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16  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 30, 2013, 02:28:57 am
That still doesn't really answer whether I will get more force from a solenoid making a long rod into a magnet or just having a small magnet.

For the sake of economy I'd at least like to know the difference before trying both at the same time.
17  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 30, 2013, 01:57:21 am
I just realized it really goes for metal stuff if I pass them into the center of it. So now I'm not sure...

Here the predicament... I believe it want's to sit in the middle of a metal rod when powered on. So if the rod is pretty long and I only allow it to move a centimeter, it is pretty strong. BUT I don't have any magnets that will fit into it so I have no idea of having a small magnet would be stronger or weaker than a large piece of metal.
18  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 30, 2013, 12:56:04 am
Yeah, I've seen that one. I definitely need to use a magnet in place of a slug, mine has almost no pull to metal but plenty to a magnet. Unfortunately there's not a lot of info on the ideal magnet size or position so I might just have to experiment.
19  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 30, 2013, 12:01:38 am
Cost is a huge issue, if I could find a way to use these bobbins that would really be good. I'm going to try to experiment to see what kind of heat is generated from a typical amount of use of a commonly used key. Also, depending on how the mechanics work out I can likely lower the voltage if I can get the power I need.

But before I know that I need to know what the most efficient setup is for the permanent magnet. I assume a magnet going through the center is best. But should I spend more to get longer magnets? Or would that not help? Maybe it would help to some extent? I have no idea, does anyone know about that?
20  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 29, 2013, 11:34:18 pm
I'd rather it sound like a calliope than a piezo buzzer. You can't just throw a buzzer into a flute and expect a flute sound because it's creating vibration.

Regardless I'd like to make an authentic Calliope so even if that were the case, I'm focusing on these solenoids now, thanks.
21  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 29, 2013, 10:28:37 pm
Ok, so I'm trying out my own solenoid. I using a plastic bobbin and 30 gauge magnet wire. I don't really know exactly how much but I think it's 100 to 150 feet. At 12v it seems to be powerful enough to attract or repel a magnet about the same diameter to or away about 1/2 inch but it gets pretty hot awfully fast. Just being on for a moment it's fine but after 10-20 seconds it gets almost too hot to touch and I'm afraid much after that it could melt the bobbin. It would never be on that long but it might be off and on repeatedly a lot for a while. So I'm wondering what I might be able to do about heat.

One idea was to use metal bobbins. The permanent magnets would be normally attracted so I could use the electromagnet to repel them. Then since they are metal I could attach them to a metal frame to sink the heat.

Is there another way to reduce the heat produced?

Also, I'm not sure if I should use a large diameter magnet on the top or bottom or if I should use a small magnet that can pass through the hole. Seems like a smaller magnet would be less attracted/repelled but also closer to the field. I'm not sure if that would be better or worse.
22  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 29, 2013, 02:00:52 pm
That is a good idea but I'm trying to go for the whistly calliope sound. I know they're usually made of metal but I've heard pvc, wood and even paper pipes and they do the trick.
23  Using Arduino / Project Guidance / Re: Lots of cheap solenoids or something similar on: May 29, 2013, 02:27:21 am
I can't find anything cheap enough on eBay (<$2) I was thinking about maybe having cork stoppers pushed against the pipes with springs and at the bottom of that little thing a permanent magnet, then just having a winding of wire to pull it down.

About how much wire does it take to get a reasonable amount of pull? (A few ounces worth maybe)
24  Using Arduino / Project Guidance / Lots of cheap solenoids or something similar on: May 29, 2013, 01:43:26 am
I'm interested in making a small organ but I'd really like to avoid spending a lot. I'm already figuring out how to make the flue pipes from PVC but I can't seem to find a way to control 3 or 4 dozen valves without spending a lot. If possible I'd like to stay under $100 for at least just the solenoids or whatever I end up using. I figure they can be pretty small, even if they aren't strong enough I only need a very tiny amount of movement so I can find some way to give them more leverage.

Is there anywhere to get solenoids very inexpensively, or any other way of controlling valves inexpensively? At this point I'm willing to adapt the design to whatever type of part I end up using.

Thanks
25  Using Arduino / Project Guidance / Re: Blinking light on: May 22, 2013, 11:37:07 pm
Is there any serial communication in your code? Perhaps you should post it.
26  Using Arduino / Project Guidance / Re: Door Entry System on: March 28, 2013, 06:59:51 pm
First off the arduino could control those systems, but not actually facilitate most of them. The camera and intercom would need their own system then maybe you could turn them on and off. The arduino itself will not be able to handle a video or audio feed.

You're gonna want to do this one thing at a time. Figure out how to sound the alarm you want. Figure out how to turn on the camera and monitor, figure out the door lock. Then put it all together once you get all those things figured out. DO NOT worry about the project as a whole until then, there will be way too many things to work out for each part.

The only other advice I have at this point is to look in to an electric door strike rather than electric door lock. This way the door still operates normally but you can let people in if you desire. An electric door lock can either fail and lock you in or fail and let anyone in.
27  Using Arduino / Project Guidance / Re: trust ebay new arduino for beginner? on: March 23, 2013, 05:45:47 pm
If cost is an issue why not buy a legitimate arduino and a bootloaded atmega328 and the few other things needed to take the project off of the arduino when done programming it so that it can be reused? I've made dozens of arduino projects and have only ever owned the one UNO board I started with.
28  Community / Bar Sport / Re: Idiot spammers on: March 20, 2013, 09:43:36 pm
I read that they purposely make them really stupid because they are targeting the truly gullible.
29  Using Arduino / Project Guidance / Re: Beginner - Need help understanding how to wire up the "word clock" on: March 16, 2013, 02:13:02 am
After you're done programming RX and TX dont need to be connected to anything. Reset is connected to 5v (through a resistor if you want to be able to reset). Keeping it pulled up to 5v keeps it from resetting randomly. The numbers of the chip (1-28) do not correspond to the pin numbers in the programming at all. You have to look at one of those diagrams to see which is which. For instance digital IO's #9-13 are chip pins #15-19.

If you uploaded blink, put it on a breadboard and connected the LED to pin 19, then that is the right idea. Make sure reset is pulled up to 5v. If it still doesn't work check your wiring. Go through the standalone tutorial again and check everything.
30  Community / Bar Sport / Re: Water & Sound & 24 Hz sine wave on: March 13, 2013, 10:13:45 pm
Yeah, the trick here is that the frequency matches the frame rate AND the shutter speed it very fast. You'd want to do this in the sun or with lots of light. In person, the water would not look like this. The speaker is only wiggling the hose, the camera gives it the still look.

If you did this with a regular North American camcorder you'd want 30Hz. You can do this with anything, even a ceiling fan would appear to do strange things if you filmed it at a high enough shutter speed.

http://en.wikipedia.org/wiki/Wagon-wheel_effect
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