#robotics Logs
Dec 01 2017
#robotics Calendar
12:37 AM rue_mohr: wow its nice to have the tablet able to use the speakers
12:40 AM rue_mohr: 3db is perfect
12:48 AM rue_mohr: ugh, I blew like $200
01:10 AM rue_mohr: !?!?!?
01:11 AM rue_mohr: hey, I can make metal baffled diaphrams via hydroforming...
01:12 AM rue_mohr: I can cnc a die plate
01:17 AM rue_mohr: I want a 70psi pressure detector
01:17 AM rue_mohr: 70lbs is too much force to use for it
01:17 AM rue_mohr: and that only a 1/2" diaphram
01:17 AM rue_mohr: er, no 1.1
01:17 AM rue_mohr: oh, hmm
01:17 AM rue_mohr: so 35lbs is plausable
01:18 AM rue_mohr: .56" is 1/4
01:19 AM rue_mohr: 17lbs
01:19 AM rue_mohr: hmm 2x4L milk jugs
01:20 AM rue_mohr: still too much force
01:23 AM rue_mohr: I need to take this to about .5lbs
01:26 AM rue_mohr: so lets say I go with a 0.5" diaphram, and thats 17lbs
01:27 AM rue_mohr: I need a 34:1 lever on it
01:27 AM rue_mohr: ugh
01:32 AM rue_mohr: maybe I should makea pieto tube
01:32 AM rue_mohr: peito?
01:37 AM rue_mohr: https://www.aliexpress.com/item/Tire-Tyre-air-pressure-Test-Meter-Silver-Pressure-Gauge-Universal-Emergency-Use-Car-Styling-Pen-Shape/32650085637.html
01:37 AM rue_mohr: anyone ever taken one of these apart
01:37 AM rue_mohr: ?
01:49 AM z64555: thought those were just a sliding piston
02:45 AM rue_bed: might be
02:45 AM rue_bed: need to take one apart
02:45 AM rue_bed: see if I can remmeber to swing by a dollar store tommorow
03:43 AM FreeBitCoin: https://freebitco.in/?r=10132979 is a "faucet" which means, every hour anyone who signs up for FREE with only an email gets .00005 of a bitcoin. But thats only the start, you can win 1.00 BTC in a free weekly lottery! 100% legit you can google it, use my referral code to start off with $3 in free bitcoin!
03:46 AM Jak_o_Shadows: I always assumed some sort of piston with a calibrated variable hole?
04:00 AM theBear: i think that's what most people assumed <grin>
04:00 AM * theBear reads more than one line back
04:18 AM Jak_o_Shadows: ahaha
09:06 AM rue_mohr: theBear, made an inline 3db line amp, usb powered, works great :)
09:08 AM rue_mohr: took a few tries
09:10 AM AchiestDragon: op amps are fun
09:11 AM rue_mohr: I should have thought to use rail-rail the first time
09:14 AM AchiestDragon: next youll be looking at the posibilaty of using opamps at doing the sin/cos calculations in analog computaion maths as its quicker than 8bit uc code
09:15 AM AchiestDragon: and can be more accurate than 8 bit results
09:15 AM rue_mohr: ?hows that work then?
09:15 AM rue_mohr: I just realized that if my idea for etching aluminum foil works, I can make strain guages
09:16 AM AchiestDragon: https://courses.engr.illinois.edu/ece486/fa2017/labs/lab1/analog_computer_manual.pdf
09:19 AM AchiestDragon: anaglog computing is like using the voltage range and electroincs to create a electronic equivelent of a slide rule , as a simple explanation
09:20 AM rue_mohr: yes but
09:20 AM rue_mohr: you implied integration into a digital system
09:20 AM rue_mohr: I see neither direct mention of trig functions or digital interfacing
09:21 AM rue_mohr: I already have enough problems with digital interfaces
09:22 AM rue_mohr: wtf, 22 mins just went *poof*
09:22 AM AchiestDragon: you could feasably do the walking position functions of a whole hexipod in analog even pwm control with v-to-f conveters
09:22 AM rue_mohr: yea, but there are no asics to do it with
09:23 AM rue_mohr: I'd rather do analog-over-digital with pfm digital platforms
09:23 AM AchiestDragon: true
09:25 AM rue_mohr: oooooo
09:25 AM rue_mohr: the pfm could be edge based, so the events would just be level change on a line
09:28 AM AchiestDragon: i have thought about doing the walking gate functions using a totaly mechanical mech , and getting the foot positioning to stay paralel over the legs movment on a hexipod , it is posible if a bit intricate , along with corrections for how low that leg is compared with others if on uneven surfaces
09:28 AM rue_mohr: ah yes, the output could be xor instructions, maybe
09:29 AM rue_mohr: AchiestDragon, it would have to be big
09:29 AM AchiestDragon: well for all the clockwork needed yea
09:30 AM rue_mohr: to work, bye!
09:32 AM AchiestDragon: but there are some advantages in using it over a micro/ digital never the less main ones beeing computation time digital is sampling calculating and producing the output making the movment choppy to some extent and if the cpu hangs then it stops
09:36 AM AchiestDragon: analong is constant and any input change changes the output and is quicker in most cases , ie you can get a signal bandwith of 80 to 100mhz respoince times would be down to comparitor responce speeds
09:37 AM AchiestDragon: but usualy makes for big pcbs with +-30v supplies and lots of individual components
09:39 AM AchiestDragon: and huggings of screening to reduce electrical noise
09:41 AM AchiestDragon: ho by the way , i do remeber vector crt consoles , from back in the late 70s / 80's the resolution is still comparable to what you would get from a current 4k monitor
09:45 AM AchiestDragon: as a circle is drawn round not pixelated
09:58 AM AchiestDragon: anyway heres one you may concider if you have a uc with analog outs but no pwm outs and have to write pwm code in the uc to drive dio
09:58 AM AchiestDragon: http://farhek.com/a/a/co/control-circuits-for-motor-images-guru_stepper-motor-controller-circuit_transistor-timer-circuit-audio-amplifier-circuits-filter-integrated-pictures-small-projects-electronic-l.gif
10:01 AM AchiestDragon: use say rp2 as the position sence in the servo remove rp1 and feed the analog level from the uc to where slider is ,, you may have to use a dual opamp so you can buffer and level set the uc analog signal
10:02 AM AchiestDragon: makes the servo into a analog control position input rather than a pwm based one
10:05 AM AchiestDragon: psitonal acuracy then is equal to nos of bits on the dac in the uc ,
10:11 AM AchiestDragon: ho and how noisy the position sence pot is , but that affects all servos and is a pain
10:24 AM AchiestDragon: no dac then = 8bit buffered latch , and r2r ladder
10:27 AM AchiestDragon: and buffer i mentioned why youd be better with a dual 741 opamp rather than 2 separate ones http://www.androiderode.com/wp-content/uploads/2013/06/Ladder-ckt.png
10:28 AM AchiestDragon: play arround with value of Rf to get range correct and goodbye pwm
10:32 AM AchiestDragon: pwm was used because of the need to multiplex signals in a single chan radio control
10:36 AM AchiestDragon: and is basicaly pulse width to volatge conversion , limiting responce time down to pulse width period , but if you dont have a need to mux the analog in the first place you dont have to rely on converting it to pwm and back
10:46 AM AchiestDragon: saves you needing this to drive a servo with pwm if the servo has a analog input anyway https://cdn.instructables.com/FGN/8X56/GBF5KOQQ/FGN8X56GBF5KOQQ.MEDIUM.gif
10:47 AM AchiestDragon: and can reduce overall power consumption
10:47 AM AchiestDragon: a fraction
11:21 AM Phreaked: does anyone have access to a copy of ARM Development Suite 1.2, by chance?
08:04 PM Tom_L: yay, parts are starting to show up
08:04 PM theBear: here's some parts for yer... https://imgur.com/a/P3lMr bear-parts that is !
08:04 PM theBear: also bare ones
08:06 PM Tom_L: not you was it?
08:06 PM Tom_L: you should really take better care of yourself
08:06 PM theBear: yerp.. and that's why you <refer to comments below image> or err, never do that, you get the idea...
08:07 PM theBear: how was i to know that was gonna happen after 10 minutes of fuel dripping outta the front of a carb and bubbles not drawing fuel into the thing and generally just being unimpressed with my buddies new toy :)
08:08 PM Tom_L: if there was just two, i'd say that looks like an entry / exit wound
08:09 PM Tom_L: of the heavy metal kind
08:10 PM theBear: heh indeed... i didn't even notice the 2nd one until thismorning when i was near a mirror without a shirt.... when it happened i could only see the little one with my shirt lifted up, so i had to act tough cos my buddy had one like my big one on his front
08:11 PM theBear: but suffice to say, neither of us, or a couple luckier observers, could have been more surprised at the time
08:11 PM theBear: last thing we woulda expected to happen next :)
08:24 PM rue_bed: theBear, you didn't get impailed again did you?
08:25 PM rue_bed: theBear, how DO you do it?
08:30 PM theBear: rue_bed, c'mon maaaaaan, how was i to know the damned little centrifugal plastic air-sucker inside the cheap power drill was gonna blow out the entire rest of the casing and spit bits of itself all over the place ? i was busy choking up the air-hole end of a little dumb 2stroke carb and pumping a gas-pedal behind me as appropriate
09:00 PM rue_shop3: dude, if your going near something that can explode or fall over, its gonna do it.
09:00 PM rue_shop3: :)
09:02 PM theBear: yeah, but i didn't really consider a fairly average mains single-speed gearbox kinda power-drill to be something that can explode, until a couple days ago :)
09:02 PM rue_shop3: I wonder if you can make a court case out of it
09:03 PM rue_shop3: "explodes when..."
09:03 PM rue_shop3: :( the project box I left printing yesterday curled all up on me
09:03 PM rue_shop3: waste of plastic
09:04 PM rue_shop3: dusty table
09:04 PM theBear: heh, think yer'd have to track down some several-noname-rebrand-stickers up the line factory deep in the land of no-westerners-come-here china town to even know who to accuse of this one
09:04 PM rue_shop3: I forget that if the printer hasn't been used in 3 days I need to clean it
09:05 PM rue_shop3: did I tell you about my 3db line amp, usb powered?
09:05 PM theBear: umm nup, what kinda line does it amp ?
09:06 PM rue_shop3: line level amp
09:06 PM rue_shop3: +3db
09:06 PM rue_shop3: I keep needing a bit more signal on things
09:08 PM theBear: yeah, but what is goin up the line ? i erring towards guessing some kinda maybe differentialised serial ? audio sure ain't something i see you bothering to boost a meager threshold of objective human audible difference in level, and certainly not with a usb 5v for a psu :)
09:13 PM rue_shop3: no, audio
09:13 PM rue_shop3: line level audio, 600 ohm
09:13 PM rue_shop3: the powered speakers I have keep needing more signal, the speakers in this monitor are pathetic
09:13 PM theBear: wowee ! how very traditional and quasi-standard-followey of you ! 600ohm is the OL' SKOO' bid'nit ;-)
09:14 PM rue_shop3: ?
09:14 PM rue_shop3: isn't all line level stuff 600 ohm?
09:14 PM rue_shop3: rca
09:16 PM theBear: what, like hifi stuff ? maybe in olden-times, these days it's all basically just high-impedance-ish opamps with maybe a resistor or two (maybe even a ac-coupley cap if it a bit fancy) between them and the outside socket/world
09:16 PM rue_shop3: tablet -> speakers
09:16 PM rue_shop3: and a computer -> monitor
09:17 PM rue_shop3: and others, but I cant remember
09:17 PM theBear: 600 was certainly common in the olden times with big old discrete transistor balanced/diff inputs on mixers and such, and with yer passive (which are the only kind that should ever have existed, sif you replace a perfectly foolproof transformer with a silly phantom powered electronic breakdownable blowuppable clippable stupid circuit !) di boxes and things like transformer couple dynamic microphones
09:17 PM rue_shop3: +3db is enough to make them workable, otherwise, its maxing out all the volumes and sitting close
09:18 PM rue_shop3: one of the articles I saw said that line levels are between 100-600
09:18 PM rue_shop3: I thought they were 1k
09:18 PM theBear: mmm, 3dB in voltage/signal land works out to double "power" for a given load impedance, which is a good bump in voltage land, even if it is only just enough for a human ear to reliably detect as louder/quiter than another sound was
09:19 PM theBear: 1k is a high impedance opamp and a resistor or two <grin>
09:19 PM rue_shop3: not 3dbm
09:19 PM rue_shop3: 2x, 3db
09:19 PM rue_shop3: but what V is 0dbm at 600R?
09:20 PM rue_shop3: blackie2:/tmp# ohm -p 0.001 -r 600
09:20 PM rue_shop3: Wattage is: 0.001000
09:20 PM rue_shop3: Current is: 0.001291
09:20 PM rue_shop3: Voltage is: 0.774597
09:20 PM rue_shop3: Resistance is : 600.000000
09:20 PM rue_shop3: vp
09:20 PM theBear: but with anything younger than me it's pretty much always voltage based electrically, even with 10 or 100k if yer "0dB" signal level (in rms) is 0.775v it takes a lotta cable and a lotta noise to be an issue, and all yer domestic/non-stage kinda stuff that doesn't use balanced signals anyway is always just a few inches away, maybe a half a tv width at most...
09:20 PM rue_shop3: .55Vrms?
09:21 PM rue_shop3: ah ok
09:21 PM theBear: i dunno maaaan, it's sat morning and i in no mood for mathering
09:21 PM theBear: howbout you math it up, and i'll trust your results <wink>
09:21 PM rue_shop3: it came up with 0.774597, you said .775, this sounds like the same number to me
09:22 PM rue_shop3: but aparantly 'line leve' stuff will go to 2V
09:22 PM rue_shop3: +2db, I think
09:22 PM rue_shop3: about?
09:23 PM rue_shop3: I was under the impression 1V, which is close to .775, so it sounds like a lack of standards understanding in the general modern world
09:24 PM theBear: mmm, and that's NEVER followed anything like accurately... think about every hifi or tv or whatever domestic volume knob you ever seen or turned, and where it is at maybe 1/10th of max (degrees-of-turn wise) when you already got roughly the gain to make yer .775vrms = just clipping output stage on the peaks... it makes sense so ya know, crappy old tapes and ancient stylus/heads on spinny disc players can be adjusted to a sensible listening level,
09:24 PM theBear: but yer certainly don't gotta worry much about staying too close to it
09:27 PM theBear: hmm, is 1v maybe +3dB past that ? ifyou keep mathing higher past there, you'll notice yer classic +-12v and even 15 and 18v opamp rail voltages you see in "all audio anything everywhere since tubes were common" workout to things like +10 or maybe 12, 15 and 18dB above that .775v, which is what the sales-jackasses marketing brand-name pro-audio gear would use to boast about how their product was better than the competitor ... "oooh look, +18dB
09:27 PM theBear: outputs with all the little leds in the vu-dept to prove it ! this must be the superior product !" course in turn you find over the years that big proaudio poweramps gained themselves down more and more to the point where you pretty much need a whole +-15v swing give or take to get them anywjhere close to clipping/full outpuit :-)
09:31 PM rue_shop3: hmm
09:31 PM * rue_shop3 recalls adjusting the tape recordings till they were about 0db
09:35 PM theBear: yeah, but you forget just how far above the average jackass you are in almost every quantifiable way !
09:36 PM anonnumberanon: such disdain
09:37 PM theBear: yep, even that, rue's superior in every aspect from disdain to oxymoronishness :)
09:53 PM * rue_shop3 looks at the sentence upside down to try to draw a ruling on it
09:54 PM * rue_shop3 goes back to trying to find caps for another amp
09:57 PM rue_shop3: I wonder if I should worry that I'm pulling these out of floppy drive circuit boards dated 1990
09:58 PM anonnumberanon: it's your job to worry so don't worry, you're already worried anyways
10:23 PM Tom_L: rue_shop3, naw... i really don't think you'll be using those floppies any time soon :)
10:26 PM * rue_shop3 pulls his hare and screams WTF ARE THERE NO 0805 2.0K RESISTORS ON ANY OF THE CIRCUIT BOARDS IN THIS SHOP!!!!
10:30 PM rue_shop3: were not talking just a few boards either
10:31 PM * Tom_L looks over at Mt. Ruebius in awe
10:40 PM rue_shop3: arg, I cant find _4_ 0805 2.0k resistors
10:40 PM rue_shop3: THIS IS STUPID
10:40 PM * Tom_L looks over at his pile of em
10:40 PM rue_shop3: I might throw the gain and use 2.2k
10:46 PM rue_shop3: found them!!!!
10:46 PM rue_shop3: wow
10:46 PM rue_shop3: insane
10:47 PM rue_shop3: I ordered 1000 from china
10:47 PM theBear: woah ! dare i suggest you're over-reacting due to high emotions ?
11:07 PM z64555: just give it a few weeks, and he still won't be able to find em. :D
11:15 PM rue_shop3: ok, second pcb is made
11:16 PM rue_shop3: p.s. ` i really don't think you'll be using those floppies any time soon ` thats good, I stripped them apart :)
11:17 PM rue_shop3: unfortunatly the parts took up as much room as the drives did, high yield stuff
11:18 PM Tom_L: rue can you print something 6.5" wide?
11:19 PM rue_shop3: 16.5cm standard table is 20cm
11:19 PM rue_shop3: in theroy, yes
11:19 PM rue_shop3: my new machine is actually larger than 20cm, but it dosn't know it
11:20 PM rue_shop3: ok lets see how long it takes rue to find a USB A socket, start your watch...
11:20 PM rue_shop3: sorry, B socket
11:28 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/Z_Pulley_Guard.JPG
11:28 PM Tom_L: something to that effect
11:30 PM SpeedEvil: On an unrelated topic.
11:30 PM SpeedEvil: https://twitter.com/RocketJoy/status/936785051643125762
11:30 PM SpeedEvil: Elon Musk is sending his car to mars in (probably) January
11:32 PM rue_shop3: got it
11:33 PM rue_shop3: how about I spot weld one up for ya
11:33 PM theBear: here's some homegrown sillyness for yer mr rue, i think you one of the few out there that will appreciate it ... https://www.youtube.com/watch?v=qnZ75xQUSpM&feature=youtu.be&t=8
11:35 PM Tom_L: i can weld one up
11:36 PM Tom_L: just thought it might be easier to print one
11:36 PM Tom_L: the details of that part won't be apparent for a while anyway
11:36 PM rue_shop3: spot weld tho
11:37 PM Tom_L: don't have one
11:37 PM Tom_L: maybe cut one from aluminum :)
11:40 PM rue_shop3: casnt youtube here now
11:41 PM Tom_L: oh
11:41 PM Tom_L: how much do i dare remove using a reamer?
11:41 PM Tom_L: .020" too much?
11:41 PM Tom_L: i think .005 to .010 is better
11:43 PM rue_shop3: oh I'm not sure
11:43 PM Tom_L: 2-3% one site says
11:44 PM Tom_L: so if it's .375 what's 2% of that?
11:44 PM rue_shop3: 805-24
11:44 PM rue_shop3: what size is the reamer?
11:44 PM Tom_L: 10mm
11:45 PM anonnumberanon: SpeedEvil, wait twf
11:45 PM anonnumberanon: wtf
11:45 PM Tom_L: from 3/8" hole
11:45 PM Tom_L: i can drill it first but i didn't really want to
11:45 PM rue_shop3: 3/8" reamer?
11:45 PM Tom_L: no 10mm reamer 3/8" hole
11:46 PM rue_shop3: if the answers in this machinists handbook, I cant find it
11:46 PM Tom_L: .375 vs .393
11:47 PM Tom_L: around .020"
11:47 PM rue_shop3: nope, no idea
11:47 PM Tom_L: http://www.gammons.com/use-of-reamers
11:48 PM SpeedEvil: anonnumberanon: yes
11:48 PM Tom_L: The usual practice is to ream from 0.004 to 0.012 inches on diameter
11:48 PM Tom_L: which is about what i said
11:48 PM Tom_L: so i should drill it first i suppose
11:51 PM anonnumberanon: SpeedEvil, it can orbit Mars for a billion years or what?
11:52 PM anonnumberanon: I don't get it lol.
11:53 PM SpeedEvil: In principle, it could be placed in a stable mars orbit
11:54 PM anonnumberanon: cause i thought things in orbit go down after a while
11:55 PM anonnumberanon: anyway what a poor use of cargo he should sand a bulldozer and land it on mars to dig a hole until water comes out
11:55 PM anonnumberanon: humanity is so slow at doing the right thing
11:56 PM anonnumberanon: in any case this is cool enough that I will not complain this time around