#robotics Logs

May 30 2021

12:09 AM rue_shop2: 3d printing is great and all but I hate having to go back to the house to do the printing
12:16 AM rue_shop1: technically, you dont ahve to THERE IS A PRINTER RIGHT BESIDE YOU
12:27 AM rue_shop2: 3d printing is great and all but I'm tired of waiting for things to print
12:27 AM rue_shop1: ... look closer, its done
12:33 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1190781.jpg <-- todays score (from the scrapper)
12:50 AM mrdata-: nice
02:06 AM flav0r: CLOG !
02:36 AM rue_shop1: flav0r,
02:36 AM flav0r: yah whats shakin dude ???
02:36 AM rue_shop1: you still here?
02:36 AM rue_shop1: read this...
02:37 AM flav0r: more horses ???
02:37 AM rue_shop1: http://ruemohr.org/%7Eircjunk/tutorials/elex/qwhathow.html
02:37 AM flav0r: sweet jesus
02:48 AM flav0r: ive got this screen that says its rated power is 980mW max … 800mW typical
02:48 AM flav0r: at 3.3V
02:48 AM flav0r: so thats upwards of 303mA
02:48 AM flav0r: ok thats step one !
02:48 AM rue_shop2: no
02:49 AM rue_shop2: that sounds like its dissipation specs
02:49 AM rue_shop2: did you read that document?
02:49 AM flav0r: im gathering info right now !
02:49 AM rue_shop2: at the end it talks about that a bit
02:49 AM flav0r: ah
02:51 AM flav0r: https://osoyoo.com/2019/11/12/instruction-for-raspberry-pi-7-dsi-touch-screen/
02:51 AM flav0r: thats the screen in question
02:52 AM rue_shop2: what are you doing with the transistor?
02:52 AM flav0r: switch the screen on or off
02:53 AM flav0r: hopefully !
02:53 AM rue_shop2: k
02:53 AM rue_shop2: "The screen will automatically sleep when it is not in use"
02:53 AM rue_shop2: ?
02:54 AM rue_shop2: says it draws up to 1W
02:54 AM flav0r: yaaah
02:54 AM rue_shop2: is it 3.3V or 5V?
02:55 AM flav0r: whats got me wanting to do this is that the screen doesnt behave as expected
02:55 AM flav0r: 3.3v
02:55 AM rue_shop2: root@blackie3:/tmp# ohm -p 1 -v 3.3
02:55 AM rue_shop2: Power is: 1.000W
02:55 AM rue_shop2: Current is: 303.030mA
02:55 AM rue_shop2: Voltage is: 3.300V
02:55 AM rue_shop2: Resistance is: 10.890Ohms
02:55 AM rue_shop2: right, ok, 303mA
02:55 AM rue_shop2: what transistor do you have
02:55 AM flav0r: flav0r: ive got this screen that says its rated power is 980mW max … 800mW typical
02:55 AM flav0r: [12:35am] flav0r: at 3.3V
02:55 AM flav0r: [12:35am] flav0r: so thats upwards of 303mA
02:55 AM flav0r: [12:35am] flav0r: ok thats step one !
02:55 AM flav0r: [12:35am] rue_shop2: no
02:55 AM flav0r: :P
02:56 AM flav0r: MMBT4403
02:56 AM rue_shop2: sorry, thoutht you were saying the transistors wattage
02:56 AM rue_shop2: ok, its rated for 600mA,
02:56 AM flav0r: yah no worries
02:56 AM flav0r: i was about to puke when you said no
02:56 AM flav0r: was thinking i was doooomed !
02:56 AM flav0r: lol
02:56 AM rue_shop2: whats its voltage drop at 300mA
02:57 AM rue_shop2: about .75V
02:58 AM flav0r: hold on dude !
02:59 AM rue_shop2: actauly, according to the chart, more like .82V
02:59 AM flav0r: yikes
02:59 AM flav0r: this might now work :)
02:59 AM rue_shop2: well, a P channel fet would be a better idea
03:00 AM rue_shop2: with logic level gate
03:00 AM flav0r: well good thing is its not too late
03:00 AM flav0r: i can drop that in
03:03 AM rue_shop2: NX3008PBK?
03:03 AM rue_shop2: er, how about a min. quant of 1
03:05 AM flav0r: https://lcsc.com/product-detail/MOSFET_Nexperia-NX3008PBK-215_C131670.html
03:05 AM rue_shop2: imagine the stuff digikey throws out eh?
03:05 AM flav0r: yup no worries
03:05 AM rue_shop2: k, whats the gate saturation voltage?
03:06 AM rue_shop2: oh, no its tooo small
03:06 AM flav0r: only 230mA !
03:06 AM flav0r: oops
03:07 AM rue_shop2: researching
03:08 AM rue_shop2: PMV160UPVL ?
03:08 AM flav0r: https://lcsc.com/product-detail/MOSFET_Diodes-Incorporated-ZXMP10A13FTA_C50185.html
03:08 AM rue_shop2: rdsOn is 1 ohm
03:08 AM rue_shop2: no
03:09 AM flav0r: the one you suggested they have no stock
03:09 AM rue_shop2: ok
03:09 AM rue_shop2: digitkey gave me a list of 1254
03:09 AM rue_shop2: I'm working thru it
03:11 AM rue_shop2: you want an rdsOn of like
03:12 AM rue_shop2: ohm -v 0.1 -i 0.35
03:12 AM rue_shop2: Power is: 35.000mW
03:12 AM rue_shop2: Current is: 350.000mA
03:12 AM rue_shop2: Voltage is: 100.000mV
03:12 AM rue_shop2: Resistance is: 285.714mOhms
03:12 AM rue_shop2: say, 250mohms
03:13 AM flav0r: minimum of that ?
03:13 AM flav0r: or pretty much exactly that ?
03:13 AM rue_shop2: no more than that
03:14 AM rue_shop2: SI2301S-2.3A
03:15 AM rue_shop2: I think everything looks good
03:15 AM flav0r: https://lcsc.com/product-detail/MOSFET_BORN-SI2301S_C431492.html
03:16 AM flav0r: looks great !
03:16 AM flav0r: lol
03:16 AM rue_shop2: you siwtching it with 3.3V?
03:16 AM flav0r: yes
03:16 AM rue_shop2: whats the rds when its switched with 3.3V?
03:17 AM rue_shop2: 140mR at 3.3V
03:17 AM flav0r: umm it says 140mohm
03:17 AM rue_shop2: so its still ok
03:18 AM rue_shop2: yea, its 1am, but I think thats the right one for that
03:18 AM rue_shop2: where are you going to put it then?
03:18 AM flav0r: you asking what the project is ?
03:18 AM rue_shop2: no
03:18 AM flav0r: or specifically where i might place it ?
03:19 AM rue_shop2: like you have a pi and a screen, right?
03:19 AM flav0r: yah
03:19 AM flav0r: a compute module
03:19 AM rue_shop2: and you want to put that transistor in the middle?
03:19 AM rue_shop2: ok, so you have another board you can put it in
03:19 AM flav0r: for testing ?
03:20 AM rue_shop2: or whatever, I dunno
03:20 AM flav0r: nah ill just go with it …. i have a jumper across it incase it doesnt work out so good :)
03:20 AM flav0r: its not really a critical piece of the puzzle at the moment
03:21 AM flav0r: so if it becomes so then ill be able to test more
03:26 AM flav0r: watching a vid on high side switching
04:16 AM flav0r: ok well i squeezed it into the board layout !
06:51 AM Steffann_ is now known as Steffann
03:37 PM DAIBUTSU is now known as DHARMAKAYA
07:31 PM flav0r: WAKE UP !!!
08:14 PM * mrdata yawns
08:16 PM rue_mohr: ok
08:16 PM rue_mohr: how about a new insert for a db9 to use it with dupont connectors?
08:22 PM rue_mohr: 8170296242
08:22 PM rue_mohr: 978-8170296249
10:53 PM flav0r: https://archive.org/details/funway_into_electronics
10:53 PM flav0r: https://archive.org/details/funway_into_electronics/funway_into_electronics_vol_2_5th_printing
10:53 PM flav0r: https://archive.org/details/funway_into_electronics/funway_into_electronics_vol_3_9th_printing/mode/2up
11:07 PM rue_mohr: and then dick smiths forgot about hobbyists and started selling assembled electronics, and then cans of beams, and now nothing
11:22 PM flav0r: dude
11:22 PM flav0r: later i will ask you to clue me in on resistor calculations !
11:23 PM flav0r: hmm how did you know about dick smith ?
11:23 PM flav0r: just happened to know ? or they had a presence near where you lived or some such ???
11:37 PM rue_mohr: they could have been digikey over there, like radioshack could have here
11:38 PM flav0r: yah
11:38 PM flav0r: was cool tho
11:38 PM flav0r: i had some of their kits back in the day
11:41 PM flav0r: speaking of kits
11:41 PM flav0r: https://www.ebay.ca/itm/114803338903?hash=item1abacfee97:g:ga4AAOSwZyxgmtPf
11:41 PM flav0r: i have one of those UNASSEMBLED
11:47 PM rue_mohr: imagine is DK did projects with part numbers?
11:47 PM flav0r: they would make LOTS of money
11:49 PM flav0r: massive PO’s from schools
11:49 PM flav0r: full curriculums
11:50 PM flav0r: hey i wonder what happene to that guy that did videos for sparkfun
11:50 PM flav0r: the dude with the mutton chops
11:52 PM flav0r: https://www.youtube.com/watch?v=6BLj9Ak2Djs
11:52 PM flav0r: wtf