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In lugnet.technic, Mark Tarrabain wrote:
> 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.
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% outputs. If 50% is on, you'll need to gate off the 25% output. If 25% is
not on, then you know you have no power, giving you four levels.
Kevin
>
> > > Mark (a man whose visions far outstrip his budget)
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Message has 1 Reply:
 | | Re: EGAD! (pneumatics)
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| (...) I was thinking that one could just use an ADC to directly convert the analog voltage level to a digital number of however many bits you could resolve it to and then taking that binary number to address a demux and have the demux's outputs (...) (21 years ago, 16-Jun-03, to lugnet.technic, lugnet.robotics)
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Message is in Reply To:
| | Re: EGAD! (pneumatics)
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| (...) 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 (...) (21 years ago, 15-Jun-03, to lugnet.technic, lugnet.robotics)
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