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Ok guys, I'm new to this forum.... I joined specifically for help on a project I'm doing that has to be done by Wed.

Here's the deal.

I'm attempting to create an electromagnet crane. I want the electromagnet to hook directly to the nxt without any extra batteries. I was able to cut the converter wire (you know, the one that attaches to the lamp) in half so I had two wires sticking out one end of the little box thing in the middle. I connected that wire to the nxt, made a simple program with the lamp block, connected the ends of the electro magnet's wire to each wire on the converter wire... and nothing.

Some more details:

-The exact same electromagnet worked when connected to a D sized battery.
-I used some kind of electricity measurer to measure some kind of output from the nxt's converter wire. It read about 15. I have no idea if that's amps or watts or volts or what, but I read that the converter wire outputs 9 volts. So that wire is outputting electricity. I also wondered if that by connecting both ends of the electromagnet wire to the two ends on the converter cable I was somehow short circuiting something. Also, would that output be A/C or D/C. I think that should make a big difference.

So my question is, How do I get a D/C closed circuit current out of the NXT through the converter cable to the electromagnet to enable it to pick up metallic things?

Remember, less than a week to get stuff done, so I can't order any parts. I can also upload some pics if anyone wants.

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EDIT: Ok, as I'm about out of time, I'm just using a battery. I designed a switch for it that works pretty well. Now, my only problem is that I need some way to measure if my crane is picking something up. I currently have the arm attached to a servo motor, and it can swing several degrees. Unfortunately, I can't balance it out enough to be able to tell if something is on it. I also have one sensor port available with which I could attach a touch sensor OR a sound sensor. I may be able to balance it out enough to be able to get the 'boom' to swing down and activate the touch sensor when something is on it.

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Thanks!

Noah Allen

Age: 15

"I repeat: I come in peace, I mean you no harm, you all will die. Gallaxar out."

Hello legostormrobot

You can find very interresting content here:

http://www.bartneck.de/wp-content/uploa ... klaver.pdf
and
http://www.tau.ac.il/~stoledo/lego/Solenoid/

once again, google is your friend... search "solenoid lego nxt robot" for example!

May i give you some advices,
1 - if you measure something, ask someone skilled to help and explain you, you will get better results and understanding of what you're supposed to measure. Ask your science professors, your neightbours, find a hacklab or an electronic supply shop, find a robotic club near you...
2 - never ask when under time pressure, let replies fly their way to you! we don't want to get your time constraints, as we have ours yet!!!

Best regards
Ben

legostormrobot wrote: EDIT: Ok, as I'm about out of time, I'm just using a battery. I designed a switch for it that works pretty well. Now, my only problem is that I need some way to measure if my crane is picking something up. I currently have the arm attached to a servo motor, and it can swing several degrees. Unfortunately, I can't balance it out enough to be able to tell if something is on it. I also have one sensor port available with which I could attach a touch sensor OR a sound sensor. I may be able to balance it out enough to be able to get the 'boom' to swing down and activate the touch sensor when something is on it.

One idea to detect when the magnet is attached... Have the arm resting on a touch sensor, and balanced so the touch sensor is NOT pressed. When the magnet picks something up, it should press the touch sensor.

Steve

pbenco wrote: 2 - never ask when under time pressure, let replies fly their way to you! we don't want to get your time constraints, as we have ours yet!!!

Thanks for the tips! I was able to figure out a lot of what I need to know i/e that 15 whatever it was was actually 15 v a/c whereas it is actually 9.5 v d/c.

hassenplug wrote: Have the arm resting on a touch sensor, and balanced so the touch sensor is NOT pressed. When the magnet picks something up, it should press the touch sensor.

Yeah, one of my ideas, actually! (great minds think alike, right?) I actually currently have it set up balanced enough on a servo motor that it can detect by means of the rotation sensor if something is attatched (it will only work for heavy(er) weights, nothing small.)

Thanks for the input!