#garfield Logs

Nov 22 2020

12:10 AM rue_mohr: Tom_L,
12:16 AM rue_mohr: images
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180086.jpg
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180087.jpg
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180088.jpg
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180089.jpg
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180090.jpg
12:16 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180092.jpg
12:35 AM rue_mohr: Tom_L, ??
10:00 AM rue_mohr: ?
10:00 AM rue_mohr: oh heh
10:00 AM rue_mohr: sorry, still sleepy
10:17 AM Tom_L: looks like they turned out nice though
10:18 AM rue_mohr: yup, it would help if I made a vac. deck
10:18 AM Tom_L: how did you know the hole centers etc?
10:19 AM Tom_L: did they give you a blueprint or such
10:20 AM Tom_L: my vac bearing started whining
10:20 AM Tom_L: i think the coolant got to em a bit
10:23 AM rue_mohr: they gave me some numbers
10:23 AM rue_mohr: the big ones came with a layout
10:24 AM rue_mohr: see if its siezed
10:24 AM rue_mohr: sometimes their just bushings anyhow
10:24 AM rue_mohr: nothing like finding its been spinning a bearing for the last year :)
10:24 AM Tom_L: i took it apart and put some vactra 2 on the bushing
10:24 AM Tom_L: it's fine now
10:24 AM rue_mohr: :)
10:26 AM Tom_L: should get my wheels in this week i'd think
10:26 AM rue_mohr: 4 winter?
10:26 AM rue_mohr: I need more sleep, reflux woke me up early today
10:27 AM Tom_L: green grinding wheel
10:27 AM rue_mohr: I need to studdy for test tommorow
10:27 AM rue_mohr: I think
10:27 AM rue_mohr: ah yea
10:37 AM rue_mohr: the internet is getting too much junk
10:38 AM rue_mohr: getting harder and harder to find REAL schematics and not just educational jabber when looking for a circuit
11:13 AM rue_bed: rue_mohr, "603" = 2sc2603
11:14 AM rue_bed: "115" = 2sa1115
11:16 AM Tom_L: he went back to bed already :(
11:40 AM rue_bed: WHAAAAT
11:40 AM rue_bed: wait
11:40 AM rue_bed: it looks like you can disable an op-amp by pulling UP on the offset nulls!?
12:09 PM rue_bed: huh, ok, chips from china just dont get cheaper than about $10/100
12:14 PM polprog: rue_bed: what was that exam you took about?
12:14 PM polprog: gonna get sparkie certification?
12:37 PM rue_mohr: its a 10 week program for the last year
12:37 PM rue_mohr: I'm at about 5 weeks now
12:59 PM rue_shop1: damn, I only know the power pins for a LM741 off the top of my head
12:59 PM rue_shop1: or are inputs 2 and 3
01:59 PM rue_shop1: ...
01:59 PM rue_shop1: if an lm741 has a GBP of 1Mhz, ...
02:00 PM rue_shop1: why does this buffer start attenutating like crazy at like 100khz
02:03 PM rue_shop1: I need a different idea
02:03 PM rue_shop1: I mean, I have things that works
02:51 PM rue_mohr: hmm, whats a hundred of tl082 worth
02:52 PM rue_mohr: $14 the ne5532 is cheaper... huh
02:53 PM rue_mohr: the tl072 isn't much less
02:54 PM rue_mohr: tl074 is about the same
02:55 PM rue_mohr: oh weird
02:55 PM rue_mohr: the tl084 is lower than them all
02:55 PM rue_mohr: well, might just be 1 seller
02:56 PM rue_mohr: I cant just have a small circuit eh?
02:57 PM rue_mohr: 4Mhz, which would be ok
07:17 PM rue_shop1: bah
09:14 PM rue_mohr: some success tho
09:14 PM Tom_L: success is good
09:15 PM rue_mohr: I have a lot more signal, but also a lot more pointless coils
09:15 PM rue_mohr: I'll try another one later
09:26 PM rue_mohr: https://twitter.com/RueNahcMohr/status/1330712703988494338
09:27 PM rue_mohr: thats why I want a triangle wave, the output is a square wave, which is really easy to grab the value of
09:27 PM rue_mohr: no messing with peak values and filters
09:28 PM Tom_L: what are you sliding thru the tube? iron?
09:31 PM rue_mohr: you know those ferrite beads with the jumper thru them?
09:31 PM rue_mohr: it has to not quench high freq
09:35 PM rue_mohr: the other one was 0-5V over 0.2inches, after the amp
09:49 PM rue_mohr: there is also a trick for a differential capacitor
09:50 PM Tom_L: early radio tuners were variable caps
09:50 PM rue_mohr: yes the trick is opposing differential ones
09:50 PM rue_mohr: a "dual throw" capacitor
09:52 PM aandrew: rue_mohr: so you're finding squarewave excitation is better than triangle now?
09:53 PM rue_mohr: I integrated the square wave
09:54 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1180108.jpg
09:54 PM rue_mohr: I let the integrator slip upwards
10:02 PM aandrew: er
10:02 PM aandrew: oh that is the input to the integrator and the output of the LVDT secondary, not the signal going to the LVDT primary
10:06 PM rue_mohr: correct
10:14 PM rue_mohr: I really thought the tight coupling of the middle coils would give me mor
10:14 PM rue_mohr: e
10:14 PM rue_mohr: I'm driving almost 100mA
10:14 PM rue_mohr: technically 91
10:15 PM rue_mohr: 90.9
10:15 PM rue_mohr: 90.909
10:15 PM rue_mohr: 90.90909
10:15 PM rue_mohr: 90.9090909
10:15 PM rue_mohr: 90.909091
10:15 PM rue_mohr: 90.9091
10:17 PM rue_mohr: oops, I forgot the resistor value for the cap bypass
10:17 PM rue_mohr: ... no wait I took that resistor out
10:17 PM rue_mohr: ugh
10:27 PM aandrew: hey rue_mohr I have a question for you
10:27 PM aandrew: this is a philosophical thing
10:28 PM aandrew: you spend almost all the time you have away from work and chores tinkering with all kinds of cool stuff, mostly electronic
10:29 PM aandrew: If you had a job doing electronic design (say as an analog guru at some company) ... do you think you'd still want to tinker on your own stuff?
10:30 PM rue_mohr: nope
10:30 PM rue_mohr: I been there a while
10:30 PM rue_mohr: you just end up burnout out on it
10:30 PM rue_mohr: as soon as there is someone looming for a result, its not fun
10:38 PM aandrew: *nods*
10:38 PM aandrew: you're a smart man
10:38 PM aandrew: keeping your hobbies hobbies.
10:39 PM aandrew: I did not do that, and find i tend to do nothing with my hobbies becuase at the end of the day I don't want to work on something like them
10:40 PM rue_mohr: at the same time, the minor crossover is neat
10:41 PM rue_mohr: being able to locate a 5V test point on a controller board to know if its regulator is atleast working
10:45 PM aandrew: one of my favourite tricks was injecting a constant-current into a shorted net and "walking around" the board to find which component the short was in/under
10:45 PM aandrew: although with enough current this can become self-clearing. :-)
10:46 PM rue_mohr: ;)