Electrical Engineering V3 - Developers

[img]http://puu.sh/hJt6f/a16106ca0c.png[/img] I have some questions about this circuit, what are the parts VC1 and VC2, and is there any way to make this work on better speakers?

VC1 & VC2 are variable/trimmer capacitors (Max 20pF & 5pF respectively). I suppose you could drop the whole final amplifier portion (R7, TR4, C6 & headphones), while connecting C5 directly into a nice speaker driver such as a TDA2003A, TDA2822m or even a LM386.

The ATMega328 has a bloody internal temperature sensor. I've been using the damn thing for like 6 months, and I didn't know about it. The datasheet is like reading a bloody bible, it's 650 pages long and you open it up once in a while because you're bored, and then after 6 months, you might actually find something that makes sense.

[QUOTE=nikomo;47703410]The ATMega328 has a bloody internal temperature sensor. I've been using the damn thing for like 6 months, and I didn't know about it. The datasheet is like reading a bloody bible, it's 650 pages long and you open it up once in a while because you're bored, and then after 6 months, you might actually find something that makes sense.[/QUOTE] That's the value of AVRs I feel, there's so many niche, tucked-away, little features that most of the times aren't used but are a joy when you discover them. Take that PICs.

[QUOTE=LoneWolf_Recon;47703592]That's the value of AVRs I feel, there's so many niche, tucked-away, little features that most of the times aren't used but are a joy when you discover them. Take that PICs.[/QUOTE] AVR's are chucked full of features (and with a pricetag to boot), while PIC's are the result of the shotgun approach.

So I got a Samlex 1235M power supply, its a low noise switching 13.8V 30A (continuous) PSU for HF radio. [T]http://u.limonene.net/IMG_20150511_114626.jpg[/t] Not exactly a DIY thing; but hey, I'm now on the air.

[QUOTE=Cakebatyr;47703836]So I got a Samlex 1235M power supply, its a low noise switching [B]13.8V [/B]30A (continuous) PSU for HF radio. [T]http://u.limonene.net/IMG_20150511_114626.jpg[/t] Not exactly a DIY thing; but hey, I'm now on the air.[/QUOTE] So is it designed to work in tandem with a lead-acid battery for powering equipment?

Yup, by convention almost all radio transceivers are designed around automotive power. It will run happily on a 12V battery, but those things are heavy.

[QUOTE=nikomo;47703410]The ATMega328 has a bloody internal temperature sensor. I've been using the damn thing for like 6 months, and I didn't know about it. The datasheet is like reading a bloody bible, it's 650 pages long and you open it up once in a while because you're bored, and then after 6 months, you might actually find something that makes sense.[/QUOTE] I fried that chip once, bought a new one I think it's still lying somewhere. Also agree about datasheet, fucking thing is heavy on brains.

The 328 datasheet recommends an LC network for filtering stuff out from the 5V rail. Any reason why I should actually do that, instead of using an RC filter? A 4k7 resistor and a 100n capacitor forms a pretty decent filter, from what I could figure out in LTSpice. [t]https://i.imgur.com/MkB0dUR.png[/t] A 4k7 resistor and 100nf capacitor are pretty stock BOM parts, it sounds like a way better idea to be to use an RC filter, especially when you consider that the ADC on the 328 is shit, so the values you get out of it, are always going to be meh. If I stick 2-3 resistors in series, it provides a bit more filtering. If I was using a proper ADC, I'd follow what the manufacturer is saying, but this just seems a bit silly. The Arduino Uno official schematic doesn't even bother with an RC filter, they just have VCC and AVCC connected together on the +5V rail, and there's a 100n capacitor to ground.

Couple of reasons, namely is that LC filters allow DC without current limiting like with RC filters. The ADC gets its power (Typically a ~200uA) from AVCC and its reference voltage from AREF. By putting in a resistor, even a low value one of 100 ohms will render about tens of mV of voltage drop. This voltage drop can screw with Aref. Typically you can get a uH range low current inductor with 0.001 to 1 ohms in equivalent resistance. Second reason is you want to not necessarily shunt high frequency AC signals with the capacitor in a RC setup, but block them entirely with an LC setup. As the noise will still super-impose on the capacitor (And thus the ADC's power and AREF pins), albeit at a reduced amplitude. Plus I'd recommend using a toroidal inductor to prevent any external magnetic fields from coupling and inducing stray noise on your Aref line. Usually its negligible, but if you're operating around high power electronics or taking high accuracy measurements (hundreds of uV to ones of mV, with a high sample rate) it's a bare bones requirement. Ultimately its up to you and the criteria/environment that your circuit will operate in. Arduino just likes to keep it simple for newbies. RC filters are okay if you have a low value R and aren't too concerned about noise, but LC is definitely superior.

YOLO, I'll just copy the setup from the Arduino Uno, it can't be too bad. I didn't even take into consideration that AVCC is used as the power source of the conversion process, so there's going to be current going through the resistor.

[url]http://www.thesalvagedboutique.com/2015/04/12/upcycled-tv-bar-cabinet-vintage-setchell-carlson-color-television/[/url] As someone who spent six months rebuilding a 50's television set, this angers me that someone would do this to a rather rare television set, then openly state they'll keep doing it if they find more. Hipsters. Fucking Hipsters.

[QUOTE=pentium;47709410][url]http://www.thesalvagedboutique.com/2015/04/12/upcycled-tv-bar-cabinet-vintage-setchell-carlson-color-television/[/url] As someone who spent six months rebuilding a 50's television set, this angers me that someone would do this to a rather rare television set, then openly state they'll keep doing it if they find more. Hipsters. Fucking Hipsters.[/QUOTE] Those people need to be shot.

[QUOTE=Chryseus;47709573]Those people need to be shot.[/QUOTE] Waste of good bullets. Rope.

[QUOTE=pentium;47709410][url]http://www.thesalvagedboutique.com/2015/04/12/upcycled-tv-bar-cabinet-vintage-setchell-carlson-color-television/[/url] As someone who spent six months rebuilding a 50's television set, this angers me that someone would do this to a rather rare television set, then openly state they'll keep doing it if they find more. Hipsters. Fucking Hipsters.[/QUOTE] Reminds me of that horrific gutting of some old vintage frequency counter into an ~aesthetically pleasing~ nixie clock. Forgot the link..

Does anyone know where I can get a cheap bluetooth reciever to 3.5mm dongle?

Ebay.

[QUOTE=Staneh;47709980]Does anyone know where I can get a cheap bluetooth reciever to 3.5mm dongle?[/QUOTE] I accidentally bought an extra one of [url=http://www.amazon.com/gp/product/B006OT2WFM/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1]these[/url] a while ago and never returned it, you can have it if you want

[QUOTE=LoneWolf_Recon;47709771]Reminds me of that horrific gutting of some old vintage frequency counter into an ~aesthetically pleasing~ nixie clock. Forgot the link..[/QUOTE] [url]http://www.evilmadscientist.com/2010/making-classic-frequency-counters-into-nixie-clocks/[/url] [url]http://www.bad-dog-designs.co.uk/testclocks.html[/url] The bastards, that second one turned one of the counters I have into a clock as well. It hurts. [url=http://i.imgur.com/skpNxQV.jpg][img]http://i.imgur.com/skpNxQVl.jpg[/img][/url] This is the clock pentium is talking about below me by the way: [url]http://www.melamed.org/clock.htm[/url].

At least that modification is completely reversible and preserved the rest of the unit. I'll give engineering points for that one. [quote]Reminds me of that horrific gutting of some old vintage frequency counter into an ~aesthetically pleasing~ nixie clock. Forgot the link.. [/quote] [url=http://www.bad-dog-designs.co.uk/testclocks.html]Oh, he didn't stop with just the meter, sadly.[/url] [editline]sdafsdfsad[/editline] God dammit Ddrl.

That feeling when you spend a few hours soldering something onto protoboard and then it doesn't even work and you can't figure out why. This is why I need an oscilloscope.

[QUOTE=papkee;47711688]That feeling when you spend a few hours soldering something onto protoboard and then it doesn't even work and you can't figure out why. This is why I need an oscilloscope.[/QUOTE] If you have the money get a Rigol DS1054Z, otherwise a cheap analog scope and a logic analyser will do the job. If the soldering is fine and everything matches up you should post the schematic. Go over it with a meter as well.

[QUOTE=PortalGod;47710417]I accidentally bought an extra one of [url=http://www.amazon.com/gp/product/B006OT2WFM/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1]these[/url] a while ago and never returned it, you can have it if you want[/QUOTE] I'll pm you!

[QUOTE=Chryseus;47711811] If the soldering is fine and everything matches up you should post the schematic. Go over it with a meter as well.[/QUOTE] I've been through all the joints with a meter, and there's a ~16kΩ short between vcc and ground somehow. Here's the schematic again, I posted it a while ago. [t]https://i.gyazo.com/6ae0867ed8d90403b00330f5f228b748.png[/t]

[QUOTE=papkee;47712596]I've been through all the joints with a meter, and there's a ~16kΩ short between vcc and ground somehow. Here's the schematic again, I posted it a while ago. [t]https://i.gyazo.com/6ae0867ed8d90403b00330f5f228b748.png[/t][/QUOTE] 16k could be normal. I think the problem may have something to do with the implementation of the MAX485, you seem to have it fixed at transmit since the 485 cannot do both at the same time (it's half duplex) there are also propagation delays to consider, also what opto-coupler are you using ?

I did not expect the ESP-12 module to be this small. [t]https://i.imgur.com/5SSsKB5.jpg[/t]

[QUOTE=Chryseus;47713106]16k could be normal. I think the problem may have something to do with the implementation of the MAX485, you seem to have it fixed at transmit since the 485 cannot do both at the same time (it's half duplex) there are also propagation delays to consider, also what opto-coupler are you using ?[/QUOTE] That could be one of the issues, and it makes sense, but for some reason I recall [URL="http://ricardo-dias.com/projects/opendmx/"]one of the articles[/URL] (found it) I read where they pulled DE High and RE low and it worked fine. The optocouplers are [URL="https://www.mouser.com/Search/ProductDetail.aspx?R=6N137VMvirtualkey51210000virtualkey512-6N137VM"]6N137[/URL]'s.

[QUOTE=nikomo;47713131]I did not expect the ESP-12 module to be this small. [t]https://i.imgur.com/5SSsKB5.jpg[/t][/QUOTE] Atleast that pitch isn't a bitch.

Im working on a Force feedback wheel using arduino, geared motor and rotary encoder. but first trying to learn how USB works. but i stuck at HID Descriptors. Does anyone explain me how the 0x81 , 0x.. //INPUT(..) thing is defined? i allready searched this pdf, but didnt found anything related to 0x81. [url]http://www.usb.org/developers/hidpage/Hut1_12v2.pdf[/url] Hard to explain, see example code: [CODE] 0xA1, 0x00, // COLLECTION (Physical) 0x05, 0x01, // USAGE_PAGE (Generic Desktop) ...... ...... ...... 0x16, 0x00, 0x80, // Logical Minimum (-32768) 0x26, 0xff, 0x7f, // Logical Maximum (32767) 0x75, 0x10, // REPORT_SIZE (16) 0x95, 0x08, // REPORT_COUNT (8) 0x81, 0x82, // INPUT (Data,Var,Abs) <------ THIS 0xc0 // END COLLECTION ..... [/CODE] in the PDF its in Generic Desktop page defined as "System Power Down" i totally stuck at this :/