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balsaboom said:
balsaboom said:The coil 200ft of 30 gauge magnet wire. the outer diameter of the pipe is .8 inches, so the circumference is 2.512in. 200 x 12 is 2400 inches, which makes for 955 total turns.
I'm not sure what you mean by a ferrous shaft? The slug is slightly smaller than the innerdiameter of the pipe, and it weighs 38.69 grams
NascentOxygen said:I reckon you'll need as much voltage and current as you can get without the enamel on the coil getting so hot that it starts to smoke, and then you will probably find that's still not enough! (Just my thoughts. )
The more voltage and current, the stronger the field. When testing, leave the battery connected only momentarily so the coil doesn't have time to get hot.
Over how much distance do you want to lift the metal slug?
rp55 said:if the ferrous inner material was magnetic it would push it either way depending on direction of turns, no? I've also seen an MIT instructor online "throw" the inner piece (which would normally be sucked in the middle of the inductor coil) out the other side like a bullet. I'm still a bit lost on practical understanding of solenoids myself... But to push outward is very every day practical and dc voltage can be reversed to have it extend or contract. Must be the placement or magnetism of the inner piece.
berkeman said:It might help for a little while, but what happens to the magnetic armature as the coil is energized and de-energized (especially if you reverse the direction of the current)...?
rp55 said:Well EMF of course at the instant the voltage stops before reversing. How does that manifest itself in the non-electromagnetic armature case?
berkeman said:The coil turning on and off (or reversing) has an effect on the permanent magnet. Can you guess what that effect might be?
rp55 said:ha I'm still staring at this from wikipedia on solenoids and trying to figure it out:
"The force applied to the armature is proportional to the change in inductance of the coil with respect to the change in position of the armature, and the current flowing through the coil (see Faraday's law of induction). The force applied to the armature will always move the armature in a direction that increases the coil's inductance."
um...well if it was a permanent magnet armature (which has bound current)... hmmm. I'm not sure.
berkeman said:Hint -- "degauss"
rp55 said:New to me (besides hearing about it per crts). I guess after reading this:
"The term was first used by (then) Cmdr Charles F. Goodeve, RCNVR, during World War II while trying to counter the German magnetic mines that were playing havoc with the British fleet. The mines detected the increase in magnetic field when the steel in a ship concentrated the Earth's magnetic field over it. "
... I'm not sure why the mines wouldn't detect eddy currents. Perhaps to do that would be too "obvious". I'm just tossing around buzz words here without understanding things.
I get it's a magnetic "bias" (I'm thinking dc bias) but not sure how it affects the solenoid situation?
And here I had no intention of learning anything today and you ruined it!
berkeman said:Sorry about that!
Here you go: http://www.adamsmagnetic.com/blogs/...t-magnets-to-lose-strength-or-to-demagnetize/
rp55 said:So basically perm mags lose their strength (per the link). So are you simply saying that rather than using perm mags that's why ferrous materials which become temp magnetized by the solenoid "stator??" are used instead? I guess I"m not seeing the degaussing piece in that link. Perhaps I don't have enough foundation yet on induction (that is for sure).
berkeman said:My reference to degaussing was just about how varying magnetic fields can demagnetize permanent magnets. And yes, I think the variability due to demagnetization is the reason that permanent magnets are not usually used as solenoid stators.
balsaboom said:i got the idea from this video: http://www.youtube.com/watch?v=sR3xmof8rZY#t=360 (already timestamped)
So youre saying that attaching magnets to it would eventually demagnetize the magnets; how fast would that happen usually?
The strength of your battery can be determined by its voltage. Most solenoids require a battery with at least 12 volts to function properly. You can also consult the solenoid's instruction manual for specific voltage requirements.
No, it is important to use the type of battery recommended for your specific solenoid. Using a different type of battery can affect the performance and potentially damage the solenoid.
If your battery does not have enough voltage to power the solenoid, it may not function at all or may not have enough strength to activate the solenoid. It is important to use a battery with the correct voltage to ensure proper function.
Yes, you can connect multiple batteries in series to increase the voltage and power of your homemade solenoid. Be sure to connect them correctly and use batteries with the same voltage.
The lifespan of your battery will depend on several factors such as the voltage and power of the battery, the strength of the solenoid, and how often it is used. It is important to monitor the battery's voltage and replace it as needed to ensure continued function of the solenoid.