PICKGUN-. a solenoid type

[yono]

i made this out of curiousity, to try if i can make one, and will it work? and yes it does work.the solenoid came from an old Betamax. I made a power supply of 12 volts DC 3Amp max. the pick stroke can be controlled by a N.O. switch. now i am figuring out for its handle. please see pic.
http://i302.photobucket.com/albums/nn11 ... 9-Copy.jpg

[TheSkyer]

Looks like it would work, just give it a shot

[michaelspaz]

NICE DIY! I'm not extremely familiar with electronics so I was wondering why you would use a DC current with the solenoid? Isn't the back and forth motion in a solenoid caused by an induced magnetic field using AC current as the wire tries to reduce the flux? Maybe this is a stupid question...

[cryptocat]

You're probably thinking of a motor like what's inside a hair clipper - it can take advantage of AC to move the armature. You can achieve much the same effect if you use a spring to return the components to their original position, rather than the opposite polarity of electricity. Sorry... sleepy and not very coherent.

[yono]

for my knowledge DC is more stable and available especially when you are out in the field. you can get direct power source from a car battery. you can prevent the unneccessary motion of the solenoid by installing a diode across the solenoid two terminals, and bear in mind install the diode opposite to your power supply polarity.

[michaelspaz]

You're probably thinking of a motor like what's inside a hair clipper - it can take advantage of AC to move the armature. You can achieve much the same effect if you use a spring to return the components to their original position, rather than the opposite polarity of electricity. Sorry... sleepy and not very coherent.

Yeah, I was thinking more along those lines, you're right Cyrptocat. So what is the function of the solenoid in this if not to cause displacement of the pick?

[cryptocat]

The solenoid causes movement in one direction, but you'll need something to cause the mechanism to recycle. That could either be reverse polarity (AC supply) or an interruption of current followed by spring force (DC supply).

A trivial example is to connect a normally-closed relay to itself: power is applied, coil energizes, opens relay, kills power, spring pulls contacts closed, power is available again... this happens fairly quickly; the last time I did such a thing, I ended up building a 40Hz buzzer.

[michaelspaz]

Interesting, I would assume this would be analogous to a charged capacitor acting like an open circuit? What sort of lifetime would you expect for the springs with them being in continuous motion at 40Hz?

[maintenanceguy]

A micro switch located where it would be opened when the solenoid plunger was retracted could drop power to the solenoid.

The plunger would retract, the switch would open causing the plunger to pop out again, the plunger would retract, and on and on and on. Weight of plunger and force of spring would control the cycle time.

And to answer michaelspaz's question about the spring, as long as the spring isn't being flexed beyond it's fatigue limit, it should last forever without any damage. Nothing lasts forever but moving at 40Hz won't damage it.

[adrenalynn]

I use small DC solenoids in my robotics hobby all the time. I haven't seen any fail in millions of cycles. I don't think I've run them _that_ fast, but certainly half that.