Jon Clausen wrote: > On Tue, Jul 15, 2003 at 11:49:27AM -0700, Matt Schalit wrote: > >>I suppose this could go on leaf-hardware, >>but I was wondering who's added a DAC to >>their box? > > Not really. (You *do* mean Digital-Analog Converter, right?)
Yup, that's right. The future is ripe for wireless interfacing of your home gadgets. Running wire is passe'.
>>It'd seem like a decent place to launch a few >>cron jobs from. > > > Indeed. > > >>Just patch in a unity gain >>op-amp for some bigtime imput impedence, and >>you get a cheap buffer you can blow if you make >>a mistake (how much is a 411 anyway?), plus you >>get a good current source for your D/A control >>(of your sprinklers or whatever). > > > I've not gone into controlling anything analog, but I *have* built a system > to open and close my blinds. I don't know if that's anywhere near what > you're thinking, but in any case the (pretty severely outdated) site is at; > > http://bund.dk/blinder
That's awesome. Really good stuff. Close to what I was posting about. You even have some sort of rudimentary input, the kill switches you added to the blinds.
Charles hasn't posted on this thread, but he may not have seen it. Too bad because he built a Battle Bot and has quite a bit of computer interfacing experience.
I got in A's in Analog Lab, Digital Lab, and in Computer Interfacing, but he's actually doing it in real life having to deal with Voltage converters, grounding planes, filters, the whole gamut. How much fun is that?
After my original post, I took a look around and found a few DACs for about $200 US or more, and a couple of less expensive solutions like the one you use. There's one for $35 bucks or so that looks cool, called the GP-3 PC I/O card, and it attaches to your serial port:
http://www.al-williams.com/gp3.htm
What's cool about the GP-3 is that it does the stepper motor control already, along with tons of other good stuff. I was sort of surprised it was only $35 US. I could run a farm with that little thing.
>>I suppose X10 is more popular than doing this >>stuff from scratch.... Still, if you're not >>building, you're crumbling :) > > > I never found out what x10 actually *is*, but it kept coming up while I was > researching the electronics parts of my contraption..
X10 is good stuff. It's sort of an Apple computer approach to inventing, in that you use *their* base station, *their* modules, *their* profit is your loss, but they have solved all the small details like wireless control, standardized control scripting. You can see how reinventing the wheel is not necessarily the most efficient use of your precious time, but on the other hand, there's no better way to learn than what you're doing.
> I just picked up development a couple of days ago. Basically the bit that > drives the stepper motor is a script that pushes out bit-sequences of the > parallelport. But being a script (and not particularly well written, at > that) it makes for some jerky motion of the motor, which I think is in part > responsible for the two mechanical failures it has suffered in the year it's > been running. (Plastic fatique).
I sort of thought that you just tell those stepper motors to slew and use an infra-red transmitter/pickup system that counts the times the IR beam is interrupted as it shines through the slits in the stepper's axel mounted circular disk.
And I thought you pretty much used the stepping feature for "fine" positioning....
I love the real world, learn-by-destruction feedback you're getting. I'd like to model that in autocad :)
> I'm hoping to get some smoother action by converting that script to C, and > taking the opportunity to add a couple of features, such as making sure that > there can be only one instance of the program running at a time a.s.o. > > Cheers, > Jon Clausen
Yup, agreed that C is a great way. The better DAC cards I've used have really nice header files already available.
You know what is a really good physics/electronics exercise is to build a solar tracker. Make it good enough so that you can kick the cart and it will reacquire the sun. The combination of (+) and (-) feedback, I/O, and A & D circuitry make it.... fung shua-ish. Heh.
You can modify it, using bandpass filters, to acquire satellite transmission frequencies for tracking purposes or positioning hi-res antennas, or set it for IR frequencies to aquire the heat from... well lots of different things ;-)
In theory, and in my brain, it's a lot of endless possibilites, but when it get's down to the real *Art* of electronics, being able to visualize massive circuits interacting in terms of color and vibration in what can be understood by non-artists as a sort of LSD B-Movie visual, I don't "get it." I don't see it well enough, and in the end, my circuits suffer some weird noise I can't filter, or like you said it get's choppy.
It's hard to seperate ground planes and +5 planes and make really good multilayer circuit boards for cheap. And you need to do that once you get past small scale wire-wrapping, ya know what I mean?
But for home stuff, it doesn't take much more than an old HP printer like you showed us. Bonus points for recycling and making it w3 compatible/online.
Let's hope you have a job that rewards your talent, because I think that routing-homecontrol-wireless is the future, and you've proven 1/3 of the concept.
Matt
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