#garfield Logs
May 11 2021
#garfield Calendar
12:40 AM rue_mohr: and the theader pins for the wire wrap!!
01:39 AM rue_bed: come to think of it, the fft code I have might be a good base for the filter stuff
01:40 AM rue_bed: I also need to make some kinda battery tabber this week
01:40 AM rue_bed: 4 days left
05:57 AM polprog: 4 days till what?
07:43 AM rue_bed: to build a battery tabber
07:44 AM polprog: hmm
08:11 AM rue_bed: generally seems to be divided into capacitor discharge and transformers
08:12 AM rue_bed: the capacitor ones seem to divide into fet switching an scr switching
08:12 AM rue_bed: there are some battery ones that are fet switched, but I'm not keen on that method
08:30 AM polprog: what are you gonna use?
08:44 AM rue_mohr: capacitor and scr would be nice
08:44 AM polprog: i got some HV caps
08:44 AM rue_mohr: just need high capacity
08:45 AM polprog: yeah i was saying in general
08:45 AM polprog: also some 400V 100uF ones
08:45 AM rue_mohr: 0.6F to 100F
08:45 AM rue_mohr: depending on voltage
08:45 AM polprog: watch out, cause some supercaps have high internal resistance
08:45 AM polprog: so they wont spark nicely :<
08:45 AM rue_mohr: yep
08:46 AM rue_mohr: tho the last supercap I got burned part of its electode off when I accidently shorted it
08:46 AM polprog: lol
08:46 AM rue_mohr: didn't completely discharge either
08:46 AM polprog: back to work
08:47 AM rue_mohr: work or school?
08:47 AM polprog: school now
08:47 AM polprog: gotta write these reports...
08:47 AM polprog: i hate it
12:13 PM rue_mohr: oh no, ma is typhoid marry
12:13 PM rue_mohr: she's been hanging around and she has a cold
12:13 PM rue_mohr: now I'm ill
01:31 PM darkrose: as long as it's just a cold
01:47 PM rue_mohr: yes but if I havea sympoms of anything it all gets quite complex
01:47 PM rue_mohr: if I phone in and get told to go on isolation so I can get work compensation, they will shut down the company I work for
02:10 PM rue_mohr: I'm discovering a pseudo-coprocessor
02:11 PM rue_mohr: when you have a secondary processor in a system thats not really being used as a processor
02:11 PM rue_mohr: the tiny85 clock gen is a good example
03:39 PM aandrew: https://hackaday.com/2021/05/11/smallest-discrete-transistor-555-timer/
03:40 PM rue_mohr: I know
03:40 PM rue_mohr: we are beyond the technology where we can make chips :)
03:41 PM rue_mohr: wait for the words "we cant make that stuff anymore"
03:42 PM Tom_L: what are the odds of me washing the omnikey keyboard switches and they still be working?
03:42 PM Tom_L: had yet another spill on it
03:43 PM Tom_L: i had it working but aparently it dried and is sticky again
03:43 PM Tom_L: i'm gonna pop the caps off on some of them this time
03:44 PM Tom_L: fortunately i have 2 of these and was able to use the spare to finish a job
03:44 PM rue_mohr: you can dissassemble, wash, and re-assemble
03:44 PM rue_mohr: oh wait
03:44 PM Tom_L: i have the pcb out already
03:44 PM rue_mohr: they are real buttons or laminated?
03:44 PM Tom_L: real
03:44 PM rue_mohr: about 0%
03:44 PM Tom_L: cherry key
03:44 PM Tom_L: no, i'll fix it one way or another
03:45 PM rue_mohr: I said "about", take that as +-2%
03:45 PM Tom_L: anyway. bbl... leave any advice and i'll read it later.
03:45 PM rue_mohr: don't walk under ladders
03:46 PM rue_mohr: don't cut towards yourself
03:52 PM polprog: rue_mohr: the anti reverse engineering coprocessor
03:53 PM polprog: "Why did they put an ARM microcontroller and a 8051 on the same board? And what is that 555 doing there??"
03:53 PM rue_mohr: don't hammer towards you crotch
03:53 PM rue_mohr: dont stare into the sun
03:53 PM polprog: accidents on the back seat may cause children
03:53 PM polprog: or the other way around
03:53 PM rue_mohr: anti reverse engineer coprocessor?
03:54 PM polprog: yes you just throw some extra chips to confuse the enemy
03:54 PM rue_mohr: oh
03:55 PM polprog: :)
03:55 PM polprog: ive been playing with phones today
03:55 PM rue_mohr: ok
03:55 PM polprog: i got a nice linemans handset with a rotary dial
03:55 PM rue_mohr: k
03:56 PM polprog: and a dect handset. but for some reason the handset doesnt ring when i call the base. But i can call outside from the handset
03:56 PM polprog: weird registration
03:56 PM rue_mohr: I used to force the rotor to speed up the dialing
03:56 PM polprog: this one works really really nice
03:56 PM polprog: and my PBX supports pulse dialling
04:00 PM rue_mohr: so, the software filter works pretty good
04:01 PM rue_mohr: I just bumped it up to 20MHz, and its holding, I need to do timed samples tho
04:01 PM rue_mohr: the arduino PID library can do a max of 1kHz
04:01 PM polprog: how does the program work? FIR or something else?
04:01 PM rue_mohr: it looks like it was intended for sample times in the seconds range
04:01 PM rue_mohr: just doing a low pass filter right now
04:02 PM rue_mohr: did you see the twitter post?
04:03 PM polprog: i saw the trace picture but not any code
04:03 PM rue_mohr: oh
04:03 PM rue_mohr: http://paste.debian.net/1197210/
04:04 PM rue_mohr: yes, thats it.
04:04 PM rue_mohr: like I say I need to set up timed samples
04:06 PM polprog: Vo += (Vi - Vo) / k ; // low pass
04:06 PM polprog: how does that work
04:06 PM rue_mohr: yup
04:06 PM polprog: its just integration right?
04:06 PM rue_mohr: diff
04:06 PM rue_mohr: er
04:06 PM rue_mohr: no your right, I keep getting mixed up
04:06 PM polprog: :)
04:07 PM rue_mohr: k is calculated by another program I wrote
04:07 PM rue_mohr: you can make it from an RC combo, or Tau, or from Fc
04:09 PM polprog: hmm
04:09 PM polprog: digital filers is something im not experienced in
04:09 PM polprog: although i should know more maths behind it now
04:09 PM rue_mohr: for an integer version, this really impressed me
04:10 PM rue_mohr: they don't seem to teach it like what I discovered in Jan
04:10 PM polprog: it does work nice
04:10 PM rue_mohr: the Fc is a bit out
04:10 PM rue_mohr: but, geez, its all integer
04:10 PM polprog: try putting some sound thru it
04:11 PM rue_mohr: I'd like to tweak a bit more
04:11 PM rue_mohr: I want to set it up to sample at 10k
04:11 PM rue_mohr: when I ran the m8 at 20Mhz, the sample rate went to about 32khz
04:12 PM rue_mohr: 42khz if I use something easy like 32 for the divide
04:12 PM polprog: with -O3?
04:13 PM rue_mohr: no, but there isn't much to optomize
04:13 PM polprog: give it a try
04:15 PM polprog: and then make a state machine based version thats even faster :P
04:16 PM rue_mohr: hahah
04:16 PM rue_mohr: its not a state machine, its a LUT
04:16 PM rue_mohr: 512k
04:17 PM polprog: even better
04:17 PM rue_mohr: I wonder if I could get the answer from a 512k eeprom faster than calculating it
04:17 PM rue_mohr: (serial one)
04:26 PM polprog: I had 5 of my students build SR latches today
04:26 PM polprog: maybe more, but only 5 showed they made one, or talked about it in voice chat
04:27 PM polprog: one of them even showed it on the webcam, but i noticed an unusual thing in the back
04:27 PM polprog: there were ketchup bottles on the shelf
04:27 PM polprog: like, at least 15 indentical ones next to eachother, arranged neatly like an exhibit
04:27 PM polprog: i cant stop thinking about these bottles
04:27 PM polprog: were they empty, or full? why?
04:28 PM polprog: and why in a bedroom
04:31 PM rue_mohr: :)
04:42 PM Tom_L: #2 i did the other day and nearly slit my wrist
05:59 PM Tom_L: ok alcohol seemed to do the trick
05:59 PM Tom_L: cleaned with that then dried with air
06:17 PM aandrew: Tom_L: did you use that fancy new milling bit on yourself?
06:17 PM Tom_L: box knife
06:18 PM aandrew: ah
06:18 PM Tom_L: but
06:18 PM Tom_L: those cutters are very very sharp
06:18 PM aandrew: yes, yes they are
06:18 PM Tom_L: more so than the average one
06:18 PM Tom_L: i can feel the difference
06:18 PM aandrew: when I was a teenager I buried a full 6" of those snap-away xacto knives into my thigh
06:20 PM aandrew: I was in the basement of my dad's apartment building, in the storage lockers, cutting the power cord off some ancient cable tv receiver, using my lap as a pivot point. the blade was rusty as hell and twice as dull, and I was giving it my all when I triumphantly sliced through it and ALL the way into my thigh
06:20 PM aandrew: that didn't hurt at all, but I'll never forget the feeling of pulling it out. I'm shuddering just typing it here 30y later
06:20 PM aandrew: then of course walking 5 flights of stairs up to his aprtment with a fairly freely bleeding leg wound
06:21 PM aandrew: I'm extraordinarily lucky I didn't hit an artery
06:25 PM Tom_L: luckily mine was not deep, it crossed over 2 arteries
06:29 PM rue_mohr: I have this sneaking feeling that ttl TFT displays are like SUPER EASY to operate
06:30 PM Tom_L: still got 2 or 3 stubborn switches
07:19 PM rue_mohr: :S
07:19 PM rue_mohr: so
07:19 PM Tom_L: ok all better now
07:19 PM rue_mohr: ttl tft screens
07:19 PM rue_mohr: they take parallel rgb and a pixel clock in
07:19 PM rue_mohr: which makes them super easy to operate
07:19 PM Tom_L: took the 2nd one apart to see what was wrong with the space bar because i'd forgotten
07:20 PM rue_mohr: bit
07:20 PM rue_mohr: but
07:20 PM Tom_L: one little plastic glide is broke
07:20 PM rue_mohr: I'm having a time finding screens to just play with
07:20 PM Tom_L: what sort?
07:21 PM rue_mohr: there seems to be serial I/F, parallel I/F, "ttl" video I/F, and lvds video I/F
07:21 PM Tom_L: i got a lvds if you want it
07:21 PM Tom_L: it's got a crack in it but it works
07:21 PM rue_mohr: I'm looking for a screen from ali I can accidently blow up
07:21 PM rue_mohr: but their all like $100
07:21 PM rue_mohr: which is new
07:21 PM rue_mohr: I have a large pile of pc screens
07:22 PM rue_mohr: but their lvds I think
07:22 PM rue_mohr: I had one on the deck and its a 4 channel lvds
07:22 PM rue_mohr: I dont know if 4 is normal or not, I see a controller with 8ch
07:22 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/SBC/lcdpannel1.jpg
07:23 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/SBC/lcdpanel.jpg
07:23 PM rue_mohr: whoa
07:23 PM Tom_L: iirc i had a spare touch screen i put on it
07:23 PM rue_mohr: is that just a touch screen that broke?
07:23 PM Tom_L: lvds
07:23 PM Tom_L: no, the display got craced in shipping too
07:23 PM rue_mohr: did you notice how many pairs it uses?
07:23 PM Tom_L: the corner
07:23 PM Tom_L: nope
07:24 PM Tom_L: i'm not even sure where it is
07:24 PM rue_mohr: https://www.aliexpress.com/item/1005001952077906.html
07:24 PM rue_mohr: then there is that thing
07:24 PM rue_mohr: which has no protocol info there
07:24 PM rue_mohr: I dont feel like digging
07:25 PM rue_mohr: I wonder if any of those IP phones I have use colour tft screens with a ttl interface
07:25 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/SBC/lcd_spot.jpg
07:25 PM Tom_L: ahh there you can see it
07:25 PM rue_mohr: heh
07:25 PM Tom_L: so it's free to blow up
07:25 PM Tom_L: :)
07:26 PM Tom_L: the guy just packed it shitty
07:26 PM rue_mohr: I have a portable dvd player beind me with a screen
07:26 PM rue_mohr: https://www.aliexpress.com/item/1005002549268343.html
07:26 PM rue_mohr: pretty cheap, internal I/F = ?????
07:26 PM Tom_L: i just got her a 32" 4k
07:26 PM Tom_L: now i want one but not that big
07:27 PM rue_mohr: shall I ship you a 12"?
07:27 PM rue_mohr: er 14
07:27 PM Tom_L: too small
07:27 PM rue_mohr: forget what my small ones are
07:27 PM Tom_L: i have 3 1080
07:28 PM Tom_L: and the old dell on the dos pc
07:28 PM Tom_L: 2 spares in the closet i dunno what they are
07:28 PM Tom_L: smaller ish
07:28 PM Tom_L: old tech
07:30 PM Tom_L: at least 3 or 4 PC104s
07:33 PM Tom_L: ok, i'm calling that done
07:53 PM rue_mohr: ok, the screen in the dvd player is not like the screen standards today
07:56 PM rue_mohr: I can buy a 7" tft monitor for $21, or a 7"tft panel with driver for $150
07:57 PM Tom_L: what about the rpi4 touch screen?
07:57 PM rue_mohr: spi
07:57 PM rue_mohr: no
07:58 PM rue_mohr: tho I suppose if I need a gpu its all the same
07:58 PM Tom_L: $29
07:58 PM Tom_L: https://www.amazon.com/Raspberry-Touchscreen-320x480-Monitor-Display/dp/B07WQW6H9S/ref=sr_1_3?dchild=1&keywords=raspberry+pi+4+screen&qid=1620780272&sr=8-3
07:58 PM rue_mohr: aha
07:58 PM rue_mohr: look at this...
07:59 PM rue_mohr: https://www.aliexpress.com/item/1005002433442764.html
07:59 PM rue_mohr: in one of the images of the side of it, you can see the ribbon cable
07:59 PM rue_mohr: thats probably a ttl panel
07:59 PM Tom_L: https://www.amazon.com/GeeekPi-1024x600-Capacitive-Monitor-Raspberry/dp/B075QCXLPF/ref=psdc_1292115011_t1_B07WQW6H9S
08:00 PM rue_mohr: $30 is more than $24
08:00 PM rue_mohr: so is $63
08:01 PM Tom_L: so is HDMI
08:01 PM rue_mohr: I'm looking for ttl signalling this time
08:01 PM rue_mohr: dont care about hdmi :)
08:01 PM Tom_L: i offered a broken lvds
08:02 PM Tom_L: you just gotta come get it
08:02 PM rue_mohr: I'm greatfull, but decline
08:03 PM rue_mohr: I'd like to come get othr things you dont want!
08:03 PM Tom_L: i could load you up so you'd never get back across the border
08:03 PM rue_mohr: "scrap metal"
08:04 PM Tom_L: take you to the scrap yard for alum
08:04 PM Tom_L: the other one is gone now
08:04 PM rue_mohr: you guys get all the good stuff
08:05 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/local_stock/stock_index.php
08:05 PM Tom_L: you've seen it
08:05 PM rue_mohr: :)
08:05 PM rue_mohr: I just need to find the bucket of scrap carbide bits
08:05 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/local_stock/9.jpg
08:05 PM Tom_L: my lathe is too small
08:06 PM rue_mohr: hah, my suspension is insufficient
08:06 PM Tom_L: no doubt
08:06 PM rue_mohr: I got the front redone tho
08:07 PM rue_mohr: peices were falling off the shocks ya know
08:07 PM Tom_L: i had the front springs out on mine once
08:07 PM Tom_L: probably for lower bushings
08:07 PM Tom_L: i don't remember now
08:07 PM Tom_L: nearly didn't get them back in, it's a tight fit
08:08 PM rue_mohr: I took 'er to the shop
08:08 PM Tom_L: what's that place?
08:08 PM rue_mohr: rule 2: don't get the truck disabled in the driveway
08:08 PM Tom_L: never heard of one
08:09 PM rue_mohr: unless its like the time the starter went and it was disabled from the driveway
08:17 PM Tom_L: i still got one of those on the floor under the lathe table
08:17 PM Tom_L: want it?
08:17 PM Tom_L: doesn't work...
08:18 PM rue_mohr: springs?
08:18 PM Tom_L: starter
08:18 PM rue_mohr: hah, no I have an extra