:O Mike and others,
My Recirculating Compressed Air Ballast System is a simple do-it-yourself project.
I take the compressor (pump) out of an AUTOMATIC, SELF INFLATING, blood pressure machine, purchased from any discount pharmacy,(around $50.) and install it in my WTC. I wire it to a Sub Tech SES II switch, for on-off control. I use a "Y" connector from the receiver, on the same radio channel, which goes to a servo with a cam, which depresses a modified tire valve.
The silicone tubing from the pump has a "T" connector in the line, inside the WTC. One line of the tubing from the "T" sends air out through a brass tube in the end cap into a rubber bladder in the free flood area to inflate it (and surface). The other side of the "T" connector tubing goes to the servo cam/valve inside the WTC, to release the air from the bladder back into the WTC (and allow diving). Since the same air is thus "Recirculating", new air does not have to be snorkeled, no compressed air tanks are necessary, and no high pressure or hand freezing chemicals need to be replenished.
If you don't have time to wait for an illustrated, detailed article to appear, and need further information quickly, e-mail me with any questions you may have.
RCABS- It's easy to control your own bladder!