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This is a real real real long shot, but I think this is the closest thread to anything on SA where someone might know: Does anyone here have a Tektronix TDS 420 digitizing oscilloscope? It's giving me an Attn/Acq POST failure which is fairly common for this scope, though I'm not looking forward to swapping out all the caps on-board. My question is regarding the A03 CPU board serial port. I'm trying to get a console readout of the scope's POST, and I should be able to by just hooking up a serial port header, then connecting a null modem, then connecting that to my computer. I didn't have a serial header handy so I "borrowed" the serial header from the option card in slot 5. Unfortunately when I boot the scope I still don't see any console messages coming across the serial line. I'm not sure why this would be, unless the RS232 header I borrowed uses some other nonstandard pinout maybe? Not really sure where to go from here. Like I said, I know I need to start replacing caps, but I was hoping to read the console out before I tore this scope to bits. Thanks! (the scope actually seems to work fine, other than channel 2 which is incredibly off, even when measuring the reference post)
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Jul 9, 2012 20:10
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Oh balls, I didn't even know this existed. Thanks a ton!
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Jul 9, 2012 21:53
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I'm just going to throw this out there, but there aren't any sort of Electronics 101 or First Year Electronics theory courses that I can find on iTunes U or anything like that, are there? I've been going through a lot of resources, but in 100% honesty I learn best in a classroom environment. By which I mean listening to someone explain something and then connecting bits and pieces of information myself. Maybe it's just how my brain works, but hearing someone lecture is so much easier for me than reading the material in a book myself.
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Nov 2, 2012 00:04
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Yes, all of these are awesome, thank you!
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Nov 2, 2012 00:26
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Ugh, I think my TDS420A digiscope is finally going back to the trash heap from whence it emerged. Now it just plain refuses to trigger properly leaving me with a useless nearly unreadable signal display. Checked prices on replacing it with something. Whoops. Guess I didn't really need a digital scope right now anyway 
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Nov 6, 2012 17:47
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Sorry for the lovely photo: Love working in academia. Walking down the corridor today and I find this metric ton of drawers being thrown out of a lab. It's actually twice as long as this photo shows but I didn't want to zoom out any more. A lot of ancient ICs, but also I'll probably never need storage space or resistors again. So many packages of unopened resistors of every type  I'm actually thinking of donating all the stuff + half the drawers to a local hackerspace or something. No way will I ever need (or have room for) all these drawers, and I can already get all the small components I need for free by tacking them onto bigger campus orders.
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Nov 14, 2012 21:21
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Just out of curiosity, how many of you guys consider yourselves hobbyists and feel you fully understand what is happening in this video: https://www.youtube.com/watch?v=XiiXSCQqVYg I don't mean this in any trolling way, but I'm trying to ground my understanding of all these basic parts and while I understand the basics of what is happening in a transistor, the second they introduce ... maths ... I sort of go cross-eyed. I realize it's important to understand the math behind it (and believe me, I am going to struggle to do so), but I'm legitimately curious how many people are getting by just knowing "eh a transistor does X" and not much more.
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Nov 16, 2012 02:34
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Thanks guys. I will definitely post questions about transistors later on, but those who called out a lack of maths/physics fundamentals are definitely right. I legitimately have not taken a math class since last year highschool because apparently getting a sweet well paying job out of school was an awesome thing for a teenager to do instead of getting an education like a normal person so you don't try to learn transistors at 33 and nearly hang yourself when they start introducing "letters" into math again  Uphill struggle, but I'm not above putting in some elbow grease. I'm going to have to go pick up some fundamentals books soon. I'm getting by by pulling bits and pieces out of a toolbox and thankfully I don't work with enough bits where if you forget a resistor or hook a transistor up wrong you will literally be sorry, but I'm trying to fast-track some of this and it seems like there's no real "fast track" to this material for a reason. It's stuff you need to know and understand. I'll definitely be back here asking dumb questions so bear with me 
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Nov 16, 2012 03:48
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Oh yeah, I definitely didn't mean to sound emo over the math or anything. I'm having a great time figuring this stuff all out. I think I legitimately found something I am excited about learning, only I'm like 15 years too late to actually get into it and make it a career choice. But I guess it should say something that I'm actually as excited about learning this as I am about what I've considered my dream career field all this time. (It's network engineering. I'm the guy who loves to do networking  )
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Nov 16, 2012 06:05
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Sounds good. Well, I've been basically diving in headfirst every day and learning a ton of new stuff every time I do, so I'm pretty stoked with the whole process, still. Question of the day: Today I made it my mission to understand how voltage regulators and voltage regulator circuits and power supplies work. It's actually a lot simpler than I ever imagined once I figured out what diodes and rectifiers and regulators are. So my question is: Armed with my newfound knowledge I obviously immediately tried to examine any and all power supplied devices I own (and are open for me to look at), which meant my Arduino Uno is a perfect candidate. I managed to trace down the 5v regulator really easily, but I'm trying to figure out where the 3.3v rail is generated. Without a magnifying glass I can't really trace down any of the smaller components, and I'm still really green at reading schematics so I tried to figure it out here (http://arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf), and while I found the 5v relatively easy to find, I'm having trouble locating a 3.3v regulator. Unless the 3.3v is generated by some other means. This might be an arduino specific question, but I mean it more as a general "how the gently caress" type of thing. I'm not actually interested in this arduino per se, just how it's implemented.
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Nov 17, 2012 05:25
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Marvellous, thank you Now that I look at it, it was a LITTLE more obvious than I made it out to be, but now I know! 
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Nov 17, 2012 06:30
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I want to murder whoever came up with the resistor colour scheme. Browns that look like purples under certain light, oranges that look like reds, silver and golds that are virtually indistinguishable from each other under any sort of light. Is that white or really light blue? And then when you pull out your meter and the actual ohms read nothing even remotely close to what the chart says.
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Nov 18, 2012 01:11
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Thanks for the advice. I did this and got better results. I went through all 60-something drawers of resistors and caps trying to clean up the mess of stuff I found and I basically hate my life right now. Not to mention I hosed up my hands on the sharp corners of these loving add-a-drawer building block shelves trying to reassemble them into a more usable shape. I'm going to just go back to learning poo poo because this hands-on torture is killing me 
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Nov 18, 2012 02:19
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I asked my dad, an EE, this exact question about 3.3 the other day. He shrugged and said "Iunno" 3.3 seems so arbitrary.
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Nov 21, 2012 21:17
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Is there a low dropout voltage regulator that will produce 3.3 and 5v in one package, or do i always need to use separate discrete regulators to get these two? Preferably available in through-hole.
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Nov 24, 2012 04:54
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Sorry, babby electronics question: Switcher is the same thing as voltage regulator, or should I be looking at something else in terms of figuring out how they work? edit: Googled my own answer. Thanks for the advice! some kinda jackal fucked around with this message at 05:10 on Nov 24, 2012 |
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Nov 24, 2012 05:06
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Excellent info. I don't think I can justify a ten-fold price increase over the linear regulators I'm looking at, and I have control over my Vin right now, but that's definitely great to know. Thanks! I basically just want to create a dual rail power regulator circuit that I can plug into my breadboards and run it off a wall wart until I can justify the expense of a bench power supply. It's not a huge project or anything, but I'm excited about having figured out what goes where. It's really cool to actually look at a power supply and have a vague idea of what's happening inside rather than "stuff comes in, stuff comes out". I guess technically I could also go find a regulated wall wart, but where's the fun in that?
some kinda jackal fucked around with this message at 05:17 on Nov 24, 2012 |
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Nov 24, 2012 05:14
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Just FYI, there's also a small (for now) embedded development megathread over at SH/SC where you can probably get some more info on the MSP. Right now it's mostly me complaining about things though. http://forums.somethingawful.com/showthread.php?threadid=3500975 priznat posted:Have you tried the digi-key parametric search? That's usually where I start for stuff. I haven't. I shop exclusively with Newark (since we have a purchase contract with them), but I think they can do the same parametric search stuff. Mostly I wasn't even sure what I was searching for though. I've got two fixed regulators in my basket right now, but I wasn't sure how to define "dual output". I think I can figure it out now though. some kinda jackal fucked around with this message at 05:24 on Nov 24, 2012 |
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Nov 24, 2012 05:22
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Watched this EEVblog thing about regulators and it really helped me understand what's happening behind the scenes: https://www.youtube.com/watch?v=cM7t1Mpu7s4
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Nov 24, 2012 06:45
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Hey guys, can someone explain to me (as you would a child) what a voltage reference is in the context of a fixed voltage reference inside a voltage regulator? What form does it take? Like if it's a 5v reference, where does the regulator magically get a 5v reference? I think I might be fundamentally misunderstanding something, or I'm missing a fundamental concept. Doesn't have to be a detailed explanation or anything, I'll do my own research once I have the faintest grasp of the concept.
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Nov 24, 2012 20:42
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Does anyone have a good link or tutorial that would explain how a capacitive touch sensor works, and how one would DIY one up? I'm interested in making one that I can read with an MCU and will report different values depending on where along its length I press it. So, I guess like a slider. It's either harder than I thought to find this info, or I'm just not searching for the right keywords though. some kinda jackal fucked around with this message at 04:13 on Dec 6, 2012 |
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Dec 6, 2012 04:09
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Awesome, thank you
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Dec 6, 2012 04:48
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Is there an IC with X number of resistors that I can use for a 7 segment display or do I just need to put in 7 discrete resistors? Something like a DIP-14 would be great, 7 resistors.
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Dec 9, 2012 02:44
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PDP-1 posted:You can also get SIP packaged resistors with a common lead, like this: My eee-lectronics knowledge is still maturing so I'm not sure how I'd use a common lead with a 7 segment display but I'm glad to learn these exist anyhow 
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Dec 9, 2012 04:29
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I had a nice Tek TDS-420A but something in it failed and the readings are all wrong and the POST reports acquisition board failure. The only fallback scopes I've got access to are all 30 year old Teks that are in horrible shape. If I throw the probes into ground coupling mode the reference waveform is seriously curved. I'm actually holding onto the nice Tek scope in case I decide to get it fixed one day. It's probably more scope than I'll ever actually need. It's really hard to go back to something basic after you've been spoiled though  Peeps, how do you like the logic sniffer? I sort of want to get my hands on that one you picked up. some kinda jackal fucked around with this message at 06:34 on Dec 9, 2012 |
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Dec 9, 2012 06:32
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The 2213 is actually one of the misaligned scopes that I have. I wonder if there's any way to adjust the plot. It seriously curves almost 1/2 a div over the range of the scope when it's ground coupled.
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Dec 9, 2012 20:33
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Bruinator posted:According to that EEV blog guy the 2 channel 50MHz version can be unlocked via firmware to go to 100MHz, so that's nice. I think one of the later firmwares disabled that so if you get one now you'll have to downgrade the FW.
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Dec 10, 2012 18:13
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Is a "decoupling" cap just used to filter noise and ripple like a filter, or is there some other meaning/use for the term?
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Dec 12, 2012 06:31
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https://www.youtube.com/watch?v=b7KG48-RUeA
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Dec 14, 2012 03:58
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That connector does look kind of thick, but I'm not sure how he'd accomplish that even with logic 
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Dec 14, 2012 05:52
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Kire posted:Separately: are there any EE blogs as good as Hackaday in terms of frequency of updates, variety, etc? I checked the OP but didn't see a very extensive blog list. http://dangerousprototypes.com/ has a pretty good blog. I basically follow that and Hack-a-day.
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Dec 17, 2012 00:58
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Maybe I'm just really bad at searching for things on the internet these days, but does anyone know where I can buy a sizeable pack of prefabbed breadboard jumper cables that are male on one end and female on the other?
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Dec 18, 2012 06:22
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Thanks guys. I think I need to refresh my google-fu.
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Dec 18, 2012 07:14
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Your image isn't showing up for me, but could it possibly be the PWM driver for a switching power supply?
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Dec 27, 2012 00:20
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Putting the cart before the horse, I collected way too much surplus electronics gear for my skill level and I'm basically drowning in parts and test equipment and stuff. Total first-world-problem but the disorganization is kind of making me want to not work on electronics when every time I whip out a multimeter probe cable it gets tangled on like 5 other cables. I don't really know why I posted this since this isn't livejournal, but it's just an observation that cleanliness and organization is important in everything
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Jan 2, 2013 11:28
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NoiseNoiseNoise posted:Soldering is something you need to learn how to do effectively, and learning early will save you headaches and burnt fingers later on. I'm just learning this myself and can't agree enough. There is nothing more aggravating than doing it wrong and ending up with a lovely looking cold joint, or worse. My "favourite" is when I'm soldering some thru-hole component and I end up with a big blob of solder on the end of the component wire and it just refuses to flow down to the PCB. I'm sure it has something to do with oxidation and all that jazz. Slowly but surely I'm getting better at soldering, but I've got a long way to go.
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Jan 11, 2013 17:51
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Hmm, good call. I actually use a super fine tip because it's just easier for me, but I can see why that might be a terrible idea. I want to pick up a chisel tip of some sort. I hate the wide conical tip I have because it just feels really inaccurate, but I think a chisel tip that is wide but still sharp feels like it would be a perfect compromise.
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Jan 11, 2013 18:06
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I know nothing about flux. Is it all the same or do I want a specific type of flux if I'm just working with through-hole components or what? A lot of my components are like 10+ years old (on the optimistic side) so I assume that oxidation is a huge problem with my soldering. If I just go buy a generic flux pen off ebay or newark, will that do the trick or should I be more discerning?
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Jan 11, 2013 21:46
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When hooking up an external osc to an ARM uC, what are some rules to follow? I gather that the crystal should be as close to the actual chip as possible, but I'm using a QFP64 breakout board and can't really mount anything super close to the CPU on the breakout board without some shenanigans. Is this likely to be a huge problem? I know next to nothing about crystals Once I'm finished prototyping my thing I'll be in a better position to lay out my own custom PCB, but for now I'm using what I have.
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Feb 19, 2013 05:32
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I haven't decided on a final speed yet. The chip itself can hit 120MHz but I haven't really figured out how much horsepower my application needs. The chip does run an internal PLL and in fact has an internal clock or timer source, but my understanding is that it's not precise enough to drive USB functionality. Apologies if this is really vague, but this is the first time I've tried to work with anything but a pre-built prototyping board so I'm going to be asking some really dumb questions until I get comfortable with the ideal system design For reference, the chip I'm using is an NXP LPC1769 but I'm partly asking just to gain generic knowledge which I can apply to any of the dozen bare ARM chips I have lying in my drawer.
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Feb 19, 2013 09:05
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