Subject:
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Re: light sensor multiplexer
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Thu, 22 Mar 2001 22:51:24 GMT
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Viewed:
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1815 times
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hi Nitin,
I'm an energy freak to, but I can't follow your reasoning
Because I'm building a multiplexer too (probably will be posted next week, so I can make still some changes) and I'm using even lower resistor values then Michael (due to a transistor inverter) I'm very interested in your design.
Nitin Patil wrote:
> In lugnet.robotics.rcx, Michael Gasperi writes:
> Ok I agree what you say about time constant of your RC
> But still by using such low resistance you are wasting power. almost 1.5 mA
> is flowing through this 4.7K.
> you can keep RC constant and increase R that should improve performance.
> what I do is I have 5.2V zener in series with 120Kand 10pF this takes
> current of 40MicroAmp.
Using CMOS IC's, feeding it from 7 Volt (NiCd cells), you have to switch the output (for a reliable operation) at least from 7V-1.5V=5.5V downto 1.5V, resulting in a swing of 4 Volt.
Using a zener of 5V2, the maximum swing you get is 1.8 Volt in a totally wrong region.
What am I missing ?
>
> >
> > "Nitin Patil" <gn1721@lycos.com> wrote in message
> > news:GAKC9v.F5A@lugnet.com...
> >
> > > Also what I did not like in your desigh is 4.7K resistor. which changes
> > > reading in measure cycle.
> >
> > With the 0.1uF in parallel with the 4.7K, the voltage on the clock circuit
> > is still above the measurement voltage during the normal read interval. It
> > doesn't effect the reading because the diodes are reverse biased. The 4.7K
> > only comes into play when the power is cut by switching to passive. Then
> > the capacitor is discharged by it down to where it would effect the reading,
> > but your not reading it then.
--
met vriendelijke groet,
Stef Mientki
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Message has 1 Reply:
 | | Re: light sensor multiplexer
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| Hi Stef, sorry for little late. What I am doing is that I need to get the voltahge down and most efficient way of doing that without losing swing ( if you divide you lose swing too) is level shift it and you can do it by putting by Zener. I need (...) (24 years ago, 27-Mar-01, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: light sensor multiplexer
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| In lugnet.robotics.rcx, Michael Gasperi writes: Ok I agree what you say about time constant of your RC But still by using such low resistance you are wasting power. almost 1.5 mA is flowing through this 4.7K. you can keep RC constant and increase R (...) (24 years ago, 22-Mar-01, to lugnet.robotics.rcx)
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