PDA

View Full Version : Need help on what components to buy



OlofE
05-05-2006, 11:49 AM
Hi all,

I'm going to try to do a rather simple project.

What I want is a physical representation of a numerical value that I calculate on my computer.

I have two ideas on how to show this number. It can either be just a little piece of string with a marker that an electric motor moves between itself and a little wheel. This doesn't need a strong motor at all, of course.

The other idea is that (and this is stupid, but that's why I like it) I'll use the blinds in my office. I'll have the blinds go up or down depending on this numerical value. This will of course require a stronger motor, but I have not concept of how strong it would have to be in any type of measure that I can tell you. It needs to lift maybe 10 pounds after all is said and done but I can use gears.

Whether I go with the string or the blinds, they won't have to move fast. If it takes a minute to move a few inches or a foot then that's fine.

Those are the two options I have. The string or the blinds.

The problem I have is that I don't even know what components to buy and what components that work together. My requirement is that it has to be USB and programmable from Windows. Also, it is more important that the project is easy to complete than that the components are cheap.

Thanks in advance for any help.

Olof Edlund

OlofE
05-05-2006, 11:53 AM
Oh, one more thing. Currently I'm only looking at controlling one motor, but if things work well I will want to control a total of 3 motors.

Jonathan
05-06-2006, 08:29 PM
Olof,

I'm not going to ask why you want to display a number with string or blinds, and assume that you know there are many easier ways of displaying a number. Of course, if you want to tell me, I'm curious. However, I'm into odd displays myself, like Nixie tubes, projection displays and the like.

Bottom line is it sounds as if you need to control a couple of motors, and you are going to need directional control. Look up "H-bridges", you will find many that you can make or buy. H-Bridges make it possible for the Stamp to control a motor, and select direction.

However, you might want to look into stepper motors. These are motors that move in "steps" hence the name. It is much easier to move a controlled amount with this motor type. If you get a Unipolar stepper, you can easily drive it with a ULN2003 and the basic Stamp.

You say you need to use USB. Either get a Board of Education with USB, or buy the FTDI USB to Serial adapter that Parallax sells.

OK, I give in, I have to ask: What the heck are you going to display with blinds??!!

Jonathan

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.madlabs.info (http://www.madlabs.info) - Home of the Hydrogen Fuel Cell Robot

OlofE
05-06-2006, 10:52 PM
I work for a hedge fund company and I'd like to display the daily movement of that fund. And potentially some other key numbers if I have more than one motor/display/gauge available.

I then saw the ambient dashboard device (http://www.ambientdevices.com/cat/dashboard/index.html) and that looked pretty cool. I could show three numbers but they can't seem to get an API out for it.

So, anyway, when I had seen that I realized that it would be cool to have some sort of analog representation of one or many numbers.

So I went about trying to find a way to look at analog representations and I found lego mindstorms nxt which looked kind of cool but its not out yet. The old version is out, but the newer isn't. And then I realised that all I needed from the lego mindstorms kit was the ability to control one or more motors from a computer. And if I bought them separately they would surely have better quality.

It doesn't really have to be a string and blinds, that was just the best thing I could think of that was both achievable by me and impressive in its dorkiness to the people that would step into my office. The "novelty" part is just bonus, and the blinds take the cake in that department with the ideas I've had so far.

If you have other suggestions on how to show a number outside a computer I'd be happy to hear your suggestions. It must be possible to display in a lit room, and it can't be distractive, yet it should give information at a glance. I'm ok with pushing a button for the information to be shown (and then it can be dancing clowns that sing the number, it just can't be on all the time if it is distractive).

I have also tried to find USB controlled LCD displays. Not quite as impressive, but it would also be a whole lot easier. In this category I found this thing (http://www.engadget.com/2006/01/31/the-optimus-mini-three-sees-release/) but it isn't released yet. And even if it was I'm not completely in love with that thing. Three screens that act as buttons? Weird.

But back to lego mindstorms. There is one more thing that lego mindstorms has that I need. Components that work together, and to me that sounds very attractive. Hence my question on this board. Maybe stuff is so standardized that I can just pick any controller and any motor pretty much. I don't mind if the things are a bit pricey either. I'm just building one of these things.

I'm not a complete novice to electronic stuff but I'm woefully rusty and I never did stepper motors. But I'm a battle scarred software engineer, so as soon as I've got something hooked up to the computer I'll be ok.

And finally, a stupid question, what is a stamp? I see the word a lot, but I haven't figured out what it means yet.

Many thanks.

A.C. fishing
05-07-2006, 12:31 AM
don't worry. A stamp is a Basic Stamp 2, (BS2)which is a very fine microcontroller which you can program with a very easy launguage called PBASIC.
What about a BOE USB? (This is a circuit that holds the BS2) and a BS2, and a servo. A servo is a bit like a slow motor that works with the stamp. The servo will pull in amounts of string which is attached to the blinds, according to a math problem or number put into the debug box. The components are relatively cheap and easy. You might have a bigger problem with programming, especially if you are new to the language. It won't be hard.
-AC

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔



Somebody said...
-Never Underestimate the power of human stupidity.



A.C. fishing
05-07-2006, 12:32 AM
"All parallax parts work together, so there is not need for mindstorms.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔



Somebody said...
-Never Underestimate the power of human stupidity.



OlofE
05-07-2006, 12:39 AM
Thanks for your answer. I'm happy to hear that Parallax stuff is picked or built to work together.

But your statement about PBasic concerns me a bit. I need to use C++ or C# (or Java or any other general purpose language but C++ or C# is preferred) as I'm going to fetch the number I'm going to display from a webservice.

So my plan was to build a windows service to run in the background that once every five minutes calls the web service to get the number and then will give commands to the stepper motor through USB to move to represent this number.

A.C. fishing
05-07-2006, 07:10 PM
Yes. You can use the C++ to get the numbers off the web, and send them down a serial cable to the stamp, and depending on what the number is, the stamp tells the servo pulls in string for a certain amount of time. I think what you want to do can be done.
If you want to use stepper motors, I have never used them before. I will try this with a servo and see if it works.
-AC

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔



Somebody said...
-Never Underestimate the power of human stupidity.



OlofE
05-07-2006, 09:18 PM
A.C,

What is the difference between a servo and a stepper motor? If a servo is better for my purposes then I'd use that. I thought a stepper motor was what I needed because when I was reading about servos they were talking about 180 or 360 degrees and I need it to spin not only 360 degrees.

A.C. fishing
05-08-2006, 02:42 AM
I servo can spin as many times as you need.(Like they power the wheels of a Boe-Bot) The servo is best choice because of this and because it is cheap, and doesn't need anything more then a BS2.
The stepper motor is a bit more expensive, and you need one of these to control it:
http://www.parallax.com/detail.asp?product_id=27938
It is better if you want to be very precise about what you are doing.
I would suggest using a servo.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔



Somebody said...
-Never Underestimate the power of human stupidity.



OlofE
05-08-2006, 05:00 AM
Thanks! Sounds like what I need is a servo then, especially if they are more precise.

Are there any advantages with a stepper motor? Are they stronger maybe?

allanlane5
05-08-2006, 05:15 AM
A "modified Servo" makes a really good 'wheel' for a robot. But the modification removes the exact positioning. For exact positioning, of multiple rotations, a stepper motor probably is best.

Kevin Wood
05-08-2006, 10:33 AM
You might want to check out the downloadable "What's a Microcontroller" manual from the Parallax site. It's a good starting point.

Also, a good kit to start with is the Basic Stamp Activity Kit, aka the "Summer Special" and "RadioShack WAM Kit."

The Summer Special includes a HomeWork board, which has an embedded stamp, and the What's a Microcontroller course kit. It's a great bargain @ ~ $80usd.

Here is a link to the Summer Special, and there is a download link at the bottom of the page for the WAM manual.

www.parallax.com/detail.asp?product_id=90005 (http://www.parallax.com/detail.asp?product_id=90005)