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cool so im thinking then: first stage is something resembling a unity gain instrumentation amplifier with its inputs AC coupled with a half-supply virtual ground second stage is a volume control circuit so the pot in the feedback loop of an inverting amplifier third stage is the single-ended to differential circuit that i have now, outputs ac coupled to the inputs of the power amplifier is it necessary to ac couple the first/second/third stages to each other with their own virtual grounds? my gut says yes because the second stage has gain so weird poo poo will happen otherwise any value in sticking some input filtering in along the way? Bloody fucked around with this message at 22:15 on Mar 20, 2017 |
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Mar 20, 2017 22:11
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| # ¿ Jun 7, 2023 13:17 |
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okay i've reworked my front stage to be: diff to SE around a 1/2 supply common mode SE goes into the volume pot SE to diff around a 1/2 supply common mode idk if im going to put any capacitance to ground at the input nodes. might shunt some really high noise crap, i guess? starting to seem unnecessary. i turned the crank on the output filter design appnote and some sims and have come up with 10 uH inductors and 0.33 uF caps, which i've swapped to some bigass film caps. the part datasheet has (and i copied) that 1nF shunt and 10nF/3.3ohm shunt on the output but i don't entirely understand what those are for and nothing really talks about them. are they there to further shunt the high frequency content of the PWM?
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Mar 21, 2017 06:04
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i think my schematic is complete and i've got a preliminary layout routed and im probably not building this board because it's 4 layers and ~36 square inches which is gonna be ludicrously expensive anywhere (eg oshpark would be 360 dollars for 3) plus a ~$100/board bom plus chassis power supply lmao i did make a sweet timelapse of the process tho and i only forgot to record a few bits https://www.youtube.com/watch?v=6tsnFSZMZUY without the top ground plane poured it looks like:  (this is not what i would call a final layout but its most of the way there) Bloody fucked around with this message at 07:05 on Mar 25, 2017 |
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Mar 25, 2017 07:01
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it looks like if i bit the bullet and went to a two sided design i could probably cram this in 12 square inches which is a more tolerable price point hmm it'd be a pain in the rear end to assemble
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Mar 28, 2017 05:25
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microcontrollers are cool and good and cheap and easy
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Mar 30, 2017 18:28
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unpacked robinhood posted:tbh it was on a microcontroller forum and it was kinda my fault whats the power draw of your circuit (ballpark)? if its mostly just the microcontroller, then its probably like a few milliwatts (milliamps). then the efficiency penalty of your linear regulator is basically just (output voltage)/(input voltage) and then well if your load is a few milliwatts you're probably just fine
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Mar 30, 2017 18:30
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ya so its gonna burn like a few milliwatts at an LDO, no problem
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Mar 30, 2017 18:40
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manhattan construction owns
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Apr 4, 2017 18:02
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install diptrace
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Apr 11, 2017 17:42
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the pin number limitation is total pin count. my tpa3251 board posted earlier is right under the limit 2 routing layers, but you can have planes, so you can do four layer boards. i believe you can shape route the planes although i haven't tried also, the restrictions in general are not super robustly implemented. i've accidentally wound up with >300 pin boards in the free version that were still routable and modifiable and stuff. no idea how 
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Apr 11, 2017 22:03
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i plop down the ground symbol from the symbols library (or w/e its called) then just copy-paste it around  it is definitely not a replacement for the enterprise grade tools but its pdeece as an eagle alternative imo
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Apr 11, 2017 22:44
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it is not saying "219 yospos bitch", voted 1
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Apr 20, 2017 04:51
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wow that post is a blast from the past
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May 22, 2017 21:17
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does it require a higher supply voltage? the class D amp i was makin with that ti part earlier itt took like a 36 or 48 or something volt supply
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May 29, 2017 00:02
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ya pc power supplies are weird and fickle beasts
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May 29, 2017 01:34
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https://obsproject.com/
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Jun 4, 2017 23:26
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lol if you dont just buy aoyue crap
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Jul 12, 2017 23:47
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flakeloaf posted:i'm refurbing a pinball machine alone with no experience; is that the sort of thing that goes here you are in the right place how to solder: use a lot of flux
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Jul 24, 2017 17:53
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i can barely solder
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i like the liquid flux (i think its 97? partially activated? idk) in lil bottles with a needle dispenser
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Jul 25, 2017 03:58
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no its probably toxic op
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Jul 25, 2017 04:22
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Trig Discipline posted:my thing is kinda done I don't get it
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Sep 17, 2017 05:02
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Who's Dan Carlin is he that comedian that died
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Sep 17, 2017 17:21
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Mister Sinewave posted:I had no idea who Dan Carlin was but could still appreciate ART, man I am incapable of appreciating art that's 45 minutes on YouTube
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Sep 17, 2017 20:50
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hand soldering a 44 qfp is not too bad just use lots of Flux and some tape as a third hand
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Oct 27, 2017 15:40
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I didn't watch the thing it seemed creepy
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Nov 18, 2017 04:40
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just dump it through a lil IIR filter
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Nov 21, 2017 01:21
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every dma is broken at least a little
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Nov 23, 2017 00:13
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Spatial posted:i got to know the M4's DSP instructions and made the core of the mixer in assembly. sweet
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Apr 2, 2018 18:28
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| # ¿ Jun 7, 2023 13:17 |
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haveblue posted:sweet find. a few years ago my former neighbor threw out 3 really old macs- an se, a plus, and one other which might have been an original classic. I could only take one with me so I went with the SE for the most iconic case. it was 100% dead so I ripped all the original parts out and bashed it into a little home management/kitchen assistant thing old computers are literal garbage. this is an excellent repurposing of one
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Apr 21, 2018 23:56
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