Electrical Engineering V3 - Developers

Is there a way for me to use the copper on copperclad board as an antenna for a 433mhz transmitter?

[QUOTE=Nightrazr;48682337]Is there a way for me to use the copper on copperclad board as an antenna for a 433mhz transmitter?[/QUOTE] Pretty damn sure that's what they do with many wireless products. You're gonna have "fun" designing the antenna so it actually works for your frequency, lots of lovely math.

Shit, I'm a novice. Eh, I'll just cut some wire and make a coil. :v:

[QUOTE=Van-man;48682424]Pretty damn sure that's what they do with many wireless products. You're gonna have "fun" designing the antenna so it actually works for your frequency, lots of lovely math.[/QUOTE] A simple dipole antenna shouldn't be too hard to design!

[QUOTE=metallics;48682986]A simple dipole antenna shouldn't be too hard to design![/QUOTE] Except at 433MHz a "simple" dipole would be ~35cm long. [url=hhttp://www.johansontechnology.com/datasheets/antennas/0433AT62A0020.pdf]You may want to check out some products.[/url] Learn about [url=https://en.wikipedia.org/wiki/Impedance_matching]Impedance matching[/url] too. [editline]14th September 2015[/editline] Actually heres a document from TI on product antenna design. [url]http://www.ti.com/lit/an/swra161b/swra161b.pdf[/url]

In my ongoing project to automate my bedroom, I got the LED strip lights in my room working [media]https://www.youtube.com/watch?v=J5ghFgEC56w[/media]

Got a couple of inverter boards from some old condensers at work, one from a Mitsubishi mini-split, and one from a Carrier Green-Speed condenser. Both have neat little bits but holy sweet bajeebus, does this Carrier inverter board have one mother of a heatsink on it. Also got a shit-ton of broken thermostats, including at least 2 of our new high-end Infinity Touch controls, which comes with a pretty decent full-color LCD with touch-screen. One of them may even be wifi-enabled, which is neat.

Want to get my LEDs working with my arduino Uno with a touch screen programmed to change the values of R G or B, but cant figure out how to program a FUCKING touch screen. Thing comes with no tutorial or instructions. I think I'm going to just develop a web interface to do it and keep hardware switches on it in case for some reason I can't get the browser up

[QUOTE=proboardslol;48684662]Want to get my LEDs working with my arduino Uno with a touch screen programmed to change the values of R G or B, but cant figure out how to program a FUCKING touch screen. Thing comes with no tutorial or instructions. I think I'm going to just develop a web interface to do it and keep hardware switches on it in case for some reason I can't get the browser up[/QUOTE] Which touch-screen?

Halted is having an anniversary sale this friday only, if you're in the silicon valley area you should go. [url]http://www.halted.com/[/url]

[QUOTE=Zero-Point;48684675]Which touch-screen?[/QUOTE] some cheap chinese shit

[QUOTE=cartman300;48680818]I don't have one. But i do have a surplus of H11A1's :v:[/QUOTE] To answer my own question, yes i can. I can perfectly fine power the optoisolator with the arduino to toggle the H bridge. In other news, i built a functional H bridge that can power the motors for the CNC machine, all that's left to do is taping something that tells me how many turns each motor did and writing a software interface that can control that thing.

[QUOTE=cartman300;48694572]To answer my own question, yes i can. I can perfectly fine power the optoisolator with the arduino to toggle the H bridge. In other news, i built a functional H bridge that can power the motors for the CNC machine, all that's left to do is taping something that tells me how many turns each motor did and writing a software interface that can control that thing.[/QUOTE] Assuming you're talking about stepper motors, why don't you use one of those [url=https://www.pololu.com/product/2970]stepper driver modules[/url] (Get them cheaper on ebay)? The modules do everything you need and even have current limiting and microstepping built in.

[QUOTE=DrDevil;48694605]Assuming you're talking about stepper motors, why don't you use one of those [url=https://www.pololu.com/product/2970]stepper driver modules[/url] (Get them cheaper on ebay)? The modules do everything you need and even have current limiting and microstepping built in.[/QUOTE] Because they are not stepper motors but normal DC motors i literally ripped out of a car door (multiple doors in fact). [editline]16th September 2015[/editline] Also holy fucking shit that's $19.95, for comparison to build that myself it just cost me $5. The optocouplers and other stuff were basically free because i found them in garbage. Shit i feel poor. [editline]16th September 2015[/editline] Also it's not fun to use pre-built stuff, is it? I like when my stuff explodes periodically.

[QUOTE=cartman300;48694623]Because they are not stepper motors but normal DC motors i literally ripped out of a car door (multiple doors in fact). [editline]16th September 2015[/editline] Also holy fucking shit that's $19.95, for comparison to build that myself it just cost me $5. The optocouplers and other stuff were basically free because i found them in garbage. Shit i feel poor. [editline]16th September 2015[/editline] Also it's not fun to use pre-built stuff, is it? I like when my stuff explodes periodically.[/QUOTE] It annoys me to say it, but buying a board with everything populated that roughly does what I want is normally cheaper than trying to design anything myself. Minimum quantities for PCBs and the like just make it not worth it in my experience.

[QUOTE=cartman300;48694623]Because they are not stepper motors but normal DC motors i literally ripped out of a car door (multiple doors in fact). [editline]16th September 2015[/editline] Also holy fucking shit that's $19.95, for comparison to build that myself it just cost me $5. The optocouplers and other stuff were basically free because i found them in garbage. Shit i feel poor. [editline]16th September 2015[/editline] Also it's not fun to use pre-built stuff, is it? I like when my stuff explodes periodically.[/QUOTE] You're not going to have a lot of fun using your cnc machine without stepper motors, let me tell you. You need a pretty good indexing system, otherwise you're going to have low repeatability. Not to mention that brushed motors also have barely any torque. [editline]16th September 2015[/editline] You can get 4 stepper drivers for really cheap here: [url]http://www.ebay.de/itm/StepStick-DRV8825-Stepper-Motor-Driver-Carrier-Reprap-4layer-PCB-with-Heat-Sink-/321511341628?hash=item4adb91be3c[/url] And there's a lot of deal for buying 5 NEMA17 stepper motors for just 50€. So for just 70€ you get 4 stepper motors with drivers, and a spare one for future use.

Do I have a story for you all, and it reflects my current plans for [URL="http://web.utk.edu/~carnivol/"]an upcoming robotics challenge my Uni is hosting for all undergrads and local HS kids[/URL]. One of my professors (Who helped design some of the chips used on the [URL="http://www.knoxnews.com/news/local-news/mission-to-mars-ut-researchers-contribute-to"]fucking Curiosity rover right now[/URL]), was apart of the my Uni's robotics team ~12 years ago before the days of Arduino/Basic Stamp when 8051s reigned. It was a line follower following a wire flowing with AC and had to make some basic left/right fork decisions. Thus instead of programming an 8051, he and two other guys gutted some old cassette tapes for their magnetic heads and through the power of analog wizardry made a fully analog (with some logic chips for L/R decisions) line follower: [img_thumb]http://oi58.tinypic.com/io2ety.jpg[/img_thumb] And now this [URL="http://web.utk.edu/~carnivol/line vollower.html"]competition[/URL] involves similar requirements with a dead stop point at the end. Thus I shall use Op Amp math and 555 PWM generation to follow, with an AND chip to stop the robot cold at the finish line: [img_thumb]http://oi58.tinypic.com/sbsbb8.jpg[/img_thumb] Fool Proof. The requirements ask for schematics and code, but I'll just shrug at the latter. :v:

[QUOTE=LoneWolf_Recon;48696576]Do I have a story for you all, and it reflects my current plans for [URL="http://web.utk.edu/~carnivol/"]an upcoming robotics challenge my Uni is hosting for all undergrads and local HS kids[/URL]. One of my professors (Who helped design some of the chips used on the [URL="http://www.knoxnews.com/news/local-news/mission-to-mars-ut-researchers-contribute-to"]fucking Curiosity rover right now[/URL]), was apart of the my Uni's robotics team ~12 years ago before the days of Arduino/Basic Stamp when 8051s reigned. It was a line follower following a wire flowing with AC and had to make some basic left/right fork decisions. Thus instead of programming an 8051, he and two other guys gutted some old cassette tapes for their magnetic heads and through the power of analog wizardry made a fully analog (with some logic chips for L/R decisions) line follower: And now this [URL="http://web.utk.edu/~carnivol/line vollower.html"]competition[/URL] involves similar requirements with a dead stop point at the end. Thus I shall use Op Amp math and 555 PWM generation to follow, with an AND chip to stop the robot cold at the finish line: Fool Proof. The requirements ask for schematics and code, but I'll just shrug at the latter. :v:[/QUOTE] The Basic Stamp isn't that new, I remember oogling over them in catalogs since I was 14, which was 17 years ago. :v: ...Fuck, I'm old. Anyway, if they ask for code, just show them the logic diagram, it's essentially the same thing. In other news, it turns out the Infinity Touch thermostat seems to work, though many of them seemed to be warranty throw-aways for reasons such as "Not communicating". Unlike most thermostats, the Infinity 'stats communicate with their respective equipment through a 2-wire protocol (haven't fired up the scope to see which one yet or to capture any data), which is what the older, non-touch non-color screen models also use, but these stats have full-color touch screens with a 32-bit RISC chip inside (of which the datasheet can be found [url=http://documentation.renesas.com/doc/products/mpumcu/doc/superh/r01uh0412ej0200_sh7266_67.pdf]here[/url] if you're curious). Unfortunately neither of the two I acquired are the wi-fi variety, which makes me sad.

Could anyone tell me why a [URL="http://www.ti.com/lit/ds/symlink/tl082-n.pdf"]TL-082 [/URL]op amp causes an amplifier to go into severe oscillation and general madness like full AC voltage swing at the output terminal while an [URL="http://www.ti.com/lit/ds/symlink/ne5532.pdf"]NE5532[/URL] works perfectly? The NE5532 has a much lower input offset voltage...slightly more complicated internal circuit. Seems like a better performing op-amp in general but I don't understand why it makes such a massive difference. Up to this point I was under the impression that op-amps were mostly interchangeable. Maybe one won't perform as well as another but should still work.

[QUOTE=No_Excuses;48701881]Could anyone tell me why a [URL="http://www.ti.com/lit/ds/symlink/tl082-n.pdf"]TL-082 [/URL]op amp causes an amplifier to go into severe oscillation and general madness like full AC voltage swing at the output terminal while an [URL="http://www.ti.com/lit/ds/symlink/ne5532.pdf"]NE5532[/URL] works perfectly? The NE5532 has a lower input offset voltage...slightly more complicated internal circuit. Seems like a better performing op-amp in general but I don't understand why it makes such a massive difference.[/QUOTE] Schematic? And frequency of oscillation? Its Bode plot is showing a 90 deg phase shift at ~500kHz with a positive feedback (negative dB gain) & -90 phase shift at ~20MHz.

[QUOTE=LoneWolf_Recon;48701919]Schematic? And frequency of oscillation? Its Bode plot is showing a 90 deg phase shift at ~500kHz with a positive feedback (negative dB gain) & -90 phase shift at ~20MHz.[/QUOTE] Hey yes it's roughly 500khz oscillation. No schematic, other than my half finished hand drawn one which isn't much help yet. I could finish drawing it though. It was part of the plan at least if no one could help here.

Maybe the TL-082 has a DC offset on the output, resulting in the amplifier to go to max output, which then causes the opamp to go to full negative etc. . It's hard to say without a schematic.

[QUOTE=No_Excuses;48701881]Could anyone tell me why a [URL="http://www.ti.com/lit/ds/symlink/tl082-n.pdf"]TL-082 [/URL]op amp causes an amplifier to go into severe oscillation and general madness like full AC voltage swing at the output terminal while an [URL="http://www.ti.com/lit/ds/symlink/ne5532.pdf"]NE5532[/URL] works perfectly? The NE5532 has a much lower input offset voltage...slightly more complicated internal circuit. Seems like a better performing op-amp in general but I don't understand why it makes such a massive difference. Up to this point I was under the impression that op-amps were mostly interchangeable. Maybe one won't perform as well as another but should still work.[/QUOTE] The TL082 has a lower GBWP which makes it more likely to oscillate, particularly at low gain (I.E voltage follower). I wrote an article on op-amp compensation which you may find useful: [url]http://www.electrical-workbench.co.uk/2015/07/op-amp-compensation_27.html[/url]

[QUOTE=Chryseus;48702740]The TL082 has a lower GBWP which makes it more likely to oscillate, particularly at low gain (I.E voltage follower). I wrote an article on op-amp compensation which you may find useful: [url]http://www.electrical-workbench.co.uk/2015/07/op-amp-compensation_27.html[/url][/QUOTE] I've been meaning to go over that blog of yours for a little while now. You are a sea of knowledge. Should I also mention it's just an audio amp? Like 20kHz max and the oscillation occurs regardless of input.

[QUOTE=No_Excuses;48706204]I've been meaning to go over that blog of yours for a little while now. You are a sea of knowledge. Should I also mention it's just an audio amp? Like 20kHz max and the oscillation occurs regardless of input.[/QUOTE] It only takes a tiny bit of noise to cause oscillation if the op-amp isn't stable, one thing you can try is put a low pass filter on the input of the op-amp which should help. Since you're dealing with audio frequencies where fast slew rate and bandwidth isn't really a concern the best solution would be output isolation by adding a 10-100 ohm resistor, particularly if you're having it drive a MOSFET or cable. In some cases power supply noise can cause oscillation, particularly if you're applying a DC offset to either input, so you want to make sure there is plenty of power supply decoupling caps around (very important with switching supplies). Often when I'm having an issue with oscillation I'll just take a 10pF or 100pF cap and try it in various locations to see if I can stop or reduce it.

If I get a wifi shield for my arduino Uno R3, will there be any room left on the pins?

[QUOTE=proboardslol;48708059]If I get a wifi shield for my arduino Uno R3, will there be any room left on the pins?[/QUOTE] If you're using the official wifi shield, here's a [URL="https://www.arduino.cc/en/Main/ArduinoWiFiShield"]list of pins used[/URL] (Plus there'll be headers for you to re

[QUOTE=proboardslol;48708059]If I get a wifi shield for my arduino Uno R3, will there be any room left on the pins?[/QUOTE] Look into the ESP8266. Really easy to use and only costs like 3$ a piece on ebay.

Is building a variable power supply as simple as a single lm317, a laptop power brick, and a potentiometer? I would like to have one for testing LEDs. [edit] On second thought, I'll probably just buy one. Any suggestions? Around 12v/1a. However, 18v might be useful for some deep cycle batteries I have. I have a $100 budget.

[QUOTE=false prophet;48709112]Is building a variable power supply as simple as a single lm317, a laptop power brick, and a potentiometer? I would like to have one for testing LEDs. [edit] On second thought, I'll probably just buy one. Any suggestions? Around 12v/1a. However, 18v might be useful for some deep cycle batteries I have. I have a $100 budget.[/QUOTE] For 100$ you can buy nice lab supplies with way more juice than 12V/1a. Just try looking around on ebay, finding those in your price and feature range, and then google their model names to see if they're good or shit. Try to get one with digital buttons/knobs instead of completely analog ones. It's easy to accidentally brush the knob and fry your stuff. [editline]18th September 2015[/editline] Also you want to make sure it has an extra ground output, so your output is floating. You can use this to create a split supply if you have a dual output supply!