Posted 01 January 2004 - 11:19 PM
I'd hate to tell you, but that won't work. To create the current you need to power any type of electromagnet more than an inch, you will need a power supply. Not batteries, a 9V will not create the current you need to pull back anything past a nail. Now even worse is that your creating resistance against the pull with the spring. Therefore your going to need mundo voltage. Probably to do what your talking with lets say a 2 lbs resistance (which is way to low) you'll probably need about 50V with an output of about 100 ohms. These are just estimates and what I can figure in my head. But figure that a 9V puts out 4 ohms, your in trouble. I am a network engineering student and we have to take an ass load of electrical engineering classes. I used these skills I've learned to build a gun I once called stalin. It had a 1500 and a 2k attached to it, and I had two solenoids (not the valves, but rather an electronic item with a lateral pull, exactly what Tex was talking aobut) attached to the firing pins and a 12V power supply that put out 50 ohms. It was just barely enough and this gun weighed almost 50 lbs. Needless to say, I needed huge solenoids and a 12v power supply is massive. I never even hooked the pumps up to the guns. The soleniods pulled and technically it worked, but it was just too heavy. I urge you to prove me wrong, I'd like to see it, but your just not going to be able to draw enough current without weighing the gun down.
Now to help you. If you go with Tex's idea, it's going to take a little more reasources then you know. First off you need to know how many pounds of preasure the solenoid has to pull, then you need to know what kind of actuation time your working with, and then how to build it. Good luck.