Show Posts
Pages: 1 ... 326 327 [328] 329 330 ... 376
4906  Forum 2005-2010 (read only) / Frequently-Asked Questions / Potential -Awesome- Robot Platform? on: May 20, 2010, 12:36:36 pm
I am a little biased on this one; I own one I picked up a Goodwill sans controller...I have yet to do anything with it, but it seems a capable beast!

Check it out - the MGA Tarantula (linking to an ebay auction with them for sale):

http://cgi.ebay.com/MGA-Tarantula-Remote-Control-RC-Rover-Remote-/370351230959

I can't vouch for the seller.

Here are a couple of papers detailing interfacing (and a LIDAR system for terrain mapping/planning):

http://raybot.cse.unsw.edu.au/aboutme/sheh05redback.pdf
http://raybot.cse.unsw.edu.au/aboutme/sheh06lowcost.pdf

Once again, I am not affiliated with any of these people; I don't stand to make any money off the auction or whatnot - it was just a source (if I had the money and a place to put them - they are HUGE for an RC car - covering about a 24 inch diameter circle - I would buy all six in a heartbeat).

Like I said, I found one of these - and I just happened upon those papers during some googling on "low cost LIDAR"...

 smiley

[edit]Hmm - I just realized this may have worked better in bar/sport - mods, if you can move it there it would probably be better since this isn't a question, per se.[/edit]
4907  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Robt ideas? HELP? on: May 19, 2010, 06:29:47 pm
You could try dead-reckoning; you would need to add quadrature encoders to your wheels, keep track of steering angles, and a lot of math; it isn't very accurate over long distances, but it can work.
4908  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: How to hook up a heat sink? on: May 17, 2010, 11:14:53 am
Interesting find, Jeff - thanks for posting that!
4909  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: How to hook up a heat sink? on: May 15, 2010, 04:52:52 am
Grumpy_Mike:

I didn't see a TO-92 heatsink in that selector; do they actually make such a thing (I've never seen one; that doesn't mean they don't exist)?

 smiley
4910  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: How to hook up a heat sink? on: May 14, 2010, 12:07:47 pm
Those aren't really designed to have heatsinks mounted to them; you may want to buy a larger regulator with a tab for bolting a heatsink on (TO-220 case, perhaps). Once you do that, you just need a boltable heatsink and some heatsink compound to go between.

For a TO-92 device, you might try to epoxy (I prefer 2-part JBWeld, personally - strongest stuff on the planet, I think - I have it holding together a backfire prevention valve on a 400ci V8 in my old Bronco, which is bolted directly to the exhaust manifold; I've also seen it used to hold together an aluminum blower on a large diesel engine for 20 years - so, if it can take that kind of temperature abuse, it will work good for a small TO-92 device!) a small piece of copper/brass/aluminium tubing over the device, and split the top 3-4 ways and spread the "fins". You can find such smaller tubing at hobby stores (they should carry a "pieces-n-parts" assortment bag of cutoffs that would work good; whole tubing can also be purchased). Be sure to have plenty of airflow.

 smiley
4911  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: In a kit, do you prefer SMD or through-hole? on: May 17, 2010, 12:25:37 am
Personally, I prefer thru-hole; I still haven't tried my chops at SMD work. I think I could handle large components where the pitch is fairly big, but some of those components have such a fine pitch that unless I was an expert, I would be afraid of screwing something up.

Something I wonder, though - other than likely using up more board real estate (which can be an issue), would it be possible to set up the board to allow for easier smd work, especially by novices? Something like larger pads, with special "wells" where the lead of the smd component (thinking ICs mainly here) fits between or in a groove or something (kinda like the "smartboards", iirc, products)?

If a method could be developed to allow SMT work by novices without the possibility of frying or shorting out an expensive device, that would be a nice way to move into SMT to build skills for more standard SMT boards.
4912  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Joystick control of a servo without computer on: May 14, 2010, 04:02:41 pm
Quote
Though crosh sounds rather pessimistic

I am not being pessimistic, I am being realistic.

VTOL aircraft are an order of magnitude more difficult to build than an airplane; even a helicopter is simple by comparison. They are flying bricks, and require computer control of some sort just to get them hover out of ground-effect. They are anything but inexpensive to build, at least at the human-carrying scale.

It sounds like you understand what you are up against, Khardreid, even if you have a kind of "pollyannish" idea of what it will take; maybe that will carry you through, ultimately. Some of the best ideas have occurred because people didn't just think outside the box, and instead they didn't know the box existed. Some have perished in trying, too. I would rather see you in the former situation, rather than the latter.

Here's to your success!

 smiley
4913  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Joystick control of a servo without computer on: May 14, 2010, 11:31:22 am
Khardreid:

First off, I applaud your drive and enthusiasm, but I want to inject a little reality here...

Quote
The reason I ask, is because I have a rather large and expensive project...[snip]...looking for a job to fund my project

You say you are in the planning and development stages; I assume you have selected the engines needed (and you know they are rated for vertical axis usage, perhaps), and I also assume you are aware of their total fuel consumption? You know their lifting capacity, and have a design in mind for your airframe to take the stress, while lifting the frame's weight, your weight, fuel weight, etc?

Are you an aviation engineer?

I am not certain that you understand the scale of what you are attempting to do, nor am I certain that you understand just what kind of funds will be needed to support such an endeavor. Moller has been attempting to do what you are saying you want to do for the past 40-50 years or more:

http://en.wikipedia.org/wiki/Moller_Skycar_M400

They've actually flown a prototype (tethered, though); but their claims have gone on for so long that it is any wonder -anyone- invests with them.

I think the world can only have one Moller-style company at a time...

Even if you did get something working, it would probably be longer than your lifetime before you would get FAA approval for flying it, assuming you could afford the fuel to do so.

I am not wanting to discourage you in your efforts, I just hope you are aware of the difficulties and expenses that surround this kind of project (really, any kind of home-built aircraft project). While there have been great strides made by hobbyists with multi-blade VTOL model aircraft using off-the-shelf microcontrollers, gyros, accellerometers, etc - scaling one of these up to "life size" isn't just a matter of changing the dimensions and adding a seat.

If you realize this, and you are confident that you have the engineering skills (or can find them), as well as the financial backing, then great. But if you don't have any one of these components, while having great drive, you could find yourself in financial ruin (with a lot of failed personal relationships along the way), with a small mountain of "scrap parts" rusting away. Its happened to many before, and will likely continue to happen; being able to see within yourself not only what you are capable of but also what you are -not- capable of is key to avoiding it (that doesn't mean you couldn't find investors and/or others to assist you - but like I said, the world can only have one Moller Sky-Car company at any one time, I think).

Good luck, and don't kill yourself experimenting!

 smiley-wink
4914  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Pin 13 LED reacts to human presence!!! on: May 14, 2010, 12:28:11 pm
zoomkat, your answer makes sense, and seems closest to what I was reading about - but that seems to only apply if you are building a circuit, and apply power before you have connected the gate up (you are talking about a pull up/down resistor, in effect, right?). This makes sense, but it felt like what I was reading was saying not to install the MOSFET until you had the resistors in place, nothing about powering it up. Maybe I misread, or the author wasn't clear (it didn't seem right to me that something would spontaneously fail before you had everything hooked up).

Though - with what westfw is saying - maybe you need to have everything set up (resistor on gate) before connecting because of stray static charges causing the failure? It sounds like ultimately I need to keep myself well-grounded when working with these devices, while taking into account the gate resistor thing.

Thanks for the explanations.

 smiley
4915  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Pin 13 LED reacts to human presence!!! on: May 13, 2010, 03:03:41 pm
Quote
So you know all those "extreme" precautions you're supposed to pay attention to when working with electronics (non-synthetic clothing, wrist straps, anti-static mats, etc)?

I have the clothing and wrist straps, but I don't have a mat yet; probably should find one...

Yesterday I was researching MOSFET-based h-bridge, and one site mentioned something about how MOSFETs are very prone to spontaneous self-destruction due to something or another (gate voltage?), unless you install certain resistors first before installing the MOSFET.

What's the "truth" on this?

I am not arguing against it, but it would be useful to know how/what/why - so if I do some experimentation on my breadboard, I will know this so if I need to install my resistors (well, those particular ones) first before the MOSFET - I will know to do so (and can plan the layout accordingly).

 smiley
4916  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: ATMega328P available at Mouser! on: May 14, 2010, 10:12:08 am
I just checked the stock (right now) - and it is back UP to 9700+ (yesterday when I last checked it, it was around 9100). That's kinda weird, unless someone couldn't take delivery for some reason...

 :-?
4917  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Recording RF signals for later playback... on: May 12, 2010, 01:46:53 pm
I am not absolutely certain (and that universal remote link probably means the rest of this is "wrong"), but from what I read yesterday, it seemed like the "433 MHz" transmitter/receiver combo the TouchTunes jukebox uses isn't a "standard" 433 MHz part; its frequency is "off" by so many KHz that prevents you from using off-the-shelf transmitters/receivers to make such a remote control.

I didn't research it in any great depth, though, and like I said, that universal remote link says something completely different; but then again, the lack of sites and discussion out there about homebrewing such a system (though there are many people asking about it; just no answers) seems to say that to do so will be a difficult proposition.

You might be able to do it if you modded one of those 433 MHz receivers and transmitters to run at the exact frequency of the jukebox (which would require more than a few extra tools most people don't have - frequency counters and signal generators, for instance); then again, maybe I was reading too much into what little I could find, and the frequency is standard...

 smiley

4918  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Recording RF signals for later playback... on: May 11, 2010, 11:15:07 am
Quote
annnnnnnnd i have no idea how to do any of that.  so maybe this wasnt a good place to jump back into the world of arduino

Look at it this way: you are wanting to somehow magically record a device that has a "clock speed" (frequency) approximately 27 times that of the Arduino, which is running at 16 MHz.

This is impossible - research "Nyquist Theorem".

Grumpy_Mike is right; you won't be able to do this with an Arduino (you might not even be able to do it with a standard PC running at 1+ GHz, but you stand a better chance).

Really, what you need to do, is to get access to the transmitter, and get access to the signal train prior to 433 MHz transmitter. Something tells me that the manufacturer of these systems likely made them as difficult to hack as possible (just personal experience with closed media systems like this); you may or may not be able to take a standard 433 MHz receiver and transmitter, and get them to work.

Something else you might try is to contact the manufacturer if they are still around, and see if you can simply buy a transmitter, or if they would be willing to give you some specs or whatnot. Likely the transmitter is expensive, and they are unlikely to give you specs, but it can't hurt to ask; you never know what they will say until you do!

There's also this:

http://www.happcontrols.com/amusement/jukebox/600069001.htm

I suppose that puts a lie to my previous statement about them being difficult to hack - so obviously someone has done it; maybe the information is out there already (ie, maybe somebody has already captured the streams and posted them on an FTP site or something)?

 smiley
4919  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Is the Arduino a microcontroller or not? on: May 09, 2010, 02:14:53 am
Ultimately, when you are talking to someone about the Arduino, are you going to tell them "Yeah, that's my Arduino, its the microcontroller that {your project}", or are you going to say "Yeah, that's my Arduino, its a custom physical computing development board that contains an ATMega8/168/328/1280, along with a Java/Processing-based IDE...blah...blah...blah..." (their eyes glaze while falling over unconscious)?

Me personally, I would be far more likely to say the latter than the former, but that's just my tarded manner; I recognize it in myself (and you have all seen the books I write), and sometimes I can stop it, most of the time I can't. But I do recognize that first utterance is more likely to win you friends (granted, not -many- friends; most people couldn't give a flying crap about micro-controllers and electronics at the level we work with them - but at least you won't have caused them to fall asleep unwantedly).

I won't bore you anymore...

 :o
4920  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Flex cables: solder or adapter? on: May 07, 2010, 04:27:07 pm
If you're talking about some kind of flexible plastic substrate that has "etched" leads to the display, most likely not; they are designed to use a special connector (but I don't know exactly what they are called either). If the pitch isn't too fine, you might be able to use some fine wire and conductive epoxy (applied with a needle?) to bond some wires to the end, but that may or may not work, and would likely be fragile anyhow. Where/who are you buying this LCD from, do you have a link/pic?
Pages: 1 ... 326 327 [328] 329 330 ... 376