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Bloody posted:this is a pretty solid looking layout. i like that your silkscreen has actually been annotated. what are the five blocks on the left? usb connectors it looks like? or maybe that's just the middle one yeah, my philosophy comes from the electrical engineer that I work with: If you're paying for silkscreen, you may as well use as much of it as you can. The five blocks on the left are designed for these little spring terminals that adafruit/sparkfun sell:  you could use regular headers too though.
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Jul 26, 2016 22:47
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peepsalot posted:Also I looked into getting ham license so I can have legit creds when the man tries to hassle me for flyin FPV. Took an example test online without studying any FCC nonsense about freqs and power levels and all that, and i knew enough general electronics to get a passin 27 of 35 questions right. (26 required to pass). So I'll prob go to a local test session or whatever and give it a shot. if you're gonna get your tech go ahead and run through the General pool. if you pass the technician test (they grade on the spot) they'll let you attempt the general for no extra charge. same with general to extra extra's tough but general is basically the tech test + add questions on the General class HF privileges
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Jul 26, 2016 22:48
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Jonny 290 posted:this is why im utterly confused at why electric vehicle manufacturers havent come out with a sick2nasty EV truck. do all your traction control/4wd in software. monster torque. no driveshaft/diff/transmission underneath to get hung up on rocks. Put a 1.0L turbo diesel 3cyl under there spinning a generator at the efficiency peak for both. unf electric? you mean like a girl would drive? or a hippie?
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Jul 26, 2016 23:48
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is there a decent sketchup tutorial out there cause im just loving around with random youtubes
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Jul 27, 2016 01:43
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Arcsech posted:i think this is on tesla's todo list probably in "super special top secret master plan part 3" which will be announced when someone is killed by their in home solar battery
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Jul 27, 2016 01:45
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C.H.O.M.E posted:probably in "super special top secret master plan part 3" which will be announced when someone is killed by their in home solar battery anyone volunteering to short a tesla battery across their chest?
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Jul 27, 2016 01:55
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epipen posted:anyone volunteering to short a tesla battery across their chest? its dc
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Jul 27, 2016 01:58
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Sagebrush posted:electric? yea i mean truck drivers intentionally make their poo poo run like garbage so they can piss off people behind them by going too slow and making tons of black smoke i dont think they care about power or control other than having a 'displatement bigger than urs' badge on the back next to a badge that says Cummins above their truck nuts
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Jul 27, 2016 02:00
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Palace of Hate posted:its dc so's a defib, it'll still kill the poo poo out of you
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Jul 27, 2016 02:03
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epipen posted:so's a defib, it'll still kill the poo poo out of you we never specified how long we would be doing this
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Jul 27, 2016 02:10
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epipen posted:so's a defib, it'll still kill the poo poo out of you no its not
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Jul 27, 2016 02:16
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Bloody posted:no its not i was wrong, we moved to waveforms in the 60s or some poo poo i guess, early units were DC
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Jul 27, 2016 02:23
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Palace of Hate posted:its dc it's 375 volts
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Jul 27, 2016 09:48
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really depends how long its there and how much of a fatty goon you are because the initial resistance might be so high you might just get a great zing but prolonged contact would start cookin into your conductive flesh juices and really deliver fatal current unless your electrodes were huge and you have thick dry skin
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Jul 27, 2016 17:22
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im not recommending it or saying its a good idea im saying its probably way less lethal than 60hz 120vac across the chest
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Jul 27, 2016 17:24
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resistance of skin is in the order of megohms so you could probably grab the terminals and be fine. however, it goes down a lot when you pierce the skin because, suprise, blood is mostly water and is filled with salt electrolytes
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Jul 27, 2016 17:49
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very dry skin is quite resistive but bad news about when it gets sweaty or otherwise damp at all
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Jul 27, 2016 18:22
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u can get <5k impedances through  on a hairy head pretty easily, for example
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Jul 27, 2016 18:23
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i've touched 330V DC from charged-up flash capacitors a number of times, and it is a really unpleasant experience even for the 200 milliseconds or whatever that it takes to discharge to an unfeelable level. i wouldn't want to have a 375v electric car battery put across any part of my body for any length of time, even if it is DC.
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Jul 27, 2016 18:36
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memories of getting stung over and over in a chain link colo cage by a bad ground somewhere by -48vdc
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Jul 27, 2016 19:23
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Connected the 1970s Marantz I'm going to rebuild to an Audio Precision APX525 analyzer last night using test probes. I only had enough to do one channel at a time, some Monoprice cables should come next week and I can do the whole thing. The signal path went from auxiliary in to the preamp out, I'm not sure if I need power resistors to test the speaker outputs or what...  Got some pretty (lovely) graphs. Let's hope performance improves after repair. The left channel is far worse than the right. Right Channel RMS with frequency (pretty good)  Left Channel RMS with frequency   It was a little nerve-wracking connecting the receiver to the analyzer, I was afraid some short to mains would kill this $15k+ piece of (rental) equipment. Hunter2 Thompson fucked around with this message at 00:55 on Jul 29, 2016 |
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Jul 29, 2016 00:49
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yeah, those finals are current sources so you're going to want to put dummy loads on the output to make sure they play nice when sourcing actual amps
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Jul 29, 2016 01:05
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Cool, I'm glad to hear some confirmation  (I don't know what I'm doing, despite the fancy equipment)I'll buy 4x 4-ohm 100W power resistors on Amazon in  green anodized cases, should do the job for four and eight ohm measurements.Any suggestions on how to set the volume knob when I do tests through the entire signal chain? Unity? Full-scale? I'm assuming I should leave the bass/mid/treble at their midpoints, and disable "loudness" right?
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Jul 29, 2016 01:40
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absolutely flat as can be, yep. Loudness switches are the devil unless you're running super low vol (obv). I would ramp up the volume from zero while testing until you see distortion numbers come up, see where you are on the knob and see how tight that correlates to the rated THD numbers for the thing, if they're available -- or a ballpark estimate from a similar amp that does have specs published.
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Jul 29, 2016 01:51
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Wouldn't full-up be unity gain on an old pot volume knob like that? I mean all it can do is reduce output, as far as I can tell. I'm wondering what to do with my H/K receiver's volume knob. It likes to drop the left channel a lot. I've blasted it with Deoxit a few times and while it temporarily improves things the problem always resurfaces. I'm guessing it's just a lovely pot (receiver is only about 10 years old) and I wonder if there is an easy way to replace it. IIRC it's mounted on its own PCB so no idea how much work it would be.
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Jul 29, 2016 01:57
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the volume knob is generally an attenuator early on in the signal chain, so the finals work less at lower volumes. technically yes unity gain but not for the whole chain. as far as pots go, only thing I can say is get the service manual, find a similar pot on Mouser with close physical dimensions and the same value/curve, and heat up the ol' iron super space age answer: get some digital pot ICs and put those in place of the old volume pot, whip up an arduino pro mini to drive that and take input from whatever fancy rotary encoder you like off ebay. enjoy your drive-by-wire volume with whatever curve you like e: you could also put it in party mode with a hard limit on volume that way lol, so no rear end in a top hat can keep cranking the stereo e2: you could also put it in PARTYYYYYY! mode with a minimum volume 
Jonny 290 fucked around with this message at 02:08 on Jul 29, 2016 |
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Jul 29, 2016 02:05
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Well from experimentation, unity was around 1/4 of the volume knob turn. Edit: Unity at the pre-amp output. Edit: After looking at the signal path and the schematic, I think I was wrong, the volume pot really is just attenuating the line-level input to the pre-amp stage. I guess I shouldn't be surprised, it's probably easier to get predictable performance if the gain is constant, rather than varying. I am *not* an EE, if you couldn't tell. E2: The reason that unity gain output from the pre-amplifier isn't at the far right of the volume knob is because the pre-amplifier gain is >1. For example, if the pre-amp gain is 10, then 1/10th the input signal would result in unity gain. Hunter2 Thompson fucked around with this message at 02:28 on Jul 29, 2016 |
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Jul 29, 2016 02:12
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That sounds pretty sane, yeah. And you're right, variable gain amps are way less common than fixed gain amps with input attenuators/pads. You CAN do them, but you rely on the device's Hfe/gain curves instead of relatively predictable resistor networks
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Jul 29, 2016 03:18
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I forgot about this thread so maybe when I start building my sikk y2k computer I'll post about it in here
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Aug 1, 2016 05:56
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certainly sounds like an idiot spare time project
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Aug 1, 2016 13:58
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its finished  
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Aug 1, 2016 17:55
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BiohazrD posted:its finished i have that same printer, a good printer
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Aug 1, 2016 18:07
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is that a niles or xantech whole home audio thing I see?
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Aug 1, 2016 18:19
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it may be, its a monoprice brand which means its just some other manufacturer with their logo and stuff slapped on it im currently writing a dll to control the thing which ill plug into a webapi and write an iphone app so i can control audio in each room with my phone, but thats a ways off From top to bottom: Ubiquiti ER-Lite3 with a rackmount adapter TP-Link 24 port gigabit switch (will eventually be replaced with an Ubiquiti EdgeSwitch 24 PoE) Colors are: Red - Unfirewalled ethernet in from ONT Green - router on a stick lmbo Yellow - standard data Orange - PoE devices at the other end (currently unused, eventually will be Ubiquiti UAP-AC-PRO APs and a couple of IP cameras) Purple - NAS ethernet Blue - Server ethernet 24 port cat-5e patch panel Monoprice 6x4 amplifier/audio router for multizone audio (controlled with a phone app thanks to the RS232 port) 1u Shelf with a 3rd gen Apple TV (Airplay audio for multiple rooms). I'm going to be adding a TiVo Mini here as well so I listen to games and stuff out on the deck. Dell PowerEdge R410 (Dual Xeon Hexacore w/ HT, 64GB DDR3 ECC RDRAM, 500GB Samsung EVO 850). Mostly used as a Plex server and for the occasion when I need Windows for something. Synology RS2416+ NAS 8x3TB drives with room for 4 more Canon injet printer (if I need to print something in color or scan) Brother laser printer (for everything else) APC SmartUPS 1500 to prevent power loss during flickers and graceful shutdown if there's a full blackout.
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Aug 1, 2016 18:24
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that's a nice rack
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Aug 1, 2016 19:03
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im allergic to that kind of power consumption these days but +1 all around, nice setup
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Aug 1, 2016 19:04
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power usage really isnt that bad! right at about 140 watts for the server, the xeons are older but still have nice thermal and power management and clock way down at idle synology uses an atom, so most power usage is really low and the wd red drives use something like 4 watts, so i think it clocks in right a 90 or so switch router and amp use around 15 total (amp at idle)
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Aug 1, 2016 19:11
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deece! nice
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Aug 1, 2016 19:21
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so when do ARM servers become a thing?
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Aug 1, 2016 19:37
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32-bit ARM servers came and went because everyone apparently wants big memory, AMD have a new ARM chipset but not much else news.
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Aug 1, 2016 20:15
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