But as R. Baer wrote, inquiring minds would like to know...just what sort of load are you wanting to put these pulses through, and what amplitude current versus time are you wanting to achieve?
For example: you could want to pulse the current in an LED to a hundred milliamps and a very few volts for a millisecond, or you could want to pulse the current in an EG&G high speed flash lamp at ten amps for a microsecond. Or you could want something completely different. I believe you mentioned an inductive load in another posting. Note that V = L di/dt: that is, if the inductance starts with zero current, it may take some time to reach the peak current you want. Adding in the inevitable resistance of the wire in the inductive coil just slows things down further. This is the sort of thing that should be designed, not just guessed at, to achieve early success.
I guess I would be good if I actually explained what I was trying to do. :)
At the very basic level what I want is sort of compact electric motor that gives me oscillatory linear motion and can run on a small bank of batteries for about an hour. What I need is about 3mm of travel, a frequency of that is tunable from about 50-200 Hz (just about any waveform will do), and "decent" force. I can't tell you how much force I need yet because I don't know for sure, but to give you a qualitative description I would say that the force needs to be enough that you couldn't stop the machine with your hand and maybe if you put a pin on the end of the oscillating shaft then the force should probably be enough to repeated puncture heavy card stock paper. I don't know if that's a useful description or not. Sorry I don't have more specific information, but I'm just starting this project and I'm trying to assess my options before I go about trying to put anything together.
The simplest idea would just be to use a DC motor and convert the rotary motion to linear motion with a cam or whatever. I still wanted to look at other options, so I started to think about linear motors and also just using an electromagnet to vibrate a spring loaded shaft (i.e. by repeatedly pushing it away). I don't know anything about linear motors and not a whole lot about electromagnets either, but given that I want the battery pack to be both small (a 2 or 3 cubic inches max) and last for a long time (and note be too expensive) I'm guessing I wouldn't have a lot of current to work with. So anyways, I was trying to think about ways to maximize the force I got out of that setup.
Quite possibly I don't know what the heck I am talking about. I'm just brainstorming here. If you have any ideas I'd love to hear them, but at this point I don't have anymore information to give you.
Did any of you guys see what the OP said about force? At first, I was thinking a big voice coil from a salvaged subwoofer, but he said it pushes hard enough that you can't push it back with hand pressure, didn't he?
For that kind of force, I'd think I'd start looking at motor/cam arrangements, or washing machine solenoids.
On a sunny day (Fri, 24 Nov 2006 19:46:54 GMT) it happened Rich Grise wrote in :
if you open the floppy drive you will see the head move from track to track. I uses a worm drive in my floppy, no way can you stop it. So the mechanism is already there. I estimate 80 tracks in about 3 cm, so 3 mm = 8 tracks = 8 step pulses. The max speed is limited.... a different worm with a different stepper, or even perhaps more power in the flop stepper could help. Steppers are great, I have seen these move big camera setups in movie industry. To a fraction of a millimeter :-)
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.