How can I build a better pulsed pressure generator?

Joerg · 2013-09-18T20:17:29+00:00

Folks, I need to generate pressure pulses of 3-4psi above ambient, frequency around 1Hz, more or less arbitrary waveform with frequency components up to 40Hz in there (but those are less than 2psi) and delivered via short hose. Currently just air pressure. I got this (sort of) running with a compressor but after a while my ears fall off from all that noise. Can't really place the compressor outside here. So then I tried various speakers. They don't move enough air around. When I pushed one of them a bit harder a few minutes ago its flexible surround rubber burst, that thin stuff doesn't hold much pressure. In other words I need something similar to an arbitrary function generator but where the output is air pressure. What I want to avoid is hacking a motor, removing a valve and using the piston. Any other ideas? Can one buy something like that at less than 4-digit prices? -- Regards, Joerg

Sep 18, 2013 161 Replies

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What is the inside diameter of the output hose? If it is 1/4 inch - 3/8 inch, an airtight box with two 15" Eminence musical instrument speakers facing inward would work. There is enough resistance in the output hose to have the speakers operating into a fairly ridgid air cushion as JF suggests. These are thick paper cones with a corrugated compliant surround - not rubber - but reinforced corrugated paper. I am pretty sure they could take the strain. Since they are readily available from MCM Electronics in Dayton OH, and at a reasonable cost, this might just fit the bill. I have no affiliation with MCM electronics, except I have bought many speakers from them and haven't been disappointed yet.

-Tom