Reciprocal motion transducer needed

[JMarkWolf]

I need to economically exercise a solid state accelerometer (the Freescale MMA2260), in the lab while writing software for reading and analyzing the data. I would like to "shake" it, on axis, at two frequencies, 8Hz and 43Hz nominally (520rpm and 2600rpm respectively).

The mass of the accelerometer board is just an ounce or two.

I don't need much stroke, perhaps 1/4", at the frequencies indicated above.

So far, I am considering

A) mechanically converting rotary motion to reciprocal motion, as in a jigsaw mechanism, or

B) some sort of voice coil actuator (possibly a large speaker), which presumably could be driven directly with a DC amplifier.

I have electronic expertise but little to no mechanical expertise in this area.

Can anyone on the forum suggest a potential economical solution?

 

[MikeHalloran]

Mount it to the tip of a hacksaw blade.

Clamp the other end of the blade, e.g. in a vise.

Mount a relay's electromagnet close to the clamped end of the blade, e.g. to the vise's jaw.

Pulse the electromagnet or drive it with a sine wave.

Slide the blade into the vise until it resonates near the frequency you want.



Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

The speaker idea is good. 1/4 inch throw is no problem, but I think you'll find that is an awful lot of acceleration at 43 Hz. 40g or so. So I doubt you'll be able to drive it.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[IRstuff]

47.3 g's at 43 Hz, 1.6 g's at 8 Hz

However, since the accelerometer has full-scale of 1.5 g, the maximum amplitude required for 43 Hz is only 0.0079 inches. And the max amplitude for 1.5 g at 8 Hz is only 0.23 inches

TTFN