooler/Cooler1.jpg
10:21 PM aandrew: does that cool the spindle well?
10:21 PM Tom_L: very
10:21 PM Tom_L: looks ghetto
10:21 PM aandrew: looks aren't everything
10:22 PM * aandrew looks in mirror and reaffirms this
10:22 PM Tom_L: i've since made a little more permanent plumbing
10:22 PM Tom_L: vinyl tubing since the motor moves
10:23 PM aandrew: hm nice I got a bunch of 150kpa sensors, looks like 20 or so
10:23 PM aandrew: that's 22psi which is perfect for this
10:26 PM aandrew: yay, found the op-amps I was using to see if the quality of the op-amp was important for my sensor
10:26 PM aandrew: LMV321, ISL28130, MCP6V11, MCP6001
10:36 PM rue_shop1: heh, I used an inductor to improve the pullup on a high freq line from an oscillator buffer
10:36 PM rue_shop1: and it worked, had to zoom the scope out
10:36 PM rue_shop1: the osc is fed by 12V
10:37 PM rue_shop1: The signal was at 3V p-p
10:37 PM rue_shop1: accept I realized I was at x10
10:37 PM rue_shop1: so the inductor was swinging 30V
10:37 PM rue_shop1: :)
10:38 PM aandrew: hahaha
10:38 PM rue_shop1: kinda funny as the osc is a test for something suitable to make a 12V->24V converter with
10:38 PM rue_shop1: its just a wee little 1mH
10:38 PM rue_shop1: @2Mhz
10:46 PM aandrew: wow, uc/os is now 100% open source
10:46 PM aandrew: https://github.com/SiliconLabs/uC-OS3
10:47 PM rue_mohr: I didn't find the sensors you mentioned in the range I'm looking for, ~100psi
10:47 PM rue_mohr: just around the 2psi mark
10:48 PM aandrew: rue_mohr: hm, I've got 20 of 'em right here on my desk :-)
10:48 PM rue_mohr: p/n?
10:48 PM aandrew: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20200421194757&SearchText=MD-PS002 all kinds here in various max pressures
10:49 PM aandrew: https://www.aliexpress.com/item/33048433506.html specifically
10:50 PM aandrew: I have a bunch of the 700kpa ones for my original intent
10:53 PM rue_mohr: ah nice
10:56 PM aandrew: use aliseeks.com to find the cheapest and lots
11:02 PM rue_mohr: hmm, thats a new one
11:02 PM rue_mohr: tho I usually find the cheapest stuff from ali is ... more problem prone
11:03 PM aandrew: i'vve had exceedingly good luck with ali
11:03 PM aandrew: I do take quite a bit of time checking different vendors selling the exact same shit to see which looks better to me
11:15 PM zhanx: might cut holes in the frame and let the pcb and battery be part of it
11:16 PM zhanx: then add a top layer with a continuous servo setup to scan
11:20 PM zhanx: oh fun the new pc's sd card reader doesn't work
11:21 PM Tom_L: :(
11:21 PM zhanx: 3d printer is on the other side of the room, now I have to get the old laptop out
11:24 PM rue_mohr: geez, I stream via usb
11:24 PM rue_mohr: ok, so, I wanted a low parts count, disable-able 200kHz oscillator
11:24 PM rue_mohr: with a 12V output
11:25 PM rue_mohr: that path isn't working out
11:25 PM rue_mohr: so, I think I need to make a power converter that doesn't need to run at 200kHz
11:46 PM zhanx: ok holes knocked in for wiring it up
11:48 PM zhanx: bracing added but might not be needed
11:49 PM zhanx: rue_mohr, its getting complex on the design
11:51 PM zhanx: and the legs wont print right if i make them like that