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c s soh wrote:
> Mark Tarrabain wrote:
>
> > The only thing I think I'd be left wishing for here would be some sort
> > of electrically controllable form of pneumatic switch -- but not just a
> > simple solenoid valve, rather a mechanism whereby multiple such valves
> > could actually be individually controlled by a single motor output from
> > an RCX (although it would probably require two motor outputs... one for
> > power and another for addressing).
>
>
>
> Is this what you're looking for?
> A 3/8 RCX Output Multiplexer for the FT solenoid valves:
> http://www.ozbricks.net/cssoh1/cpedia/ftmulti.htm
>
> Btw, the circuit diagram is a piece of art from France :-)
Close. What I would actually be wanting is eomthing that could use the
voltage level being output from a *SINGLE* RCX port to do the
addressing. So for controlling up to four devices from one port, for
example, would require that 25% power to the port control the first
device, 50% the second, 75% the third, and 100% the fourth, and the
direction of the current flow would determine whether I was wanting the
addressed device to be flipped one way or the other. The devices would
be such that when no control signals were being applied at all, they
would retain their last set state (this may require a constant available
power supply to the devices themselves, but I'm okay with that). By
dividing up the RCX motor voltages into even smaller divisions, I'm
betting that you could probably control a dozen or more such devices.
To my understanding, the RCX uses pulse width modulation to actually
control motor speed, so I'm thinking the first thing you'd need is a
capacitor to even out an RCX output to a level voltage, then an ADC to
convert that into a digital signal, and a demux to take that digital
signal to address any one of several individual devices. I don't own
the appropriate hardware to try this idea out though. If I did, I'd
probably just do it myself and if it worked, I'd just announce it.
>> Mark (a man whose visions far outstrip his budget)
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Message has 3 Replies:
 | | Re: EGAD! (pneumatics)
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| (...) You are doing well Mark. You can use three voltage comparators to detect which voltage level is being output. What you need is three comparators. One for 25%, then 50%, and 75%. If 75% is on, then you'll need to gate off the 25% and 50% (...) (21 years ago, 15-Jun-03, to lugnet.technic, lugnet.robotics)
| | | Re: EGAD! (pneumatics)
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| (...) IMHO, it would be much simpler and precise to measure directly pulse width instead of voltage, that could be done easily with a small microcontroller... Philo www.philohome.com (21 years ago, 16-Jun-03, to lugnet.technic, lugnet.robotics)
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