#robotics Logs

Jun 19 2018

02:42 AM rue_shop3: OMG something new
02:46 AM rue_shop3: in this RF box,
02:46 AM rue_shop3: on the pcb, they mounted all the smt parts SIDEWAYS to save space
02:46 AM rue_shop3: like, all the parts are on their edge
02:46 AM rue_shop3: wow
02:46 AM rue_shop3: 0806 resistors are 0801
02:46 AM rue_shop3: but I found the VCO controller chip I was looking for
02:49 AM polprog: neat. any pics?
02:52 AM rue_shop3: http://ruemohr.org/~ircjunk/images/pi/IMG19Jun2018_071540.jpg
02:52 AM rue_shop3: ;)
02:52 AM rue_shop3: now I just need a vco to control
02:53 AM rue_shop3: ta8637?
02:53 AM polprog: dont ask me, im all green in this field
02:54 AM polprog: building a 2 pole adjustable LP now
02:55 AM rue_shop3: voltage tunable?
03:06 AM rue_shop3: ah D1709C
03:09 AM rue_shop3: oh my, its a whole brain
03:16 AM rue_shop3: well, a 4 bit brain
03:16 AM rue_shop3: with a 4 bit adc
03:16 AM rue_shop3: (hahahaha)
04:04 AM rue_shop3: ok I think
04:05 AM rue_shop3: I know how I can use these rf modules as a freq gen
05:24 AM rue_shop3: I'm learning waaaaaaay too much about vcr tuners
05:39 AM Jak_o_Shadows: ahaaha
05:44 AM rue_shop3: ok, I"v found some 2Ghz transistors to use for a vco, I'v found some varicaps, and some 19 bit pll controllers, Its 3am
07:17 AM Jak_o_Shadows: What the ever living....
07:17 AM Jak_o_Shadows: This serial adaptor I have is inverting the bits.
07:32 AM Jak_o_Shadows: nah, not the adaptor. Must be the python?
07:34 AM Jak_o_Shadows: apparently that isn't really a thing.
09:31 AM z64555: anybody ever use acrylic clear coat paint as a sort of insulation/enamel replacement?
09:31 AM z64555: need to repair headphone cables again, and was wondering about it
09:32 AM SpeedEvil: any tape pretty much works.
09:34 AM z64555: wires too dang small, vinyl tape won't stick to it
09:35 AM z64555: they're like, 22 gauge or something ridiculous
09:37 AM SpeedEvil: The tape doesn't stick to it, you roll the tape in a tight wrap around one wire, and then place the next wire in the same wrap.
09:37 AM SpeedEvil: typically
09:38 AM z64555: hm
09:38 AM z64555: well the other issue is that I have sausages for fingers
12:34 PM rue_bed: Jak_o_Shadows, is the serial bit banged?
12:34 PM rue_bed: the max232 inverts the bits
12:34 PM rue_bed: an rs232 1 is -12V, a 0 is 12V
12:35 PM rue_bed: if you pour slew rates on that, you see why modern busses use low voltages for high speed comms
12:36 PM rue_bed: in the old dayz we used 8 serial busses at once, we called it 'parallel'
12:36 PM rue_bed: it was synchronous
12:36 PM rue_shop3: spec can have it jacked passed 30v
12:36 PM rue_bed: huh, I thought about 15 was the top
12:37 PM rue_shop3: nah i think original spec says +36 to -36
12:37 PM rue_shop3: or maybe 24?
12:37 PM rue_bed: seeing as it was done mechanically origionally, I'm not that surprised
12:38 PM rue_bed: I'm gonna get a shower, lots of things to do today
12:39 PM rue_bed: see if I want to use the RF stuff that took me till 3am to round up last night
12:40 PM rue_bed: OR I could use the freq gen board I got from china...
12:40 PM rue_bed: which I should do
12:40 PM rue_bed: or not
12:40 PM rue_bed: ugh
08:25 PM Tom_itx is now known as Tom_L
09:11 PM AchiestDragon: rue_bed: what freq range you after from a VCO ?
09:24 PM AchiestDragon: you may find http://www.analog.com/media/en/technical-documentation/data-sheets/AD9850.pdf interesting
09:53 PM rue_shop3: top @ 10Mhz
09:53 PM rue_shop3: I can divide down
09:53 PM rue_shop3: 10:1 would be nice, so 1Mhz to 10Mhz, but that is aparently crazy
09:53 PM rue_shop3: I have a china module that I should set up to use
09:54 PM * rue_shop3 tries to fix the chainsaw
09:57 PM rue_shop3: haha its working now
09:58 PM rue_shop3: waiting for the problem to just go away worked!
09:58 PM rue_shop3: go go hedgehog!
10:33 PM rue_shop3: heh
10:33 PM rue_shop3: the pullcord went back to not working right after I shut it off
10:34 PM rue_shop3: ah well, I did the important stuff
11:02 PM AchiestDragon: last time i looked the ad9850 will do almost dc to 70 mhz and is quite stable ie no noticable drift , they do a cheaper dds chip that will do almost dc to 16mhz that may be worth a look ie set freq over spi and it produces a sine wave of that freq out
11:03 PM AchiestDragon: by almost dc thats like 0.1hz or something
11:04 PM AchiestDragon: and none of the feedback and stabilaty issues associated with pll's
11:04 PM AchiestDragon: instant freq change also not a quick drift to it
11:08 PM AchiestDragon: i used one in a design some time back cant remeber the part nos though , it was a 16 pin So dip device that did spi to sine and gave a dc to 80mhz range , that was quite cheap at about £5 unlike the ones i found on todays quick google search
11:12 PM AchiestDragon: ie £10 to £200 ,, ok so the £200 ones did up to 3ghz
11:23 PM rue_shop3: yes, the ad9833 isn't a pll, its a divider
11:54 PM AchiestDragon: you could prob home brew a 3 chan 120mhz dds using a old vga card video dac and a look up table ,
11:54 PM rue_mohr: oh dammnit, I didn't think of video hardware
11:55 PM rue_mohr: I'm playing with rounding up parts for an RF VCO, partly to have been there and done that
11:55 PM rue_mohr: rf stuff never works for me, but digital usually isn't a problem, so, to get things to work, I have to play with symantics
11:57 PM AchiestDragon: with rf its not just the schematic that matters phisical component positioning also affects it and screening etc
11:57 PM rue_mohr: yea, in my world electricity travels thru wire and not air
11:57 PM rue_mohr: all that goes out the window with rf
11:58 PM AchiestDragon: windows are no obstical
11:58 PM rue_mohr: this is all triggered by the fact that my old HP signal gen is pretty slopie (slope-ie?) around 1Mhz
11:58 PM rue_mohr: I had to run it thru a 555 to clean it up
11:59 PM rue_mohr: and i got thinking
11:59 PM rue_mohr: and here we are now
11:59 PM rue_mohr: I'm supposed to be working on a force feedback servo controller module