New reply from Spike Spencer
<p>Too many variants from suppliers of that type of switch. As you have already done the research, can you define the actuating pressure range that you ended up with ?</p>
Original Post by paulbenn
Sip & Puff unit
We made a simple sip and puff unit that could work alongside the normal Liberty controller. There’s an article attached from Variohm, the company that kindly supplied the pressure switches at know cost.
The pressure switches can only handle a few milliamps so they drive 12 volt relays that can handle the higher current draw of the sheet motors.
We use the system to run the jib sheet servo but there’s no reason why it couldn’t drive the main or even steering (although I think steering would require an awful lot of blowing and sucking which would get pretty tiring).
Contact me if you want to build this and need assistance, I can help you in find components and connectors etc.
If you go it alone I must just share one major learning: Mk 1 was built in a watertight box…. which was also air-tight. Atmospheric pressure changes kept operating the system! You need a small vent hole in the box to allow for atmospheric highs and lows.
There’s a press release from Variohm attached that give the basis idea.