Electrical Engineering V3 - Developers

[QUOTE=aydin690;51236478]Anybody got any suggestions/recommendations for a super accurate (~1ppm) arbitrary function generator? Price isn't an issue (but don't get carried away, let's say less than 2k ideally).[/QUOTE] Any high quality instrument by HP / Agilent / Keysight should meet those needs, provided it's calibrated on a regular basis and has a good frequency reference such as an OCXO or rubidium frequency standard, getting it on a 2k budget however I would consider very difficult, certainly it would have to be in non-working condition, if you drop the arbitrary requirement then it's certainly possible, HP 8648B for example.

Thanks, the thing is my application is really low frequency (0.1-20Khz). For example, i just need to generate a sin or square signal with a frequency of 10567.5Hz and not have it drift. I think those high end agilent/hp ones are overkill for my application. [URL="http://www.tek.com/arbitrary-function-generator"] These tektronix ones should be sufficient? [/URL]

[QUOTE=aydin690;51238121]Thanks, the thing is my application is really low frequency (0.1-20Khz). For example, i just need to generate a sin or square signal with a frequency of 10567.5Hz and not have it drift. I think those high end agilent/hp ones are overkill for my application. [URL="http://www.tek.com/arbitrary-function-generator"] These tektronix ones should be sufficient? [/URL][/QUOTE] Yes those will do fine.

I got it to work with a bolt cutter, thank you for the replies guys.

[QUOTE=aydin690;51238121]Thanks, the thing is my application is really low frequency (0.1-20Khz). For example, i just need to generate a sin or square signal with a frequency of 10567.5Hz and not have it drift. I think those high end agilent/hp ones are overkill for my application. [URL="http://www.tek.com/arbitrary-function-generator"] These tektronix ones should be sufficient? [/URL][/QUOTE] You might also want to consider something like the Rigol DG1032Z / DG1062Z if you want to have a useable ARB gen with more than 8000 points.

[t]http://u.cubeupload.com/Chryseus/3XgYo1.png[/t] This is going to be fun

Remember to liquid nitrogen treat the cables.

Also be sure to use gold-plated silver circuit traces for ultra-fidelity.

Alright, i just ordered the AFG1062 function generator. But now i'm thinking i need to buy a fancy oscilloscope to match the function generator and retire my current one. Any recommendations for a good but cheap (less than 800 CAD ideally) oscilloscope?

[QUOTE=aydin690;51255848]Alright, i just ordered the AFG1062 function generator. But now i'm thinking i need to buy a fancy oscilloscope to match the function generator and retire my current one. Any recommendations for a good but cheap (less than 800 CAD ideally) oscilloscope?[/QUOTE] Rigol DS1054Z, as far as I'm aware there isn't really anything new that can beat it under 1000 bux.

[quote]Peak Power 10kW max Avg. Power .60kW maz[/quote] I wonder how long that typo has existed on the [url=http://www.amphenolrf.com/connectors/n-type.html]Amphenol N connector page[/url]...

So something of a silly idea I have in mind is retrofitting a shutter motor on my window shutter, then have it controlled with a Raspberry Pi. My idea is to make it work from both my computer using a keyboard shortcut to either open or close it (or simply stop it, in case I want to fit my AC hose between it for example), and let it open the shutter when my alarm goes off on my phone. Something that I'm currently thinking about however is the fact that those motors work with AC power, so how would I go about starting / stopping the motor, and reversing the motor direction by changing the polarity with a Pi? This is something I've never worked with, but it's something I want to look into so I can work on it during the Spring, while I do all the research first.

[QUOTE=Merijnwitje;51258782]So something of a silly idea I have in mind is retrofitting a shutter motor on my window shutter, then have it controlled with a Raspberry Pi. My idea is to make it work from both my computer using a keyboard shortcut to either open or close it (or simply stop it, in case I want to fit my AC hose between it for example), and let it open the shutter when my alarm goes off on my phone. Something that I'm currently thinking about however is the fact that those motors work with AC power, so how would I go about starting / stopping the motor, and reversing the motor direction by changing the polarity with a Pi? This is something I've never worked with, but it's something I want to look into so I can work on it during the Spring, while I do all the research first.[/QUOTE] You can buy premade RPi shields/hats that are effectively a bunch of relays or hell you could cut out the RPi all together and buy a [URL="http://www.phidgets.com/products.php?category=9&product_id=1014_2"]relay board that is controlled over USB[/URL]. This isn't something to be taken lightly though, I suggest checking the current draw of the motors and/or seeing if there is existing driver circuitry because high voltage.

[QUOTE=Merijnwitje;51258782]So something of a silly idea I have in mind is retrofitting a shutter motor on my window shutter, then have it controlled with a Raspberry Pi. My idea is to make it work from both my computer using a keyboard shortcut to either open or close it (or simply stop it, in case I want to fit my AC hose between it for example), and let it open the shutter when my alarm goes off on my phone. Something that I'm currently thinking about however is the fact that those motors work with AC power, so how would I go about starting / stopping the motor, and reversing the motor direction by changing the polarity with a Pi? This is something I've never worked with, but it's something I want to look into so I can work on it during the Spring, while I do all the research first.[/QUOTE] [url]https://www.automationdirect.com/adc/Overview/Catalog/Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control)[/url] would be a safe way of controlling them from a low volt control.Else i would suggest [url]http://ab.rockwellautomation.com/Motor-Control/Contactors[/url] if you want to be able to do On/Off with some limit switches. If you only need the motor to turn one direction you can grab a relay. Just make sure that it is capable of supporting the motor without issues. Some will list they can handle X HP, while if you need both directions the Contactors are your best bet since when you get a pair of them you get an interlock to prevent one turning on if the other is on.

You say you're wanting to switch the direction on an AC motor? What sort of AC motor?

Hey guys, I'm figuring out how to test my previously posted chip to compare it to the simulation data. I have most of my test setup planned out however my main hiccup is the o-scope and is probes. I'm trying to test the output stage of my chip at various capacitive loads (1pF to 5pF) and the scope probe is ~13pF. Is there any way to isolate this using maybe an Op Amp? Or could I put a 1pF cap in series with the scope probe to attempt to null out this capacitance? (Assuming this 13pF is connected to ground and if I'm reading this model right): [img_thumb]https://cdn.sparkfun.com/assets/3/7/4/7/3/52f3bddece395f19378b4567.png[/img_thumb]

I can't think of any simple way of doing what you want, normally in such a situation you'd use something with extremely low input capacitance such as a spectrum analyser, it is possible to null out the capacitive reactance by using an inductor l but it would have to be tuned to a fixed frequency, this is the sort of case where you want a network analyser. If you know the frequency / rise time and output impedance of the IC it's usually good enough to just do the math or run a simulation, 5pF is pretty small, unless your chip has a high output impedance the effect would be minimal.

[QUOTE=Chryseus;51264651]I can't think of any simple way of doing what you want, normally in such a situation you'd use something with extremely low input capacitance such as a spectrum analyser, it is possible to null out the capacitive reactance by using an inductor l but it would have to be tuned to a fixed frequency, this is the sort of case where you want a network analyser. If you know the frequency / rise time and output impedance of the IC it's usually good enough to just do the math or run a simulation, 5pF is pretty small, unless your chip has a high output impedance the effect would be minimal.[/QUOTE] I do have simulation data from 1pF all the way up to 20pF. Could I just extrapolate the propagation, rise & fall times given the experimental data at ~13pF?

[QUOTE=LoneWolf_Recon;51266740]I do have simulation data from 1pF all the way up to 20pF. Could I just extrapolate the propagation, rise & fall times given the experimental data at ~13pF?[/QUOTE] Yes if you work backwards to remove that capacitance you should be able to work out the capacitance of the chip with reasonable accuracy, of course inductance has some effect as well but as long as your test setup is good capacitance is the dominant factor.

So the CO2 laser at out local makerspace malfunctioned last night. [img]http://i.stack.imgur.com/bppXz.jpg[/img] Nothing big though. Just a blown power supply.

[t]http://i.imgur.com/KB6FX8e.png[/t] Almost ready for construction, everything is being mounted to a 4mm aluminium plate.

I was mailed a replacement VFD for a project. [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6323.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6316.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6324.jpg[/img] [i]FUCK.[/i] Literally the revision letter meant the pin arrangement changed.

I'm thinking of going to San Diego for 3 months next summer and I'd like to get some work in an engineering company. I'm in my 3rd year of biomedical/electronic engineering. Does anybody know any companies out there that would be interested in undergrads? My only other work experience is 3 and half months in medical device regulation that I did this summer.

[QUOTE=cathal6606;51291871]I'm thinking of going to San Diego for 3 months next summer and I'd like to get some work in an engineering company. I'm in my 3rd year of biomedical/electronic engineering. Does anybody know any companies out there that would be interested in undergrads? My only other work experience is 3 and half months in medical device regulation that I did this summer.[/QUOTE] What would you be interested in doing? Sounds like you want to design/work on bio devices like pacemakers, heartbeat sensors or other health monitoring related electronics.

I'll take anything tbh, but yes health monitoring/ signal processing, especially if it involves the brain (eegs, deep brain stimulation etc). I dont want to rule out the mechanical side either because I've done statics,dynamics and fluid mechanics last year and didnt completely hate them.

[QUOTE=pentium;51290363]I was mailed a replacement VFD for a project. [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6323.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6316.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/New%20Bucket/IMG_6324.jpg[/img] [i]FUCK.[/i] Literally the revision letter meant the pin arrangement changed.[/QUOTE] Version letters are hell in software development, I see it's even worse in electrical engineering.

[QUOTE=cathal6606;51292212]I'll take anything tbh, but yes health monitoring/ signal processing, especially if it involves the brain (eegs, deep brain stimulation etc). I dont want to rule out the mechanical side either because I've done statics,dynamics and fluid mechanics last year and didnt completely hate them.[/QUOTE] I can't really name any one company off the bat but you might want to look into the IoT (Internet of Things) spaces as well for sensing and stuff. I'd also recommend checking out opportunities in the area through IEEE (Assuming you have a student membership) as they're typically more willing and a better channel for undergraduate internships (Especially if you're out of town/state/country).

Note to self: [img]https://wistia.com/learning/assets/guides/lighting/skylux-ca7d0cbc036458191f6592686c542f16.jpg[/img] LED backlights are blindingly bright, even when running at half the normal voltage. I am blind.

Hello electrical wizards, I'm hoping some of you might be able to help me out with an idea I have. I have an old [url=http://gadgets.ndtv.com/lg-google-nexus-5-1115]LG Nexus 5[/url] that I reappropriated into a security camera. It's been working fine for a few years now but I recently noticed the phone case was coming apart and upon further investigation I found the battery had swollen. I wasn't surprised since the device is plugged in 24/7 and the same thing happens to my drones li-po batteries when I leave them charged for too long. I ordered an OEM replacement battery for $12 from China but I've been considering the idea of bypassing the battery all together. This is what I have so far: Battery connection on phone (sorry it's blurry, had a hard time getting my camera to focus on it) [thumb]http://i.imgur.com/LuaIZEw.jpg[/thumb] Connection on battery [thumb]http://i.imgur.com/4BYpefC.jpg[/thumb] Front of battery [thumb]http://i.imgur.com/U2ve8nP.jpg[/thumb] My electrical tools (including the whiskey and scotch required for this project) [thumb]http://i.imgur.com/4IbDfbN.jpg[/thumb] I found tutorials and videos on how to do this but the batteries they used in the examples had a plastic edge or shell they removed that they were able to solder the charger cable wires to. This battery seems to be inside some sort of bag with only the ribbon sticking out at the top. The edges of the battery feel solid like they might have a plastic edge inside the bag but I'm afraid to cut it open because it's swollen. I'm also not sure if I'll need something to limit the electrical input. I don't have the technical knowledge in this field to complete this myself (without turning the phone into a Galaxy Note 7), can anyone help me pull this off?

With the tools that you have bypassing the battery will be quite problematic. You'd need a much finer point soldering iron tip and smaller solder. However you might be able to jury rig some sort of fake battery using a tutorial like [URL="http://www.instructables.com/id/How-to-use-phone-without-battery/?ALLSTEPS"]this[/URL], that way all you need is a direct power supply right to the battery terminals.