Advice
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I am hooking up a Hal effect sensor to a motor to
monitor the rpm's.
What I am getting is a square wave that is 13 volts as
expected but I am also getting a
1 volt sine wave ontop of the square. Will the stamp
see this and affect my counting??
Should I run this signal though a opamp to clean it
up??
And will the stamp be able to handle the 13 volt
pulse??
Thanks
Gene
monitor the rpm's.
What I am getting is a square wave that is 13 volts as
expected but I am also getting a
1 volt sine wave ontop of the square. Will the stamp
see this and affect my counting??
Should I run this signal though a opamp to clean it
up??
And will the stamp be able to handle the 13 volt
pulse??
Thanks
Gene
Comments
Not sure, but doubt that the Stamp will handle the 13 volt signal and suggest
you limit input to stamp to its supply voltage. Also suggest you square up
the signal from Hall effect sensor with opamp configured as Schmidt trigger
to get rid of any noise on signal and then use diodes tied to ground and plus
supply at the input to Stamp and 10K ohm resistor between op amp output and
Stamp. This will limit the voltage excursion to Stamp to supply plus 0.6
volts and ground minus 0.6 volts.
Good Luck, Burt
amps...
Original Message
From: <burtsz@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, February 12, 2001 11:20 PM
Subject: Re: [noparse][[/noparse]basicstamps] Advice
> Hi Gene,
> Not sure, but doubt that the Stamp will handle the 13
volt signal and suggest
> you limit input to stamp to its supply voltage. Also
suggest you square up
> the signal from Hall effect sensor with opamp
configured as Schmidt trigger
> to get rid of any noise on signal and then use diodes
tied to ground and plus
> supply at the input to Stamp and 10K ohm resistor
between op amp output and
> Stamp. This will limit the voltage excursion to
Stamp to supply plus 0.6
> volts and ground minus 0.6 volts.
> Good Luck, Burt
>
>
>
>
To: basicstamps@yahoogroups.com
Date: Tue, 13 Feb 2001 00:20:12 EST
>Not sure, but doubt that the Stamp will handle the 13 volt signal and suggest
>you limit input to stamp to its supply voltage. Also suggest you square up
>the signal from Hall effect sensor with opamp configured as Schmidt trigger
>to get rid of any noise on signal and then use diodes tied to ground and plus
>supply at the input to Stamp and 10K ohm resistor between op amp output and
>Stamp. This will limit the voltage excursion to Stamp to supply plus 0.6
>volts and ground minus 0.6 volts.
This looks like the answer to a question that I've been asking myself about how
to safely use 12-14V or so as a trigger for a PIC. My initial thoughts were on
the lines of a zener diode or an optoisolater.
I can't quite see how one would connect the two diodes in the scheme that
you've outlined though?
--
Regards, Derryck
/ The Cheshunt Computer Club /
/ The essential for your Atari /
/ Monthly meetings /
/ http://www.cix.co.uk/~derryck /
>monitor the rpm's.
>
>What I am getting is a square wave that is 13 volts as
>expected but I am also getting a
>1 volt sine wave ontop of the square. Will the stamp
>see this and affect my counting??
The 1 volt sine wave will have no effect on the Stamp, because it is
well above the Stamp switching threshold. A voltage divider (22k/10k
or 22k/4.7 volt zener) could bring the 13 volts safely down to the 5
volt level of the Stamp.
>
>Should I run this signal though a opamp to clean it
>up??
The CD4050 is a CMOS chip that does bring a signal from the higher
voltage (13 volts) down to 5 volts, and clean it up in the process.
Another alternative, could you run the hall effect sensor off of a 5
volt supply instead of off the 12v battery? The op-amp would be
overkill and still requires extra parts.
>
>And will the stamp be able to handle the 13 volt
>pulse??
see above,
-- good luck
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
with no problems, Where are you getting your power and is it filtered
real good or not, you may look at running off the stamp's 5vdc supply
Tracy Allen wrote:
>
> >I am hooking up a Hal effect sensor to a motor to
> >monitor the rpm's.
> >
> >What I am getting is a square wave that is 13 volts as
> >expected but I am also getting a
> >1 volt sine wave ontop of the square. Will the stamp
> >see this and affect my counting??
>
> The 1 volt sine wave will have no effect on the Stamp, because it is
> well above the Stamp switching threshold. A voltage divider (22k/10k
> or 22k/4.7 volt zener) could bring the 13 volts safely down to the 5
> volt level of the Stamp.
>
> >
> >Should I run this signal though a opamp to clean it
> >up??
>
> The CD4050 is a CMOS chip that does bring a signal from the higher
> voltage (13 volts) down to 5 volts, and clean it up in the process.
> Another alternative, could you run the hall effect sensor off of a 5
> volt supply instead of off the 12v battery? The op-amp would be
> overkill and still requires extra parts.
>
> >
> >And will the stamp be able to handle the 13 volt
> >pulse??
>
> see above,
>
> -- good luck
> Tracy Allen
> electronically monitored ecosystems
> http://www.emesystems.com
pulse is looking better.
I will try it up to the stamp now.
Still have the 1 volt riding on top of the square wave,
this won't be a problem?
Original Message
From: "L .Gaminde" <lgaminde@t...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, February 13, 2001 10:35 AM
Subject: Re: [noparse][[/noparse]basicstamps] Advice
> I have used the hall effect sensor with 5 vdc and 15
feet from the stamp
> with no problems, Where are you getting your power
and is it filtered
> real good or not, you may look at running off the
stamp's 5vdc supply
>
> Tracy Allen wrote:
> >
> > >I am hooking up a Hal effect sensor to a motor to
> > >monitor the rpm's.
> > >
> > >What I am getting is a square wave that is 13
volts as
> > >expected but I am also getting a
> > >1 volt sine wave ontop of the square. Will the
stamp
> > >see this and affect my counting??
> >
> > The 1 volt sine wave will have no effect on the
Stamp, because it is
> > well above the Stamp switching threshold. A
voltage divider (22k/10k
> > or 22k/4.7 volt zener) could bring the 13 volts
safely down to the 5
> > volt level of the Stamp.
> >
> > >
> > >Should I run this signal though a opamp to clean
it
> > >up??
> >
> > The CD4050 is a CMOS chip that does bring a signal
from the higher
> > voltage (13 volts) down to 5 volts, and clean it up
in the process.
> > Another alternative, could you run the hall effect
sensor off of a 5
> > volt supply instead of off the 12v battery? The
op-amp would be
> > overkill and still requires extra parts.
> >
> > >
> > >And will the stamp be able to handle the 13 volt
> > >pulse??
> >
> > see above,
> >
> > -- good luck
> > Tracy Allen
> > electronically monitored ecosystems
> > http://www.emesystems.com
>
>
>
>pulse is looking better.
>I will try it up to the stamp now.
>Still have the 1 volt riding on top of the square wave,
>this won't be a problem?
>> I have used the hall effect sensor with 5 vdc
>> and 15 feet from the stamp with no problems,
>> Where are you getting your power and is it
>> filtered real good or not, you may look at
>> running off the stamp's 5vdc supply
The 1 volt sine wave is probably pickup from nearby wiring. Is the
sine wave at 60hz, or some other frequency? If the hall effect
switch has a pullup resistor, you could reduce the pickup by lowering
the resistor value, say, from 10k down to 1k. To minimize pickup,
use a shielded cable, even so far as to include the sensor inside the
shield.
That said, the 1 volt sine wave on top of the 5 volt square wave
should not be a problem. It would be above the switching threshold
of the Stamp, which is at 1.4 volts.
-- Tracy