Hi. I'm searching for an actuator or some kind of motor, that has only two positions. What I'm looking for is a very small device, that allow me to release a very small compressed spring when a small current is applied. (kind a circuit breaker, or something like a relay). It has to be small, and cheap. I don't know how this devices are called (i believed they are "actuators"), therefore I cannot google it, , so I'm asking here.

Do you know anything like that? how expensive they are?

thank you very much

You might try searching for "solenoid," they have plenty at electronics goldmine surplus, inlcuding a pinball mechanism, if I recall, which seems similar to what you've described.

I'm kind of in the same boat as you right now, I think, with an application I'm working on. I should warn you to save you the trouble I went through that using solenoids require more current than, for instance, a DC motor would for equivalent power output. For that reason, I'm considering using a gearmotor instead and just converting the rotary power to linear to suit my mechanical needs. With a gear ratio that's fast enough for your application, but high enough to hold in the two positions you've described, it might be an option worth considering. Take a look at the recent thread I started about the tamiya motors in this part of the forum to get an idea of what I'm thinking about.

If this doesn't suit you, is there anything more you can tell me about your application?

Thank you Hank.

Have you seen those ballpoint pen that have a mechanism for retracting the tip?

http://en.wikipedia.org/wiki/Image:Ballpoint-pen-parts.jpg

That's exactly the kind of action I'm looking for, the only difference is that I want to release the spring using a small current: The user of the device push down a key/switch (smaller, lighter, than a keyboard key). The swicth compress an spring and get stucked by some mechanism. When I want to release the switch, I make a small current run through something and voila, the spring releases and the switch go back to normal position.
Because I want to have a lot of this, in an small area, I want it to be cheap, simple, and if possible, with low consumption.

Thank you very much

What you've described seems identical to power locks on a car. Is that right, but you want them on a scale about the size of pen instead?

How many do you need?
How fast do they need to switch from one position to the other?
What's your budget?
Does it matter how loud it is, that is, can it be as clicky as a pen?

How about this doodad?
http://www.solarbotics.com/products/gm10/
It looks like it presses forward, and then returns with spring. You could modify the actual mechanism from a cheap pen to serve your purpose, and use this thing to tap the end to switch positions? Looks like you'd just have to put power to it briefly when tapping the pen, and it wouldn't be using any power when idle.

Just had another thought that's kind of related to your interest. Recently I was fixing some trumpets, and the pistons on trumpets are returned to their open position with springs. The problem with these trumpets is that the springs had somehow become more stiff, I think with age and oxidization, so the pistons were harder to press down, and returned to open quite fiercely and with a bit of a clunk.

If you find that the springs in your pens are the same way too hard to compress, you might try tinkering with them a little bit. It should only take a very light spring to return a pen mechanism, and no doubt many of them are sold with tighter springs than need be. Just something you might consider when you're shopping around in the stationary shop for pen options. A lighter spring will mean less of a power/tprque requirement from your motor, allowing it to be smaller and/or more efficient.

Tinker with the spring in your pens. Lol.

pretty amazing mini actuators , many applications and RC hookup
http://www.robotshop.ca/home/product...-298-06-I.html

Hey guys, I'm all new here to this great looking forum.

I have been doing research for my crawler project, thought you all might like these.
they come in many configurations



good luck to you

Ri

try Firgelli or servo city

Old cell phones (or pagers) might yield a solution, those that have the ability to vibrate when a call is received. This is achieved by the use of an small electric motor that may be suitable for miniature robotics applications.

You should look into muscle wire. It's a wire that contracts when a current passes through it, and then can be stretched back with a spring (or another piece of muscle wire pulling the other way like a see-saw) You can get spools of it. Check out the inchworm robot on youtube.