#robotics Logs

Jun 20 2018

12:00 AM rue_mohr: I spent all day clearing up scrap wood in the yard and modifying 3 sets of speakers, two of which are unsuitable for shop sound system
12:04 AM rue_mohr: then I mowed the lawn
12:04 AM rue_mohr: its 9:25pm
12:04 AM rue_mohr: I have till about 3 or 4am to work on the servo controller
12:04 AM rue_mohr: so I'm talking to the wall on irc...
12:06 AM rue_mohr: the control voltage takes it from 0.01 to 25k?
12:06 AM AchiestDragon: in 6 ranges
12:07 AM rue_mohr: so whats the ratio in a range?
12:07 AM rue_mohr: and how is it that were both working on vco?
12:08 AM AchiestDragon: https://drive.google.com/file/d/1TGBKFh7h5F5bQKMEAhVGzt9PEg7hoiAJ/view?usp=sharing
12:08 AM AchiestDragon: 1000:1 so the ranges overlap
12:08 AM rue_mohr: what?
12:08 AM rue_mohr: no, I mean Fh/Fl
12:10 AM AchiestDragon: https://www.intersil.com/content/dam/intersil/documents/icl8/icl8038.pdf
12:10 AM rue_mohr: I might have that chip
12:15 AM AchiestDragon: its cv controled , 1v per octave on the cv input s and with +-12v supply i still have more than 12 octaves in one range
12:17 AM rue_mohr: arg, I have to wait a minute for chromium to start back up every time you post one of those silly google links
12:17 AM rue_mohr: I'll look later
12:17 AM AchiestDragon: lol
12:17 AM rue_mohr: I cant leave chromium running, it faults my video card via some kinda memory leak
12:18 AM AchiestDragon: 3d printed synth keyboard , i got 3 of the 5 octaves printed so far and currently out of filiment , but no rush to get it finished
12:19 AM rue_mohr: ah
12:21 AM AchiestDragon: its my sons birthday this month so spending on my projects is on hold for the month
12:22 AM AchiestDragon: as its seems to be getting spent on a ps4
12:24 AM AchiestDragon: have 5 of those icl8038 funcion gen chips and another 4 on there way in the post
12:25 AM rue_mohr: the simple solution would be to get him a computer and a spool of plastic
12:25 AM rue_mohr: I think I ahve one, but its not quite what I'm looking for
12:25 AM AchiestDragon: they only do up to about 1mhz
12:26 AM rue_mohr: my approach would be to generate the signal as a sine wave, compare it into a square wave, and shape that to triangle
12:26 AM AchiestDragon: but as there intended for audio thats way more than enough
12:26 AM rue_mohr: but, the china dds will do fine with some output processing
12:26 AM rue_mohr: I suppose
12:27 AM rue_mohr: I still want to make a varicap based osc
12:28 AM rue_mohr: I wonder if I could get that phase shift sin osc to 1Mhz
12:28 AM AchiestDragon: last high performance rf front end mixer i looked at used a square wave osc in rather than a sine ,, since the mixer chops it anyway there starts to be little point in using a true sine osc where a square wave will do
12:29 AM rue_mohr: yes
12:29 AM rue_mohr: I want mine for digital tho
12:29 AM rue_mohr: not sure of output connector, a BNC might be a good idea if my target is 10Mhz
12:31 AM AchiestDragon: trouble with vericap diodes is the capacatance change is tiny so the range of the osc is usualy limited to about 500khz
12:34 AM AchiestDragon: yea bnc's are good to uhf and low noise as there impedance balanced though the connectors -1db loss at 432mhz per connector not too bad
12:35 AM AchiestDragon: there a sod to put on though , i much prefer the bigger n-type , not as lossy about -1db at 1250mhz , and easyer to assemble
12:36 AM rue_shop3: but with the BNC I can use old scope probes to get signal to the board
12:38 AM rue_shop3: I wonder if I can buy a stupid number of 2N7000 for cheap
12:38 AM AchiestDragon: not a good idea to use scope probes in reverse some have diodes in them as well as switched attenuators ,, old t10 coaxial ethernet cables with bnc's on are better for that
12:39 AM rue_shop3: mine has a switched atten, but that wouldn't matter
12:39 AM rue_shop3: I have a bunch of T10 jumpers and splitters
12:39 AM rue_shop3: by the scope
12:39 AM rue_shop3: sometimes its nice to know the freq count and see it on the scope at the same time
12:40 AM rue_shop3: hmm, $4/100
12:41 AM AchiestDragon: other thing to remeber you may not know is bnc's come in 2 types 50ohm and 75 ohm , the they both appear to connect fine if mixed but if you push 75ohm plugs into 50ohm sockets it splays the socket pin so it nolonger makes a good connection when you put a 50ohm one into it later
12:41 AM rue_shop3: !? didn't know that one
12:42 AM rue_shop3: I think everything I ahve is 50
12:43 AM AchiestDragon: most of the time you then end up tinking the 50ohm cables have faulty ends as there contacts are loose
01:33 AM rue_shop3: I have some 2Ghz transistors, I think they will work
01:47 AM rue_mohr: part of the problem will be that I dont think I can just breadboard this
01:49 AM rue_mohr: https://www.electronics-tutorials.ws/oscillator/osc55.gif
01:49 AM rue_mohr: https://www.nutsvolts.com/uploads/wygwam/NV_1103_Marston_FIGURE13.jpg
01:49 AM rue_mohr: https://obrazki.elektroda.pl/3556779100_1372330566.gif
02:00 AM rue_mohr: https://www.nutsvolts.com/uploads/wygwam/NV_1103_Marston_FIGURE10.jpg
02:01 AM rue_mohr: https://i.stack.imgur.com/PEr4u.gif
02:07 AM rue_mohr: http://www.qsl.net/va3iul/High_Frequency_VCO_Design_and_Schematics/High_Frequency_VCO_Design_and_Schematics_files/image010.gif
02:14 AM rue_shop3: the picture in my head for the pencil holder does not jive with reality
02:14 AM rue_shop3: I will have to change it.
02:14 AM rue_shop3: (reality)
02:52 AM AchiestDragon: yea rf breadboard usualy looks like this http://kd1jv.qrpradio.com/ap80/AP_80_ugly.jpg
03:03 AM AchiestDragon: https://lh5.googleusercontent.com/-eBvB55qAcho/TvQZVNsI4DI/AAAAAAAAFeI/P5GCw9rdtI0/s1600/1Mhz-3Mhz-diff-neg-VCO-low-tank-energy.jpeg
03:04 AM AchiestDragon: ,, with notes https://sites.google.com/site/linuxdigitallab/low-noise-crystal-experiment/diff-neg-vco-1mhz-30mzh , and construction pic
03:07 AM AchiestDragon: just what your after ,, well 1mhz to 30mhz
03:18 AM Jak_o_Shadows: Rue, nah, the serial on the pc side is a CH340 serial adaptor, whilst on the uC side, it's a stm32.
03:18 AM Jak_o_Shadows: So like, 5V logic, ma
03:32 AM AchiestDragon: just drill a series of equaly spaced 10mm holes across the wall drilling at an angle down to 45 degree , then just slot the pencils into the holes , no holder needed :D
03:56 AM AchiestDragon: and as for rf breadboarding on plan copper clad board , who needs to etch it when done neatly http://www.w1vd.com/Phasingexciter2.jpg
03:56 AM rue_shop3: its panel board, not drywall
03:57 AM AchiestDragon: bit of woo drill holes in it to hold pencils , but not all way though , and screw it to the wall
03:58 AM AchiestDragon: woo /wood even
04:10 AM rue_shop3: I'm supposed to do that when I'm sitting within 3m of 3 3d printers?
04:10 AM Jak_o_Shadows: ahaha
04:12 AM AchiestDragon: in days of old ,, when men where bold ,, before women where invented ,, they used to drill holes ,, in telegraph poles ,, and had to be contented
04:14 AM rue_shop3: I have new toys tho :)
04:31 AM rue_shop3: +- printing foof, looks good
04:31 AM rue_shop3: post on thingverse and move along
08:05 PM rue_shop3: <rue_mohr> http://ruemohr.org/~ircjunk/images/canosc1.jpg
08:05 PM rue_shop3: <rue_mohr> http://ruemohr.org/~ircjunk/images/canosc2.jpg
08:07 PM mrdata-: holy deadbug
08:33 PM Tom_L: powered from a grapefruit?
08:34 PM rue_shop3: dont be silly, its a vegitable soup can, its potato powered
08:54 PM SpeedEvil is now known as Guest3018
11:07 PM rue_mohr: I need to make a VCO
11:07 PM rue_mohr: need, heigh, want
11:07 PM rue_mohr: I desire the vco