Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Using larger diameter silicone tubing means it isn't hard to fully
collapse the tube for a peristaltic pump. And you always use 3 ball
bearing rollers, can't just rub. A geared surplus DC motor or a
stepping motor should work for this.

To maintain pressure you could have a small reservoir tank. Sealed,
with air inside. If you pump until it is half full, you've got 1
atmosphere of pressure. You could even rig up a few photosensors to
control the speed of the motor to regulate pressure.

I was thinking of a pump idea for something else that may work here:

Two one way valves (those little rubber ones you can get from a pet
store for aquariums) rigged to a cavity. One wall of the cavity is a
rubber membrane with a small woofer sealed to it. Not -quite- airtight
so barometric changes don't bottom out the woofer. Experiment with a
signal generator and find the best pumping frequency when it is
pumping fluid.

No idea how scalable that is or if it would provide sufficient
flow/pressure. Maybe the outlet oneway valve could be exposed and it
would spray out of that with sufficient flow (I'm talking about the
ones that look like a flattened baby bottle nipple).

Since the woofer has a back, too, potentially you could make a
doublesided pump. Otherwise all that energy just goes into making your
workshop noisy. Then you could seal the woofer in completely as
barometric changes would make no difference, and rely on slow
diffusion through the cone to keep pressure equalized across the woofer.

There, I just gave away a good idea I probably should have kept to
myself and developed, and offered for sale. :'/

Steve Greenfield