How to Reduce the Electromagnetic Field

Your Million Thanks are appreciated.

Now come the Million questions.

First; What are you trying to do?

I have bought a electrical staple.

But my real purpose is to modify it, using its mechanical power to drive something rather than firing staple.

My assignment is to create something like a "hammer piling equipment model" or a "pinball shooting arm".

Electrical staple is quite a nice available equipment for me to modify, but even the most handy one, the power is still so large for me to finish my assignment

Solenoids are quite interesting and complex. You would do well to study the basics of solenoids and you will know better what to do. You are on the right track, perhaps 150 or so volts will do the job.

Here is one link : http://www.magnet-schultzamerica.com/

Anyway, most of us are trying to increase the pull of a solenoid per a given size and amount of power. You seem to want to reduce it .. may i ask why ?

Is is possible/practical to increase the mass of the armature?

Put a series variable resistor for a start and adjust it. later you can modify the apparatus.

You mean this way can modify the appartus?

The AC power supply is fixed and stable, and the resistance of solenoid is constant.

Does it work?

The solenoid is inductive when the armature is out and very highly inductive when it is in (minimal air path for the magnetic flux). So, the actual current drawn is high in the beginning and low at the end of the armature travel. The voltage dropped across the rheostat will therefore be high in the beginning and low in the end, resulting in more low voltage to the coil at start and high at the end.

If you want to feed a constant voltage, i would suggest a "variac" type trafo.

My electrical staple consume 1800W at the time of firing (switch on) and zero at rest (as it will be switched off after firing). Now I want to reduce the power to 400-500W (1/4 of original value)

What is the capacity of rheostat should I choose (ohm, power etc)?

Thanks

Pin connection of rheostat.

For 3 "leg" rheostat, is the middle leg for earth connection while the others for live and neutral?

Sorry youngken. what you need is a single-shot solenoid.

Here is a google search link : http://www.google.co.in/#hl=en&source=hp&q=electron+gun&aq=f&aqi=g10&aql=&oq=&gs_rfai=&fp=cfc9211123dfe02f

The rheostat might work

The centre connection is for the "wiper" connection IE the variable connection. The other two are for each end of the resistance track. Earth is provided by the metal housing that the spindle passes through.

It is likely way more complex than that unfortunately. The solenoid will have a "knee" voltage at which it will either work or not work. I doubt you can effectively reduce the strength without actually changing the mass of the armature or the number of windings, or both. If solenoid strength manipulation were that easy, coil mfrs would simply make one coil and use a dropping resistor for every different application.