#garfield Logs

Jul 05 2015

00:04 rue_shop3 wow
00:04 rue_shop3 the world is being overrun with bot created web pages that make no sense at all
00:04 rue_shop3 and the bots are using google, which is why none of the completions make sense anymore
00:16 rue_shop3 kat, you have a copy of a manual for a micronta 22-8230 supply?
00:17 any16403519 no
00:17 any16403519 there's schematics for some of the Tek and hp supplies tho
00:17 rue_shop3 tek made power supplies?
00:18 any16403519 this may be a grand scheme for you to use an h-bridge output, switcher to the top to make voltage and the bottom to current limit
00:18 any16403519 yeas
00:18 rue_shop3 did tek make power supplies as good at their scopes?
00:18 any16403519 TM50x and TM500x series and some regular free-standing units
00:18 any16403519 yeas
00:19 any16403519 the TM500x series are 488 buss controllable
00:19 y16403519 has schema
00:20 any16403519 PS series
00:20 rue_shop3 :/ ok, I just failed to find it, I'm going to go back to base and start again, I'll bookmark you have the info..
00:21 any16403519 i just looked, i have tek PS501, PS503a, and PS505 schematics
00:24 any16403519 i have owner-operator-tune data on the PS280, PS2520, PS5004, PS5010, but no schematcs for them
00:39 rue_shop3 figuring out the micronta schematics
00:39 rue_shop3 I did, with errors
00:39 rue_shop3 the things that dont make sense are pointing out where I made transfer errors
00:39 rue_shop3 :)
00:45 rue_shop3 this supply uses an op-amp to regulate votlage, and the output of it is grounded out by a transistor if the gate votlage is more than the emitter votlage
00:46 any16403519 ok
00:46 rue_shop3 which explains the anomolies as I think they cant snub the output enough when the votlage is low
00:46 any16403519 [22:36] <any16403519> or,, and this is cheating, make conventional adjustable current sense , use that signal to clobber the voltage feedback, just make sure that if the Cfeedback kills the Vfeedback signal that no smoke is released
00:47 rue_shop3 sorry, kinda thinking aloud
00:47 rue_shop3 I'm studdying the micronta bench supply I have
00:47 any16403519 yeas, and you found a current limit transistor that kills the voltage regulator opamp
00:47 rue_shop3 I had to fix it once, and reverse engineered out the schematic
00:47 rue_shop3 but it didn't make any sense
00:47 rue_shop3 since then, I'm working out what they are doing
00:48 rue_shop3 the controller floats above the + output rail
00:49 rue_shop3 I want to understand what these guys are up to
00:55 rue_shop3 ah, yea
00:56 rue_shop3 they ignored another design problem
00:56 rue_shop3 the transistor drive current dumps into the load
00:56 rue_shop3 so, you cant get the output current for less than the drive current
00:56 any16403519 [23:10] <any09109744> "when i said 'how do you account for...." did yu say
00:56 any16403519 [23:10] <any09109744> "don't just ignore it"or
00:56 any16403519 [23:10] <any09109744> "don't , just ignore it" ?
00:56 any16403519 hence darlingtons or mosfets
00:57 rue_shop3 iirc, I last decided to use the P channel mosfets I got
00:57 rue_shop3 all the drive current goes into the supply..... you know what I mean
00:57 any16403519 darlingtons will give you 20amps with only milliamps of error
00:58 rue_shop3 I'm still window shopping :)
00:58 any16403519 20amps with 10ma of drive is only 1/2000 error
00:58 rue_shop3 the supply is 30V 5A
00:58 rue_shop3 (x2)
00:58 any16403519 k
00:58 rue_shop3 linked grounds
01:00 rue_shop3 I dont get how this supply is so stable tho
01:00 rue_shop3 maybe the gain on the shutdown transistor is low
01:01 rue_shop3 100pf compensation cap
01:02 any16403519 i suspect a RC somewhere too
01:03 rue_shop3 votlage feedback is a lowpass T with 1k and 10uF
01:38 rue_shop3 there is 8V overhead between its voltage error amp and the last driver transistors output
01:49 any16403519 ok
01:50 any16403519 that is to account for opamp output swing under load, and various Vbe drops, and maybe the current sense resistor drop too
01:50 rue_shop3 so, what are diferences between using a transistor (base, emitter) vs a comparitor for checking the limit (asside from current)
01:52 any16403519 transitor is usually linear, a comparator is usually used with a digital output
01:52 any16403519 limit/no_limit digital
01:53 any16403519 comparator has gain, usually lots of it, and many have true and not-true outputs
01:53 any16403519 some have very low input thresholds and are bloody fast
01:54 any16403519 transistor will come on tween .55v and .65v, and maynot saturate till .75v
01:54 any16403519 transistor base requires current
01:54 any16403519 comparator may have input resistance of megohms
01:55 any16403519 comparator is physically larger than a sot transistor, simply because transistor is only 3 leads
01:57 rue_shop3 hm
01:57 rue_shop3 maybe its the low gain that helps it all not oscillate on current cutoff
01:58 rue_shop3 so then, can I use a amp with a gain of 1 as a comparitor
01:58 rue_shop3 that question didn't form right
01:58 rue_shop3 and I need supper
01:59 any16403519 Boundry Dam in Sask..wan is pumping CO2 undergound? where is a dam getting CO2?
02:01 rue_shop3 sounds like a environmental idea, like tire reefs
02:02 any16403519 sounds like an explosion to me, high pressure air underground? like a balloon?
02:02 any16403519 <pop>
02:02 any16403519 then everyne downwind dies
02:04 rue_shop3 part of the votlage feedback challange is to not have the gain go all over the place when you adjust the reference,
02:06 any16403519 research 2014 : HIV was first sampled in blood in 1959 in the Congo
02:07 any16403519 they calculated it originated in the late 1800's , possibly 1884 , but was in the general population for sure in 1922
02:07 rue_shop3 on this supply they did it by keeping the ref at 6.33V and setting up the output to effectivly generate a negitive voltage to counter against the ref
02:08 rue_shop3 I might pull that off if I use a negitively biased pull for the feedback votlage
02:09 any16403519 i fail to understand why the gain must go all over the place when you adjust the Vref
02:09 any16403519 your error and gain is on the (-) input, the Vref is on the (+) input, no crosstalk going on there
02:10 rue_shop3 say you set ....
02:10 rue_shop3 if....
02:10 rue_shop3 if your + input is hooked up to a pot as a control signal
02:10 rue_shop3 and your - goes to your output divider
02:10 any16403519 ok
02:11 rue_shop3 the .....
02:11 rue_shop3 I'm trying to remember how this problem works, at low voltages, you get oscillation
02:11 rue_shop3 but the system is stable at high voltage
02:11 rue_shop3 s
02:12 any16403519 i bet some input voltage is going outside the datasheet
02:13 rue_shop3 I'v had this problem with every op-amp voltage regulator I'v ever made
02:13 rue_shop3 the stability varries with output voltage
02:13 any16403519 are you making enough base drive?
02:14 rue_shop3 I dont recall the information for everything I'v ever tired
02:14 rue_shop3 I just know this to be an issue
02:14 any16403519 k
02:15 rue_shop3 then again, I'v only recently (few years) about the common mode voltage range for the op-amps, and how crumby it is for most of them
02:16 rue_shop3 so I might have been too close to the rails for what I was making
02:16 y16403519
02:16 any16403519 i try to stay 3v away from them
02:17 any16403519 if you pullmore than 10ma from one, doublecheck the datasheet for Vout under load
02:17 rue_shop3 to make matters more ugly, the DAC I have centers its output at 2.5V
02:17 any16403519 gotta use +/- supplies, even if it's unbalanced, like +15/-5
02:18 rue_shop3 I got some "rail to rail" op-amps, I can get within about 20mv
02:18 rue_shop3 not that I should push it
02:19 any16403519 and prolly not under a load
02:19 any16403519 like 20mv with a 10k load
02:20 any16403519 not even 1ma
02:31 rue_shop3 now I know I'm losing it
02:31 rue_shop3 to make a voltage divider with a gain of 1/12
02:32 rue_shop3 1k and ...
02:32 rue_shop3 11k?
02:33 any16403519 it's 2m, my brian isn't werking, sory
02:33 rue_shop3 say, 12V feed
02:33 rue_shop3 1k on bottom 11k on top
02:34 rue_shop3 so the current is 12/12k
02:34 rue_shop3 and the bottom resistor is 1k*(12/12k)
02:34 rue_shop3 and the bottom resistor is 1k/1*(12/12k)
02:34 rue_shop3 and the bottom resistor is 1/1*(12/12)
02:35 rue_shop3 and the bottom resistor is 1*(1)
02:35 rue_shop3 1
02:35 rue_shop3 ok
02:35 rue_shop3 1V
02:38 rue_shop3 damn I missed
02:42 rue_shop3 heh, I cant design a DC amp thats got an input range from 1.2 to 3.7 and an output range of 0-30
02:42 rue_shop3 I'v worked out the gain to be 12
02:47 any16403519 told ya, use a small to-220-ish audio power amplifier module, it can handle the volts and the 2amps
02:48 any16403519 or use a begger module
02:48 any16403519 bigger
03:06 any16403519 http://www.vexrobotics.com/gears.html
03:16 any16403519 "kills bugs on contact" "but the bugs don't get inside to the contact" "so you need a spray that kills just in case?"
03:17 any16403519 "it's a metal case" "you need a bugspray that kills in case of metal?
03:17 any16403519 "what is this, Terminator?"
03:27 any16403519 ok, gnite
21:37 any69168222 If a partition disappears � one that a particular computer could see before
21:37 any69168222 1. Power off the computer and SC101 as described in �Power off and restart your network in this order�.
21:37 any69168222 umm, no
21:39 any69168222 2 minutes to go, $25 , 2 drive bays, but you gotta put upwith shutting OFF your puter if itloses contact witht eh nas boxhttp://www.ebay.com/itm/Neatgear-SC-101-NAS-Storage-2-bays-PATA-IDE-EIDE-/161726494483
21:39 any69168222 2 minutes to go, $25 , 2 drive bays, but you gotta put upwith shutting OFF your puter if it loses contact with the nas box ==>> http://www.ebay.com/itm/Neatgear-SC-101-NAS-Storage-2-bays-PATA-IDE-EIDE-/161726494483
22:13 any69168222 ======
22:14 any69168222 i-Cub was given a virtual version of itself, which it runs in parallel to ther eal world, and can cmpare the expected behavior in the VR to itself in the real
22:14 any69168222 ======
22:47 any69168222 rfid tags for all your stuff, so burglars can know where your stuff is before they break in
23:33 rue_shop3 hi kat
23:33 any69168222 hi rue
23:34 rue_shop3 uh ho, they figured out the dual reinforced conciousness
23:34 rue_shop3 its amazing how much the relative humidity varries
23:35 y69168222
23:35 rue_shop3 I'm still regulator challanged
23:35 any69168222 funky google front page
23:36 rue_shop3 loosk normal
23:36 rue_shop3 so the trick is to not overload the op-amp and to stay off the rails
23:36 rue_shop3 so,
23:37 any69168222 "usa and japan are each in the top two highest ranked teams" ,, well duh, be a heck a trick for there to be 3 teams in the "two highest ranked teams"
23:37 rue_shop3 :)
23:39 any69168222 http://www.washingtonpost.com/news/speaking-of-science/wp/2015/06/30/the-worlds-most-beautiful-greenhouses-are-underwater-and-growing-strawberries/
23:56 rue_shop3 cool
23:56 rue_shop3 thermally that is,
23:56 rue_shop3 warm for water
23:58 any69168222 not sure how they get enough sunlight, but it is noticeably awefully bright near the equator