#garfield Logs

Dec 03 2013

00:10 rue_shop2 I missed bedtime again
00:10 rue_shop2 arg
00:11 rue_shop2 kat, what op-amp can I use as a line driver for a 5V signal?
00:11 katsmeow-afk almost any, depends on the speed and current needed
00:11 rue_shop2 741 386 311 071 081
00:11 katsmeow-afk yeas
00:12 rue_shop2 its a 300' circuit to an elevator carrige
00:12 rue_shop2 the open collector circuit on it now isn't happeneing
00:12 rue_shop2 maybe i should use a max232
00:12 katsmeow-afk twisted pair?
00:12 rue_shop2 hell no
00:12 rue_shop2 its an elevator cable
00:13 rue_shop2 oh wait, its a shielded 2c
00:13 katsmeow-afk so non-twisted pair? or single ended unbalanced?
00:13 rue_shop2 but I have 2 signals to transfer thru it
00:13 rue_shop2 single ended
00:13 rue_shop2 not many options, its an elevator cable
00:13 katsmeow-afk err,, 2 singles in a biax?
00:13 rue_shop2 yea
00:14 katsmeow-afk two signals, in bi-ax,, well, drive it at both ende differentially, using the coax as return on both, but you will still get interference
00:14 katsmeow-afk can you send one signal, wait, then send the otehr signal?
00:15 rue_shop2 hmm I have the sneaking suspicion I have a static electricity problem with metal parts of my boiler system
00:15 rue_shop2 the temp chips keep doing strange things
00:15 rue_shop2 oh, wow, hello, the firesheds temp goes way up when the house circ pump comes on
00:15 katsmeow-afk ground loop, you gotta differential those ling lines
00:15 rue_shop2 no, its clock/data for a card reader
00:16 rue_shop2 its the elevator to the mental unit, its got a card reader
00:16 katsmeow-afk is it one day, or two way?
00:16 rue_shop2 depends if you have a card or not :)
00:16 katsmeow-afk heh
00:16 rue_shop2 ... you have to have a card to get IN...
00:16 rue_shop2 trikes me as strange just now...
00:17 katsmeow-afk if it's clock and data both from the reader, i'd try to make a bipolar signal so clock is negative and data is positive,, or i'd use tones (one for clk and one for data)
00:17 rue_shop2 a temp sensor glitched and now its reading 60c low
00:17 rue_shop2 oo, hmm
00:18 rue_shop2 I think its only like 2400 baud
00:18 rue_shop2 I have to go to bed
00:19 rue_shop2 can static build up on isolated metal fittings of a boiler water loop?
00:19 katsmeow-afk i am wary of using that bi-ax as anything but a shielded twisted pair at 300ft
00:19 katsmeow-afk yeas
00:19 rue_shop2 huh
00:19 katsmeow-afk so can voltage drops in grounds
00:19 rue_shop2 I'll have to do a grounding excersize
00:20 katsmeow-afk i have seen 10v in a ground vs neutral
00:20 rue_shop2 I'v had a few sensors go screwball, like, more than bit errors in the serial
00:20 katsmeow-afk heck, i have seen volts in ground pins of two outlets in teh same room
00:21 katsmeow-afk ALWAYS isolate your signals from gnd and everything else
00:22 katsmeow-afk there is a reason why pata is limited to 18 inches, and why sata/usb exists
00:23 katsmeow-afk same reason i am optoisolating the t13, when you get that finished
00:24 rue_house :( I wanted to work on it today, I was trying to have the extender done for the hospital.... last monday..
00:25 katsmeow-afk can you put a 2-bit adc at the recieving end?
00:25 katsmeow-afk like using the t13 you are working on for me?
00:26 rue_house I dont think this cable is that signal-clean
00:26 katsmeow-afk use the open collector, fixed current sender you already have, but combine the signals to make a 3-bit binary analog in the elevator, send downt he twisted pair in the biax, then adc out the 2 or 3 voltage levels with the t13, you have enough pins to do it
00:28 katsmeow-afk driving the two conductors in the biax differentially will eliminate the outside interference in the cable , and floating the t13 to the boax shield will eliminate the interfence from the car itself
00:28 rue_house the card reader has open collector outputs and the controller has 2.2k pullups on 5V
00:28 katsmeow-afk can you steal anotehr of the twisted pair in another biax line?
00:29 rue_house there isn't one
00:30 katsmeow-afk then you need to electrically float one end of the reader line, either the reader int he car or the reciever, and use the biax like it's a shielded floating twisted pair
00:30 katsmeow-afk the elevator car has a 1/2hp motor, lites, etc, all tossing out random noise to the lines
00:30 rue_house yup
00:31 katsmeow-afk and the cable runs to the top of the shaft where the 50hp lift motor and controller lives
00:31 rue_house I came out of the initial diagnosis convinced that a totempole intermediate could tip the balance
00:31 rue_house hmmm...
00:31 rue_house no, hydraulic elevator, pump at the bottom
00:31 katsmeow-afk oh
00:32 rue_house across the 3 towns there are about 7 elevators, the new new building (6 stories!) just got the first cable driven one
00:33 katsmeow-afk well, this is no help : https://www.google.com/search?q="twisted+pair+two+channel+line+driver"
00:33 rue_house I was looking for my rs422/485 driver chips
00:34 katsmeow-afk option two: again with twisted pair differential: sampe the two existing lines, and mux each signal onto the the line, and demux at the otehr end
00:35 rue_house yea, I'm thiniking about muxign schemes
00:35 rue_house I wonder what the cable bandwidth is
00:35 katsmeow-afk or, cook up a schematic to put the clock negative and the data positive, muxed onto the twisted pair
00:35 rue_house you know, it IS clocked serial data....
00:36 katsmeow-afk i still WAY prefer the difefrential drive to cancel ALL the noise
00:36 rue_house if I just capture it at one end, push it thru in fixed baud over diff cable, and convert it back at the other end to clocked...
00:36 katsmeow-afk or use two tones, and fm them
00:36 rue_house I dont know enough about the baud rate and cable bandwidth
00:37 katsmeow-afk https://www.google.com/search?q=lm566+pll
00:38 katsmeow-afk that's PLL
00:38 katsmeow-afk for 2400 baud, sent a 50khz and a 70khz signal
00:38 katsmeow-afk sigla present = 1, no signal = 0
00:39 rue_house the reader is standard winegart
00:39 katsmeow-afk i don't care
00:39 katsmeow-afk you WILL need to change how it communicates if the link it's communicating over is screwing up the signal
00:40 katsmeow-afk a pcb with a 556 dual osc onit, or an avr and pwm osc ouptts, in the car
00:40 katsmeow-afk and two PLL at the reciever end
00:41 tsmeow-afk used L
00:43 katsmeow-afk http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=snosbq4d&fileType=pdf
00:43 rue_house :] no problem with datasheet supplies, thanks kat.
00:44 katsmeow-afk use a couple dtmf generators and recievers, if ya got em
00:44 katsmeow-afk 2 (or whatever) = clock pulse, 6 (or whatever) = data pulse
00:45 katsmeow-afk altho you will haveto run them up really higher than telco dtmf generators go
00:46 katsmeow-afk if you pic the right pairs, i think you can use one generator and one reciever
00:56 katsmeow-afk LM565
00:58 katsmeow-afk Tadya has 10 LM567 for $4 free s&h
00:59 katsmeow-afk Thai shine has 5 for $5 4day delivery free s&h
01:03 rue_house Ihave a drawr of them
01:03 rue_house and CD4046
01:03 katsmeow-afk use them?
01:03 rue_house if I remove tis SC415112FU chip from my foot, what functionality might I lose?
01:04 katsmeow-afk you will lean a littel to the otehr side for a while
01:04 rue_house hmmm
01:06 rue_bed better a qfp than a dip
01:06 katsmeow-afk http://www.smbc-comics.com/index.php?id=1946#comic
01:06 katsmeow-afk why? the LM5xx chips are good for only a Mhz anyhow
01:06 katsmeow-afk dip is fine at one Mhz
01:07 rue_bed hah
01:07 rue_bed (comic)
01:07 katsmeow-afk http://www.smbc-comics.com/index.php?id=1948#comic
01:07 rue_bed no I meant in my foot
01:27 katsmeow-afk http://www.smbc-comics.com/index.php?id=1991#comic
02:32 katsmeow-afk http://www.smbc-comics.com/index.php?id=2124#comic
04:38 katsmeow-afk the last Matrix movie came out in 2003 , so the end of 2013 makes it over 10 yrs old
06:58 katsmeow-afk http://www.smbc-comics.com/index.php?id=2349#comic
07:06 katsmeow-afk http://www.smbc-comics.com/index.php?id=2362#comic
08:36 katsmeow-afk www.foxnews.com/us/2013/12/03/woman-shot-dead-after-iron-bowl-game-sister-says-person-charged-was-upset-over/
09:17 rue_house that was 2003?
09:17 rue_house wow
12:45 katsmeow-afk .
12:45 katsmeow-afk i hate going to town when the humans are out
12:46 katsmeow-afk but TIL walmart has a ~3ft darth vade doll, or action figure, or robot, i am not sure, i didn't stop to look, but it was screaming for a couple dozen servoes to be installed into it
12:58 katsmeow-afk http://www.smbc-comics.com/index.php?id=2526#comic
16:22 rue_working zlog
18:28 rue_house "I extremely object to it following me calling me inate" "I think it needs to take a pee..." "OOOOOhhhhh..."
18:32 rue_house When the cats come in, I feed them canned food, one of them has figured out to go out, wait a minute and come back in, get food, then back out again...
18:36 Tom_itx and you fall for it every time?
18:37 rue_house happy to, that one never comes when called
18:42 katsmeow-afk lol
18:43 katsmeow-afk {psst: it's "innate", but that's not relavant}
18:43 rue_shop2 ta
18:45 katsmeow-afk humans stress me so,, and that truck is going to break my back again eventually,, arrrggggggggggggggggggggggggggggggggggggggggggg<cough>gggggggggggggg
18:46 rue_shop2 ? truck needs help?
18:48 any21908280 eiuty9pq346toqw84ytclw3i64yv938
18:48 any21908280 humans stress me so,, and that truck is going to break my back again eventually,, arrrggggggggggggggggggggggggggggggggggggggggggg<cough>gggggggggggggg
18:48 any21908280 i think the weather people are lying to me, the "record cold" Tom gets, we get here a couple days later, but they keep saying it's going to be above 50F all week, even the 70's the next couple days
18:50 any21908280 so is anyone running out to get a Darth Vader doll and a case of servos?
18:51 rue_shop2 .... not I
18:51 any21908280 too scarey for the cats, eh?
18:51 rue_shop2 :)
18:51 any21908280 your cats may be smart enough to train the robot, you should give them the chance
18:52 any21908280 that would be a hoot, and a heck of a research paper
18:52 rue_shop2 heh
18:52 rue_shop2 I'm working on "tap the food dish if you want food"
18:52 any21908280 won't work, they'll just talk about how stupid you are for not seeing the obvious, without the tapping
18:53 rue_shop2 it worked with the last cat
18:53 rue_shop2 be he was like 16
18:53 any21908280 they'll feel betetr about you if the tapping is on a lever that automatically gives food when you aren't tehre
18:53 rue_shop2 thats the upgrade later
18:53 any21908280 course, they'll wonder what they need you for then
18:54 rue_shop2 I'm the bed warmer
18:54 rue_shop2 and door access system
18:54 any21908280 ah
18:54 rue_shop2 and backup hiss when fending off the neighbour cat
18:55 any21908280 yanno, i find when i meow at the neighbors' cats, back before the dogs ate them, they do repeated visual scans at ground level
18:56 rue_shop2 hehe
18:56 any21908280 it's as if it's an auditory hallucinogen crossing to the occipital lobes,, and they cannot find me
18:56 rue_shop2 just your feet, the rest must be hiding somewhere
18:57 any21908280 "woah.. meowing people-feet"
18:58 any21908280 "i hear someone talking, but there's no cats there!"
18:59 rue_shop2 ok, none of the rs485/422 converters I have will work for this, I'm gonna try and bodge it with a rs232 buffer
19:00 y21908280 would still do a dual tone keypad inter
19:01 any21908280 your t13 can intercept the clk/data lines, trip the df chip to send out "1", "2", or "3", the reciever can decode the "?", tell anotehr t13, which outputs the clk/data to the existing reciever
19:02 any21908280 it's cheap, easy, clean, you can expand it many times over
19:02 any21908280 use a t44 if you wanna etch a pcb for expansions in advance
19:03 any21908280 and because it uses hf audio, on a balanced twinax that's also shielded, it's cannot be interferenced
19:03 any21908280 ideally, opto or transformer couple to the twinax
19:04 any21908280 "1" = clock high
19:04 any21908280 "2" = data high
19:04 any21908280 "3" = clock and data high
19:04 any21908280 etc
19:06 any21908280 or, on the same wire pair, you can run a two-wire ethernet line to the car, put a full laptop in the car with touchscreen, video, and microphone
19:07 any21908280 "uhhh, yea, it's a legit card swipe, but the person doing it is wearing a bloody straightjacket"
19:09 y21908280 notes that ethernet is the same balanced isolated two wire she has been propo
19:09 any21908280 but it may run at only 10M on that wire
19:09 rue_shop2 I want tto keep this as seimple as I can, if a max232 works, I'd rather that route
19:09 any21908280 even 1M may give you ok low-rez video, or audio
19:10 any21908280 ok
19:10 any21908280 being 232 is not balanced, i don't have tons of hope for it
19:10 rue_shop2 definitly taking the serial, pushing over twisted pair, and reconverting would be beter
19:10 any21908280 you have an unbalanced system now, and it's not working
19:10 rue_shop2 the open collector just barely worked
19:11 rue_shop2 if you swipe the card 30 times or so, it'll get it once
19:11 any21908280 ground bounce alone is enough to totally trash ttl on a non-isolated system
19:11 rue_shop2 if I could modify the reciever I'd try just bumping up the pullup resistor
19:13 y21908280 hands rue a TIP40-41 pair and a 741 to make a 4amp line dr
19:13 rue_shop2 hopefully its more forgiving, but I'd thought about it
19:14 rue_shop2 and a 7414 ont eh other end
19:14 any21908280 you may swamp the noise with more current, but i'd not do it that way
19:14 any21908280 to seriously swamp the noise, i'd use a 48v system, but then you have other issues
19:15 any21908280 real serial being +/- 12v, may be ok
19:15 rue_shop2 I think the open collector pullup just cant outpace the cable capacitance
19:15 any21908280 oscope it and see
19:15 rue_shop2 I'd like to
19:18 any21908280 ifit really is merely a matter of pullup current, interpose a totempole driver
19:18 rue_shop2 not getting involved, thats the max232
19:18 any21908280 k
19:19 rue_shop2 I dont have any of hte 74xx 50R line driver chips
19:19 any21908280 i meant like a quad opamp chip made for rail-to-rail on 5v circuits, put all the outputs in parallel
19:20 any21908280 or any quad opamp with a separate supply
19:20 rue_shop2 I didn't get to looking thru all the op-amps I have for hte one with the totempole ouput
19:20 any21908280 they all have totempole
19:20 rue_shop2 I know a bunch of the op-amps I have are open collector
19:20 any21908280 <blink> opamps??
19:21 rue_shop2 yea, seems every time I *just* grab one
19:22 y21908280 tosses rue a couple TL084/74/64/ MC3
19:22 any21908280 LM324
19:22 rue_shop2 I'd like to go with the max232 for now, I have a bunch
19:22 y21908280 not
19:22 rue_shop2 I like that they are made for driving cable
19:22 y21908280
19:23 rue_shop2 just looking at their line capacitance vs datarate charts
19:23 rue_shop2 they are good to 2.5nF at high baud rates
19:23 any21908280 i figure the opamps won't get hurt driving a dead short, so capacitance isn't a big problem
19:24 rue_shop2 are all those short protected?
19:24 any21908280 most are at some VCC below max rated
19:24 any21908280 besides, you will prolly use a series 10 or 20 ohm resistor anyhow
19:25 rue_shop2 I was thiniking orig, totem-> line ---> vdivider ----/\/\/\-- 7414->transistor
19:26 y21908280 shudders a
19:27 any21908280 it's all so............... dc-connected and still accepting of interference (like ground bounce)
19:28 rue_shop2 I think I'll get away with it, if not, its my next try
19:29 rue_shop2 hmm note to self, really low on 7805
19:29 any21908280 did you figure in the 300ft dc line resistance?
19:30 any21908280 got any TL431 ?
19:30 any21908280 or any LM317?
19:31 any21908280 eitehr one, you can drive the gnd ref pin very easily, and make a modulated current source
19:32 any21908280 300ft of 24awg is ~8ohms
19:32 any21908280 20ma drive is 0.16v drop
19:33 any21908280 anyhow, i hope you solve it
19:35 y21908280 occasionally uses a TL431 as a transistor with a precise fixed 1.2v
19:37 rue_shop2 I'm not disagreeing
19:37 y21908280 offes to shake rue's
19:37 y21908280 shakes the one holding the writing
19:38 rue_shop2 :)
19:38 rue_shop2 note to self, low on 16 pin dip sockets
19:38 any21908280 -----~~~~~~~~~~----
19:38 y21908280 saws off 2 pins from a dip-18 and hands it to
19:39 rue_shop2 I must have been plugging the 7805s into them
19:39 any21908280 what huh? 7805 into dip-16 sockets?
19:41 y21908280 grabbed 1320 dip-18 for $5.50 one
19:41 any21908280 if i cross my eyes, i can make them be 2640 dip-8 sockets
19:42 rue_shop2 ! did you get them!?
19:42 any21908280 yeas?
19:42 rue_shop2 wow
19:43 rue_shop2 THATS a lifetime supply
19:43 rue_shop2 I have almost that many 10 position dip switches
19:43 any21908280 wow
19:43 any21908280 wanna swap some?
19:43 rue_shop2 yea
19:43 rue_shop2 chipping sucks tho :/
19:44 any21908280 true
19:45 any21908280 really needs a cheap portland-to-van shipper
19:46 any21908280 if it floats out on the outgoing tide and back in on the rising tide, it's still only 24hr shipping, and almost free
19:48 rue_shop2 the island has a lot of stupid little islands on the end to get around
19:48 rue_shop2 "the island" = vancouver island
19:48 any21908280 yeas
19:49 any21908280 an avr, a sail, slow steam engine, gps on an arduino, etc
19:50 any21908280 the tech issues can be solved, i cannot solve the human issues at each end tho
19:53 y21908280 has been pondering is a "steam" engine can be slowed to a controlled stop at a calculated steady torque like a dc motor
19:55 any21908280 the interestng problem is when the engine is stopped, the expanding gasses in the cylinder begin cooling and contracting
19:56 any21908280 if the gasses cool enough to liquify, then the cylinder has liquid in it, and that liquid may not make it out the exhaust port before the piston makes the end of the stroke against the head, making immoveable things move
19:58 any21908280 ut if the steam engine can be made to operate with the same torque curve as a dc motor, it could make for an interesting hydraulic power source in a robot
20:00 Tom_itx 5v logic, 22k pulldown 2.5v threshhold. i need a pullup to overcome the pulldown
20:00 any21908280 22k would center it at 2.5v
20:02 y21908280 doesn't know how much you wanna pull it up to, or if that is even what you
20:03 any21908280 any ttl logic can overcome a 22k resistor, what are you driving with?
20:04 Tom_itx open collector that needs to be pulled high
20:04 any21908280 ah
20:05 any21908280 1k
20:05 Tom_itx 10k enough?
20:05 any21908280 10k is prolly enough
20:05 any21908280 1k is 1ma pullup at 4v, 1ma will swamp the 22k totally
20:06 any21908280 pulling the 1k to .5v is 4.5ma, again any ttl chip can do that
20:07 any21908280 i suspect you can go up to 4.7k to save power, depending a lot on speed and the chip input you are driving
20:08 any21908280 etc
20:08 any21908280 i am leery of real high impedances on ttl logic, i wouldn't go up to 10k
20:08 Tom_itx ok
20:30 y21908280 got zero sleeps last nite and 2 hrs today so may goto bed early to
20:45 Tom_itx worked. thanks
20:46 any21908280 <curtsey>
20:51 y21908280 goes to lay down to be warm and hurt less, but might sleep
21:30 rue_house hey now I can work on kats program
22:41 rue_house http://www.ebay.ca/itm/IIC-I2C-TWI-SPI-Serial-Interface-Board-Module-Port-Arduino-1602LCD-Display-TE-/121199913075
22:42 rue_house you didnt' want to operate the lcd display directly over a serial line did you?