Subject:
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Re: digital ins
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 26 Aug 1997 19:26:20 GMT
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Original-From:
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Chuck McManis <cmcmanis@FreeGate#saynotospam#.net>
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Reply-To:
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cmcmanis@freeSTOPSPAMMERSgate.net
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Viewed:
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1222 times
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David.J.Dostal@lawrence.edu wrote:
> Hi all,
> At what voltage on the digital ins does one risk damaging the
> HB?
5.12 volts
> I want to feed an amplified signal to the digital ins on my HB to
> exaggerate
> the response of a photosensor in the 2-3V range of its operation.
> Unfortunately, this means that at the 5V end of its range, the input
> signal
> will be near 10V. Will I fry my HB doing this?
Yes.
> What are the maximum and
> minimum safe voltages for the digital ins?
5.12 volts max, 0 volts minimum
> Resolution and accuracy don't
> matter at these extremum; I just want to know what the circuit can
> physically
> handle.
The correct solution to your problem is to use an op-amp signal
conditioner,
possibly feeding into a schmidt trigger if you need some hysteresis.
(sp?)
You can also rig a zener diode across the input to clip the input to
5volts, be
sure the diode can handle the current from your amplifier stage.
Generally the response of a digital input port to a signal that is no
definitely "on"
(greater than the logic 1 detection threshold) or off (near the ground
state) is
undefined.
--Chuck
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Message is in Reply To:
 | | digital ins
|
| Hi all, At what voltage on the digital ins does one risk damaging the HB? I want to feed an amplified signal to the digital ins on my HB to exaggerate the response of a photosensor in the 2-3V range of its operation. Unfortunately, this means that (...) (27 years ago, 26-Aug-97, to lugnet.robotics.handyboard)
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