Electrical Engineering V2 - Developers

Fuck Wiimotes, Kinect and other motion control technology that's a steal of a deal and a technological marvel! For serious, that's still nice.

[QUOTE=alexaz;43700327] Gold[/QUOTE] I'll take eight!

Dammit, Hayes used negative logic for driving their status LED's. Oh well we can just add a 7404 between the 3904's

what do people think of the AVR XMEGA Microcontrollers ? [media]http://www.youtube.com/watch?v=HKrgVZ_b9Eo[/media] Hot.

[QUOTE=nuttyboffin;43703447]what do people think of the AVR XMEGA Microcontrollers ? [media]http://www.youtube.com/watch?v=HKrgVZ_b9Eo[/media] Hot.[/QUOTE] In itself, the XMega is awesome. In reality, it is a failed product, as they have a lot of long known unfixed silicon bugs, aswell as a chronic unavailability of ICs and dev boards. I can't recommend them.

Ugh, that horrible feeling when you build something and it doesn't work. I built an adapter that converted 20ma current loop to RS-232 serial. Nothing big. Just a MAX232 and two expensive ($15 each) HCPL4100 and 4200 optocouplers. The 4100 can't keep the loop closed and the 4200 doesn't convert loop pulses to TTL serial. I've gone over the schematic probably half a dozen times and double checked my wiring. Please don't tell me the two most expensive parts are BOTH dud for some weird reason. :(

[QUOTE=pentium;43709953]Ugh, that horrible feeling when you build something and it doesn't work. I built an adapter that converted 20ma current loop to RS-232 serial. Nothing big. Just a MAX232 and two expensive ($15 each) HCPL4100 and 4200 optocouplers. The 4100 can't keep the loop closed and the 4200 doesn't convert loop pulses to TTL serial. I've gone over the schematic probably half a dozen times and double checked my wiring. Please don't tell me the two most expensive parts are BOTH dud for some weird reason. :([/QUOTE] A schematic would be nice.

Quick question, if you give a summing op amp configuration a positive and negative voltage, will it function as expected? (ie subtract the negative voltage).

[QUOTE=chaz13;43711165]Quick question, if you give a summing op amp configuration a positive and negative voltage, will it function as expected? (ie subtract the negative voltage).[/QUOTE] Yep. "Negative" is only a convention relative to your defined ground.

[QUOTE=DrDevil;43704668]In itself, the XMega is awesome. In reality, it is a failed product, as they have a lot of long known unfixed silicon bugs, aswell as a chronic unavailability of ICs and dev boards. I can't recommend them.[/QUOTE] Really? thats a pity... anything similar? i was really looking forward to making use of all its abilitys...

[QUOTE=O Cheerios O;43710879]A schematic would be nice.[/QUOTE] [img]http://www.ds-electronics.de/pictures/rs232cv.gif[/img] Ignore the 78L05 for now. I'm directly powering the circuit from a regulated bench supply. The ICL232CP has been substituted with a MAX232CPE.

[QUOTE=nuttyboffin;43713318]Really? thats a pity... anything similar? i was really looking forward to making use of all its abilitys...[/QUOTE] Well, I am currently waiting for my [URL=http://www.digikey.com/product-detail/en/STM32F4DISCOVERY/497-11455-ND/2711743]STM32 Discovery Board[/URL]. There's a big community supporting it, and there's a lot of documentation available for it apparently. Also you can build a cheap programmer out of one of their lower end devboards. Also supports all kinds of open source toolchains, so yeah.

[QUOTE=pentium;43713646] Ignore the 78L05 for now. I'm directly powering the circuit from a regulated bench supply. The ICL232CP has been substituted with a MAX232CPE.[/QUOTE] Try add a pull down or pull up to pin 11 of the MAX232, 10k should do.

[QUOTE=DrDevil;43714937]Well, I am currently waiting for my [URL=http://www.digikey.com/product-detail/en/STM32F4DISCOVERY/497-11455-ND/2711743]STM32 Discovery Board[/URL]. There's a big community supporting it, and there's a lot of documentation available for it apparently. Also you can build a cheap programmer out of one of their lower end devboards. Also supports all kinds of open source toolchains, so yeah.[/QUOTE] Neat! Can it do much with TFT screens? im rather interested in experementing with them.

[QUOTE=nuttyboffin;43716193]Neat! Can it do much with TFT screens? im rather interested in experementing with them.[/QUOTE] It certainly has more than enough oomph to do that.

[QUOTE=DrDevil;43716243]It certainly has more than enough oomph to do that.[/QUOTE] [url=http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203908&Ns=P_PRICE_FARNELL_UK|0&Ntk=gensearch&Ntt=STM32F+DISCOVERY&Ntx=mode+matchallpartial&suppressRedirect=true&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D2031%2B203908%26Ntk%3Dgensearch%26Ntt%3DSTM32F%2BDISCOVERY%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_UK%26divisionLocale%3Den_UK%26catalogId%3D%26skipManufacturer%3Dfalse%26skipParametricAttributeId%3D%26prevNValues%3D2031%2B203908]Farnell[/url] seem much cheaper when you include the postage of the one you linked Any of the cheaper ones you think i should consider getting too?

[QUOTE=nuttyboffin;43717034][url=http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203908&Ns=P_PRICE_FARNELL_UK|0&Ntk=gensearch&Ntt=STM32F+DISCOVERY&Ntx=mode+matchallpartial&suppressRedirect=true&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D2031%2B203908%26Ntk%3Dgensearch%26Ntt%3DSTM32F%2BDISCOVERY%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_UK%26divisionLocale%3Den_UK%26catalogId%3D%26skipManufacturer%3Dfalse%26skipParametricAttributeId%3D%26prevNValues%3D2031%2B203908]Farnell[/url] seem much cheaper when you include the postage of the one you linked Any of the cheaper ones you think i should consider getting too?[/QUOTE] No idea, I'm not really into the matter yet. Although I heard you can turn an stm8 devboard (they cost like 6€) into a programmer by sawing off half the board (which acts as a programmer anyways), and then flashing it with new firmware. The firmware it's using: [url]http://www.blacksphere.co.nz/main/blackmagic[/url]

[QUOTE=Chryseus;43715821]Try add a pull down or pull up to pin 11 of the MAX232, 10k should do.[/QUOTE] That didn't accomplish anything.

[IMG]http://imgur.com/tyhmre5.jpg[/IMG] where's my stuff Tayda?

Hey, I posted about my laser project a few days ago in WAYWO and wanted to go into detail here. First of all, there aren't too many (good) options to control a showlaser. Easy/NetLase and Pangolin controllers are closed source DACs that cost from 350 to 600 bucks. The [url=http://ether-dream.com/]Ether Dream[/url] seems quite nice, and I will probably want to achieve the same features in the end. I've started out with a RPi and a similar board to this: [url]http://www.raspberrypi.org/phpBB3/viewtopic.php?p=366647[/url] My RPi is running Raspbian and there is no way to keep a steady output over SPI (between 5k and 30k) other than polling a hardware clock, thus eating all the CPU time. My question is, what would be a good configuration (be it a custom board, Arduino / RPi combo, whatever) for running - a webserver (for settings, easy access) - steady output to the DAC (5k to ~60k) - input via network / DMX If anyone worked on a similar project let me know! Here is what I got so far, 6W Laser and the RPi playing a ILDA demo file: [vid]http://luastoned.com/ilda_v1.webm[/vid]

So when I was at the Living Computer Museum I asked how they were doing running teletype machines all the time. They said that they had to install timers on them so they were not running all the time. The model 33 is a light duty machine and they were finding that after not even a year the machines were getting really worn out running eight hours a day six days a week. The modem I'm using with my teletype has Automatic Answer (AA) so I could switch it on and when someone calls it they can connect, send a message and disconnect without anyone being around. running the modem, current loop adapter and the selector driver 24/7 isn't the problem. It's the motor, bearings and driveshaft that will wear out extremely fast so I need a way to control the motor without any form of intervention so I developed this. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/logic2.jpg[/IMG] Assuming the teletype is in LINE mode and you've pressed START on the panel to turn the modem and microcontroller on, pressing LOCAL causes the microcontroller to inject a command string into the serial port (AT S0=1) telling the modem to turn auto-answer on. This makes the AA lamp on the modem turn on but for what I'm doing I have all the status lamps running through a logic inverter and transistors so whatever I'm controlling with the lamps draws power off a dedicated 5v source and not off the modem. Aside from turning on a light this also powers a NAND gate and makes one of its inputs TRUE. With the NAND active but only one input TRUE, its output powers a transistor which causes a Normally Closed relay to open and turn the motor off so now everything is setup to receive but we aren't constantly running the motor. When someone calls its hard-coded in the modem to blink the AA lamp in half second intervals. Normally this would make my circuit switch on and off and strain the motor with repeated power cycling. A capacitor keeps the NAND and the transistor powered during the low side of the blink and charges itself again on the high side. After the modem has picked up the blinking stops and once the modems have started to handshake the CD lamp comes on and makes the other input TRUE. This switches the transistor off, closing the relay and starting the motor. When the call is finished the CD light goes out and the relay opens once again. A flywheel diode prevents the relay from blowing up the transistor. If you want to turn auto-answer off you press the LOCAL button again which sends AT S0=0 to the modem, turning off the AA lamp and cutting power to the circuit. When the capacitor drains the logic dies, the relay closes and the motor starts so you can carry on. I'm not entirely positive how beefy the capacitor will need to be to keep the circuit alive.

If I have a stepper motor which is moving a load, is it possible to find out if some external force is pushing against the load by reading the current going into the stepper motor? And if yes, is there a motor driver which translates the current into a microcontroller compatible form, so that I could make the motor do things depending on how the external forces are acting on the load? What I wanted to do, was have a load behave like it is in zero gravity. So it would be standing still in space at first, but if you grab it and try to move it left or right, the motor driver would be able to sense the torque by the extra current going through the motor. So a microcontroller could then interpret this current and make the stepper motor slowly move the load as if it were being slowly accelerated in zero gravity. If you let go of the load, it would keep going until you grab it again and stop it.

[url]http://www.ebay.co.uk/itm/New-3in1-Soldering-Iron-SMD-Rework-Station-Hot-Air-Gun-Kit-DC-Power-Supply/310770452723[/url] A very interesting combination....

[QUOTE=nuttyboffin;43758527][url]http://www.ebay.co.uk/itm/New-3in1-Soldering-Iron-SMD-Rework-Station-Hot-Air-Gun-Kit-DC-Power-Supply/310770452723[/url] A very interesting combination....[/QUOTE] Not that unusual, but you should probably get a proper brandname, otherwise the hot air gun might melt your fingers/your entire house.

[QUOTE=DrDevil;43758703]Not that unusual, but you should probably get a proper brandname, otherwise the hot air gun might melt your fingers/your entire house.[/QUOTE] I have no intention of buying that, i just found it amusing how many things these people fit into a single product, chances are, every single one is crap.

Oh dear, I used to own a "Mei-Chuang 850" reflow station that looked awful similar to that in terms of build. It had a rather spectacular end to its life.

[QUOTE=nuttyboffin;43758755]I have no intention of buying that, i just found it amusing how many things these people fit into a single product, chances are, every single one is crap.[/QUOTE] Well, the proper versions of these are super handy, because everything is in a single box. It saves room on your shelf aswell as plug-slots for other devices.

[QUOTE=DrDevil;43759193]Well, the proper versions of these are super handy, because everything is in a single box. It saves room on your shelf aswell as plug-slots for other devices.[/QUOTE] I prefure seperate peices of equipment, usually means it is designed much better as they focused on a single thing. It also makes each peice more reliable.

[QUOTE=freakadella;43747412]If I have a stepper motor which is moving a load, is it possible to find out if some external force is pushing against the load by reading the current going into the stepper motor? And if yes, is there a motor driver which translates the current into a microcontroller compatible form, so that I could make the motor do things depending on how the external forces are acting on the load? What I wanted to do, was have a load behave like it is in zero gravity. So it would be standing still in space at first, but if you grab it and try to move it left or right, the motor driver would be able to sense the torque by the extra current going through the motor. So a microcontroller could then interpret this current and make the stepper motor slowly move the load as if it were being slowly accelerated in zero gravity. If you let go of the load, it would keep going until you grab it again and stop it.[/QUOTE] It is possible to do this with current measurement, but it'd be kinda strange as the motor coil's resistance can change a bit between motors in the same family. So you'd have to find the details yourself with some bench tests of the current vs load relationship. Then you can use that data to calculate external forces. I'm fairly certain there isn't a specific IC that can translate current to opposing force, so you'll have to whip one up with a current sense setup and a microcontroller. Another option is torque transducers, I've seen a couple on [URL="http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR3.TRC2.A0.Xtorque+transducer&_nkw=torque+transducer&_sacat=0&_from=R40"]eBay[/URL] for a fair price (~$75 USD), keep in mind these are imperial units and the metric ones may be way more expensive toward several hundred USD.

[QUOTE=nuttyboffin;43759977]I prefure seperate peices of equipment, usually means it is designed much better as they focused on a single thing. It also makes each peice more reliable.[/QUOTE] I would like to see proof for your claims.