Current sensing
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Posts: 46,084
I have an application for a BSII where I need to sense the current of
an automotive (13.8v) lamp. My thought was to somehow measure current
across a know resistance (1ohm 1% 20W). Using a 16-keypad, I also
would like to have the option to calibrate the whole apparatus when
the lightbulb is not powered up and use this 'zero' factor into the
current measurement. Any suggestions on hardware and code? Thanks in
advance. Dan
an automotive (13.8v) lamp. My thought was to somehow measure current
across a know resistance (1ohm 1% 20W). Using a 16-keypad, I also
would like to have the option to calibrate the whole apparatus when
the lightbulb is not powered up and use this 'zero' factor into the
current measurement. Any suggestions on hardware and code? Thanks in
advance. Dan
Comments
If you can ground the resistor and directly read its voltage with respect
to ground, there would be no need for zeroing. www.rentron.com has a neat
setup for this in his data logging section. He uses an ADC0831 A/D
converter controlled by a Stamp talking to a PC with a slick readout window.
A 1 ohm resistor would read up to 5 amps... however, it would also drop 5
volts of your available supply. Don't know if this is the approach you had
in mind.
Good luck,
Ray McArthur
> I have an application for a BSII where I need to sense the current of
> an automotive (13.8v) lamp. My thought was to somehow measure
current
> across a know resistance (1ohm 1% 20W). Using a 16-keypad, I also
> would like to have the option to calibrate the whole apparatus when
> the lightbulb is not powered up and use this 'zero' factor into the
> current measurement. Any suggestions on hardware and code? Thanks
in
> advance. Dan
If you need a circuit that simply senses current on or off (in other words,
you are not trying to measure continuously variable current), use a reed
switch and magnet wire. The nice feature of using this simple method is the
detection circuitry is completely isolated from the circuit you are sensing.
For example, if you want to detect 2 amps, and you are using a reed switch
(like Newark #50F7984) that has a pull-in rating of 10-25 amp-turns, you
will need about (25 amp-turns/2 amps = 12.5 turns) 13 turns of wire around
the reed switch.
Jim
>
> From: Daniel D Dangremond
> Reply To: basicstamps@egroups.com
> Sent: Thursday, June 22, 2000 2:58 pm
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Current sensing
>
> I have an application for a BSII where I need to sense the current of
>
> an automotive (13.8v) lamp. My thought was to somehow measure
> current
> across a know resistance (1ohm 1% 20W). Using a 16-keypad, I also
> would like to have the option to calibrate the whole apparatus when
> the lightbulb is not powered up and use this 'zero' factor into the
> current measurement. Any suggestions on hardware and code? Thanks
> in
> advance. Dan
>
>
>
>
>
on several lamps on an automotive wire harness and verifing that the
amp draw is within spec. for each lamp. As each lamp is turned on,
current is measured and compared to the spec. The amp draw is
obviously increased as each lamp is turned on. Each lamp cannot be
measured seperately as the wire harness is terminated in one location
using two wires(ie. xmas lights). There will be much more that is
inputed and outputed (lcd, keypad, leds, etc.) but the current draw is
the problem I am looking for assistance.
Thanks for the input Ray and Jim, Dan
I have an application for a BSII where I need to sense the current of
an automotive (13.8v) lamp. My thought was to somehow measure current
across a know resistance (1ohm 1% 20W). Using a 16-keypad, I also
would like to have the option to calibrate the whole apparatus when
the lightbulb is not powered up and use this 'zero' factor into the
current measurement. Any suggestions on hardware and code? Thanks in
advance. Dan
>> From: Daniel D Dangremond <daniel.d.dangremond@j...>
Hi Dan, I recall seeing several integrated circuits made with
high side current sense resistors on chip.
I don't have the specific part numbers handy but I would look at
-National Semiconductor
-Linear Technology
-Maxim
-Analog Devices
for parts [noparse][[/noparse]in that order...] in their special function chips.
To use an op amp of moderate common mode capability:
A way to build this up with discrete parts is simply a
differential amplifier with high common mode rejection
and fixed gain feeding an A/D converter the BSII can
talk to. In your original post you mentioned a 10 watt
resistor for current sense - ordinarily you'd use a lower
value of resistor to not dissipate this power...
Say you put a 1 ohm resistor in series with the high side of
your loads; then from _each_ side of the 1 ohm resistor put a
pair of series resistors to low side [noparse][[/noparse]ground "-" etc.]. Make
the two resistor series pairs identical - say 9,000 ohms in
series with 1,000 ohms - now you have 1/10 the 1 ohm resistor
voltage across the high sides of the two 1000 ohm resistors,
referenced to low side. You can put a couple of bypass capacitors
across the 1000 ohm resistors to kill spikes -
Now the common mode voltage is reduced to 1/10 of the high
side voltage. Then you put your differentially connected op
amp across the two 9K/1K voltage divider resistors' junctions
and adjust it to amplify appropriately to scale it's output into
the A/D converter. [noparse][[/noparse]note the two 9K/1K pairs must be matched
or use a pot to adjust for zero voltage when zero current].
I hope this is in the right direction... ask if not...
________________________________________________________________
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in series with the battery. Note the reading with what you have to have on
in order to turn on the lamps you want. Turn on the lamps anyway you desire
and measure the current. Subtract the prior base reading and VOLA!! the
desired current.
At 04:53 PM 6/23/00 -0500, you wrote:
> To add more detail to my application: I will be checking the current
> on several lamps on an automotive wire harness and verifing that the
> amp draw is within spec. for each lamp. As each lamp is turned on,
> current is measured and compared to the spec. The amp draw is
> obviously increased as each lamp is turned on. Each lamp cannot be
> measured seperately as the wire harness is terminated in one location
> using two wires(ie. xmas lights). There will be much more that is
> inputed and outputed (lcd, keypad, leds, etc.) but the current draw is
> the problem I am looking for assistance.
> Thanks for the input Ray and Jim, Dan
>
>
>
> Duhhhh why does this problem sound so simple to me? A calibrated, ampmeter
> in series with the battery. Note the reading with what you have to have on
> in order to turn on the lamps you want. Turn on the lamps anyway you desire
> and measure the current. Subtract the prior base reading and VOLA!! the
> desired current.
>
One thing to keep in mind though, just after turning on a light, current
will be very high until inrush current subsides. Thus multiple samples
would need to be made and averaged, otherwise a reading taken just after a
single lamp is activated could look like several lights are activated.
Just my .02,
Dale Harwood [noparse][[/noparse] N4VFF ]
internet> dale@h...
ax.25> n4vff@n4vff.#cha.tn.usa.noam
#include <std_disclaimer.h>
water supply. A Sprinkler system flow switch let the controller know
when the flow dropped below 10 G.P.M. on a 1 inch pipe. The pump would
shut down to allow the well to recover. An initial time delay allowed
start up of the pump with out flow.
I sure a stamp could handle the task.
Paul
Ok, I'm not very smart. What I really need is current sensing, not voltage
sensing as I asked earlier. I have searched and called Fairchild and I can't
see any similar device to the HCPL-3700 that reads current. Any suggextions
as to how to let a Stamp know when current is flowing?
Jonathan
www.madlabs.info
Original Message
From: "Sean T. Lamont .lost." <lamont@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 20, 2003 1:14 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Basic Stamp and DMX
>
> No, that's not what I'm saying. There are devices for driving DMX systems
> with midi control, which would be an alternative to doing conversion from
> serial to DMX.
>
> On Sat, 18 Jan 2003, selket_10027 <selket_10027@y...> wrote:
>
> > No you can't. Just because they use the same plug doesn't mean that
> > the protocols are the same. Midi is 31k baud and DMX is 250k baud.
> > the stamp can go up to 125k baud.
> >
> > --- In basicstamps@yahoogroups.com, "Sean T. Lamont .lost."
> > <lamont@a...> wrote:
> > >
> > > Can't you do MIDI->DMX? You can *certainly* drive midi from a
> > stamp, I do
> > > it all the time.
> > >
> > > On Fri, 17 Jan 2003, selket_10027 <selket_10027@y...> wrote:
> > >
> > > > Short answer: no
> > > >
> > > > DMX is an extention of RS-485 serial protocol that is run
> > > > asynchonously over a 5 pin XLR cable. It also runs at 250kBPS
> > which
> > > > I believe is faster than is possible with Basic Stamp SEROUT
> > > > command. If you could speed it up, then there is no reason why
> > not.
> > > > There might be a way to use some kind of external serial driver.
> > > >
> > > > They also sell dumb DMX controlers that are programed via RS232.
> > You
> > > > could definatly use the stamp to control the box which in turn
> > > > controls the dimmers. These things cost ~$200 which, for stage
> > > > lighting is damn cheap -- compare to a dimmer. So if you can
> > spend a
> > > > little money and just want a stamp to control lights then you're
> > all
> > > > set. If you were trying to use the stamp to avoid shelling out
> > $200
> > > > for such a box, then you're SOL.
> > > >
> > > > -selket
> > > >
> > > > --- In basicstamps@yahoogroups.com, "richeybrooksiii
> > <richey@c...>"
> > > > <richey@c...> wrote:
> > > > > does anyone know if you can send a dimmerpack (for stage
> > lighting)
> > > > a
> > > > > DMX single from a stamp?
> > > > >
> > > > > Thanks
> > > > > Richey
> > > >
> > > >
> > > > To UNSUBSCRIBE, just send mail to:
> > > > basicstamps-unsubscribe@yahoogroups.com
> > > > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > > >
> > >
> > > Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc.
> > (ServNet)
> > > Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma -
> > Bremerton
> > > email: lamont@a... WWW: http://www.serv.net
> > > "Do not fear mistakes, There Are None" - Miles Davis
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
>
> Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc. (ServNet)
> Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma - Bremerton
> email: lamont@a... WWW: http://www.serv.net
> "Do not fear mistakes, There Are None" - Miles Davis
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
just look up transformer and look for current then you can
read current with an ADC chip.
Original Message
From: "Jonathan Peakall" <jpeakall@m...>
To: <basicstamps@yahoogroups.com>
Sent: January 20, 2003 1:38 PM
Subject: [noparse][[/noparse]basicstamps] Current sensing
: Hi All,
:
: Ok, I'm not very smart. What I really need is current
sensing, not voltage
: sensing as I asked earlier. I have searched and called
Fairchild and I can't
: see any similar device to the HCPL-3700 that reads
current. Any suggextions
: as to how to let a Stamp know when current is flowing?
:
: Jonathan
:
: www.madlabs.info
:
:
:
Original Message
: From: "Sean T. Lamont .lost." <lamont@a...>
: To: <basicstamps@yahoogroups.com>
: Sent: Monday, January 20, 2003 1:14 PM
: Subject: Re: [noparse][[/noparse]basicstamps] Re: Basic Stamp and DMX
:
:
: >
: > No, that's not what I'm saying. There are devices for
driving DMX systems
: > with midi control, which would be an alternative to
doing conversion from
: > serial to DMX.
: >
: > On Sat, 18 Jan 2003, selket_10027
<selket_10027@y...> wrote:
: >
: > > No you can't. Just because they use the same plug
doesn't mean that
: > > the protocols are the same. Midi is 31k baud and DMX
is 250k baud.
: > > the stamp can go up to 125k baud.
: > >
: > > --- In basicstamps@yahoogroups.com, "Sean T. Lamont
.lost."
: > > <lamont@a...> wrote:
: > > >
: > > > Can't you do MIDI->DMX? You can *certainly* drive
midi from a
: > > stamp, I do
: > > > it all the time.
: > > >
: > > > On Fri, 17 Jan 2003, selket_10027
<selket_10027@y...> wrote:
: > > >
: > > > > Short answer: no
: > > > >
: > > > > DMX is an extention of RS-485 serial protocol that
is run
: > > > > asynchonously over a 5 pin XLR cable. It also
runs at 250kBPS
: > > which
: > > > > I believe is faster than is possible with Basic
Stamp SEROUT
: > > > > command. If you could speed it up, then there is
no reason why
: > > not.
: > > > > There might be a way to use some kind of external
serial driver.
: > > > >
: > > > > They also sell dumb DMX controlers that are
programed via RS232.
: > > You
: > > > > could definatly use the stamp to control the box
which in turn
: > > > > controls the dimmers. These things cost ~$200
which, for stage
: > > > > lighting is damn cheap -- compare to a dimmer. So
if you can
: > > spend a
: > > > > little money and just want a stamp to control
lights then you're
: > > all
: > > > > set. If you were trying to use the stamp to avoid
shelling out
: > > $200
: > > > > for such a box, then you're SOL.
: > > > >
: > > > > -selket
: > > > >
: > > > > --- In basicstamps@yahoogroups.com,
"richeybrooksiii
: > > <richey@c...>"
: > > > > <richey@c...> wrote:
: > > > > > does anyone know if you can send a dimmerpack
(for stage
: > > lighting)
: > > > > a
: > > > > > DMX single from a stamp?
: > > > > >
: > > > > > Thanks
: > > > > > Richey
: > > > >
: > > > >
: > > > > To UNSUBSCRIBE, just send mail to:
: > > > > basicstamps-unsubscribe@yahoogroups.com
: > > > > from the same email address that you subscribed.
Text in the
: > > Subject and Body of the message will be ignored.
: > > > >
: > > > >
: > > > > Your use of Yahoo! Groups is subject to
: > > http://docs.yahoo.com/info/terms/
: > > > >
: > > > >
: > > > >
: > > >
: > > > Sean T. Lamont, CTO / Chief NetNerd, Abstract
Software, Inc.
: > > (ServNet)
: > > > Seattle - Bellingham - Vancouver - Portland -
Everett - Tacoma -
: > > Bremerton
: > > > email: lamont@a... WWW:
http://www.serv.net
: > > > "Do not fear mistakes, There Are None" -
Miles Davis
: > >
: > >
: > > To UNSUBSCRIBE, just send mail to:
: > > basicstamps-unsubscribe@yahoogroups.com
: > > from the same email address that you subscribed. Text
in the Subject
: and Body of the message will be ignored.
: > >
: > >
: > > Your use of Yahoo! Groups is subject to
: http://docs.yahoo.com/info/terms/
: > >
: > >
: > >
: >
: > Sean T. Lamont, CTO / Chief NetNerd, Abstract Software,
Inc. (ServNet)
: > Seattle - Bellingham - Vancouver - Portland - Everett -
Tacoma - Bremerton
: > email: lamont@a... WWW:
http://www.serv.net
: > "Do not fear mistakes, There Are None" - Miles
Davis
: >
: >
: > To UNSUBSCRIBE, just send mail to:
: > basicstamps-unsubscribe@yahoogroups.com
: > from the same email address that you subscribed. Text
in the Subject and
: Body of the message will be ignored.
: >
: >
: > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
: >
: >
: >
: >
:
:
: To UNSUBSCRIBE, just send mail to:
: basicstamps-unsubscribe@yahoogroups.com
: from the same email address that you subscribed. Text in
the Subject and Body of the message will be ignored.
:
:
: Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
:
:
>Hi All,
>
>Ok, I'm not very smart. What I really need is current sensing, not voltage
>sensing as I asked earlier. I have searched and called Fairchild and I can't
>see any similar device to the HCPL-3700 that reads current. Any suggextions
>as to how to let a Stamp know when current is flowing?
Need some parameters.
Min current to sense.
Max current the circuit has to survive.
AC or DC
operating voltage
Maximum allowable burden voltage (drop across sensing element).
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
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Digikey sells a line of their sensors. They have built-in signal
conditiners. AC current flow will give you an AC output voltage
proportional to the current flow. A DC current will give you a DC
voltage proportional to the current flow. They work with AC/DC
current and have a freq responce of 100kHz I believe. Kind of
expensive but they work and are easy to use. I'm using 2 of these
right now sensing if a vac pump is being turned on by a SSR and then
is turned off. Basicly testing the SSR to see if it sticks on(which
it has in the past).
I have an op amp with a gain of 11 to amplify the AC current signal
out of the LEM sensor and then run that to a compairator to turn on
when it reaches a certain voltage. To generate a constant 5 volt
logic, I am using a 73HC123 one shot to trigger on the pulses out of
the compaitator. The oneshot is set to 20 ms. This way I don't have
to use a A/D convertor on an AC signal(SAMPLE RATE ISSUE) and it
still tells me when the vac pump is on or off with 1 I/O pin.
Jason
--- In basicstamps@yahoogroups.com, "Jonathan Peakall"
<jpeakall@m...> wrote:
> Hi All,
>
> Ok, I'm not very smart. What I really need is current sensing, not
voltage
> sensing as I asked earlier. I have searched and called Fairchild
and I can't
> see any similar device to the HCPL-3700 that reads current. Any
suggextions
> as to how to let a Stamp know when current is flowing?
>
> Jonathan
>
> www.madlabs.info
>
>
>
Original Message
> From: "Sean T. Lamont .lost." <lamont@a...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, January 20, 2003 1:14 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Re: Basic Stamp and DMX
>
>
> >
> > No, that's not what I'm saying. There are devices for driving DMX
systems
> > with midi control, which would be an alternative to doing
conversion from
> > serial to DMX.
> >
> > On Sat, 18 Jan 2003, selket_10027 <selket_10027@y...> wrote:
> >
> > > No you can't. Just because they use the same plug doesn't mean
that
> > > the protocols are the same. Midi is 31k baud and DMX is 250k
baud.
> > > the stamp can go up to 125k baud.
> > >
> > > --- In basicstamps@yahoogroups.com, "Sean T. Lamont .lost."
> > > <lamont@a...> wrote:
> > > >
> > > > Can't you do MIDI->DMX? You can *certainly* drive midi from a
> > > stamp, I do
> > > > it all the time.
> > > >
> > > > On Fri, 17 Jan 2003, selket_10027 <selket_10027@y...> wrote:
> > > >
> > > > > Short answer: no
> > > > >
> > > > > DMX is an extention of RS-485 serial protocol that is run
> > > > > asynchonously over a 5 pin XLR cable. It also runs at
250kBPS
> > > which
> > > > > I believe is faster than is possible with Basic Stamp SEROUT
> > > > > command. If you could speed it up, then there is no reason
why
> > > not.
> > > > > There might be a way to use some kind of external serial
driver.
> > > > >
> > > > > They also sell dumb DMX controlers that are programed via
RS232.
> > > You
> > > > > could definatly use the stamp to control the box which in
turn
> > > > > controls the dimmers. These things cost ~$200 which, for
stage
> > > > > lighting is damn cheap -- compare to a dimmer. So if you
can
> > > spend a
> > > > > little money and just want a stamp to control lights then
you're
> > > all
> > > > > set. If you were trying to use the stamp to avoid shelling
out
> > > $200
> > > > > for such a box, then you're SOL.
> > > > >
> > > > > -selket
> > > > >
> > > > > --- In basicstamps@yahoogroups.com, "richeybrooksiii
> > > <richey@c...>"
> > > > > <richey@c...> wrote:
> > > > > > does anyone know if you can send a dimmerpack (for stage
> > > lighting)
> > > > > a
> > > > > > DMX single from a stamp?
> > > > > >
> > > > > > Thanks
> > > > > > Richey
> > > > >
> > > > >
> > > > > To UNSUBSCRIBE, just send mail to:
> > > > > basicstamps-unsubscribe@yahoogroups.com
> > > > > from the same email address that you subscribed. Text in
the
> > > Subject and Body of the message will be ignored.
> > > > >
> > > > >
> > > > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > > > >
> > > > >
> > > > >
> > > >
> > > > Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc.
> > > (ServNet)
> > > > Seattle - Bellingham - Vancouver - Portland - Everett -
Tacoma -
> > > Bremerton
> > > > email: lamont@a... WWW: http://www.serv.net
> > > > "Do not fear mistakes, There Are None" - Miles Davis
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the
Subject
> and Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> >
> > Sean T. Lamont, CTO / Chief NetNerd, Abstract Software, Inc.
(ServNet)
> > Seattle - Bellingham - Vancouver - Portland - Everett - Tacoma -
Bremerton
> > email: lamont@a... WWW: http://www.serv.net
> > "Do not fear mistakes, There Are None" - Miles Davis
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
Well, what I want to do is have the Stamp know when the heater of my
aquarium is operating. It draws less than 5 amps, minimum draw would be
fine at 2A+. All I want is knowledge of on or off, I don't need to know how
much current is being drawn. The heater is AC, and of course I want a 5V
output.
Thanks for the input!
Jonathan
www.madlabs.info
Original Message
From: "Dwayne Reid" <dwayner@p...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 20, 2003 1:49 PM
Subject: Re: [noparse][[/noparse]basicstamps] Current sensing
> At 01:38 PM 1/20/03 -0800, Jonathan Peakall wrote:
> >Hi All,
> >
> >Ok, I'm not very smart. What I really need is current sensing, not
voltage
> >sensing as I asked earlier. I have searched and called Fairchild and I
can't
> >see any similar device to the HCPL-3700 that reads current. Any
suggextions
> >as to how to let a Stamp know when current is flowing?
>
> Need some parameters.
>
> Min current to sense.
> Max current the circuit has to survive.
> AC or DC
> operating voltage
> Maximum allowable burden voltage (drop across sensing element).
>
> dwayne
>
> --
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
> Celebrating 18 years of Engineering Innovation (1984 - 2002)
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summer connected to the stamp. You also need a temp probe in the
water. If your boiler stops working, the temp drops under a limit
and the stamp send a low signal to the summer as an alarm.
--- In basicstamps@yahoogroups.com, "Jonathan Peakall"
<jpeakall@m...> wrote:
> Dwayne,
>
> Well, what I want to do is have the Stamp know when the heater of
my
> aquarium is operating. It draws less than 5 amps, minimum draw
would be
> fine at 2A+. All I want is knowledge of on or off, I don't need to
know how
> much current is being drawn. The heater is AC, and of course I
want a 5V
> output.
>
> Thanks for the input!
>
> Jonathan
>
> www.madlabs.info
>
>
>
Original Message
> From: "Dwayne Reid" <dwayner@p...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, January 20, 2003 1:49 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Current sensing
>
>
> > At 01:38 PM 1/20/03 -0800, Jonathan Peakall wrote:
> > >Hi All,
> > >
> > >Ok, I'm not very smart. What I really need is current sensing,
not
> voltage
> > >sensing as I asked earlier. I have searched and called
Fairchild and I
> can't
> > >see any similar device to the HCPL-3700 that reads current. Any
> suggextions
> > >as to how to let a Stamp know when current is flowing?
> >
> > Need some parameters.
> >
> > Min current to sense.
> > Max current the circuit has to survive.
> > AC or DC
> > operating voltage
> > Maximum allowable burden voltage (drop across sensing element).
> >
> > dwayne
> >
> > --
> > Dwayne Reid <dwayner@p...>
> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> > (780) 489-3199 voice (780) 487-6397 fax
> >
> > Celebrating 18 years of Engineering Innovation (1984 - 2002)
> > .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> > `-' `-' `-' `-' `-' `-' `-' `-' `-'
> > Do NOT send unsolicited commercial email to this email address.
> > This message neither grants consent to receive unsolicited
> > commercial email nor is intended to solicit commercial email.
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
keeping them warm [noparse]:)[/noparse] ?
If you put a 1 ohm resistor (I'd use a 10 watt resistor if the heater draws
2 amps) in series with the heater, you will get 2 volts across it when the
heater is running (at 2 amps). You could then drive an optoisolator from
this voltage (using a series resistor). The output of the optoisolator
could then drive the PIC. You will have to play with component values somewhat.
Larry
At 04:38 PM 1/20/2003 -0800, you wrote:
>Dwayne,
>
>Well, what I want to do is have the Stamp know when the heater of my
>aquarium is operating. It draws less than 5 amps, minimum draw would be
>fine at 2A+. All I want is knowledge of on or off, I don't need to know how
>much current is being drawn. The heater is AC, and of course I want a 5V
>output.
>
>Thanks for the input!
>
>Jonathan
>
>www.madlabs.info
>
>
>
Original Message
>From: "Dwayne Reid" <dwayner@p...>
>To: <basicstamps@yahoogroups.com>
>Sent: Monday, January 20, 2003 1:49 PM
>Subject: Re: [noparse][[/noparse]basicstamps] Current sensing
>
>
> > At 01:38 PM 1/20/03 -0800, Jonathan Peakall wrote:
> > >Hi All,
> > >
> > >Ok, I'm not very smart. What I really need is current sensing, not
>voltage
> > >sensing as I asked earlier. I have searched and called Fairchild and I
>can't
> > >see any similar device to the HCPL-3700 that reads current. Any
>suggextions
> > >as to how to let a Stamp know when current is flowing?
> >
> > Need some parameters.
> >
> > Min current to sense.
> > Max current the circuit has to survive.
> > AC or DC
> > operating voltage
> > Maximum allowable burden voltage (drop across sensing element).
> >
> > dwayne
> >
> > --
> > Dwayne Reid <dwayner@p...>
> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> > (780) 489-3199 voice (780) 487-6397 fax
> >
> > Celebrating 18 years of Engineering Innovation (1984 - 2002)
> > .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> > `-' `-' `-' `-' `-' `-' `-' `-' `-'
> > Do NOT send unsolicited commercial email to this email address.
> > This message neither grants consent to receive unsolicited
> > commercial email nor is intended to solicit commercial email.
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
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>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Larry Bradley
Orleans (Ottawa), Ontario, CANADA
Yes, it is a 110VAC heater. And fish stew is NOT the object ;-)
I like it. Good idea. And much simpler and cheaper than anything else so
far. Unless there is a mircale IC out there, I bet I go this way.
Thanks for the help!
Jonathan
www.madlabs.info
Original Message
From: "Larry Bradley" <lhbradley@i...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, January 20, 2003 5:40 PM
Subject: Re: [noparse][[/noparse]basicstamps] Current sensing
> I presume this is a 110 volt heater - are you boiling the fish, or just
> keeping them warm [noparse]:)[/noparse] ?
>
> If you put a 1 ohm resistor (I'd use a 10 watt resistor if the heater
draws
> 2 amps) in series with the heater, you will get 2 volts across it when the
> heater is running (at 2 amps). You could then drive an optoisolator from
> this voltage (using a series resistor). The output of the optoisolator
> could then drive the PIC. You will have to play with component values
somewhat.
>
> Larry
>
>
> At 04:38 PM 1/20/2003 -0800, you wrote:
> >Dwayne,
> >
> >Well, what I want to do is have the Stamp know when the heater of my
> >aquarium is operating. It draws less than 5 amps, minimum draw would be
> >fine at 2A+. All I want is knowledge of on or off, I don't need to know
how
> >much current is being drawn. The heater is AC, and of course I want a 5V
> >output.
> >
> >Thanks for the input!
> >
> >Jonathan
> >
> >www.madlabs.info
> >
> >
> >
Original Message
> >From: "Dwayne Reid" <dwayner@p...>
> >To: <basicstamps@yahoogroups.com>
> >Sent: Monday, January 20, 2003 1:49 PM
> >Subject: Re: [noparse][[/noparse]basicstamps] Current sensing
> >
> >
> > > At 01:38 PM 1/20/03 -0800, Jonathan Peakall wrote:
> > > >Hi All,
> > > >
> > > >Ok, I'm not very smart. What I really need is current sensing, not
> >voltage
> > > >sensing as I asked earlier. I have searched and called Fairchild and
I
> >can't
> > > >see any similar device to the HCPL-3700 that reads current. Any
> >suggextions
> > > >as to how to let a Stamp know when current is flowing?
> > >
> > > Need some parameters.
> > >
> > > Min current to sense.
> > > Max current the circuit has to survive.
> > > AC or DC
> > > operating voltage
> > > Maximum allowable burden voltage (drop across sensing element).
> > >
> > > dwayne
> > >
> > > --
> > > Dwayne Reid <dwayner@p...>
> > > Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> > > (780) 489-3199 voice (780) 487-6397 fax
> > >
> > > Celebrating 18 years of Engineering Innovation (1984 - 2002)
> > > .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> > > `-' `-' `-' `-' `-' `-' `-' `-' `-'
> > > Do NOT send unsolicited commercial email to this email address.
> > > This message neither grants consent to receive unsolicited
> > > commercial email nor is intended to solicit commercial email.
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > basicstamps-unsubscribe@yahoogroups.com
> > > from the same email address that you subscribed. Text in the Subject
and
> >Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
> >
> >
> >To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> >from the same email address that you subscribed. Text in the Subject and
> >Body of the message will be ignored.
> >
> >
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>
> Larry Bradley
> Orleans (Ottawa), Ontario, CANADA
>
>
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>