Electrical Engineering V2 - Developers

[QUOTE=Cakebatyr;46004489]Yep, meant series. So running a regulated 5V power supply to charge them up is safe correct?[/QUOTE] As long as there is a series resistor to prevent a huge current spike yes. Something like 10 Ohms will limit the peak current to 0.5A and take ~50 seconds to fully charge 1F.

I have this random idea. It's absolutely pointless but whatever. I'm curious what you would need to emulate (at low switching speeds) the base, collector and emitter of a conventional 2N3904 using nothing but conventional vacuum tubes. I'd seriously be interested in building something like this granted it's not the size of a desk.

[QUOTE=MIPS;46004723]I have this random idea. It's absolutely pointless but whatever. I'm curious what you would need to emulate (at low switching speeds) the base, collector and emitter of a conventional 2N3904 using nothing but conventional vacuum tubes. I'd seriously be interested in building something like this granted it's not the size of a desk.[/QUOTE] You'd probably be able to get away with some of the lower voltage (Maybe a [URL="http://en.wikipedia.org/wiki/12AX7"]12AX7?[/URL]) triodes. Correct me if I'm wrong, but since triodes are closer to FET in terms of operation (voltage controlled current instead of current controlled), could you add a resistor across the grid-ground to get a current controlled current source? That's what I'm getting from these equivalent circuits: BJT: [img_thumb]http://people.seas.harvard.edu/~jones/es154/lectures/lecture_3/bjt_models/pi_model_1.jpg[/img_thumb] Tube: [img_thumb]http://www.cjseymour.plus.com/elec/valves/VEQUIV.jpg[/img_thumb]

You can get a reasonably similar response to a NPN transistor with appropriate cathode biasing, you could add a smallish resistor between the grid and ground but that would ruin the nice input impedance.

Hello! I have one question, how can I 'measure' what is ratio of transformer coils?? I have no signal generator.

[QUOTE=Fourier;46005476]Hello! I have one question, how can I 'measure' how much voltage transformer converts to? [b]I have no signal generator.[/b][/QUOTE] [img]http://solar-power-station.co.uk/images/home_solar_power_kit_uk.jpg[/img] Yes you do.

[QUOTE=Chryseus;46005487][img]http://solar-power-station.co.uk/images/home_solar_power_kit_uk.jpg[/img] Yes you do.[/QUOTE] You got me thinking now, I really can just add one big resistor to drop voltage and voila.. :D Damn I am dumb sometimes. Please rate me dumb.

Anyone has any experience building quadcopters? I am absolutely zero to building them but would love to build one for college project, have to include networking and mobile technologies in project (BSc in Computer Science), I guess if I build an android app (no problem with that) that would directly be able to communicate to quadcopter controller (somehow) that would be pretty decent and interesting project compared to others in my course (mainly making shitty html *not even html5 websites). Would this work somehow? Where would I start? Some points: *I have tiny bit of Arduino Experience. *I would like to give quadcopter controller commands from my phone. *If signal to master controller (my phone) is lost it returns home. *I know Java pretty good, Android Native (java) excellent, Android Google Maps API V2 excellent too. *I also kind of know C# (made games in Unity, so I guess that's close enough) And side shit like JS. I did bit of search and I came up with these possible solutions: Communication over distance: Arduino GSM Shield (I could send SMS to quadcopter which would be processed and commands done). or Arduino GSM Shield (I could call it perhaps and give basic commands like forward, backward, left, right, alt up, alt down, return etc...) BT and Wifi is not an option since it's short distance. I would really like to make this since it's something interesting actually to do rather than just code software. I have pretty much 10 months to make this. I know it's a big project but is it possible for me? (with no knowledge of building).

You could use a 433 MHz module like the nRF905 for moderately long range communications at tolerable power levels. [editline]18th September 2014[/editline] Otherwise, making a quadrocopter fly autonomously is no trivial task, and requires a lot of knowledge on the topic of autonomous flight. If you're ready to spend every hour of those 10 months reading up on the topic, learning the math and doing the calculations it's doable. Otherwise you might have to resort to some moderately expensive premade solutions you can hack into to control them on a very high level.

[QUOTE=DrDevil;46008270]You could use a 433 MHz module like the nRF905 for moderately long range communications at tolerable power levels. [editline]18th September 2014[/editline] Otherwise, making a quadrocopter fly autonomously is no trivial task, and requires a lot of knowledge on the topic of autonomous flight. If you're ready to spend every hour of those 10 months reading up on the topic, learning the math and doing the calculations it's doable. Otherwise you might have to resort to some moderately expensive premade solutions you can hack into to control them on a very high level.[/QUOTE] Well I guess there goes my idea down the drain so, I can't really dedicate 100% of my time to one module in college, have 4 other (just simpler) projects to make. That's been the 3rd idea which I had for final year project, but again because of it's big scale and my time window I have to continue thinking. Thanks anyway, might take on this idea/project as hobby after I graduate.

I've been flying multirotors for about 2 years now (tri preferred) and have only just recently begun trusting this thing to do simple GPS based holds and maneuvers. This thing is FAR from autonomous. Personally I recommend starting simple with a config of your choice running on multiwii, get spare parts (frame arms/esc/lots of props) because no matter what you think, you will break shit. Stay away from strictly gyro based control boards like the "hobbyking KK board" people love the kk2 but there are way better options for equal price. Start simple and get used to flying safely before you dive in head first. Pro tip: You can build your own flight controller with a arduino micro/pro mini and a 12 USD 10-degree sensor board

[QUOTE=KinderBueno;46008567]Well I guess there goes my idea down the drain so, I can't really dedicate 100% of my time to one module in college, have 4 other (just simpler) projects to make. That's been the 3rd idea which I had for final year project, but again because of it's big scale and my time window I have to continue thinking. Thanks anyway, might take on this idea/project as hobby after I graduate.[/QUOTE] I don't want to crush your idea here. What I'm trying to say though is that you shouldn't choose a project with such high ambitions. Instead you could try to get telemetry from the quadrocopter back down to your phone and display it that way.

This may be a bit simple for your projects, but have you considered building a weather balloon?

[QUOTE=DrDevil;46008700]I don't want to crush your idea here. What I'm trying to say though is that you shouldn't choose a project with such high ambitions. Instead you could try to get telemetry from the quadrocopter back down to your phone and display it that way.[/QUOTE] I'm not even sure you should be telling him not to dream big. He just needs to understand that what he wants is big and wont happen over night, but if he really wants to do it, he can just in sensible steps. We built an autonomous helicopter as part of one of our projects at uni and bugger me was it difficult - the main issues though were stability and lfiting capacity since we werent allowed a proper multirotor, at most just a pair of contra rotating blades, which are a bugger to stabilise with. We did the remote control all via a gsm module, so you sent it commands via SMS.

what's a good method for in-home wireless signal transmission/receiving? I've been thinking about putting small sensors around the home (nothing special or spying stuff, temprature/light sensors maybe). I can't afford WiFi modules for all, and having wires all over the place would not fare well with my parents. [editline]18th September 2014[/editline] would RF modules be sufficient, or is their signal too weak to get trough walls?

[QUOTE=scratch (nl);46011129]what's a good method for in-home wireless signal transmission/receiving? I've been thinking about putting small sensors around the home (nothing special or spying stuff, temprature/light sensors maybe). I can't afford WiFi modules for all, and having wires all over the place would not fare well with my parents. [editline]18th September 2014[/editline] would RF modules be sufficient, or is their signal too weak to get trough walls?[/QUOTE] nRF24l01p would be my bet. The modules are cheap enough and have something like 10mW of transmission power. Also there are more libraries than there is sand on the beach for all kinds of devices you might want to use.

hey fellas suppose you use a voltage regulator with no feedback resistors and just use the reference voltage is your load regulation gonna get really fucked up or something

[QUOTE=POLOPOZOZO;46012574]hey fellas suppose you use a voltage regulator with no feedback resistors and just use the reference voltage is your load regulation gonna get really fucked up or something[/QUOTE] No, if you're referring to something like the LM317 there is an internal 1.25V reference which maintains regulation, so if you ground the adjust pin you're going to get ~1.25V out.

Rebuilt a laptop battery using shitty $4 chinese lithium cells. Partly proof of concept. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/CGS_0926.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/CGS_0929.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/CGS_0931.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/CGS_0933.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/CGS_0934.jpg[/IMG] The charge rate is really shitty (we've already dropped down to 370ma) but it works. I would probably get much better pack life if I used Panasonic cells but untabbed and $20 each, it's a lot of extra work and cost.

Is it possible to integrate a trace in LTspice? I can't for the life of me figure out how to do it. In Pspice, it's just called S(), but I've tried so many different things and tried to find answers on google but find nothing. Please help me if you're used to LTspice. :) (I just started using it yesterday).

Anyone have a preferred method of cutting and stripping a large number (260+) of short wires (2-3cm)? Obviously I could do them one at a time and probably get it done somewhat accurately but I'd like to speed up the process whilst hopefully making it completely accurate.

I'd just sit in front of the TV with a tray and a pair of automatic wire strippers myself.

[QUOTE=BuG;46015115]Is it possible to integrate a trace in LTspice? I can't for the life of me figure out how to do it. In Pspice, it's just called S(), but I've tried so many different things and tried to find answers on google but find nothing. Please help me if you're used to LTspice. :) (I just started using it yesterday).[/QUOTE] I don't think there is an integration function in LTSpice, you can integrate to get the RMS and average of a waveform by holding ctrl and left clicking on the waveform label, it will integrate the displayed extent of the waveform.

[QUOTE=Chryseus;46015894]I don't think there is an integration function in LTSpice, you can integrate to get the RMS and average of a waveform by holding ctrl and left clicking on the waveform label, it will integrate the displayed extent of the waveform.[/QUOTE] I figured that much out, an integration function would be really useful though, used it all the time in Pspice. :( Thanks for the help though.

[QUOTE=Leestons;46015878]I'd just sit in front of the TV with a tray and a pair of automatic wire strippers myself.[/QUOTE] This was my plan. Thankfully I have 3 seasons of Oz left to watch, so here I go!

Yeah, about that battery.... [img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/TransNote/firstcharge.png[/img] Worse than I expected. Where the hell can you even source new Panasonic/Sanyo/Samsung cells?

LiPo laptop It's safe, I promise.

Tonight, I got around to working on my SMS remote starter project a bit and have made some progress. I soldered wires to the remote's battery terminals and button pads, then connected everything directly to an Arduino. Nothing caught fire, so I threw together some code to pick up serial commands and press the buttons on the remote. And it worked! I felt like a god turning my car on by typing commands into a laptop. Now I just have to wait for the GSM shield and everything to arrive so I could run it from my car and accept text messages. World's worst video of it. It's a snapchat that I saved but was to lazy to rotate. [vid]http://benjeffery.ca/video/2014-09-18_19-49-52.mp4[/vid]

Don't forget to hook up the horn to a "HONK" command.

[QUOTE=Cakebatyr;46018470]Don't forget to hook up the horn to a "HONK" command.[/QUOTE] The horn was one of the few things we didn't hook up to the remote starter, mostly because I didn't want to be "that guy" who leans on the panic button (Well, holding down the lock button for about 2 seconds) and has his crappy car annoying the fuck out everyone. And ideally, I would like this project to be somewhat easily-removable. The most I might connect directly to the car is the activation input for my remote starter, which just starts the car as if I pressed the button on the remote. Except it might be a tad more trustworthy than a hacked up remote. I don't want to fuck around with not having a warm car when I've gone through all that effort!