#garfield Logs
Feb 19 2022
#garfield Calendar
05:26 AM Tom_L: morning
06:51 AM polprog: morning
08:01 AM rue_bed: mmm
08:22 AM Tom_L: mmm?
09:00 AM rue_mohr: 2335
09:00 AM Tom_L: up or dn?
09:01 AM * Tom_L thinks rue_mohr is such a popular guy he can't touch this no mo
09:01 AM rue_mohr: according to the scrollback still up
09:01 AM rue_mohr: apparently we sent a bunch of handles out with machine screws holding the plastic instead of plastic screws
09:01 AM rue_mohr: ugh
09:02 AM Tom_L: well even though i was up at 12, 2, 4 & 8 i slept pretty good
09:02 AM Tom_L: that's the split problem then i bet
09:02 AM rue_mohr: yea
09:02 AM rue_mohr: and it'll be a "my handle fell off" problem
09:03 AM Tom_L: easy to diagnose
09:03 AM rue_mohr: he's having a lot of family issues, I told him via phone and email and sent him a thread profile and he still boofed it
09:03 AM rue_mohr: :/
09:03 AM Tom_L: wk/hm don't mix
09:05 AM rue_mohr: 5V -> -47V
09:05 AM Tom_L: helluva boost converter :)
09:09 AM rue_mohr: inverting tho!
09:09 AM Tom_L: oh i missed that. still half asleep
09:36 AM polprog: thinking about a 3S LiIon chrger
09:36 AM polprog: did someone make an all in one IC for that
09:37 AM Tom_L: it's probably on the unobtanium list if there is one
09:38 AM polprog: hm
09:38 AM polprog: i guess rev2 will have no charge capability
12:25 PM miss0r2: rue_mohr: As I have previously pestered you with ignorant questions regarding electronics, I am hoping I will be able to do so again.
12:27 PM miss0r2: At this point in time I am trying to make a functional dc-dc flyback converter. I'm using an arduino to supply me with a ~62KHz PWM signal. I use this signal to drive a power mosfet through a mosfet gate driver. All of this seems good'n well. The tests of this works "perfectly" when it is located on my bench, and the connection between the PCB with the mosfet on it and the coupled inductor are connected with test leads.
12:28 PM miss0r2: This ofcourse generates alot of heat from said wires, and that is just a stupid loss. I came to the conclution that *NOW* the design was working, so I mounted it up in the box and gave it another go. This, ofcourse, led me back down the path of perfuming my workshop with mosfet insent. *sigh*.
12:29 PM rue_mohr: he
12:29 PM miss0r2: So I have a few questions, which may/may not have something to do with what is going astray here
12:29 PM rue_mohr: do you have a scope?
12:29 PM miss0r2: yes
12:29 PM rue_mohr: ok, how much power do you want out of it
12:29 PM miss0r2: as much as possible
12:29 PM miss0r2: :]
12:29 PM rue_mohr: 30GW?
12:29 PM rue_mohr: 100TW?
12:30 PM miss0r2: considering the size constraints of the box, which I accept you know nothing of, I think that is a bit over the top :)
12:30 PM miss0r2: 4-500watts would make me happy
12:30 PM rue_mohr: ok
12:30 PM rue_mohr: 500W flyback, what output voltage?
12:30 PM miss0r2: heck, at this point, if I can get 200watts with no attached smoke, I would be glad too
12:31 PM miss0r2: 500volts
12:31 PM rue_mohr: your pushing the duty too far and not using the right freq
12:31 PM rue_mohr: I'm playing with a flyback now
12:31 PM miss0r2: quite possible.
12:31 PM rue_mohr: what is the input voltage?
12:31 PM miss0r2: 12.5ish volts
12:31 PM rue_mohr: https://twitter.com/RueNahcMohr/status/1495099713833488384
12:32 PM rue_mohr: ok
12:32 PM rue_mohr: so, set the drive to 50% duty
12:32 PM rue_mohr: what size inductor do you have?
12:32 PM miss0r2: that was one of the questions I was going to ask :)
12:32 PM miss0r2: well, not that you know. but its a 'home spun' one.
12:32 PM rue_mohr: the type of inductor and the size are important
12:33 PM rue_mohr: the flyback works like a transfer bucket
12:33 PM rue_mohr: you put water in the bucket, then empty it
12:33 PM rue_mohr: you can move a lot of water with a small bucket, if you move really fast
12:33 PM rue_mohr: or you can move the same amount with a larger bucket, and do it slower
12:33 PM rue_mohr: BUT
12:33 PM miss0r2: I'll paste the links to the two components used to put the inductor together, if that is okay?
12:34 PM rue_mohr: whats important is that you dont move so fast that you havn't completely filled or emptied the bucket for each cycle
12:34 PM rue_mohr: ^^ summarize that for me
12:34 PM miss0r2: Summarize what you just told me? :)
12:34 PM rue_mohr: yes, nobody ever understands or absorbs what I say
12:35 PM rue_mohr: so from yesterday on, everyone has to use handshaking
12:35 PM miss0r2: I like the way you told it, actualy :) how can I say it differently?
12:35 PM rue_mohr: tell me how it works as an inductor
12:35 PM miss0r2: other than using a different medium of transfer than a bucket
12:35 PM rue_mohr: yes
12:36 PM rue_mohr: (did you open that link?)
12:36 PM miss0r2: well. Then I will go with a pot. a small pot. This pot has the capacity to hold a small amount of soil. I want to move alot of soil, so I fill and empty it rapidly
12:37 PM miss0r2: not too fast, as I want to completely fill and empty it. but not too slow, as I will end up overfilling it
12:37 PM miss0r2: yes
12:38 PM miss0r2: So I think I have somewhat of a grasp on it.
12:38 PM miss0r2: But there are a few things I have completely failed at; i.e. when I wound the flyback transformer, I thought of it as a regular transformer, so I didn't pay attention to phasing
12:39 PM miss0r2: *could* all of this be caused by poor placement of the output diode?
12:39 PM rue_mohr: ah
12:39 PM rue_mohr: is it closed loop core?
12:39 PM rue_mohr: closed loop is for transfer
12:39 PM miss0r2: https://docs.rs-online.com/0a18/0900766b813c0cf6.pdf
12:39 PM rue_mohr: gapped core is for storage
12:39 PM miss0r2: Take a look
12:40 PM miss0r2: gapped core
12:40 PM miss0r2: thats the one :)
12:40 PM rue_mohr: ok, so
12:41 PM rue_mohr: 500V 200W is 400mA
12:41 PM rue_mohr: ohm -v 500 -p 200
12:41 PM rue_mohr: Power is: 200.000W
12:41 PM rue_mohr: Current is: 400.000mA
12:41 PM rue_mohr: Voltage is: 500.000V
12:41 PM rue_mohr: Resistance is: 1.250kOhms
12:41 PM rue_mohr: so the wire doesn't have to be huge
12:41 PM rue_mohr: what guage wire did you use?
12:41 PM rue_mohr: about 22?
12:42 PM miss0r2: let me do a calculation to gauge, hang on
12:42 PM rue_mohr: or dia, whatever
12:42 PM miss0r2: 0.5mm diameter
12:42 PM rue_mohr: probably too big, your losing space for turns
12:42 PM rue_mohr: but ok
12:42 PM rue_mohr: do you know what the approx inductance is?
12:42 PM miss0r2: That is on the secondary
12:43 PM rue_mohr: secondary?
12:43 PM rue_mohr: hmm ok
12:43 PM rue_mohr: what ratio did you use?
12:43 PM miss0r2: 1:80 aprox
12:43 PM rue_mohr: ok
12:44 PM rue_mohr: 6.25
12:44 PM miss0r2: Something is not right about that number. it doesn't add up (wire diameter), let me go grap a set of cilibers, 2 secs
12:44 PM rue_mohr: 78V on the primary
12:47 PM miss0r2: okay so. *WITH* the coating, the secondary winding measures 0.35mm in diameter
12:48 PM rue_mohr: so, start with a drive of 50% at 10khz
12:48 PM rue_mohr: the mosfet needs to be rated for about 100V
12:48 PM rue_mohr: what fet? are you using
12:48 PM rue_mohr: igbt?
12:48 PM miss0r2: FET, and it is rated 600volts at 78amp(continous) and 360A pulsed
12:49 PM rue_mohr: ok
12:49 PM miss0r2: the problem with using the arduino as I am, I only have a select few frequenzies I can choose from
12:49 PM rue_mohr: hu?
12:49 PM rue_mohr: you dont have any signal generator code for it?
12:50 PM miss0r2: I guess I could do it like that. but hitting 10KHz *and* using it do manage other stuff is starting to put a strain on that 16mhz processor
12:50 PM rue_mohr: if it coughs, your converter will explode
12:50 PM miss0r2: indeed
12:51 PM miss0r2: I can do 62.3, 31.17
12:51 PM rue_mohr: you need to do inductor tests
12:51 PM rue_mohr: did you open that link I dropped?
12:51 PM miss0r2: yes
12:51 PM rue_mohr: ok, so, does it make sense?
12:51 PM miss0r2: yes
12:52 PM miss0r2: apart from the 'black magic' ringing :)
12:52 PM rue_mohr: ok, what you want to do, is start with 50%, and adjust the duty (under full load) until the black magic section is *almost* gone
12:52 PM rue_mohr: leave a little
12:52 PM rue_mohr: if you push the duty more than that, the current will go up FAST
12:52 PM rue_mohr: and the efficiency will go down FAST
12:53 PM miss0r2: one thing I forgot to mention: I'm using this to charge capacitors. so the load is continously changing
12:53 PM rue_mohr: the output voltage will also go up
12:53 PM rue_mohr: thats fine
12:53 PM rue_mohr: have a load resistor you can use for testing?
12:53 PM rue_mohr: 500w, 1.2k ?
12:53 PM miss0r2: not that big, no
12:53 PM rue_mohr: you want one!
12:53 PM rue_mohr: so you can sniff out the inductor
12:53 PM miss0r2: wait... maybe yes. I have some constantan(spell) wire wound on ceramic
12:54 PM miss0r2: That could work
12:54 PM rue_mohr: 500W?
12:54 PM miss0r2: if I put a fan to it, sure. I think it ought to handle it
12:54 PM rue_mohr: ok
12:54 PM rue_mohr: so, you need a signal generator
12:54 PM miss0r2: got one
12:54 PM rue_mohr: the idea, is to find the best operating point for the inductor
12:55 PM rue_mohr: then build a system to generate that signal
12:55 PM rue_mohr: for me, its about 3.3khz, 86% duty
12:55 PM miss0r2: okay. Tell me something: on the link you posted: where is that proped?
12:55 PM rue_mohr: proped?
12:56 PM rue_mohr: er, must be 96%
12:56 PM miss0r2: yes: is that the signal from the gate? coupled with the current sens resistor or something?
12:56 PM rue_mohr: no, thats the drain of the mosfet
12:56 PM rue_mohr: but its P channel
12:56 PM miss0r2: okay
12:56 PM rue_mohr: I'm making a -47V inverter
12:56 PM rue_mohr: from 5V
12:57 PM rue_mohr: yours will just be upside down
12:57 PM miss0r2: yeah, why not :)
12:57 PM rue_mohr: 50% should be a safe start
12:57 PM rue_mohr: you should see the inductor charge and release,
12:57 PM miss0r2: that is good, because my signal generator cannot adjust duty cycle, it can only do 50%
12:57 PM rue_mohr: with a load, it'll "drain" then do the black magic thing and settle at the supply voltage
12:58 PM rue_mohr: after ringing like hell
12:58 PM rue_mohr: oh, you... should assemble an arduino signal gen...
12:58 PM miss0r2: will I be able to use this for anything after dumping the energy into a wound resistor? won't that just ring back?
12:58 PM miss0r2: the results I mean; won't this make it act up potentially?
12:59 PM rue_mohr: yes, the resistor is just to load it while you get the operating point right for the inductor
12:59 PM miss0r2: Okay. So, do you think I can use my inductor as is, or should I do another one?
12:59 PM rue_mohr: the ring is just an odd thing that happens after the inductor is discharged
12:59 PM miss0r2: I still have a few "houses" for it, that I haven't used
01:00 PM rue_mohr: sounds ok to me
01:00 PM miss0r2: even with only 5 turns of 2mm diameter primary?
01:00 PM rue_mohr: you could also just test with a primary
01:00 PM rue_mohr: its big, I think 10khz 50% will still be ok
01:00 PM rue_mohr: but it needs a load or it'll pop
01:01 PM miss0r2: There are many things in this world I don't understand.. Lets grap one example now. :)
01:01 PM rue_shop3: hmm
01:01 PM miss0r2: as I have been running this at 62khz, with a vareity of different duty cycles, ending up at only 5%. Shouldn't this have allowed my circuit to survive?!
01:01 PM miss0r2: :S
01:02 PM miss0r2: I mean, I guess I should be able to, however ineffective, use a big bucket to move a small amount of water fast? without saturating it and burning up everything?
01:03 PM rue_shop3: no
01:03 PM miss0r2: Great! :D
01:03 PM rue_shop3: your bucket was't empty
01:03 PM rue_shop3: and then it didn't get filled
01:03 PM miss0r2: that I cannot understand
01:03 PM rue_shop3: you were cutting over to charge before the discharge had finished
01:04 PM rue_shop3: the average current in the inductor wasn't zero
01:04 PM rue_shop3: so, you had load current plus the leftover current from the last cycle
01:04 PM miss0r2: so I ended up saturating it
01:04 PM rue_shop3: currents spiraling out of control
01:04 PM miss0r2: melting solder & generating mosfet insent over and over
01:05 PM rue_shop3: scope it, do not apply more duty than it takes to have the discharge finish
01:05 PM rue_shop3: said again another way, make sure the inductor is discharged before you start charging it again
01:05 PM miss0r2: theres something I fundamentally don't understand, it now seems clear: I thought the 'on' time in the duty cycle was charging it
01:06 PM rue_shop3: yea, mines upside down
01:06 PM rue_shop3: I'm pulling up to 5V to charge
01:07 PM rue_shop3: then when I let go, the inductor flies down to -47V
01:07 PM miss0r2: if that so; then how come I can end up getting saturation, running it at 5% duty(on time). that should leave ALOT of time for it to discharge?
01:07 PM miss0r2: I'm just realy trying to understand what I am doing here :)
01:07 PM rue_shop3: when its out of spunk, it inverts (?) and pushes up above 5V for a while before going into a ring around 5V
01:08 PM rue_shop3: oh
01:08 PM rue_shop3: your right something is odd
01:08 PM rue_shop3: how are you driving the fet?
01:08 PM rue_shop3: I think your signal is backwards
01:08 PM miss0r2: with a mosfet gate driver
01:08 PM rue_shop3: inverting?
01:08 PM miss0r2: no
01:08 PM miss0r2: I've probed the gate of the mosfet, it looks as I would except it to look
01:08 PM rue_shop3: do you know for sure that your only 5% and not 95%?
01:09 PM miss0r2: absolutly
01:09 PM rue_shop3: well
01:09 PM rue_shop3: 5 turns?
01:09 PM miss0r2: yes
01:09 PM rue_shop3: whats ur?
01:09 PM rue_shop3: mu-r
01:09 PM miss0r2: my what? resistance on the primary?
01:09 PM rue_shop3: thought they said somehting like 1800nH
01:09 PM rue_shop3: no, the inductance/turn
01:10 PM miss0r2: I don't know
01:10 PM rue_shop3: I dont have that datasheet up
01:10 PM miss0r2: https://docs.rs-online.com/0a18/0900766b813c0cf6.pdf
01:10 PM rue_shop3: root@freebee6:/files/programming/c/avr/atmega328# inductor -k 1900n -n 5
01:10 PM rue_shop3: Inductance is: 47.500uH
01:10 PM rue_shop3: Turns is: 5.000
01:10 PM rue_shop3: Constant is: 1.900u
01:10 PM rue_shop3: oh, hmm
01:10 PM rue_shop3: I think you need more turns
01:11 PM rue_shop3: 512 turns!?
01:11 PM rue_shop3: hmm
01:11 PM rue_shop3: maybe thats not a good core...
01:11 PM miss0r2: oh?
01:11 PM rue_shop3: 500uH to 1mH is good
01:12 PM rue_shop3: oh wait, which material is it?
01:12 PM miss0r2: ferrite
01:12 PM rue_shop3: N--
01:13 PM rue_shop3: oh N41
01:13 PM rue_shop3: whcih gap?
01:13 PM miss0r2: let me doublecheck
01:13 PM rue_shop3: ugh
01:14 PM miss0r2: N41, with 160nH
01:14 PM miss0r2: is the one I ordered
01:15 PM miss0r2: meh. Hard to grind the gap smaller. Had it only been the other way around.
01:16 PM miss0r2: sad things is; I don't know what this translates too
01:17 PM miss0r2: if you'd care to enlighten me, I'd love to get a bit smarter here
01:19 PM rue_shop3: oh
01:19 PM rue_shop3: n not u
01:20 PM rue_shop3: er no
01:20 PM miss0r2: :]
01:20 PM rue_shop3: 56 turns
01:20 PM rue_shop3: root@freebee6:/files/programming/c/avr/atmega328# inductor -k 160n -l 500u
01:20 PM rue_shop3: Inductance is: 500.000uH
01:20 PM rue_shop3: Turns is: 55.902
01:20 PM rue_shop3: Constant is: 160.000n
01:20 PM rue_shop3: hmm
01:20 PM miss0r2: so, 56 turns on the primary
01:20 PM rue_shop3: well
01:20 PM rue_shop3: it could be less for a higher frequency
01:21 PM miss0r2: what frequenzy are you calculating with there?
01:21 PM rue_shop3: but the higher your freq goes, the more switching loss you have
01:21 PM rue_shop3: at 500khz, all sorts of evil things start to happen
01:21 PM rue_shop3: I like to be above 20kHz
01:21 PM miss0r2: indeed. Is the ~62KHz that I can easily generate with the arduino completely out of the park?
01:22 PM rue_shop3: what freq did you try to use?
01:22 PM rue_shop3: hmm
01:22 PM miss0r2: I can also quite easily do ~31KHz
01:22 PM rue_shop3: 31 would give you less trouble
01:22 PM rue_shop3: but
01:23 PM rue_shop3: swap the inductor out for a resistor
01:23 PM rue_shop3: and make sure its all switching right
01:23 PM miss0r2: so, try to drive the resistor instead of the inductor? and see if the switching elements survive? :)
01:24 PM rue_shop3: yes
01:24 PM rue_shop3: make sure your drive is the right way around
01:24 PM rue_shop3: did you heatsink the fet?
01:24 PM miss0r2: okay. Now that i've got to remake the coil part of the inductor;
01:24 PM miss0r2: yes
01:24 PM rue_shop3: oh wait, you didn'thave any load did you?
01:25 PM miss0r2: well, capacitors on the secondary side of the inductor
01:25 PM miss0r2: but I think I can make up a resistor of parts I have floating around
01:26 PM rue_shop3: hmm
01:26 PM rue_shop3: so flyback shouldn't have been an issue
01:27 PM rue_shop3: sometimes this is hard without being hands on
01:27 PM miss0r2: I build an RC across the mosfet and an RCD across the inductor. The former made alot of difference in cleaning up the signal, the later didn't
01:29 PM miss0r2: because I thought that perhaps the ocational stray transient was at fault.
01:29 PM miss0r2: but I doubt it
01:33 PM rue_shop3: leakage can cause some brutal spikes
01:33 PM miss0r2: Indeed
01:34 PM miss0r2: so. based on your understanding the subject and I hardly know the proper terms: what turn ratio should I go for? and what wire gauge should I use for the 56 primary turns and what wire gauge for the x secondary turns?
01:39 PM miss0r2: Because If I were to do 56 turns with the 2mm diameter on, that would leave no room for the ~4500 turns of 0.3mm diameter wire. hehe. The transformer is simply not big enough for that
01:39 PM miss0r2: I doubt it can even hold 56 turns of that wire alone
01:43 PM miss0r2: or do you think I should scrap this core altogether and see if I can find a toroid?
01:57 PM rue_shop3: yea
01:58 PM rue_shop3: turns ratio is an evil balance
01:58 PM rue_shop3: but
01:58 PM rue_shop3: there is a feel-it-out cheat
01:58 PM miss0r2: listening :D
01:58 PM rue_shop3: get the primary to generate the 200W you want, then make a secondary that matches the performance to give you the voltage
01:58 PM miss0r2: I am under the perhaps old fashion impression that the primary should be able to handle the current of the wanted output power?
01:59 PM rue_shop3: you want a gapped core
01:59 PM rue_shop3: the *power*
01:59 PM miss0r2: which is what I have
01:59 PM miss0r2: You are speaking in tounges again :D
01:59 PM rue_shop3: if you can generate 200W on the primary (at the wrong voltage) then its just a matter of moving the load to a secondary with a turns ratio that makes the voltage what you want
02:00 PM miss0r2: not unlike an old-school transformer then
02:00 PM rue_shop3: so, lets say you choose 24V on the primary
02:01 PM rue_shop3: root@freebee6:/files/programming/c/avr/atmega328# ohm -v 24 -p 200
02:01 PM rue_shop3: Power is: 200.000W
02:01 PM rue_shop3: Current is: 8.333A
02:01 PM rue_shop3: Voltage is: 24.000V
02:01 PM rue_shop3: Resistance is: 2.880Ohms
02:01 PM miss0r2: I've sorta designed myself into a corner with a 11.1volt lithium battery :)
02:01 PM rue_shop3: make a power supply, that using the single pimary winding, generates 24V across a 2.9 ohm resistance
02:01 PM rue_shop3: with the flyback
02:02 PM rue_shop3: if you can get the duty/freq that makes the core do that, then you just need to add the secondary thats 20.8x as many turns
02:02 PM rue_shop3: get what I mean?
02:02 PM miss0r2: reading it for the 3rd time now, and sadly no
02:02 PM rue_shop3: ok,
02:03 PM rue_shop3: you need the core to produce 200W
02:03 PM miss0r2: yes
02:03 PM rue_shop3: for the moment, it doesn't matter how or what or why
02:03 PM rue_shop3: 200W
02:03 PM rue_shop3: the flyback happens without a secondary
02:03 PM rue_shop3: its just above the supply voltage
02:04 PM rue_shop3: I'm not set up to draw a bunch of diagrams
02:04 PM rue_shop3: but for just a coil, there is flyback
02:04 PM rue_shop3: thats output power
02:04 PM miss0r2: indeed
02:05 PM rue_shop3: if you can get 200W out of it, then you have it operating at the right point
02:05 PM rue_shop3: the bucket is moving the right amount of water
02:05 PM rue_shop3: just at the wrong pressure/flow ratio
02:05 PM rue_shop3: to get there, you need to have the right frequency and duty
02:05 PM rue_shop3: those are the magic numbers
02:06 PM rue_shop3: choosing 24V can be arbitrary
02:06 PM rue_shop3: but you need to make that flyback produce that power
02:06 PM rue_shop3: it doesn't matter if the power comes off the primary or secondary, its output power
02:06 PM rue_shop3: so screw the secondary and get the core doing what you want first
02:07 PM miss0r2: should I try doing it like so: https://www.researchgate.net/profile/Saurabh-Kumar-176/publication/312290052/figure/fig2/AS:564581682225153@1511618170516/Circuit-diagram-of-boost-converter-From-Fig-3-during-the-switch-is-closed-10-Vs-is.png
02:08 PM miss0r2: for this test, that is
02:08 PM rue_shop3: not quite
02:08 PM rue_shop3: the load and the capacitor need to be tied to the + supply power, not ground
02:09 PM rue_shop3: otherwise the input power is contributing, which it wont be when its a seperate winding
02:10 PM miss0r2: yes, I see that
02:11 PM miss0r2: I will go do a test setup. Thanks for the help! I was realy stomped
02:12 PM rue_shop3: I dont use math, its always wrong
02:12 PM rue_shop3: I prefer to build and feel out tings
02:12 PM rue_shop3: it accounts for awefull real-world stuff
02:17 PM miss0r2: I hear that. But math would be helpful for me, as I seem to have no idea where to start :D
02:23 PM rue_shop3: yea, and its not straighforward
02:23 PM rue_shop3: magnetics are evil
02:23 PM rue_shop3: that black magic part
02:23 PM rue_shop3: I still dont get that
02:23 PM rue_shop3: if the inductor is out of energy, how does it manage to reverse hard, then ring
02:24 PM rue_shop3: thats not what something does when its out of energy
02:29 PM miss0r2: Its all black magic.
02:30 PM miss0r2: I've reached a sad sad point in this project. I've now spend two months trying to get this to do the way I want, reading all the material I could find (at a level I can understand, mind you). But alas, I am now at the "if I can just get 1/3 X, and it now blowing up, I'm happy"
02:31 PM miss0r2: now = not* :)
02:32 PM miss0r2: alright. I'm preparing to head to the lathe to do the primary winding. I've found some 1mm diameter enameled copper wire. Care to venture a guess at what amount of windings I should kick it off with?
02:34 PM miss0r: if you've already answered my last question, please repeat. I am now in the shop
02:37 PM polprog: ringing comes from the parasitic capacitance
02:37 PM polprog: if you measure the ring frequency you can
02:38 PM polprog: ah no, you cant find anything.. if you knew the inductance precisely you could find the parasitic C
02:40 PM rue_shop3: polprog, what about that huge reverse kick?
02:40 PM rue_shop3: just after its out of spunk, and before it rings
02:41 PM polprog: transient effect, comes from v = L di/dt
02:41 PM polprog: so L is constant, dt is constant (lets say), then V is huge when di is huge
02:41 PM polprog: when you cut current, di is huge because it suddenly goes to zero, so the V is huge too
02:42 PM polprog: there should be a minus in the equation there but whatever, just swap the meter leads
02:42 PM miss0r: rue_shop3: Do you think it wise to start out with the 56 turns?
02:42 PM polprog: https://www.electronics-tutorials.ws/wp-content/uploads/2020/11/ind5.gif
03:18 PM rue_shop3: see how it behaves
03:18 PM rue_shop3: you need to find some signal generator code for the arduino
03:18 PM rue_shop3: so you can try things with freq/duty
03:19 PM rue_shop3: polprog, I'm not talking about the discharge tho
03:19 PM rue_shop3: the reverse pulse after it
03:19 PM polprog: hm
03:19 PM polprog: im too tired for it now
03:19 PM polprog: goodnight
03:43 PM rue_shop3: drat
03:43 PM rue_shop3: I cant remmeber is the SCR oscillator was the lowest component count 5V osc we did
04:58 PM Tom_L: wasting time on a rail gun?
05:02 PM Tom_L: need some test parts to test?
05:15 PM Tom_L: if it ever dries out i may grab some more of that material
05:15 PM Tom_L: too muddy right now
05:32 PM rue_shop3: its pouring here
05:32 PM rue_shop3: I need it to break so I can make more paint tubes
06:02 PM Tom_L: you cut them outside?
06:21 PM rue_shop3: router, yea
06:21 PM rue_shop3: the slots
06:22 PM Tom_L: mmm
08:33 PM Tom_L: working on the setup
08:34 PM Tom_L: (will need to be done eventually)
08:34 PM Tom_L: nothing else running on it atm anyway
08:49 PM rue_shop3: hmm, I need to standard resistors with a particular ratio
09:17 PM Tom_L: did you figure anything out on the A9 A12 hole size?
09:17 PM Tom_L: latch
09:18 PM rue_shop3: working on power converters :)
09:58 PM Tom_L: k
10:13 PM * Tom_L goes back to doing nothing
11:06 PM rue_mohr: finished the power converter
11:07 PM rue_mohr: in the process, I came up with a few new lessons
11:08 PM rue_mohr: how to generate compoment efficient power supply oscillators and pwm generators
11:08 PM rue_mohr: some stuff about flyback inductors and efficiencies
11:08 PM rue_mohr: FET oscillators