#robotics Logs

Nov 30 2020

04:45 AM Jak_o_Shadows: Hey. This is actually perfect for me: https://www.aliexpress.com/item/4001197263516.html?spm=a2g0o.productlist.0.0.18a94a7flSwIYj&algo_pvid=a5e602c8-76bd-4ae4-8ba0-3324a7a8dd64&algo_expid=a5e602c8-76bd-4ae4-8ba0-3324a7a8dd64-4&btsid=0bb0600116067329823287746eff17&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_
04:52 AM Jak_o_Shadows: purely by accident, I made this footprint on my pcb
05:29 AM mrdata-: this part looks 3D printed
09:19 AM rue_mohr: yea
09:19 AM rue_mohr: looka that, they 3d printed it for you
09:20 AM rue_mohr: its not resin either
09:26 AM veverak: hmmmm
09:26 AM veverak: servos not givin enough power
09:32 AM rue_mohr: https://www.aliexpress.com/item/33046037411.html
09:32 AM rue_mohr: wow, even with $7 shipping, THAT IS CHEAP
09:34 AM veverak: any tips for board for measuring current?
09:34 AM veverak: 12V 20A
09:34 AM rue_mohr: yea
09:35 AM rue_mohr: constant 12V doesn't go down to, say, zero ever?
09:35 AM veverak: it goes down actually
09:35 AM veverak: it's top limit
09:35 AM veverak: I suppose that in the end I will use 3s lipo ?
09:35 AM veverak: or somethign like that
09:35 AM rue_mohr: ok
09:35 AM rue_mohr: but there is still more than like 5V left
09:36 AM veverak: yes
09:36 AM veverak: definetly
09:37 AM rue_mohr: https://www.aliexpress.com/item/4001107786936.html <-- do NOT get those! more noise than signal
09:37 AM rue_mohr: I dont remember the part number...
09:37 AM rue_mohr: its a sense amp, you use it with a shunt
09:38 AM veverak: I have UBA219 here
09:38 AM veverak: *INA219
09:38 AM veverak: but the board is designed to 3A
09:38 AM rue_mohr: that might be it
09:38 AM veverak: I can hack it, but having link to something more suited would be better
09:38 AM rue_mohr: yea, you just change the resistor
09:38 AM veverak: yeah, but the PCB has limits
09:39 AM rue_mohr: uh, just a sec
09:39 AM rue_mohr: no not 219
09:39 AM rue_mohr: but..
09:40 AM rue_mohr: 1009
09:40 AM veverak: 1009?
09:41 AM rue_mohr: stand by I'm searching
09:42 AM rue_mohr: zxct1009
09:42 AM rue_mohr: stand by...
09:43 AM rue_mohr: https://www.aliexpress.com/item/32881624845.html
09:43 AM rue_mohr: stand by...
09:45 AM rue_mohr: I have a 4 wire shunt resistor I use mine with
09:46 AM rue_mohr: I might run out of time I have to be online class in 6 mins
09:47 AM veverak: nevermin, thanks for the tips
09:51 AM rue_mohr: took new pics
09:52 AM rue_mohr: http://ruemohr.org/~ircjunk/projects/newpower2/p1180188.jpg
09:52 AM rue_mohr: http://ruemohr.org/~ircjunk/projects/newpower2/p1180189.jpg
09:52 AM rue_mohr: http://ruemohr.org/~ircjunk/projects/newpower2/p1180190.jpg
09:52 AM rue_mohr: mine is a 5A range
09:53 AM rue_mohr: but the point is that if you have the 4 wire shunt, you dont need to worry about trace size
09:53 AM rue_mohr: then you can just plumb it into an adc channel and your good to go
09:56 AM srk: apm power modules use ina169 and shunt, up to 60A iirc
09:56 AM veverak: rue_mohr: yeah, good tip
10:01 AM rue_mohr: a 60A shunt (75mv) will give you 25mv @20A
10:02 AM veverak: but I want to check that the wiring is strong enough, that batteries can handle etc..
01:18 PM rue_mohr: most of the pulse servos are not PID
01:18 PM rue_mohr: their PD
01:18 PM rue_mohr: http://ruemohr.org/~ircjunk/tutorials/elex/hobbyservo/images/schematic.png
01:19 PM rue_mohr: the P is internal, the D is that 560k resistor off the motor
01:19 PM rue_mohr: there are other chips, but they all minor variations
01:52 PM veverak: this is not standart pulse servo
01:52 PM veverak: but yeah, lack of I explains a lot