Too much time, not enough pressure
Friday, November 13, 2009
[Audin] got a hold of a pressure gauge and decided to turn it into a clock. We were under the impression that these types of gauges were filled with oil but he didn’t detail cleaning it up for his purposes. Once he gained access to the guts he replaced them with a stepper motor. The motor connects to an Arduino with the help of a Darlington array for handling the large load. [Audin's] plans include using a real time clock (on order) and moving to an AVR ATmega8 microprocessor once the prototyping is finished. In the mean time, he has posted the code used in his current prototype.
Stay with us past the page break for some video of this in action. He’s got the needle dialed in for very precise movement and has coded a “jitter” effect as well. We’re not sure this would be the most convenient clock, but we’d love to affix it to our kitchen stove for a gnarly looking timer. [Audin] acquired the gauge at his local Habitat for Humanity ReStore, a place we’ve used many times to source reclaimed and unused items of all kinds for our projects.
5 komentar:
As far as them being oil filled… a few are. Extreme duty gauges are to dampen vibrations. The cheaper ones that I’ve taken apart just have a curled copper tube that straightens out slightly and turns a gear as the pressure goes up.
Would’ve been cooler to drive it using actual pressure (electronic valve connected to an air cylinder?)
Like Happosai, I would have liked to have seen it use air pressure. It would have taken a lot more work to set one up to use air. You’d have the air supply, 2 pressure transducers (one for the air tube and one for the atmosphere), and the controller. This is kind of cool, though, if you’re into this kind of thing.
This gauge didn’t have any oil in it. It was simply a piece of sealed, coiled copper tube which
expanded slightly when pressurized. The small movement of the end of the coil was amplified by a gear arrangement. Sadly I appear to not have taken any pictures of the original innards. :(
I figured the stepper was acceptable to get the project moving along.
When I run into another gauge I might try animating it with steam. A small electric boiler and two solenoid valves. If nothing else it would make neat sounds….hhhhiiiiiiiisssssssss. But it wouldn’t be something you could leave running for extended periods. One question I have on this though is what sort of pressure ranges these gauges run over. There isn’t a unit printed on the face of this one. So I’ve no idea how much pressure ‘60′ would imply.
I like the idea of a kitchen timer. You could do a completely analog one. A button to pressurize the gauge and then a controlled release of pressure (i suppose that would be the hard part) would cause it to count down. You could use co2 cartridges for the pressure supply.
Really nice looking work, will be nice to see how it progresses without the arduino. Why bother with air though? Surely it would make more sense to leave it hydraulic it your not going to go the stepper motor route – much more accurate.
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