#garfield Logs
Oct 16 2022
#garfield Calendar
02:22 AM rue_mohr: the silly post is up to 652 likes...
04:58 AM polprog: which post?
06:18 AM Tom_L: the silly one, silly
06:35 AM Tom_L: ferrite bead
03:23 PM polprog: ferrite bread
03:25 PM polprog: oh wow, thats interesting !
03:26 PM rue_shop3: hah
03:26 PM rue_shop3: I got the 1 wire 595 thing working on the esp8266
03:27 PM rue_shop3: its sure a fast processor...
03:34 PM polprog: been reading optics papers today
03:35 PM polprog: funny how most systems can work the opposite way if you modify them just a little
03:35 PM polprog: also optical pulse stretchers
03:35 PM polprog: clever, very clever devices
03:35 PM polprog: the principle is based on the fourier transform of the pulse __/\___
03:36 PM polprog: in the EM frequency domain
03:36 PM rue_shop3: ?
03:36 PM polprog: basically you have a pulsed laser
03:36 PM polprog: a femtosecond laser
03:36 PM rue_shop3: k
03:36 PM polprog: thats what my thesis talks about, among other things
03:36 PM rue_shop3: ah
03:36 PM polprog: and you have the oscillator that generates femtosecond-wide pulses of light
03:37 PM rue_shop3: low duty?
03:37 PM polprog: up to MHz pulse rates
03:37 PM polprog: very, very low duty
03:37 PM rue_shop3: yup, low duty
03:38 PM polprog: so the oscillator itself generates the basic fs-wide pulses, but they are low power
03:38 PM polprog: you have to amplify that
03:38 PM rue_shop3: I need to install the fet driver in this pc supply
03:38 PM rue_shop3: to detect it yea
03:38 PM polprog: no, you can detec them allright but if you want to say, cut glass sheets then you need more power
03:38 PM rue_shop3: what is being studdied at the fs level?
03:39 PM polprog: Looads of things, you can do crazy stuff
03:39 PM polprog: you can rip apart atoms
03:39 PM rue_shop3: cant you do that with longer pulses?
03:39 PM polprog: no, because the energy is too small
03:39 PM polprog: you can cut things without heating them
03:40 PM polprog: "cold ablation"
03:40 PM rue_shop3: ah
03:40 PM polprog: so you have an extremely short pulse with extremely high energy
03:40 PM rue_shop3: aaaah
03:40 PM rue_shop3: so its about using the lasers that can only operate up to fs pulses
03:40 PM polprog: yeah
03:41 PM rue_shop3: for the high levels of energy they put out
03:41 PM rue_shop3: I presume then, that their efficiency is crap?
03:41 PM rue_shop3: part of the time limitation?
03:41 PM polprog: it is acceptable, but its the best you can get
03:41 PM polprog: imagine, you have a laser where you can cut a hole in a match head
03:41 PM polprog: and it does not ignite
03:42 PM rue_shop3: right, without pushing it over its ignition temp
03:42 PM rue_shop3: pulsed tig welding is great for many things
03:42 PM polprog: it does not even heat it up at all! the energy is so high that the atoms instead of starting to shake (and heat up) they just have their electrons knocked out
03:42 PM polprog: the thing just disintegrates
03:42 PM rue_shop3: huh
03:42 PM polprog: zero heat
03:43 PM rue_shop3: well, heat at the pico watts level
03:43 PM rue_shop3: er, fw
03:43 PM polprog: yeah
03:44 PM polprog: so basically the pulse stretcher
03:44 PM polprog: you know how FFT works right?
03:44 PM rue_shop3: yes
03:44 PM rue_shop3: how do you stretch pulses?
03:44 PM polprog: if i have a sine wave then i have one single frequency
03:44 PM polprog: ill tell you how
03:44 PM polprog: and if you have a pulse or edge, it is composed of multiple frequencies
03:45 PM rue_shop3: yes
03:45 PM polprog: so the same goes with light, frequency corresponds to wavelength
03:45 PM polprog: if you have a constant wave laser, like the usual ones
03:45 PM rue_shop3: interesting
03:45 PM polprog: it emits a single frequency (ok, not really, but very close to)
03:45 PM rue_shop3: so the pulses have a lot more in them
03:45 PM polprog: so thats a single wavelength
03:45 PM polprog: yes!
03:46 PM polprog: pulses have a very broad spectrum if you think about it
03:46 PM polprog: like, you still have a center frequency but the specral width is very wide
03:46 PM polprog: you have a superposition of many sine waves
03:47 PM rue_shop3: a stream of short pulses has more high frequency energy in it
03:47 PM polprog: they are all high frequency cause they are light but the pulses have very broad spectrum
03:48 PM polprog: like, if you have a prism or a diffraction grating and you shoot a constant wave laser through it you get one line
03:48 PM polprog: cause there is one frequency
03:48 PM polprog: but if you shoot a pulse you would get a (very short in time) kinda rainbow, all colors
03:48 PM polprog: now if you run that light through a system which will delay some of it less and some of it more
03:49 PM rue_shop3: ah
03:49 PM polprog: then the output pulse will be stretched
03:49 PM polprog: when you put it back together
03:49 PM polprog: it is so damn smart
03:49 PM rue_shop3: so, your not stretching a wavelength, but smearing a spectrum of them
03:49 PM polprog: yeah
03:49 PM polprog: ___/\___ -> __--^--__
03:50 PM polprog: now i was thinking about it..
03:50 PM polprog: and basically you can compress the pulse the same way so its even shorter
03:50 PM polprog: just.. reverse the delay order
03:51 PM polprog: and i was thinking if i had a circuit that has a different phase delay for different frequencies I could shorten electrical pulses
03:51 PM polprog: i have that contraption that makes 5ns wide pulses
03:52 PM polprog: this is <1GHz still
03:52 PM polprog: so bearable in a home lab
03:52 PM polprog: UHF if you will
03:52 PM polprog: if i had a circuit that could delay the high frequencies by a different amount than low i could stretch or compress the pulse
03:53 PM rue_shop3: it might be fun to play with at low frequencies
03:54 PM rue_shop3: there must be a payoff to shifting them much
03:54 PM polprog: i mean you could even do it at low MHz
03:54 PM rue_shop3: all pass amp
03:54 PM rue_shop3: er
03:54 PM rue_shop3: sadfk
03:54 PM rue_shop3: all-pass filter
03:56 PM polprog: hmm
03:56 PM polprog: i have to study filters
03:56 PM polprog: it should be passive if i want to push it up to GHz range
03:57 PM rue_shop3: yea, I need to finish my filter analizer
04:05 PM polprog: also funny how the laser cavity theory is the same as electronic oscillator theory
04:05 PM polprog: the cavity with active medium must have a gain > 1 for the wavelength you want
04:05 PM polprog: thats 1)
04:05 PM rue_mohr: phase too?
04:05 PM rue_mohr: hmm
04:06 PM polprog: and 2) is that the phase must match, ie it must be a multiple of 2pi at the wavelength you want (you adjust the cavity length to adjust optical path)
04:06 PM polprog: yes!
04:06 PM polprog: its the same
04:06 PM polprog: Gain and phase
04:06 PM polprog: just replace frequency with wavelength and you get the same stuff
04:06 PM rue_mohr: that makes sense
04:08 PM polprog: no one talks about it, i had to come up with the analogy myself and i wrote it
04:12 PM rue_mohr: it must make high freq lasers brutal to tune
04:14 PM polprog: wdym by high freq?
04:14 PM polprog: The resonator length is a lot longer than wavelength
04:14 PM polprog: and the active medium has a very wide range where it does the amplification
04:14 PM rue_mohr: you ahve to get the phase of the wave right tho ... right?
04:14 PM polprog: yes, but it happens by itself
04:15 PM rue_mohr: ah
04:15 PM polprog: you have many frequencies which are very close and a few of them will always be in the range where the active medium amplifies them enough
04:15 PM rue_mohr: https://github.com/ruenahcmohr/OneWire595
04:16 PM rue_mohr: I'll stop there on that, I dont think anyone gets it anyhow
04:16 PM polprog: so to make a gas laser not lase you need to knock the end mirror out of alignment (so it does not reflect the light back into the resonator cavity)
04:16 PM polprog: or let the gas out
04:16 PM rue_mohr: I just wanted to have it up so others could use it
04:17 PM rue_mohr: I had been working on making laser tubes eh?
04:17 PM rue_mohr: I couldn't get two Ts to work on the same glass
04:22 PM polprog: sadly the only laser you can make at home without having a glass workshop is quite dangerous cause it runs on mains generated kV voltages and emits infrared
04:22 PM polprog: and emits it with quite some power so you can blow your eyes out
04:23 PM polprog: youre better off buying a Helium-Neon tube, with or without the power supply
04:24 PM polprog: it has like, 2 unique ways to kill or hurt you for the price of one
04:25 PM rue_mohr: heh
04:58 PM Tom_L: lively bunch today
05:02 PM rue_mohr: :)
05:02 PM polprog: i was driving today
05:09 PM rue_shop3: :)
05:09 PM rue_shop3: polprog, we drive... a lot.
05:09 PM rue_shop3: personally, I hate it
05:09 PM rue_shop3: borring
05:09 PM polprog: i saw how a us driving exam looks like
05:09 PM polprog: haahahaha
05:10 PM rue_shop3: you should see the drivers tho
05:10 PM rue_shop3: there is a reason the cars are being made to steer and stop themselvs
05:10 PM polprog: yeah, not here
05:10 PM polprog: for my exam i had to take two left turns in the most screwed up and busy street in the area
05:10 PM polprog: like, you have a ton of lane changes
05:11 PM rue_shop3: mhm
05:11 PM polprog: cars stopped in the middle for loading and unloading (this is the chinatown kind street, nail salons and asian bars all along)
05:11 PM polprog: random people jaywalking
05:11 PM polprog: and a tiny roundabout at one end
05:12 PM polprog: and a two road three lane street with tram tracks in the middle on the other end
05:46 PM rue_mohr: polprog, you still there?
05:46 PM polprog: yep
05:47 PM rue_mohr: thoughts...
05:47 PM rue_mohr: for a tqfp44
05:47 PM rue_mohr: https://www.aliexpress.com/item/32962351315.html
05:47 PM rue_mohr: or https://www.aliexpress.com/item/1005002805105986.html
05:47 PM rue_mohr: or ?
05:48 PM polprog: hmm, for you id use the dip44 breakout
05:50 PM rue_mohr: hey wait
05:50 PM polprog: ?
05:50 PM rue_mohr: they... they just skipped some pads
05:50 PM polprog: no
05:50 PM polprog: it just lookslike that
05:50 PM polprog: wait no
05:50 PM polprog: oh lol
05:51 PM rue_mohr: oh aha and its 0.8mm
05:51 PM polprog: i guess you gota get creative soldering
05:51 PM rue_mohr: ugh
05:51 PM polprog: x_X
05:51 PM rue_mohr: yea really
05:51 PM rue_mohr: I'll keep digging
05:51 PM rue_mohr: I have one of the multisize baords that goes to 100, but its big
05:53 PM polprog: i bought one of these 4 years ago and never used
05:54 PM rue_mohr: XC9536
05:55 PM rue_mohr: 100pcs pc817 for $4
05:55 PM rue_mohr: maybe I should work out how to make the T flipflop from those
05:55 PM polprog: whaaa?
05:56 PM rue_mohr: did you see the 3 element ring counter?
05:56 PM rue_mohr: from them?
05:56 PM rue_mohr: 1-4Hz?
05:56 PM polprog: whos them
05:56 PM polprog: link?
05:56 PM rue_mohr: from the pc817
05:56 PM rue_mohr: when we did the oscillators and stuff
05:57 PM rue_mohr: I should digitize my book
05:57 PM polprog: pc817....
05:57 PM rue_mohr: make an online pdf
05:57 PM rue_mohr: opto isolator, 4 pin
05:57 PM polprog: ah yeah
05:57 PM polprog: i recall
05:59 PM rue_mohr: I cant find any other suitable qfp44->dip adaters
05:59 PM rue_mohr: https://www.aliexpress.com/item/32776379373.html
05:59 PM polprog: tbh if you drew them up in kicad and ordered on jlc they would probably be there in the same time as the ali obes
05:59 PM polprog: ones*
06:00 PM rue_mohr: maybe I should buy a roll of mylar tape and learn to do it the hard way
06:00 PM rue_mohr: thats a good point
06:00 PM rue_mohr: I'v never use jlc tho
06:00 PM rue_mohr: they require gerbers?
06:00 PM polprog: your thermal transfer game is quite good, im sure you can make a batch in a day or so
06:00 PM polprog: i just hate the drilling
06:01 PM rue_mohr: hah, its not that good
06:01 PM rue_mohr: hmm
06:01 PM rue_mohr: I dont know if I want to bother trying sub 0.05" at home
06:02 PM polprog: yeah
06:02 PM polprog: today at the market guy had a 3 axis cnc
06:02 PM polprog: 30x30 cm
06:03 PM rue_mohr: mask helps a lot for soldeirng too
06:03 PM polprog: and a fusebox housing the controller
06:03 PM rue_mohr: nice
06:03 PM polprog: i did not ask how much
06:03 PM rue_mohr: I'v noticed that most of my stuff would fit in 8.5"x11"
06:03 PM rue_mohr: I'v pondered building one just that size
06:03 PM rue_mohr: replace the other two?
06:04 PM rue_mohr: I have a space issue
06:04 PM polprog: *you* have a space issue :D
06:04 PM Tom_L: the tinning you get on fabbed boards makes soldering easier too
06:05 PM rue_mohr: should I make a tunneling machine and build an underground layre?
06:05 PM polprog: allright, bed time
06:05 PM Tom_L: rue_mohr, why not?
06:05 PM rue_mohr: oh, you dont want to spend the night scolling ali results with me?
06:06 PM Tom_L: get thru the clay and no tellin what you might find
06:06 PM rue_mohr: yea...
06:06 PM polprog: i wish but i have uni at 8:00 tomorrow
06:06 PM polprog: god damnit, they could let us sleep
06:06 PM polprog: it s the last semester
06:06 PM polprog: few more months and im done
06:07 PM polprog: eng. polprog
06:07 PM Tom_L: took the nieces to the pumpkin patch today
06:07 PM Tom_L: wound up on a chopper ride
06:07 PM Tom_L: fun day
06:07 PM polprog: night!
06:07 PM rue_mohr: hah fun
06:08 PM * Tom_L crosses that off his bucket list
06:08 PM rue_mohr: I'm bad with heights, had to pretend there were big long legs
06:09 PM Tom_L: coasters i hate, this i thououghly enjoyed
06:29 PM rue_mohr: I'm dead tired
06:29 PM rue_mohr: want to get the high voltage motor driver assembled
06:30 PM rue_mohr: hmm
06:30 PM rue_mohr: the fet drivers that do high and low side
06:31 PM rue_mohr: need a part number
06:33 PM rue_shop3: FAN7842
06:33 PM rue_shop3: its a soic8
06:33 PM rue_shop3: ah 200V difference
06:33 PM rue_shop3: ok
06:33 PM rue_shop3: I was wondering because of the package sizez
06:34 PM rue_shop3: not a lot of room for high voltage
07:59 PM rue_shop3: hahha the chip is 0.8mm
08:04 PM Tom_L: the whole chip?
08:44 PM rue_shop2: 0.8mm lead pitch
08:46 PM Tom_L: OOhh
11:54 PM rue_mohr: mmm I didn't cook those potatoes quite as good as I thoguht I did
11:55 PM rue_mohr: supper is generally a fail
11:55 PM rue_mohr: -------------U------------
11:55 PM rue_mohr: I/O/GTS2 34 |o1 40 | VCC
11:55 PM rue_mohr: I/O/GTS1 36 | 2 39 | 33 I/O/GSR
11:55 PM rue_mohr: 37 | 3 38 | 32
11:55 PM rue_mohr: 38 | 4 37 | 31
11:55 PM rue_mohr: 39 | 5 36 | 30
11:55 PM rue_mohr: 40 | 6 35 | 29
11:55 PM rue_mohr: 41 | 7 34 | 28
11:55 PM rue_mohr: 42 | 8 33 | 27
11:55 PM rue_mohr: I/O/GCK1 43 | 9 XC9536XL 32 | 23
11:55 PM rue_mohr: I/O/GCK2 44 | 10 DIP40 31 | 22
11:55 PM rue_mohr: I/O/GCK3 1 | 11 30 | 21
11:55 PM rue_mohr: 2 | 12 29 | 20
11:55 PM rue_mohr: 3 | 13 28 | 19
11:55 PM rue_mohr: 5 | 14 27 | 18
11:55 PM rue_mohr: 6 | 15 26 | 16
11:55 PM rue_mohr: 7 | 16 25 | 14
11:55 PM rue_mohr: 8 | 17 24 | TDO
11:55 PM rue_mohr: 12 | 18 23 | TCK
11:55 PM rue_mohr: 13 | 19 22 | TMS
11:55 PM rue_mohr: GND | 20 21 | TDI
11:55 PM rue_mohr: --------------------------
11:55 PM rue_mohr: I uh,
11:55 PM rue_mohr: made a DIP40 CPLD