#garfield Logs
Oct 26 2022
#garfield Calendar
02:51 AM polprog: rue_mohr: i couldnt sleep last night so i worked out how to measure the BH curve
03:02 AM polprog: ever done that?
03:36 AM polprog: i need a fast current source
03:36 AM rue_mohr: I need to make a bipolar tester
03:36 AM polprog: hi
03:36 AM rue_mohr: I'm just using Vt
03:36 AM rue_mohr: hi
03:36 AM * polprog hands rue_mohr a coffee
03:36 AM rue_mohr: I cant have coffee, I'm going to bed after this
03:37 AM polprog: ah
03:37 AM rue_mohr: :)
03:37 AM polprog: i forgot you have a phase shift
03:38 AM rue_mohr: heh
03:38 AM rue_mohr: so, no need on your side for a paramteric stock search eh?
03:38 AM polprog: no, not yet
03:39 AM polprog: so i was thinking about a board that has a pair of flying leads, a current source square wave and the integrator amplifier
03:39 AM polprog: and it has the E(t) and mu(t) outputs like in the pdf
03:40 AM polprog: so that you hook it up to the scope in xy mode and you get a BH curve
03:40 AM rue_mohr: I just need to know the shape and the saturation point
03:40 AM polprog: thats checkable too
03:40 AM polprog: i should put together the 3 rail power supply, its been sitting for a month now
03:41 AM polprog: but i have to finish thesis
03:41 AM rue_mohr: but I'd also like to arrange things so the area is part of the constant
03:41 AM rue_mohr: becasue you cant quite measure that right
03:41 AM rue_mohr: real world stuff creeps in and mauls the numbers
03:41 AM polprog: you dont need the area
03:42 AM rue_mohr: well
03:42 AM rue_mohr: the turns calc I have uses it for the royer
03:42 AM polprog: hm
03:42 AM rue_mohr: they use it to work out the freq
03:42 AM rue_mohr: right now the royer is my goal
03:42 AM polprog: its a different equation
03:43 AM rue_mohr: the royer is build around the saturation point
03:43 AM rue_mohr: so far, my royers have worked via transistor saturation
03:43 AM polprog: this tells you the mu(t) or the mu(phiB) [phiB = \int Edt ]
03:43 AM rue_mohr: of small transistors
03:43 AM rue_mohr: so they wont scale
03:45 AM polprog: from that you can figure out what the phiB (flux) is when it saturates
03:46 AM polprog: now the total field is the flux times area (assuming normal direction, so perpendicular to the plane)
03:48 AM rue_mohr: well see
03:48 AM rue_mohr: thats the thing, with the formula
03:48 AM polprog: if you use flux instead of the total field it then scales
03:48 AM rue_mohr: phiB and area are both things I dont know and dont care about, as long as I know what they are togethor
03:49 AM rue_mohr: and I can happily glob them into one constant
03:49 AM rue_mohr: which was my goal with that formula stuff
03:49 AM rue_mohr: but one of the dragons pointed out, that I need to make sure I'm not using just unipolar pulses to test the cores
03:49 AM rue_mohr: makes a difference of 2B
03:50 AM rue_mohr: I get the 3 of them mixed up
03:50 AM polprog: whats your formula for the royer
03:50 AM rue_mohr: growfly, uh, and ummmm
03:50 AM rue_mohr: dear god, 3136
03:50 AM polprog: phiB and area you can measure easily, one is the integral of E(t) and the other is well, area
03:51 AM rue_mohr: no I want the measured values under a test
03:51 AM polprog: wdym
03:51 AM rue_mohr: hold on, searching
03:52 AM rue_mohr: https://twitter.com/RueNahcMohr/status/1584807191764402176/photo/1
03:52 AM polprog: whats beta_s
03:53 AM rue_mohr: saturation flux density
03:53 AM polprog: and A is area?
03:53 AM rue_mohr: or flux, cause they are multiplying it by area
03:53 AM rue_mohr: no, its the density
03:53 AM rue_mohr: because they are multipling it by area for total flux
03:53 AM polprog: whatverer it is the answer needs to be in the units of [1]
03:54 AM polprog: so beta_s * A = [V*s]
03:55 AM polprog: Yeah. so thats the magn field in Webers.
03:55 AM polprog: Area you know
03:55 AM polprog: if you know the flux density at which the permeability drops then that gives you your constant
03:57 AM rue_mohr: https://twitter.com/RueNahcMohr/status/1584824754741338112
03:57 AM rue_mohr: I can to a Vt saturation test, and use the numbers to work back to a k that is the saturation flux (density * area)
03:58 AM polprog: i guess that works
03:58 AM rue_mohr: from there, I can forward with that constant to design a Royer based on that measurement
03:59 AM polprog: tho i think seeing the BH curve will tell you much
03:59 AM polprog: because the area under the curve is a figure of merit of the losses in the core
03:59 AM polprog: ie core heatup when working
03:59 AM polprog: larger = worse
04:00 AM rue_mohr: well, I ahve to know two other things
04:00 AM rue_mohr: I need to know how sharp the saturation is
04:00 AM rue_mohr: for royer, the sharper the better
04:01 AM rue_mohr: and I THINK, it needs a high reminance
04:01 AM polprog: saturation is the pointy ends on the bh
04:01 AM polprog: so you need the BH curve :>
04:01 AM rue_mohr: which sounds odd, but becasue all the work is being done while reversing the polarity on the secondary, the reminance makes it take longer = get more work done
04:02 AM polprog: https://www.coolmagnetman.com/magfund07.htm
04:02 AM rue_mohr: high rentntivity
04:02 AM polprog: you insert your test core into the test inductor, take 1 look at the scope and see a go/no go result
04:03 AM polprog: BH curve shows both of these parameters
04:03 AM rue_mohr: yea
04:03 AM rue_mohr: I need to make a bipolar driver
04:03 AM polprog: I wanted to ask you do you have some fast VCCS ideas
04:03 AM rue_mohr: m2 is apparently better for a royer
04:03 AM rue_mohr: last diagram
04:04 AM polprog: yeah
04:04 AM polprog: even though it has higher losses, the sat is sharper and retentivity is higher
04:04 AM rue_mohr: you saw my saturation test setup on twitter?
04:04 AM rue_mohr: but its just unipolar
04:04 AM polprog: yeah, i did
04:05 AM rue_mohr: I'm going to make a totem pole driver, use a series cap, and leave it at 50% while changing the freq
04:05 AM polprog: [small voice in your head] *just couple the inductor through a big ass series cap*
04:05 AM rue_mohr: I'm start high and dial the freq down
04:05 AM polprog: o haha
04:06 AM rue_mohr: cause -v rail driving sucks
04:06 AM rue_mohr: and I have a few "half bridge fet drivers" that auto invert the high and low sides
04:06 AM rue_mohr: I think IRFZ44 and a 12V battery should do it
04:07 AM rue_mohr: maybe, 10 turns and ... 200kHz start point?
04:07 AM polprog: i would go lower
04:07 AM rue_mohr: dial the freq down and watch the current
04:07 AM polprog: i would go 20kHz
04:07 AM rue_mohr: I want to start way over the time for saturation
04:07 AM rue_mohr: er, under, technically
04:15 AM polprog: yea :)
04:15 AM rue_mohr: usually I just use pwm and dial the duty up
04:15 AM rue_mohr: but I cant do that pushpull
04:15 AM polprog: i think ill just make the curve tracer
04:15 AM rue_mohr: :)
04:15 AM rue_mohr: I dont wnat to have to put a secondary winding on the test cores
04:15 AM rue_mohr: I have 1 ea
04:15 AM rue_mohr: I'm getting closer on the casting sand
04:18 AM rue_mohr: I'm going to make sure I have a process that works then post it
04:19 AM rue_mohr: I'm quite interseted if, after measuring a core, the royer freq comes out the same order of magnitude as the cacl
04:19 AM polprog: cacl?
04:19 AM rue_mohr: calc
04:19 AM polprog: ah
04:19 AM rue_mohr: hard to eat supper and type :)
04:19 AM polprog: haha
04:19 AM polprog: ill leave you alone then
04:19 AM rue_mohr: :]
04:19 AM rue_mohr: no no
04:19 AM polprog: aight
04:20 AM polprog: so tell me
04:20 AM rue_mohr: we never cross paths, I love the chance to talk to someone about it
04:20 AM polprog: if i should type that pdf that is sent you
04:20 AM rue_mohr: and I hate that just about anything I say thats wrong on twitter, nobody ever points out
04:20 AM polprog: im always here, i read every evening, just that i have no free time now
04:20 AM rue_mohr: hmm
04:20 AM polprog: but ill finish the thesis any day now and be finally free
04:21 AM rue_mohr: heh
04:21 AM polprog: for real
04:21 AM rue_mohr: I'd suggest targeting an application for the information in the pdf, and posting a page on that
04:22 AM polprog: yeah, i wanted to add a schematic for the bh tracer later
04:22 AM rue_mohr: integrator or secondary coil?
04:22 AM polprog: integrator
04:23 AM polprog: i wanted to just stick a material into the test coil and see the _[]' curve on the scope
04:23 AM rue_mohr: I still do not understand why they dont use triangle waves on LVDT
04:23 AM polprog: LVDT?
04:23 AM rue_mohr: linear variable differential transformer
04:23 AM rue_mohr: position sensor
04:23 AM polprog: ah
04:23 AM rue_mohr: they use sine waves, then go to a HELL of a lot of work to determine average energy
04:24 AM polprog: ugh
04:24 AM polprog: that sounds like crap
04:24 AM rue_mohr: opposed to a triangle input and measuring the constant voltage out
04:24 AM polprog: that makes more sense yes
04:25 AM polprog: So for the tracer i need a current source that can give me an as-square-as-possible trace
04:25 AM polprog: (within reason)
04:25 AM rue_mohr: http://www.solenoidsupplier.com/wp-content/uploads/2019/12/LVDT-principle.jpg
04:25 AM polprog: and maybe up to 1A
04:25 AM polprog: got anything?
04:26 AM rue_mohr: the fastest current source to date is that resistor trick
04:26 AM rue_mohr: no overhead
04:26 AM polprog: what trick?
04:26 AM rue_mohr: ?
04:26 AM rue_mohr: 1 sec
04:26 AM polprog: i want no low side resistor to skew the curve
04:26 AM polprog: i could go evil and do high side sensing with a PNP
04:28 AM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1260391.jpg
04:28 AM rue_mohr: keep the resistance high
04:28 AM rue_mohr: I usually use it with 2N4403
04:29 AM polprog: this, hmm
04:29 AM rue_mohr: those values, iirc give about 1.6mA
04:29 AM rue_mohr: obviously not completely predictable or temperature stable
04:30 AM polprog: i just need it to be flat
04:30 AM Tom_L: <rue_mohr> I cant have coffee, I'm going to bed after this
04:30 AM rue_mohr: but its no-dropout and fast
04:30 AM * Tom_L snickers a bit
04:30 AM rue_mohr: :] its onyl 2:30am
04:30 AM polprog: think ill just simulate a classic transistor vccs with a P type
04:31 AM rue_mohr: dont use a tl431
04:31 AM Tom_L: i used to have an old transistor tester...
04:31 AM rue_mohr: their slow as hell and have like 2V dropout
04:31 AM Tom_L: dunno what i did with it
04:31 AM polprog: nah not the reference
04:31 AM rue_mohr: Tom_L, I have a tube tester that disintegrated on the deck
04:31 AM rue_mohr: the TL431 is horrid
04:32 AM Tom_L: i used to take them to RS to test
04:32 AM rue_mohr: the only use I know of for it right now is a 2.5V ref
04:32 AM rue_mohr: Tom_L, :) I had a battery club card
04:33 AM rue_mohr: I ordered a voice rec'g chip, but they couldn't get it
04:33 AM rue_mohr: too late
04:33 AM rue_mohr: to date I'm still sure I pre-paid for it
04:34 AM rue_mohr: I was too young tho, I'd have probably blown it up
04:37 AM Tom_L: :)
04:37 AM rue_mohr: once upon a time I'd built a robot
04:38 AM rue_mohr: my aunt was visiting and I wanted to show her it all
04:38 AM rue_mohr: so I replaced all the batteries
04:38 AM rue_mohr: but I didn't know about current limiting resistors for LEDs
04:38 AM rue_mohr: so the dead batteries were the only reason they were working ok
04:38 AM rue_mohr: all the leds blew up and I couldn't figure out why
04:39 AM rue_mohr: I was upset
04:40 AM rue_mohr: I'm not sure if I should build a pushpull saturation tester before bed
04:40 AM rue_mohr: its quite nice and warm in the shop
04:40 AM Tom_L: i stuck a fork in an outlet at ~5
04:40 AM polprog: :< poor robot
04:40 AM rue_mohr: :]
04:41 AM polprog: build a fast 500mA VCCS :)
04:41 AM rue_mohr: I'm just going to apply voltage thanks :)
04:41 AM Tom_L: also had a xtal radio i'd gnd to the water heater
04:41 AM rue_mohr: I could never get them to work
04:41 AM Tom_L: pre diode era...
04:42 AM rue_mohr: zinc oxide?
04:42 AM rue_mohr: wisker
04:42 AM Tom_L: galena
04:42 AM rue_mohr: ah
04:42 AM Tom_L: i could get a couple stations faintly
04:42 AM rue_mohr: I think those ear pieces must have been most of the magic
04:42 AM rue_mohr: I wonder what the impedance on them was
04:43 AM rue_mohr: oh piezo
04:43 AM rue_mohr: huh
04:43 AM Tom_L: yeah
04:43 AM rue_mohr: that makes so much more sennse now
04:44 AM rue_mohr: piezo must go way back
04:48 AM rue_mohr: well
04:48 AM rue_mohr: I'm gonna have to sign up for a new job sooner or later
04:49 AM Tom_L: what you want to do?
04:50 AM rue_mohr: there are two candidates for maintenance jobs
04:50 AM rue_mohr: and one for security installer
04:50 AM Tom_L: hospital?
04:50 AM rue_mohr: hospital and school
04:50 AM Tom_L: hospital probably pays more
04:51 AM rue_mohr: maybe, it looks like no income will make enough for the new house I need
04:52 AM rue_mohr: so I'm kinda discouraged
04:52 AM Tom_L: look into those lightweight blocks?
04:52 AM rue_mohr: 15 years of savin and worth diddly
04:52 AM Tom_L: ppl don't save
04:52 AM rue_mohr: I have a few more things to look up
04:52 AM rue_mohr: no, they borrow
04:53 AM rue_mohr: everyone borrows everything
04:53 AM rue_mohr: even the moneyt o pay their loans
04:54 AM rue_mohr: how long does it take credit card companies to come after ya
04:54 AM rue_mohr: I need to make a good estimate of when i'm gonna die
04:54 AM Tom_L: dunno
04:55 AM polprog: i thought you were gonna upload yourself to the computer
04:55 AM rue_mohr: yes
04:55 AM rue_mohr: but I need a big shop to do it
04:56 AM Tom_L: he probably thought that back when he had a tandy but look where he'd be stuck
04:56 AM rue_mohr: I should probably keep digging one
04:56 AM polprog: lol
04:59 AM Tom_L: i still think i have the heathkit with the breadboard on top somewhere
05:00 AM rue_mohr: digital trainer?
05:00 AM Tom_L: probably
05:00 AM rue_mohr: I noticed I'm collecting a lot of my DIY CPLD baords
05:01 AM rue_mohr: polprog, what if I put out a book, of schematics, as a 3 ring binder
05:01 AM rue_mohr: and publish adder-pages to it?
05:02 AM rue_mohr: I was excited about the skeletonics suit thing
05:03 AM rue_mohr: its not playing out, the wieght-rigidity ratio is bad
05:04 AM Tom_L: that's why planes are made from alum and ti or composite
05:04 AM rue_mohr: the japaneese suits are alum, but they use 20mm tube thats got to be like 2mm thick
05:04 AM rue_mohr: and they weigh like 80kg
05:05 AM rue_mohr: heavy heavy bird for an unpowered suit
05:05 AM Tom_L: my kid makes a few parts for the blackhawk and he told me they are so precision the delivered helo must be within 20 lbs
05:05 AM rue_mohr: huh
05:05 AM polprog: rue_mohr: thats a good idea
05:06 AM rue_mohr: easy to publish :)
05:06 AM Tom_L: your 3000 would be 6000 overnite
05:06 AM rue_mohr: pff no
05:06 AM Tom_L: but they wouldn't know why
05:07 AM rue_mohr: there have to be only about 100 real people in that
05:07 AM rue_mohr: actaully, I get about 20 regulars
05:07 AM Tom_L: how many regulars were in avr robotics etc
05:07 AM rue_mohr: lots of the followers look like bots when I check 'em
05:08 AM rue_mohr: Tom_L, just polprog and one other
05:09 AM rue_mohr: polprog, my binder here is broken into sections
05:10 AM rue_mohr: oscillators, pwm generators, frequency dividers, ADC/DAC, filters, fet drivers, power supplies, current sources, and misc ( I think)
05:10 AM polprog: yeah i remember
05:11 AM rue_mohr: I'm wondering If I should take one of the smaller ones and try making a starter book of it
05:11 AM polprog: what drove me crazy about the books with schematics was lack of commentary
05:11 AM rue_mohr: yea, mine have none either
05:11 AM rue_mohr: but I have perfomance data
05:12 AM polprog: i didnt know electronics back then and the worst thing is when you build something and it does not work and you dont know why it does not work cause you dont understand it
05:12 AM rue_mohr: lots of the circuits in those books were missing critical details to make the cuirits usefull
05:12 AM polprog: yeah
05:12 AM rue_mohr: and errors :/
05:13 AM polprog: yours arent like that but still a few sentences on how it works or some important eqn for picking the values would be a good addition
05:13 AM rue_mohr: didn't want to put a lot of time into making them into a book :]
05:14 AM rue_mohr: but 8.5"x11" book is awkward
05:15 AM rue_mohr: textbook size is nicer
05:15 AM polprog: scan them, then resize as you wish
05:15 AM rue_mohr: 7x9.5 or something
05:15 AM rue_mohr: I was thinking I might need to recompose the schematics
05:16 AM rue_mohr: but that’s an avenue for errors
05:16 AM rue_mohr: k, I'm gonna sleep
05:16 AM rue_mohr: wake up later and try to assemble the bipolar tester
05:16 AM rue_mohr: and try to find a chiropractor to check my back issue
05:26 AM polprog: goodnight
01:41 PM rue_mohr: morning?
01:41 PM rue_mohr: what am I going to eat...
01:43 PM rue_mohr: wait, its 12, I'll just have lunch
03:41 PM polprog: mornign
03:41 PM polprog: morning
04:38 PM rue_mohr: hi
04:38 PM rue_mohr: more ali arrived
05:37 PM rue_shop3: well, can anyone find the datasheet with the EP1CT144c8N pin assignments?
05:39 PM polprog: night
05:39 PM rue_shop3: one day polprog
05:39 PM polprog: (sorry, i wish i could help but i have to get up at 6:30 tomorrow x_x)
05:39 PM rue_shop3: one day we will work on a project at the same time
05:39 PM polprog: but we had a nice chat yesterday :)
05:40 PM polprog: Yes, when i screw all here and move to canada
05:43 PM rue_shop3: there are no pdfs in the world with the pin assignments for the cyclone
05:43 PM rue_shop3: wtf
05:44 PM Tom_L: did you say please?
05:44 PM rue_shop3: I searched everything
05:45 PM rue_shop3: "mosi" is not in any pdf regarding the EP1C3T
05:46 PM rue_shop3: ok I give up for now
05:47 PM rue_shop3: ok what am I going to do next that wont work
05:47 PM rue_shop3: }:/
06:31 PM aandrew: hm?
06:32 PM aandrew: EP1C3T?
06:35 PM aandrew: why would that have a SPI bus?
06:42 PM aandrew: https://www.intel.com/content/www/us/en/content-details/676988/pin-information-for-the-cyclone-ep1c3t144-device-pdf-format.html isn't that the pinout?
06:43 PM aandrew: these devices don't have dedicated SPI ports. They have a SPI-like configuration interface but you don't get to use that once it's configured
06:46 PM aandrew: I mean if you need I have a SPI slave VHDL block I can share with you. Works reasonably well
06:46 PM aandrew: I have a nice simple UART one too
07:18 PM rue_shop3: no, jtag
07:19 PM rue_shop3: I was able to hook up the jtag on the board it was on tho
07:19 PM rue_shop3: oh, I was looking for the wrong words ahahahahaha
07:20 PM rue_shop3: thankyou
07:20 PM rue_shop3: I still didn't find that document
07:20 PM rue_shop3: YAY! 18 and 19 are supposed to be shorted!!!
07:20 PM rue_shop3: I thought it was a solder bridge
07:21 PM rue_shop3: I dont have an spi memory chip for it tho :/
07:21 PM rue_shop3: they seem to talk a special protocol
07:23 PM rue_shop3: 10 turns, 12.18V, 244us
07:57 PM aandrew: yeah the old cyclops stuff seem to use specific config memory, Im not sure how compatible it is with regular SPI flash
07:57 PM rue_mohr: I'll just jtag it
07:57 PM aandrew: however in PS mode you could use an attiny and spi flash to do it with no problem
07:57 PM rue_mohr: yes
07:57 PM aandrew: or, knowing you, a 555, couple shift registers and a 2716
07:58 PM rue_mohr: I think thats why none of the baords with them have the special rom chip
07:58 PM rue_mohr: heh
07:58 PM rue_mohr: no evil temptations
07:58 PM aandrew: 74LS575... you know you wnat to use it
07:58 PM rue_mohr: is that what I got for serial on the z80?
07:59 PM aandrew: that I don't know
07:59 PM rue_mohr: 299
08:00 PM aandrew: OR!
08:00 PM rue_mohr: its 16c in my room and I'm COLD
08:00 PM aandrew: you could program a CPLD to do it, clocked with a 555
08:00 PM rue_mohr: heh
08:00 PM aandrew: I'm sitting in my car with the butt warmer on
08:00 PM aandrew: oh
08:00 PM aandrew: that reminds me
08:01 PM rue_mohr: oh I got the 299 for i2c/spi
08:01 PM aandrew: like 20y ago my boss had a nice car with heated seats (before they were pretty common)
08:01 PM rue_mohr: I realized a lot of things I want to use on the z80 are serial I/F
08:01 PM aandrew: I was driving it and picked up a customer and had his seat warmer on
08:01 PM aandrew: about 15s in he said "does this car have sear warmers?"
08:01 PM aandrew: "yes..."
08:02 PM aandrew: "oh good. for a minute there I thought I shit myself"
08:02 PM rue_mohr: :/
08:02 PM rue_mohr: oh dear
08:02 PM aandrew: completely deadpan
08:02 PM rue_mohr: okok
08:03 PM rue_mohr: I got this old ferrite core
08:03 PM aandrew: looking at the 299 now. interesting chip
08:03 PM rue_mohr: fingers are freezing
08:03 PM aandrew: man I miss the old encyclopedia-sized databooks from ti and national and so on
08:03 PM rue_mohr: yea I need an auto "8 clock pulses"
08:03 PM aandrew: loved how they smelled, loved just paging through them
08:03 PM rue_mohr: heh
08:03 PM rue_mohr: ok this core
08:03 PM aandrew: I can't work when my hands are cold. don't know how you're doing it
08:04 PM aandrew: I'd be making some tea
08:04 PM rue_mohr: 10 turns, 12.18V it took 244 us to saturate
08:04 PM rue_mohr: I should go back to the shop
08:05 PM aandrew: your shop's warmer than your house??
08:05 PM rue_mohr: way warmer
08:05 PM aandrew: is there an issue with the furnace?
08:05 PM aandrew: that sucks
08:05 PM rue_mohr: its off
08:05 PM rue_mohr: the issue is $300/mo for descent heat
08:05 PM aandrew: might want to remedy that
08:05 PM aandrew: yikes
08:05 PM rue_mohr: or $50/mo for standby
08:05 PM rue_mohr: I might just stay in the shop this winter
08:06 PM rue_mohr: have to keep the pipes from freezing tho
08:06 PM aandrew: perhaps you should build some electric thermal underwear
08:06 PM rue_mohr: zzzt! OOoo!
08:06 PM aandrew: nah
08:06 PM aandrew: inductive. plug your chair/bed in to the wall
08:06 PM aandrew: they don't draw anything unless you're in them
08:07 PM aandrew: only downside to that is you can't do it with the toilet seat
08:07 PM rue_mohr: so I'v defined, for a single transformer royer (saturation based)
08:07 PM rue_mohr: Nprimary = k*Vp/2*f
08:07 PM rue_mohr: where k is basically the saturation flux for that core
08:08 PM rue_mohr: to determine k, I'm supposed to use k=N/t*V from the test coil
08:08 PM rue_mohr: so
08:09 PM rue_mohr: if I take this aprt and put it back togethro for the test coil, I should get 1:1
08:11 PM rue_mohr: I get k = 3364.8
08:11 PM rue_mohr: so, 244us is
08:11 PM rue_mohr: 4.098khz
08:13 PM rue_mohr: exactly 50% wrong
08:14 PM rue_mohr: frequency vs on-time
08:15 PM rue_mohr: if I have an on-time (50% duty) of 100hz
08:15 PM rue_mohr: no
08:15 PM rue_mohr: try again
08:15 PM rue_mohr: if I have an on-time (50% duty) of 5ms
08:17 PM rue_mohr: to get the freq, I would double and invert htat
08:17 PM rue_mohr: f = 1/2t
08:18 PM rue_mohr: or, isolated for t, t = 1/2f
08:18 PM rue_mohr: ok
08:21 PM rue_mohr: I think my 2 went the wrong way
08:46 PM Tom_L: found what you couldn't find i see
08:51 PM Tom_L: no heat in the house? or just don't wanna use it?
08:51 PM Tom_L: i know the water system gave up..
08:55 PM rue_mohr: yea, I dont want to turn the furncae on till I have to
09:04 PM Tom_L: can't say i blame ya
09:04 PM Tom_L: shop stays warmer?
09:04 PM Tom_L: or have you heated it?
09:07 PM rue_mohr: no heat in the shop
09:07 PM rue_mohr: just crazy insulation
09:08 PM Tom_L: yeah unless i'm out there the shop will stay thawed down in the teens with just a pilot going
09:08 PM Tom_L: doesn't take much to warm it up
09:11 PM Tom_L: what'd you think of those cinder block houses?
09:12 PM Tom_L: or whatever they were made of
09:18 PM rue_mohr: hard to modify
09:18 PM rue_mohr: especially the way they did it
09:18 PM rue_mohr: but I been wondering about brick
09:19 PM Tom_L: if you built it though, would you really need to modify it more later?
09:19 PM Tom_L: i know i won't be changing mine
09:19 PM Tom_L: i dunno how well brick insulates
09:20 PM rue_mohr: I should price bricks
09:20 PM rue_mohr: I wonder about pre-cast tilt up concrete...
09:21 PM Tom_L: typically brick are just a face to either block or 2x4
09:21 PM rue_mohr: steel stud
09:21 PM rue_mohr: avoid wood
09:21 PM rue_mohr: its expensive
09:21 PM Tom_L: even up there?
09:21 PM Tom_L: huh
09:21 PM rue_mohr: yea
09:21 PM rue_mohr: we dont cut it anymore
09:22 PM rue_mohr: everyone sold out
09:22 PM Tom_L: was gonna suggest log cabin type
09:22 PM Tom_L: but not now
09:22 PM rue_mohr: a wood beam structure with steel stud might work
09:23 PM Tom_L: industrial have to use steel
09:23 PM Tom_L: with fire retardent sheetrock
09:24 PM Tom_L: i had to put fire retardent under my stairs when i did my basement
09:25 PM Tom_L: that's a young man's job
09:25 PM rue_shop3: so, If I assemble this with a manual osc and run it at 6kHz
09:28 PM Tom_L: so if you don't cut anymore who buys the sprayers?
09:29 PM rue_shop3: oh I mean cut them into lumber
09:29 PM Tom_L: oh
09:29 PM rue_shop3: we cut down and export all the trees
09:37 PM rue_mohr: wow
09:37 PM rue_mohr: core I was going to use:
09:38 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/magsat.png
09:38 PM rue_mohr: core made for what I'm trying to do:
09:38 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/magsat2.png
09:38 PM rue_mohr: 8-|
09:38 PM rue_mohr: ok
09:41 PM rue_shop3: (learn learn learn)
09:42 PM rue_shop3: EMI cores, look great for this
10:00 PM rue_mohr: from the test winding, calculate k, k=N/(2*t*V)
10:00 PM rue_mohr: then for the design, calculate N, N=k*V/f
10:01 PM rue_mohr: where t is the saturation time, and f is the target operating freq
10:32 PM rue_shop3: YAY!!! it works!
10:33 PM rue_shop3: its oscillating and not blowing up!!!
10:33 PM rue_shop3: and, after doing all the maths...
10:33 PM rue_shop3: the results are only out by 200%!!!
10:33 PM rue_shop3: that 2, wherever it goes or comes from, is really scerwing with me
11:26 PM rue_shop3: YES!, ok, I dropped a 2 from the formula and a completely different test came out right on the mark
11:26 PM rue_shop3: or as close as can be expected
11:46 PM rue_mohr: ahhh!!! my test voltage is only half of the number I was using!!!