Electrical Engineering V2 - Developers

[QUOTE=VistaPOWA;39957746]I don't have access to a CNC machine, I can't even design PCBs that are meant to be manufactured. I am really just a beginner.[/QUOTE] Well, that's the only mechanical way I know of. You should probaby just go with perfboard/stripboard then.

[img]http://puu.sh/2k0ej[/img] First of two workshop tables complete! Well, sort of. I ran out of lumber for the braces between the legs on the second half, so the legs aren't exactly straight. This isn't an issue though, since the second table is joined to the first and both of them are joined to the wall, the entire thing feels incredibly sturdy. I'll get more lumber for the braces at a later time. [img]http://puu.sh/2k0fF[/img] This entire space will be used for machines. The pillar drill will have a permanent position here as well as a bench grinder which I will purchase eventually. Dad even offered to bring in his lathe and bandsaw from the garage (which is too crowded to use as a workshop). As I'm sure I've mentioned there will be a similar (but slightly smaller) table in the oposite end of the room which will have my PC and electronics workbench. For now though I need to start thinking about lighting, the single ceiling lamp is not nearly enough. I'm thinking about fluro tubes or LEDs in the ceiling above the bench, depends on what gives me the most light for the least amount of money.

What would be the best way to convert an IBM Model M keyboard from PS/2 to some type of wireless? Bluetooth or 2.4GHz. I've got no experience making/deigning PCB's, but I'm fairly skilled with a soldering iron. So I could put something together if I needed to, but something pre-built would be preferable. I have a cheap 2.4 GHz keyboard that I could gut, but it would be rather hard to individually solder all of the wireless contacts to the model M keys. There's a fair amount of room inside of the top part of the keyboard. Also I'd be wanting to attach another key or two for the windows key and the three volume buttons. Maybe this is a bit ambitious...

Man, I really need to build a new desk soon. My current one is hurting my wrists (it's too high for my chair), do you have any more info on your desk, like which materials did you use, how much of it did you use, or possibly, do you have any drawings of it?

[QUOTE=Gulen;39960746]Man, I really need to build a new desk soon. My current one is hurting my wrists (it's too high for my chair), do you have any more info on your desk, like which materials did you use, how much of it did you use, or possibly, do you have any drawings of it?[/QUOTE] I came up with the design myself and I didn't make any substantial drawings. It's all built out of 45x45mm square lumber, though on reflection 45x70 or 45x90 would have been more structurally sound, though also more expensive. That's not to say the current design is unstable, but it's worth considering. The tabletop is just 12mm construction plywood. The trick is that on something like a dinner table, the actual tabletop is thick massive wood which gives much of the structural rigidity. Problem with that is it gets VERY expensive in large sizes, like the tables I'm building. Thus I made a frame of wood so that the plywood doesn't have to supply much at all of the structural rigidity. The frame is made up of two beams going lengthwise the entire length of the bench and braces going between them. You can see what I mean in my previous post [url]http://facepunch.com/showthread.php?t=1250138&p=39935199&viewfull=1#post39935199[/url] The legs are the same square wood as the rest. Since there's only a single point affixing the legs to the frame it's hard to get them straight. That and the fact that this thickness of wood wobbles in these lengths means that for my design the braces between the legs are a must. If I'd have laminated two 45x90mm boards into a thick 90x90 pillar I might have gotten away without the braces, but I probably still would have put them in. All in all I used 40 meters of the stuff building what you see and about one and a half sheets of plywood. I also went through almost 300 screws, some 50-100x 35mm screws to affix the plywood to the frame and some 100-200 80mm screws to put the wood together. Total cost (keeping in mind I have some leftover plywood (I bought a total of two 1200x2400mm sheets) and lots of leftover screws) was about 1300 SEK or about €150. I didn't pick the cheapest place but I did get some higher quality wood than what the cheaper places have. If you wanna build yourself some benches hit me up on steam anytime and I can help you hammer out a design.

Yeah, I might add you tomorrow, can't right now as I'm on my Mac, and Steam is really slow here, and it's late, so I have to get to bed for school tomorrow. But I'll hit you up tomorrow if I can remember it.

Wondering why my Arduino didn't seem to connect to the data bus... [t]http://i.imgur.com/DJwLsge.jpg[/t] Oh :(

[QUOTE=chimitos;39960698]What would be the best way to convert an IBM Model M keyboard from PS/2 to some type of wireless? Bluetooth or 2.4GHz. I've got no experience making/deigning PCB's, but I'm fairly skilled with a soldering iron. So I could put something together if I needed to, but something pre-built would be preferable. I have a cheap 2.4 GHz keyboard that I could gut, but it would be rather hard to individually solder all of the wireless contacts to the model M keys. There's a fair amount of room inside of the top part of the keyboard. Also I'd be wanting to attach another key or two for the windows key and the three volume buttons. Maybe this is a bit ambitious...[/QUOTE] This is a rather doable project, I'm sure you could find a Bluetooth dongle that has a configurable USB Device class ID and another bluetooth transmitter that pairs with it with built in I/O. Give these a shot: [URL="http://www.instructables.com/id/how-to-Control-arduino-by-bluetooth-from-PC-pock/"]http://www.instructables.com/id/how-to-Control-arduino-by-bluetooth-from-PC-pock/[/URL] Brush yourself up with the PS/2 protocol (Or atleast the hardware abstraction layer of it) to understand its electrical signalling protocols, most likely you won't be able to directly connect it to an xmitter without some sort of mediating circuitry: [URL="http://www.computer-engineering.org/ps2protocol/"]http://www.computer-engineering.org/ps2protocol/[/URL] You might have more luck with other wireless standards if you want to configure the device class, look around with Zigbee's products as a starting point. Also, here's a ref for the device classes: [URL="http://en.wikipedia.org/wiki/Universal_Serial_Bus#Device_classes"]http://en.wikipedia.org/wiki/Universal_Serial_Bus#Device_classes[/URL]

[QUOTE=r0b0tsquid;39961604]Wondering why my Arduino didn't seem to connect to the data bus... [t]http://i.imgur.com/DJwLsge.jpg[/t] Oh :([/QUOTE] Welcome to the club

[QUOTE=alexaz;39957558]You could try ordering ferric chloride or ammonium persulfate powder/crystals on ebay ( or just look in your local electronics shop ) and hope they slip through customs, although i believe there won't be any problems. Have you tried looking for hydrochloric acid in hardware stores? I usually find it in the paint section near all the solvents and spirits. Trust me, making your own PCB's ( low quantities, not product manufacturing ) is so much cheaper and faster than ordering them from China. Also: where do you live that you can't get basic chemicals because someone might make meth out of them?[/QUOTE] I live in the US, and I can't even buy Super Glue anymore without showing my ID. They're cracking down hard on this shit. Heard a family once had a church function and they needed alot of tinfoil. Apparantley tinfoil in large quantities = lolmakingmeth because they got stopped at the check-out and the cops were called in.

[QUOTE=ddrl46;39955351][url]http://www.bitsbox.co.uk/hardware.html[/url] Scroll down, the large and medium boards with round pads actually have square pads (at least when I last ordered them).[/QUOTE] Until the website is updated to reflect that, I don't believe it one bit. [editline]19th March 2013[/editline] [QUOTE=Zero-Point;39964884]I live in the US, and I can't even buy Super Glue anymore without showing my ID. They're cracking down hard on this shit. Heard a family once had a church function and they needed alot of tinfoil. Apparantley tinfoil in large quantities = lolmakingmeth because they got stopped at the check-out and the cops were called in.[/QUOTE] [url]http://hackaday.com/2012/02/15/etching-pcbs-with-vinegar/[/url] Hydrogen peroxide has uses for home emergency kits & cleaning, so that should be possible to get at a drug store / pharmacy without too much trouble.

[QUOTE=Van-man;39967289]Until the website is updated to reflect that, I don't believe it one bit. [/QUOTE] Try emailing them.

I think i might be doing something wrong. I have an opamp that i'm trying to use as a comparator. The negative input is grounded and the positive input is at 3.5 volts, yet the output is only 2.38 volts? Do opamps have voltage drops? Nevermind, its a perk of the 324.

[QUOTE=alexaz;39969385]I think i might be doing something wrong. I have an opamp that i'm trying to use as a comparator. The negative input is grounded and the positive input is at 3.5 volts, yet the output is only 2.38 volts? Do opamps have voltage drops?[/QUOTE] What are your supply voltages? It won't go all the way to the supply rails but it should get pretty close. Depends of course on the op amp and the technology it's based off.

[QUOTE=alexaz;39969385]I think i might be doing something wrong. I have an opamp that i'm trying to use as a comparator. The negative input is grounded and the positive input is at 3.5 volts, yet the output is only 2.38 volts? Do opamps have voltage drops?[/QUOTE] op-amps don't have voltage drops. What is your supply voltage, most (all?) op-amps cannot go to the positive rail. God damnit metallics you beat me to it.

[QUOTE=Chryseus;39969415]op-amps don't have voltage drops. What is your supply voltage, most (all?) op-amps cannot go to the positive rail. God damnit metallics you beat me to it.[/QUOTE] Open collector comperators certainly go to both ends. [editline]19th March 2013[/editline] Use a LM311 as a comperator, cheap and definitely goes to VCC.

[QUOTE=DrLuckyLuke;39969601]Open collector comperators certainly go to both ends. [editline]19th March 2013[/editline] Use a LM311 as a comperator, cheap and definitely goes to VCC.[/QUOTE] [quote]I have an [b]opamp[/b] that i'm trying to use as a comparator[/quote] One thing you could certainly do is to hang a transistor on the output, of course proper comparators have a much greater slew rate which may or may not be important for your application.

I fount somewhere that the LM324 op-amps can't go to Vcc due to the way they are built. The LM311 seems to be for 5 V supply, while i need something for 3.3. Would the LM311 work or could you suggest something for 3v3 that is widely available?

LM311 will work on 3.3V LM193 is another option.

[QUOTE=Van-man;39967289]Until the website is updated to reflect that, I don't believe it one bit. [editline]19th March 2013[/editline] [url]http://hackaday.com/2012/02/15/etching-pcbs-with-vinegar/[/url] Hydrogen peroxide has uses for home emergency kits & cleaning, so that should be possible to get at a drug store / pharmacy without too much trouble.[/QUOTE] If I ever got to the point where I etched my own boards, I can get muriatic acid through my work (they use it to clean ice machine parts here). Hooray, HVAC licenses. :v:

I got a few LM311 comps today and made this circuit: [img]http://i.imgur.com/J8Qj04Q.png[/img] Now the idea is that when the voltage in the positive input is 1 volt the voltage across R2 should also be 1 volts. Too bad it isn't and i can't figure out why. The comparators output at pin 7 also isn't VCC, but quite lower when the comparator should be outputing high. I believe it has something to do with my lack of understanding of transistors, which is inside the 311.

This is how the output is made up: [img]http://i.imgur.com/mWQQMk6.png[/img] Basically in your configuration, the transistor pulls the output to GND when the output is "low", and if the output is high, the transistor is closed and R1 pulls the ouput up high. I think the fault is the way you created your circuit. From the sounds of it you're trying to build a linear voltage regulator that outputs the same voltage as you apply with your DAC. Is that right?

I assume you're making a voltage regulator. You have two problem here, the first and most serious is that 3.3V may not be enough to fully saturate a MOSFET (particularly power ones) so your output voltage will not equal your input voltage. Secondly a comparator is not ideal here, while the high slew rate in theory is good given that this is a regulator that will often have a fair amount of output capacitance the advantages are limited, in addition there is a potential serious failure mode here, should the comparator for any reason cease to function the regulator will be turned on fully most likely causing the destruction of anything connected to it, you also forgot a resistor on the gate to discharge the capacitance. The best option I can think of is to use a super beta BJT or a low Vt power mosfet, you may also want to source the inverting feedback through a voltage divider to extend the adjustment range. On second thoughts why don't you just gives me the specs and I'll design you one.

And now for the shitty kickstarter of the month: [url]http://www.kickstarter.com/projects/1531311296/picsu-the-power-supply-that-fits-in-your-computer[/url] Fucking hilarious

[QUOTE=DrLuckyLuke;39979841]And now for the shitty kickstarter of the month: [url]http://www.kickstarter.com/projects/1531311296/picsu-the-power-supply-that-fits-in-your-computer[/url] Fucking hilarious[/QUOTE] "I filed a Patent Application with the US Patent Office" For what? A programmable power supply inside of a PC that uses the noisy ATX power supply and doesn't even make use of the computer it's internal communication connectors (RS232, USB) while it is inside of a computer case?

[QUOTE=ddrl46;39979844]"I filed a Patent Application with the US Patent Office" For what? A programmable power supply inside of a PC that uses the noisy ATX power supply and doesn't even make use of the computer it's internal communication connectors (RS232, USB) while it is inside of a computer case?[/QUOTE] Pretty much

I have a great slogan for him: Picsu - A power supply for the mentally deficient.

I forgot to mention that the mosfet I've got is logic level. Also Is it common for comparators to break? I guess I could add a check in the MCU for too high of a voltage and cut off the supply incase something goes wrong. That way it would be only a thousand of a second that the device would be exposed to higher voltage than expected. For the gate discharge, would a 10k resistor across gate and ground do the job?

[QUOTE=alexaz;39980387]I forgot to mention that the mosfet I've got is logic level. Also Is it common for comparators to break? I guess I could add a check in the MCU for too high of a voltage and cut off the supply incase something goes wrong. That way it would be only a thousand of a second that the device would be exposed to higher voltage than expected. For the gate discharge, would a 10k resistor across gate and ground do the job?[/QUOTE] Unless you hooked it up in reverse, there is no way to destroy it with your circuit.

[QUOTE=DrLuckyLuke;39979841]And now for the shitty kickstarter of the month: [url]http://www.kickstarter.com/projects/1531311296/picsu-the-power-supply-that-fits-in-your-computer[/url] Fucking hilarious[/QUOTE] Classic case of getting entrenched in your own idea. It's when you have a seemingly innovative or different idea that you think is brilliant and pursue that idea without any practical considerations, like if there's actually any demand for the product. I kinda feel sorry for the guy, he's putting all this hard work and effort into a stupid idea and he doesn't even realize it.