Measuring DC Amps.
Archiver
Posts: 46,084
I saw on the basic stamp nots on how to measure DC volts.
Just wondering if anyone has any resources on measuring DC amps ? I've
tried looking on google but cant find any info (saw a lot of voltage
measurements), I dun mind adding a few more compoenents to the stamp, but
just want to keep costs down.
I've to test some items that are 14-15v, and will range from 0 to 10amps+
(No i dun need to use the clamps)
Thanks in advance..
Elvin
-
Just wondering if anyone has any resources on measuring DC amps ? I've
tried looking on google but cant find any info (saw a lot of voltage
measurements), I dun mind adding a few more compoenents to the stamp, but
just want to keep costs down.
I've to test some items that are 14-15v, and will range from 0 to 10amps+
(No i dun need to use the clamps)
Thanks in advance..
Elvin
-
Comments
v Idc
| |
| +
to ADC Analog In
| |
| /
| \ Rs
| /
| |
+
+
to ADC GND
Rs shunt resistor according to current and compliance voltage,
eg. 1R00 for 1V/1A, or 0R1 for 1V/10A.
Regards
Adrian
places that sell shunt resistors. A shunt resistor is calibraged to
give a 50 or 100 mV drop across it at the maximum rated current. For
example, 50 mV= 500 Amps. They can be used on dc or ac, and usually are
designed to be temperature insensitive. If 50 mV is too little for the
A2D, then a small op amp amplifying the output of the shunt is
appropriate. I've done this on several projects and it works well. The
idea is to have the resistor small enough so that it doesn't interfere
with the circuit (or get hot), and yet large enough to have a Voltage
drop that is measureable<G>.
Original Message
From: Adrian Schneider <adrian.schneider@t...>
[noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=sOz8PZEx7SBB0lSaRnWMSFrctF55MeO204OslQR3_rQHgSfw4QLPDsjbme7I9567JWu0gbMyDDrs5KrZ4a_KHTmXDhoAKAIwgA]adrian.schneider@t...[/url
Sent: Thursday, February 27, 2003 5:26 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
What about the following circuit:
v Idc
| |
| +
to ADC Analog In
| |
| /
| \ Rs
| /
| |
+
+
to ADC GND
Rs shunt resistor according to current and compliance voltage, eg. 1R00
for 1V/1A, or 0R1 for 1V/10A.
Regards
Adrian
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/
current.
Chuck
tough time visualizing how it can be used in the in the original post of 15
volts and up to 10 amps, What am I missing in the reading of this chip.
Can you explain a little better for an dumb old nuts and bolts guy
Original Message
From: CHIPKEN@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=BaW1tPIK2GDjGSN99K7ev4tiA7S1OHGZyf2rIJ_wYC2kw-i7GX_PlG3r5RL8Kjwjf1ZoBkn-oT8J]CHIPKEN@a...[/url
Sent: Thursday, February 27, 2003 10:52 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Measuring DC Amps.
The DS2760 from Dallas, a 1-wire device, will measure both voltage and
current.
Chuck
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/
[noparse][[/noparse]Non-text portions of this message have been removed]
you will be looking for part # snt-50
its a 50 amp shunt bar a bit of over kill but for $12.00
Larry Gaminde
Original Message
From: "Sadler Porter" <porter.sadler@s...>
To: <basicstamps@yahoogroups.com>
Sent: February 27, 2003 8:00 AM
Subject: RE: [noparse][[/noparse]basicstamps] Measuring DC Amps.
: I'm a mech type and reading the apps notes for this product I'm
having a
: tough time visualizing how it can be used in the in the original
post of 15
: volts and up to 10 amps, What am I missing in the reading of this
chip.
:
: Can you explain a little better for an dumb old nuts and bolts guy
:
:
Original Message
: From: CHIPKEN@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=40sUm1Ev7QFSwrWbWfpKwkSFCWqhRmWTpwW3OId1WrT7YswMTg9JEJHPgeNEutqfrcm9Qs0]CHIPKEN@a...[/url
: Sent: Thursday, February 27, 2003 10:52 AM
: To: basicstamps@yahoogroups.com
: Subject: Re: [noparse][[/noparse]basicstamps] Measuring DC Amps.
:
: The DS2760 from Dallas, a 1-wire device, will measure both voltage
and
: current.
: Chuck
:
: 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/
:
:
:
: [noparse][[/noparse]Non-text portions of this message have been removed]
:
:
: 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/
:
:
layman's view of 1-wire technology. You will, also, need a BS2p to make the
pbasic code easy. I think on the Parallax web site you can find some example
code to get started.
The DS2760 has a 25 micro ohm shunt that you measure the voltage drop across
via the DS2760. You will, also, need a voltage divider to reduce your 15 vdc
down to 5 vdc to power the DS2760. This power input voltage can be measured
by the DS2760.
Chuck
So the ghist is to measure voltage across the resistor to get the amps ?
(V = I * R)
I just got more info from my fren (who's asking me to build this) is that
he has 12 x 1.2v battery cells which he's hooked up to a charger and he
wants to constantly meausre the current level in the batterys to track
performance,etc.. (I'll hook this up to a basic stamp which will interface
with a LCD display to graph data every 5min+)
Elvin
-
On Thu, 27 Feb 2003, Grover Richardson wrote:
> Date: Thu, 27 Feb 2003 08:09:36 -0500
> From: Grover Richardson <grover.richardson@g...>
> Reply-To: basicstamps@yahoogroups.com
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
>
> That's what we do. Usually use a 0.1 Ohm resistor. However, there are
> places that sell shunt resistors. A shunt resistor is calibraged to
> give a 50 or 100 mV drop across it at the maximum rated current. For
> example, 50 mV= 500 Amps. They can be used on dc or ac, and usually are
> designed to be temperature insensitive. If 50 mV is too little for the
> A2D, then a small op amp amplifying the output of the shunt is
> appropriate. I've done this on several projects and it works well. The
> idea is to have the resistor small enough so that it doesn't interfere
> with the circuit (or get hot), and yet large enough to have a Voltage
> drop that is measureable<G>.
>
>
Original Message
> From: Adrian Schneider <adrian.schneider@t...>
> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=XGPCOdqgclXxxKmfZiqC8yyNlhuOtDdMw35Tv_Hj-6Ahhv3w8PyKjS1tT9jLiMKX07Brsup1zeC3jMZ7AWaRYWDn_PTeFdce4Q]adrian.schneider@t...[/url
> Sent: Thursday, February 27, 2003 5:26 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
>
>
> What about the following circuit:
>
>
> v Idc
> | |
> | +
to ADC Analog In
> | |
> | /
> | \ Rs
> | /
> | |
> +
+
to ADC GND
>
> Rs shunt resistor according to current and compliance voltage, eg. 1R00
> for 1V/1A, or 0R1 for 1V/10A.
>
> Regards
> Adrian
>
>
> 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/
>
>
>
battery performance is to measure both charge and
discharge thrue a known constant load
just a thought. [noparse]:)[/noparse]
--- Alf <elvin@e...> wrote:
> I'm rusty on my electronics so pardon me.
>
> So the ghist is to measure voltage across the
> resistor to get the amps ?
> (V = I * R)
>
> I just got more info from my fren (who's asking me
> to build this) is that
> he has 12 x 1.2v battery cells which he's hooked up
> to a charger and he
> wants to constantly meausre the current level in the
> batterys to track
> performance,etc.. (I'll hook this up to a basic
> stamp which will interface
> with a LCD display to graph data every 5min+)
>
>
> Elvin
> -
>
> On Thu, 27 Feb 2003, Grover Richardson wrote:
>
> > Date: Thu, 27 Feb 2003 08:09:36 -0500
> > From: Grover Richardson
> <grover.richardson@g...>
> > Reply-To: basicstamps@yahoogroups.com
> > To: basicstamps@yahoogroups.com
> > Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
> >
> > That's what we do. Usually use a 0.1 Ohm
> resistor. However, there are
> > places that sell shunt resistors. A shunt
> resistor is calibraged to
> > give a 50 or 100 mV drop across it at the maximum
> rated current. For
> > example, 50 mV= 500 Amps. They can be used on dc
> or ac, and usually are
> > designed to be temperature insensitive. If 50 mV
> is too little for the
> > A2D, then a small op amp amplifying the output of
> the shunt is
> > appropriate. I've done this on several projects
> and it works well. The
> > idea is to have the resistor small enough so that
> it doesn't interfere
> > with the circuit (or get hot), and yet large
> enough to have a Voltage
> > drop that is measureable<G>.
> >
> >
Original Message
> > From: Adrian Schneider
> <adrian.schneider@t...>
> > [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8T6mN2CC48SivlVrVzQSryhimknDFJRRHsW_3XgS3VVLpmYBcgsDzx5o7TBmxKKFnr7rqbJ-3ZrO1YYwiKA_jm-1aJPCY0vP]adrian.schneider@t...[/url
> > Sent: Thursday, February 27, 2003 5:26 AM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
> >
> >
> > What about the following circuit:
> >
> >
> > v Idc
> > | |
> > | +
to ADC Analog In
> > | |
> > | /
> > | \ Rs
> > | /
> > | |
> > +
+
to ADC GND
> >
> > Rs shunt resistor according to current and
> compliance voltage, eg. 1R00
> > for 1V/1A, or 0R1 for 1V/10A.
> >
> > Regards
> > Adrian
> >
> >
> > 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/
> >
> >
> >
>
>
> 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/
>
>
__________________________________________________
Do you Yahoo!?
Yahoo! Tax Center - forms, calculators, tips, more
http://taxes.yahoo.com/
onset (I don't consider myself thhaaatt old<G>).
Yes. Measure a small Voltage across a resistor and calculate the amps.
The way that we've done it in the past is to (stating it somewhat oddly
here for clarity<G>) use the battery negative terminal for ground for
the entire system. Connect up everything as it will be run normally.
Now, lift the negative lead from the battery charger which is
connected to the negative side of the battery stack. Put the small
resistor between that lead and the "ground," which is the negative side
of the battery stack. This will allow you to have a quality ground for
the system. It will also allow you to read the Voltage on the resistor
relative to ground, which is a one wire measurement. The polarity will
be backwards, but can be dealt with in calculations.
I've read resistors on the high side of the batteries, and
trying to get a small .02 Volt difference when both sides are floating
at 8-9 Volts is not as simple as it seems<G>.
Sounds like you are measuring Nicads. If you are using a 10%
charge, but using a high rate of discharge, you should calculate the
power dissipated in the resistor during high rates of discharge. This
ensures that it will survive and not become an impromptu fuse<G>.
Personally, I like the old style carbon composition resistors.
They are non-inductive and perform well. If you need to know EXACTLY
how much the current is when using junk box non-precision resistors, you
can use a multimeter to measure a power supply Voltage, and then measure
the current through the resistor. This will give the exact resistance
of the resistor (through calculation), and saves the effort of finding a
1% resistor. This sounds like false economy, but at home, I have to use
what I have lying around<G>.
Make sense?
Original Message
From: Alf [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=cBycoHHc5lXHc-gwIs4v9YHirwE9i0d-QE4eZQqIgvic9_W8ORYPMKanFHLf651YYn2XwsU3]elvin@e...[/url
Sent: Thursday, February 27, 2003 9:38 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
I'm rusty on my electronics so pardon me.
So the ghist is to measure voltage across the resistor to get the amps ?
(V = I * R)
I just got more info from my fren (who's asking me to build this) is
that
he has 12 x 1.2v battery cells which he's hooked up to a charger and he
wants to constantly meausre the current level in the batterys to track
performance,etc.. (I'll hook this up to a basic stamp which will
interface
with a LCD display to graph data every 5min+)
Elvin
-
On Thu, 27 Feb 2003, Grover Richardson wrote:
> Date: Thu, 27 Feb 2003 08:09:36 -0500
> From: Grover Richardson <grover.richardson@g...>
> Reply-To: basicstamps@yahoogroups.com
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
>
> That's what we do. Usually use a 0.1 Ohm resistor. However, there
> are places that sell shunt resistors. A shunt resistor is calibraged
> to give a 50 or 100 mV drop across it at the maximum rated current.
> For example, 50 mV= 500 Amps. They can be used on dc or ac, and
> usually are designed to be temperature insensitive. If 50 mV is too
> little for the A2D, then a small op amp amplifying the output of the
> shunt is appropriate. I've done this on several projects and it works
> well. The idea is to have the resistor small enough so that it
> doesn't interfere with the circuit (or get hot), and yet large enough
> to have a Voltage drop that is measureable<G>.
>
>
Original Message
> From: Adrian Schneider <adrian.schneider@t...>
> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=CV1Apv_PS-F3vA78CNLKB9o2cFnYdpIIJVK68F0mY_ECfKKM8zO2NE4WXURxsHo7AqlmBiyLoN7o4UtXnxjzsUfJ1K9NhA7f]adrian.schneider@t...[/url
> Sent: Thursday, February 27, 2003 5:26 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
>
>
> What about the following circuit:
>
>
> v Idc
> | |
> | +
to ADC Analog In
> | |
> | /
> | \ Rs
> | /
> | |
> +
+
to ADC GND
>
> Rs shunt resistor according to current and compliance voltage, eg.
> 1R00 for 1V/1A, or 0R1 for 1V/10A.
>
> Regards
> Adrian
>
>
> 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/
>
>
>
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/
is left. I guess Elvin is trying to keep up with how much power is left
through "coloumb counting."
Original Message
From: kenneth magers [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oRbUKQSuORo2sS2zDodNAK0_hDWtmupBpNXtdZ2BpmVA12KN4Hli76d4_o6dm8KsCcq24P3hPEZGNc10xv5BLNPJJg]kenneth_m_73149@y...[/url
Sent: Thursday, February 27, 2003 11:23 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
i might be wrong but the only way i know to gage
battery performance is to measure both charge and
discharge thrue a known constant load
just a thought. [noparse]:)[/noparse]
--- Alf <elvin@e...> wrote:
> I'm rusty on my electronics so pardon me.
>
> So the ghist is to measure voltage across the
> resistor to get the amps ?
> (V = I * R)
>
> I just got more info from my fren (who's asking me
> to build this) is that
> he has 12 x 1.2v battery cells which he's hooked up
> to a charger and he
> wants to constantly meausre the current level in the
> batterys to track
> performance,etc.. (I'll hook this up to a basic
> stamp which will interface
> with a LCD display to graph data every 5min+)
>
>
> Elvin
> -
>
> On Thu, 27 Feb 2003, Grover Richardson wrote:
>
> > Date: Thu, 27 Feb 2003 08:09:36 -0500
> > From: Grover Richardson
> <grover.richardson@g...>
> > Reply-To: basicstamps@yahoogroups.com
> > To: basicstamps@yahoogroups.com
> > Subject: RE: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
> >
> > That's what we do. Usually use a 0.1 Ohm
> resistor. However, there are
> > places that sell shunt resistors. A shunt
> resistor is calibraged to
> > give a 50 or 100 mV drop across it at the maximum
> rated current. For
> > example, 50 mV= 500 Amps. They can be used on dc
> or ac, and usually are
> > designed to be temperature insensitive. If 50 mV
> is too little for the
> > A2D, then a small op amp amplifying the output of
> the shunt is
> > appropriate. I've done this on several projects
> and it works well. The
> > idea is to have the resistor small enough so that
> it doesn't interfere
> > with the circuit (or get hot), and yet large
> enough to have a Voltage
> > drop that is measureable<G>.
> >
> >
Original Message
> > From: Adrian Schneider
> <adrian.schneider@t...>
> > [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=FvIdoVs7AAkNaySwDAgXYbUQzW7qmyPeIX_6yOmJW5Rj08w_jHCLiFsKhbX7-DrRent5rByDy9bWvoeVonmF0-7oUjNR6KgEnA]adrian.schneider@t...[/url
> > Sent: Thursday, February 27, 2003 5:26 AM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Measuring DC Amps.
> >
> >
> > What about the following circuit:
> >
> >
> > v Idc
> > | |
> > | +
to ADC Analog In
> > | |
> > | /
> > | \ Rs
> > | /
> > | |
> > +
+
to ADC GND
> >
> > Rs shunt resistor according to current and
> compliance voltage, eg. 1R00
> > for 1V/1A, or 0R1 for 1V/10A.
> >
> > Regards
> > Adrian
> >
> >
> > 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/
> >
> >
> >
>
>
> 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/
>
>
__________________________________________________
Do you Yahoo!?
Yahoo! Tax Center - forms, calculators, tips, more
http://taxes.yahoo.com/
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/