Electrical Engineering V3 - Developers

[QUOTE=Cakebatyr;50535928]If I wanted to put something in a box (which I'm about to do with an arduino mega) I would much prefer terminal blocks than pin headers.[/QUOTE] Considering PLCs are effectively industrial grade arduinos, who connect simply through terminal blocks. That freeduino makes alot of sense yeah. But the choice to use USB mini over USB B (Considering the USB B pads are already there) was a mistep. And look...an FTDI chip. :vomit:

[t]http://w3axl.com/wp-content/uploads/2016/05/sch3.png[/t] So back to this circuit - it doesn't work. I soldered everything up properly on the board, but the gate doesn't do anything. So this was a bust and a waste of $15. Is there a simpler way to do a flip flop? What would be the easiest way to toggle something from high to low at a pulse of low? [editline]16th June 2016[/editline] [URL="http://www.mouser.com/ds/2/308/MC14027B-D-103949.pdf"]Here's the gate I bought.[/URL] [editline]16th June 2016[/editline] Nevermind, it looks like I needed to add a pullup from TRIG to VDD. Seems to work now, albiet a bit bouncy.

So today's project required me to do some woodworking. [img]http://i11.photobucket.com/albums/a166/ballsandy/IMG_4289.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/IMG_4291.jpg[/img] [img]http://i11.photobucket.com/albums/a166/ballsandy/IMG_4293.jpg[/img]

[QUOTE=gjsdeath;50536147]I would like it because if I'm working on a project and haven't finalized the wiring, it would be nice to just unscrew it instead of having to re-solder everything. Although, I know some people would prefer to only mount the processor itself to their project instead of the entire Arduino prototyping board, but I don't have time for that shit.[/QUOTE] A Teensy would suit my application just fine, except an Arduino Mega clone is much (80% less before shipping) cheaper and theres space in the box. Although with my feature creep I may have to get one.

So i'm working on a tv which had a couple of problems. One of the last things i need to fix is putting in [URL="https://spares2repair.co.uk/philips-32pfl5522d-05-lvds-cable-me7-lvds-313913108282-plati"][B]a new lvds cable[/B][/URL]. I ordered one online but i got a different one in the mail then advertised although it's still say's it's specifically for this model of the tv. The main difference seems to be [B]4 pins not being used[/B] (gonna check the pinout more precise in a minute) and [B]extra pin added[/B] on the new cable. [B]Does anybody know if i could give this a shot without damaging anything or should i just redo the cable to make an exact copy of the old one?[/B] I don't know much about tv's and displays so i'm not gonna take any risks. [B]Edit:[/B] The pinouts are completely off so no way this is gonna work. Can i just rewire it by soldering the connections or is that gonna give trouble as that part won't be shielded?

Since I ended up spending the best part of two days trying to debug a signal integrity issue as a software issue I've decided I would be best to purchase an oscilloscope finally. Has anyone got any better suggestion that the Rigol DS1054Z at £330, in the same ~£400 budget. Also any suggestions for getting an inexpensive DC power supply?

[QUOTE=ben1066;50540947]Since I ended up spending the best part of two days trying to debug a signal integrity issue as a software issue I've decided I would be best to purchase an oscilloscope finally. Has anyone got any better suggestion that the Rigol DS1054Z at £330, in the same ~£400 budget. Also any suggestions for getting an inexpensive DC power supply?[/QUOTE] If you dont mind a few set voltages, go for a PC power supply. At worst if you need something fine tuned, you could also throw a buck/boost converter. So with the power supply you can get 3.3V, 5V, 12V and some of the older ones have -12V i think

Modern ones have -12V as well. (it's the blue wire on the ATX connector) [img]http://i.stack.imgur.com/g2b7h.png[/img]

[QUOTE=andreblue;50541250]If you dont mind a few set voltages, go for a PC power supply. At worst if you need something fine tuned, you could also throw a buck/boost converter. So with the power supply you can get 3.3V, 5V, 12V and some of the older ones have -12V i think[/QUOTE] That's not a bad idea I guess, the only voltage I think I'd like that isn't there is 1.8V in some cases. I guess the major omission is current limiting there in case I screw up.

[QUOTE=Zero-Point;50541321]Modern ones have -12V as well. (it's the blue wire on the ATX connector) [IMG]http://i.stack.imgur.com/g2b7h.png[/IMG][/QUOTE] Wrong way around, old ones have -12V. The -12V rail is mostly used for RS232, so it's not actually needed. PCI (not Express) still has -12V on the pinout, so you still need to provide the negative rail in order to be compliant with ATX, but if you don't have a PCI device that uses -12V, nobody is going to give a shit if the rail is missing.

[QUOTE=ben1066;50541474]That's not a bad idea I guess, the only voltage I think I'd like that isn't there is 1.8V in some cases. I guess the major omission is current limiting there in case I screw up.[/QUOTE] Well the price is decent. At worst it would cost you about 20ish £ [url]http://www.ebay.co.uk/itm/COLORSit-PSU-330U-350W-Desktop-Power-Supply-Unit-/252416032312?hash=item3ac52afe38:g:VAsAAOSwepJXVe4U#shpCntId[/url] With [url]http://www.ebay.co.uk/itm/6-35V-to-1-35V-DC-DC-Converter-Buck-Boost-Charger-Power-Converter-Module-P5-/181929194745?hash=item2a5bd334f9:g:BJEAAOSwAYtWQwOG[/url] and [url]http://www.ebay.co.uk/itm/10pcs-4mm-Binding-Post-Speaker-Cable-Banana-Female-Test-Connector-5-Colors-/281724347627?hash=item41981464eb:g:D9gAAOSwv0tVf9Nd[/url]

I would strongly recommend avoiding ATX supplies, for two reasons, firstly the negative rail is tied to earth ground which can be problematic once you throw other earth referenced equipment in the mix (I.E oscilloscope, other devices, etc). Secondly the noise performance is horrific, if you do any analog low voltage stuff (I.E a microphone amplifier, particularly simple discrete designs) it will almost certainly degrade your signal and in some cases make it completely unusable. Get yourself a cheap chinese power supply with current limiting, even if the construction quality is dubious it'll serve you much better than an ATX supply. The only time I'd consider using an ATX power supply is if I needed a lot of current and noise was not an issue.

[QUOTE=Chryseus;50543712]I would strongly recommend avoiding ATX supplies, for two reasons, firstly the negative rail is tied to earth ground which can be problematic once you throw other earth referenced equipment in the mix (I.E oscilloscope, other devices, etc). Secondly the noise performance is horrific, if you do any analog low voltage stuff (I.E a microphone amplifier, particularly simple discrete designs) it will almost certainly degrade your signal and in some cases make it completely unusable. Get yourself a cheap chinese power supply with current limiting, even if the construction quality is dubious it'll serve you much better than an ATX supply. The only time I'd consider using an ATX power supply is if I needed a lot of current and noise was not an issue.[/QUOTE] The Chinese one I got (30V 5A ) works really well. I've even had dead shorts and it handles it all like a champ. Theyre all over [url]http://m.ebay.com/sch/i.html?_nkw=variable+power+supply&isNewKw=1&_sacat=92074&cnm=Electrical+%26amp%3B+Test+Equipment[/url] I regret not getting the 10A one. But I'm also tempted to get a Variac, some caps, and a bad ass rectifier to make a ~115V 15A+ AC/DC unregulated power supply. Only because I havent managed to be kill myself yet on the stuff I currently have.

Time to apply some of my control theory knowledge! [media]https://www.youtube.com/watch?v=E1Ra5JDzx0M[/media]

It's about time you use that Laplacian transform. Seriously, what will you do? I once studied (ok for 2 days only) control theory and shit is interesting

[QUOTE=Fourier;50560663]It's about time you use that Laplacian transform. Seriously, what will you do? I once studied (ok for 2 days only) control theory and shit is interesting[/QUOTE] I just want to use it as a motor fader, meaning that I want to be able to tell it to go to a certain position, and it will move there as quickly as possible without overshooting. In order to achieve that I'm currently recording the step response of the sled. I think that I can model the sled velocity as a PT1 block. [img]https://my.mixtape.moe/tdhrdn.png[/img]

Reddit /r/technology is the worst. I posted a fairly detailed explanation of why 5G radio would in theory allow for higher data caps. Nope, downvoted by people responding with things like [I]"No data will never run out ISPare just evil"[/I]. If you don't even remotely understand RF signaling or things like TDMA and signal bandwidth then don't fucking respond. I acknowledged that current data caps are at the levels they are from mostly business decisions but that doesn't change the fact that there have to be data caps if you want a reliable network with reasonable speeds for everyone.

[QUOTE=Dolton;50562330]Reddit /r/technology is the worst. I posted a fairly detailed explanation of why 5G radio would in theory allow for higher data caps. Nope, downvoted by people responding with things like [I]"No data will never run out ISPare just evil"[/I]. If you don't even remotely understand RF signaling or things like TDMA and signal bandwidth then don't fucking respond. I acknowledged that current data caps are at the levels they are from mostly business decisions but that doesn't change the fact that there have to be data caps if you want a reliable network with reasonable speeds for everyone.[/QUOTE] /r/technology is the worst for that. Limiting usage totally makes sense when you have a medium with not a ton of capacity. In a lot of areas for work, we use 900 MHz Motorola Canopy PMP100 gear to provide internet because literally nothing else will work. 300 feet of tower and many customers will still be behind shitloads of trees. Per AP (6x60° sector antennas), we can only push out a max of 4 Mbps down and we restrict customers to 1.5 Mbps on that gear, so no shit we're going to [I]try[/I] to control usage.

[QUOTE=benjgvps;50563535]/r/technology is the worst for that. Limiting usage totally makes sense when you have a medium with not a ton of capacity. In a lot of areas for work, we use 900 MHz Motorola Canopy PMP100 gear to provide internet because literally nothing else will work. 300 feet of tower and many customers will still be behind shitloads of trees. Per AP (6x60° sector antennas), we can only push out a max of 4 Mbps down and we restrict customers to 1.5 Mbps on that gear, so no shit we're going to [I]try[/I] to control usage.[/QUOTE] Sad part is I live in the middle of Bumshart, New Mexico, which is flat as fuck so there's literally NOTHING to block the towers, and there's still tons of places where you get shit/no signal.

So I modelled the step response above as an integrated PT1-system: [img]https://my.mixtape.moe/wyfpcb.png[/img] That was a lengthy process of trying out values for 2 hours until I arrived at the fit above. I differentiated that by hand, and thus got a PT1 system. I immediately compared it to the numerically differentiated and heavily filtered measurement: [img]https://my.mixtape.moe/wzsykd.png[/img] And it's pretty much a perfect fit! The dip into negative values at the beginning is mostly an artefact of the filtering. It feels SO so good to get this result. It's pretty much the culmination of 2 years of theory which I finally applied to a real world problem.

Hello again EE thread. After forgetting about ya'll for a while(Why is it hidden away in dev/programing of all places?), I'm back with another project. While at the electronics store, I noticed they had some lovely futaba VFDs going pretty cheap; of course, I had to buy one! [t]http://i.imgur.com/i0ORHHN.jpg[/t] I managed to drop and break my 12v plugpack, so the 12v grid and segment power rail is being provided by the world's dodgiest regulated boost circuit. Uses an arduino nano for PWM, and has feedback going in the ADC to try and keep the voltage somewhat constant. TCCR2B = 0x02 also happens to give a PWM frequency which works decently well; lucky me. [t]http://i.imgur.com/ADwSFZe.jpg[/t] [t]http://i.imgur.com/7Po0PKz.jpg[/t] [t]http://i.imgur.com/f3hFGLG.png[/t] Seeing as I have nothing better to do over winter break, I figure I'll make a display driver 'backpack' for this thing. For some added fun, I'm going to try and do it with 74-series discrete logic while keeping the data interface down to two wires(data and clock). Time to raid the crusty end of the parts drawers :v:

[QUOTE=Dolton;50562330]Reddit /r/technology is the worst. I posted a fairly detailed explanation of why 5G radio would in theory allow for higher data caps. Nope, downvoted by people responding with things like [I]"No data will never run out ISPare just evil"[/I]. If you don't even remotely understand RF signaling or things like TDMA and signal bandwidth then don't fucking respond. I acknowledged that current data caps are at the levels they are from mostly business decisions but that doesn't change the fact that there have to be data caps if you want a reliable network with reasonable speeds for everyone.[/QUOTE] Would you mind pasting your explanation? I'd like to read your explanation out of interest.

So I put a 10k/2k voltage divider across 230VAC without thinking. Long story short, it basically exploded :v: RIP optocouplers, they did their job.

74xx Series logic is a hell of a drug. [t]http://i.imgur.com/cJKW0M7.png[/t] With just a serial data and clock line, this design will display 11 characters of 7-segment(plus decimal point!). Features include an onboard 12v boost circuit, 74HC** heresy, AC filament switching for even brightness, and a PCB footprint that's easily 2x the size of the display it drives :tried: [t]http://i.imgur.com/FCtnZyb.png[/t] This version has PROM chips to store UTF-8 character data. Anyone want to give me a copy of not-lite EAGLE so I can try and route this? [t]http://i.imgur.com/ydRywN6.png[/t] actually, on second thought, maybe not. :suicide: Edit: After having a look at pricing for eagleCAD :nope:, I think it's time to switch before I get too comfortable with it. KiCAD is looking good; any suggestions?

DipTrace is pretty good IMO, and it already comes with a sizeable library from various vendors/manufactures plus all the through hole/SMD basic parts. Also the UI/workflow isn't a clusterfuck like Eagle. Its freeware version is limited to 300 pins/2 layer boards, but I've never really gotten close to that limit and I think your project may come in under the 300 pin limit as well (You might have to split it into two different boards). A nice comparison between them was posted [URL="https://www.element14.com/community/groups/diptrace/blog"]here[/URL].

KiCAD certainly isn't the icing on the cake as far as CADs go, but it's the best free one out there.

I think accidentally vaporizing my entire +230V rail gave me more respect for mains power than shocking myself with it ever has. At least the board still works somehow after moving the input over :v: [editline]24th June 2016[/editline] I'll make a real PCB out of this piece of stripboard junk and pot it before I set the building on fire.

Eurgh, so I had a grand plan to design a proper controller for my motor fader, but it turns out that this thing is anything but linear, and has quite a lot of hysteresis. Fuck this shit, I'll just throw a PID-controller on it and use Ziegler-Nichols-Rules to find the values.

[QUOTE=Tobba;50587619]I think accidentally vaporizing my entire +230V rail gave me more respect for mains power than shocking myself with it ever has. At least the board still works somehow after moving the input over :v: [editline]24th June 2016[/editline] I'll make a real PCB out of this piece of stripboard junk and pot it before I set the building on fire.[/QUOTE] Reminds me of the story of Bizznar. Co-worker used to do a lot of different jobs before he got into HVAC, and some way or another, he ended up working with 230V lines (3-ph), somehow ended up grabbing one, and it grabbed him back, making a loud "BZZZZZZZZ" noise. As his co-workers turned to see what the racket was, it finally launched him across the roof, releasing him with a "NAR!". Hence, Bizznar (which is the nickname his co-workers gave him after the incident).

Running the math on potting this thing in epoxy, I'm carrying 5A over a 3000 mils long 60 mil trace. I'm getting that with 1oz copper, it'd generate 600mW of heat and reach 30C above ambient sitting under 1cm of epoxy (assuming 1.5 W/(mK)), I feel like that calculation is wonky at best though, and since it's sitting inside a pretty hot area (it drives a heater) it seems that it might become an issue. Can't really figure out if I should bother with 2oz copper for this kinda current, it'll take OSHpark up to a month to get them here. I'm starting to feel like 1oz will be fine though, anyone got any experience with this?