#avr Logs

Apr 14 2018

12:43 AM rue_mohr: I got a LC75834 working!
02:31 AM rue_mohr: almost finished mapping all the funny segments
02:42 AM rue_mohr: http://ruemohr.org/~ircjunk/images/p1090936.jpg
02:42 AM rue_mohr: I'm not sure what it is
02:42 AM rue_mohr: if its about pulling a pcb out of a water soaked trash heap
02:42 AM rue_mohr: if its about sitting down reverse engineering it
02:42 AM rue_mohr: if its about writing code for a new chip
02:43 AM rue_mohr: or if its about getting a board, pulled from a heap, hacked and working
03:30 AM polprog: Haha. Good job!
03:31 AM polprog: I wish i could hack something like that ;)
05:26 AM MrFahrenheit: I gotta get docker up and running on my server, seems like the only sane way to install web applications nowadays since no one bothers to package their software properly
05:30 AM Thrashbarg: heh
05:51 AM MrFahrenheit: TIL, this exists: https://github.com/gotbletu/shownotes/blob/master/any_term_dropdown.sh
06:04 AM gruetzko- is now known as gruetzkopf
08:06 AM polprog: im confused, just took apart an old onkyo speaker amp (basically, our current onkyo amp has the input selector encoder broken, sometimes it jumps aound switching inputs)
08:07 AM polprog: and there are 3 boards inside. What i presume is the PSU board, the amplification board (4 big BJTs and output poles) and a small board in the front panel with a big chip, the input selector and all the rest of the knobs
08:09 AM polprog: what im confused about are connections between boards - from psu to the front there are a lot of wires (at least 10), but from the IO board to the front panel board there are barely 6 wires. The amp has six stereo inputs. thats weird to me
08:09 AM polprog: i have no idea how they are doing the input switching
08:10 AM polprog: also the encoder in the old one is dead so i cant just replace them. i think ill take apart/find the service manual for the new one and just order a replacement, so thats not a problem
08:13 AM Thrashbarg: got a model number? Might help to check the service manual
08:14 AM polprog: ill look for a service manual; the old one is onkyo a-8820 and the new one is onkyo a-9210
08:15 AM polprog: if you do an image search on the first one you will see how the inside looks like
08:16 AM polprog: http://www.hifishock.org/galleries/electronics/onkyo/integrated-amplifier/a-8820-1b-onkyo.jpg
08:17 AM polprog: look how only 6 wires go from the left board to the front (behind the metal shield, this pic is taken from the back)
08:20 AM Thrashbarg: I've got the schematic for the 9211. There appears to be a serial interface going from the main micro to the channel selector
08:21 AM polprog: hmm, that explains the number of wires
08:21 AM polprog: also got a schematic of 9211, people on the forums say its a similar device
08:21 AM Thrashbarg: ok
08:22 AM polprog: this mechanical-analogue-digital hybrid. whyyy
08:22 AM Thrashbarg: yup
08:22 AM polprog: why did someone bother
08:22 AM Thrashbarg: I've seen vacuum cleaners like that. They're impossible to fix
08:23 AM Thrashbarg: the main control will be a pot, and its voltage output would determine the function
08:23 AM Thrashbarg: so it's not a rotary encoder at al
08:23 AM Thrashbarg: all
08:23 AM polprog: lol im only finding vintage hifi sites :D true, this amp is at our house ever since i remember
08:23 AM Thrashbarg: hehe
08:24 AM Thrashbarg: but yea the input selector is a resistive divider and its output current determines the input function
08:25 AM polprog: fuck
08:26 AM polprog: you are right. im looking at the 8820 service manual.. and its a resistive divider
08:26 AM polprog: what are they thinking
08:26 AM Thrashbarg: sounds like they specified an all electronic switch that doesn't make the speakers pop when the input is changed
08:27 AM Thrashbarg: personally I'd prefer a mechanical switch
08:27 AM Thrashbarg: even if that means forgoing the remote control
08:29 AM polprog: my mixer has one that doent go pop when you unmute it (and there is a signal on it)
08:30 AM polprog: anyway
08:30 AM polprog: i think they are doing it inside one of the chips
08:30 AM polprog: trying to track the encoder part no
08:31 AM Thrashbarg: ok
08:32 AM polprog: got it
08:32 AM polprog: allright
08:32 AM polprog: we'll see. maybe we will just get a newer amp
08:33 AM polprog: but my panasonic boom box works awesome, since i changed the speakers to a pair of b&w
08:43 AM polprog: so
08:45 AM polprog: the good news is that i can replace it with any encoder that has the same pin config. doest even have to be the same size physically, as long as it fits between the board and the panel
08:45 AM polprog: i would just route some kynar wires to connect it
09:18 AM MrFahrenheit: kynar sounds like some fantasy metal
09:19 AM MrFahrenheit: this kynar sword detects goblins
09:43 AM polprog: lol
10:30 AM polprog: http://allegro.pl/analizator-widma-hp8563e-30-hz-26-5-ghz-i7220574467.html
10:30 AM polprog: want
10:30 AM polprog: but its 15k gold
10:30 AM polprog: :/
10:30 AM polprog: 13 actually
10:30 AM polprog: still 12000 pln too much
10:51 AM MrFahrenheit: 26 gig? lower your standards a bit
10:55 AM rue_bed: polprog, that board I hacked,
10:55 AM rue_bed: all the buttons were along a resistor chain
10:55 AM rue_bed: whne you push one, it grounds the chain at some point
10:56 AM rue_bed: I hate to think what happens when its a few years old and the buttons have some resistance to them
10:56 AM polprog: rue_bed: oh look
10:57 AM polprog: our amp uses an rotary switch that uses the same thing to select an input
10:57 AM rue_bed: maybe thats why it spent a few years in a scrap metal pile, run over, in the weather
10:57 AM polprog: the selector is acting up
10:57 AM rue_bed: but its a pot?
10:57 AM polprog: MrFahrenheit: what if i want to do some hobby radar :D
10:58 AM polprog: rue_bed: no, its a rotary switch that grounds a chain if resistors
10:58 AM rue_bed: hah
10:58 AM polprog: of*
10:58 AM polprog: the amp is probably from the early 90s
10:58 AM rue_bed: so give it some contact cleaner
10:58 AM polprog: i think ill do that
10:58 AM polprog: havent hought about that
10:58 AM polprog: thanks
11:32 AM twnqx: my amp once used a rotary switch
11:32 AM twnqx: i replaced it with a chip (was prepared on the PCB)
11:32 AM twnqx: and emulated the switch with an avr
11:32 AM MrFahrenheit: polprog, you should probably start with some humble bode plots and scope fft :P
11:34 AM polprog: Nah, were p r o f f e s i o n a l here
11:34 AM polprog: Jokin
11:34 AM polprog: I will be characterizing my mixer with my pc sound card and then later with a signal gen and my riglol
11:35 AM polprog: Using your scpi code ;)
11:35 AM polprog: Gonna learn rust
11:35 AM MrFahrenheit: packages almost done
11:35 AM polprog: And this just in: im swapping a mobo on a laptop, couldnt undo a tiny screw. Tried to freeze it, nope. I grabbed my butane iron and heated the screw up and it let go!
11:37 AM MrFahrenheit: did the laptop melt
11:37 AM rue_mohr: did you set the apartment on fire?
11:43 AM polprog: Not much
11:47 AM MrFahrenheit: btw. polprog, you know that diy spectrum analyser project?
11:47 AM polprog: No
11:48 AM MrFahrenheit: even uses a diy ~10ghz cavity filter
11:49 AM MrFahrenheit: gotta use archive.org for a lot of the pages, but here it is http://scottyspectrumanalyzer.us/
11:50 AM MrFahrenheit: I remembered wrong, the filter is 1ghz
11:56 AM polprog: Wow nice
11:57 AM polprog: Gah this laptop doesnt want to get taken apart
11:57 AM polprog: I undid all the screws and still something is holding it together
12:09 PM polprog: Plastic rivet. What a piece of junk
01:29 PM Emil: Hmm
02:17 PM MrFahrenheit: polprog, also, there was this kid on youtube that was building that SA piece by piece, but he stopped halfway through
02:38 PM polprog: Woooo
02:38 PM polprog: Mobo swap done!
02:38 PM polprog: MrFahrenheit: ill loom into it
02:38 PM polprog: Look*
02:38 PM polprog: First id have to get or make a sig gen!
02:40 PM polprog: Maybe an analogue one but with digital feedback (so i can have precise generation, and a display) . preferably a hard power button, one knob and two buttons
02:41 PM polprog: Minimalistic design
02:47 PM MrFahrenheit: just go with dds, analog has some nice dds chips that are like $5 and go up to 180MHz sampling frequency
02:48 PM MrFahrenheit: http://www.analog.com/media/en/technical-documentation/data-sheets/AD9851.pdf
02:49 PM MrFahrenheit: actually, that one is more than $5, but still, it's an entire solution in one chip, just gotta control it
03:48 PM polprog: Wow awesome!
03:48 PM polprog: Thanks MrFahrenheit
03:55 PM polprog: i mean
03:55 PM polprog: thats just plainly awesome!
03:56 PM polprog: i have a bunch of crystal gens which are too fast for any AVR (14.3 MHz could do, but not 20 or 32)
03:59 PM MrFahrenheit: they have cheaper chips that have a lower max frequency
03:59 PM MrFahrenheit: down to 40MHz iirc
04:01 PM MrFahrenheit: even lower actually, this one is 25MHz, costs just $2 http://www.analog.com/media/en/technical-documentation/data-sheets/AD9833.pdf
04:02 PM MrFahrenheit: not a dds though, but maybe you don't need arbitrary waveforms
04:02 PM polprog: Arbitrary would be nice - but i dont think i have any way to load stuff
04:03 PM polprog: I think i can see the interface in my mind.
04:04 PM polprog: One knob, one display, several buttons to switch waveforms
04:07 PM polprog: A small, cute, field generator
04:09 PM MrFahrenheit: make sure it has 1: sweeps, 2: a sweep sync output
04:12 PM polprog: Thats a software thing. But good point
04:13 PM polprog: What i would also like is to make it a crude 10 meg analyzer with a tracking gen
04:13 PM polprog: Basically to test filters and whatnot
04:13 PM MrFahrenheit: my generator doesn't have the sweep sync output, sucks
04:13 PM MrFahrenheit: you can use a scope for that, either fft or like what I did
04:14 PM polprog: I have an active rectifier done and tested, so id just have to measure the amplitude
04:14 PM MrFahrenheit: if you set the fft to peak mode, it acts a lot like an SA
04:14 PM polprog: Yeah i know. I could make a serial dumping box as well
04:15 PM polprog: That would just use that chip to generate a sweep and measure the returning amplitude and dump this data over serial
04:15 PM polprog: But first. I wanna make muh mixer
05:02 PM polprog: niters
05:03 PM MrFahrenheit: n
05:43 PM rue_mohr: polprog, catch me when your more awake, our schedules dont miss by muchj in the weekdd
11:30 PM day__ is now known as day