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Hello everybody,

To measure the current in my 3 phases house electricity system and=20
in the neutral, I am using 4 Honeywell Current Sensors CSLA2CD=20
powered with 5V.=20=20
5 V is on the low end of the specifications!=20
I send the outputs of the current sensors to the Input pin (Pin 13=20
to 16) of the BX-24.=20
The Current sensor give a DC voltage of 5V / 2 =3D 2.5 V when I have=20
no current in the sensor.
The AC voltage is around 300 mV RMS on Input pin when I have 15 A in=20
the phase, measured with a standard DVM.
The idea is to search the Max AC voltage in a loop faster than the=20
50 Hz frequency.
The RMS voltage is then given by dividing the Max Voltage by 1.414=20
(Square root of 2).
The RMS Voltage is proportional to RMS current flowing in the phase=20
wire.
This is the basic.

My problem is to try to remove the DC voltage of 2.5V by putting a=20
serial capacitor but I like to know if somebody as the input=20
impedance of the pin 13 to 16 (ADC Inputs) of the BX-24 for 50 Hz=20
frequency?

Any idea what should be the value of the capacitor?
I put one Micro Farad (1 =B5f) but when I have no current the=20
capacitor remain charged to 5 V and when I apply a current, it take=20
very long time to reach the right value (the capacitor remain=20
charged) .

Thanks for your feedback and best regards.

Patrick

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hi,

I checked the sensor output and I could not=C2=A0 come up if the voltage ou=
tput was Dc or AC. Since they are using +5 in the power supply I assumed th=
at is DC.
=C2=A0I try using the capacitor in parallel to the input instead serial and=
if it is too noisy I use a 1k resistor in series.

rosarite=20
=20
=20

-----Original Message-----
From: gouardopatrick
To: b...@yahoogroups.com
Sent: Fri, 13 Feb 2009 3:58 pm
Subject: [BasicX] BX-24 Input Impedance for ADC conversion of small 50 Hz V=
oltage

=20=20=20=20

=20=20=20=20=20=20=20=20=20=20=20=20

Hello everybody,

To measure the current in my 3 phases house electricity system and=20

in the neutral, I am using 4 Honeywell Current Sensors CSLA2CD=20

powered with 5V.=20=20

5 V is on the low end of the specifications!=20

I send the outputs of the current sensors to the Input pin (Pin 13=20

to 16) of the BX-24.=20

The Current sensor give a DC voltage of 5V / 2 =3D 2.5 V when I have=20

no current in the sensor.

The AC voltage is around 300 mV RMS on Input pin when I have 15 A in=20

the phase, measured with a standard DVM.

The idea is to search the Max AC voltage in a loop faster than the=20

50 Hz frequency.

The RMS voltage is then given by dividing the Max Voltage by 1.414=20

(Square root of 2).

The RMS Voltage is proportional to RMS current flowing in the phase=20

wire.

This is the basic.
0AMy problem is to try to remove the DC voltage of 2.5V by putting a=20

serial capacitor but I like to know if somebody as the input=20

impedance of the pin 13 to 16 (ADC Inputs) of the BX-24 for 50 Hz=20

frequency?

Any idea what should be the value of the capacitor?

I put one Micro Farad (1 =C2=B5f) but when I have no current the=20

capacitor remain charged to 5 V and when I apply a current, it take=20

very long time to reach the right value (the capacitor remain=20

charged) .

Thanks for your feedback and best regards.

Patrick

=20

=20=20=20=20
=20=20

=20=20=20=20
=20=20=20=20
=20=20=20=20
=20=20=20=20

=20=20=20=20
=20=20=20=20
=20

[Non-text portions of this message have been removed]

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... I put 1 µf but when I have no current the capacitor remain
charged to 5 V and when I apply a current, it take very long time to
reach the right value...

No surprise. If you look at the ADC input specifications of the
ATMEGA8535 processor, you'll find that RAin is ~100megohms. The time
constant of that in series with 1µF is 100 seconds.

It sounds to me that you need do nothing but directly connect the sensor
output to the ADC input pin. Since it is already biased at 2.5v and the
maximum swing is well within the 0v and 5v rails, a direct connection
should work. However, 300mVRMS is only about 1vpp, so you will not see
the best resolution. Still, you'll have at least eight bits. To get
best resolution, you'll need some AC-coupled amplification - or a sensor
with more sensitivity, I believe.

Tom

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

I said:
> It sounds to me that you need do nothing but directly connect the sensor...

I left out an important constraint. If the supply voltage is 6vDC, the output will be biased at 3vDC and should be able to be directly connected. Higher sensor supply voltages will decrease the maximum current that can be measured with a direct connection.

Also, it might make sense to put a series resistor between the sensor and the ADC input pin to limit current caused by AC current spikes. Since the ADC input impedance is very high, almost any value will suffice, like 5k, which will limit the overvoltage input pin current to 1mA.

Tom

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hello Rosarite,

Thanks for your reply.

Yes, the output of the sensor without current in the sensor is a DC=20
voltage equal to 1/2 of the VCC.
Vcc mini should be bigger than 8 V Dc.

On this DC voltage, is "superposed" the useful signal when current=20
go thought the sensor.

Yes, I will try to put a smaller capacitor (0.1 =B5F) to reduce the=20
noise and see.
Too big capacitor will short circuit of the 50 Hz useful signal.

I keep you inform of my trial.

I am also going forward using an LTC 1966 circuit to convert AC in=20
DC RMS.
It is a simple IC and will avoid the loop in BX-24 programming to=20
find the Max. So the overall result will be a faster program.

Thanks for all the comments which are useful and welcome.

Best Regards

Patrick.
--- In b...@yahoogroups.com, rosarite@... wrote:
>
>=20
> Hi,
>=20
> I checked the sensor output and I could not=C2=A0 come up if the=20
voltage output was Dc or AC. Since they are using +5 in the power=20
supply I assumed that is DC.
> =C2=A0I try using the capacitor in parallel to the input instead=20
serial and if it is too noisy I use a 1k resistor in series.
>=20
> rosarite=20
>=20
>=20
>=20=20
>=20
>=20
>=20=20
>=20
> -----Original Message-----
> From: gouardopatrick
> To: b...@yahoogroups.com
> Sent: Fri, 13 Feb 2009 3:58 pm
> Subject: [BasicX] BX-24 Input Impedance for ADC conversion of=20
small 50 Hz Voltage
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20=20=20=20=20
>=20
>=20=20=20=20=20=20=20=20=20=20=20=20=20
>=20
>=20
>=20
>=20
> Hello everybody,
>=20
>=20
>=20
> To measure the current in my 3 phases house electricity system and=20
>=20
> in the neutral, I am using 4 Honeywell Current Sensors CSLA2CD=20
>=20
> powered with 5V.=20=20
>=20
> 5 V is on the low end of the specifications!=20
>=20
> I send the outputs of the current sensors to the Input pin (Pin 13=20
>=20
> to 16) of the BX-24.=20
>=20
> The Current sensor give a DC voltage of 5V / 2 =3D 2.5 V when I have=20
>=20
> no current in the sensor.
>=20
> The AC voltage is around 300 mV RMS on Input pin when I have 15 A=20
in=20
>=20
> the phase, measured with a standard DVM.
>=20
> The idea is to search the Max AC voltage in a loop faster than the=20
>=20
> 50 Hz frequency.
>=20
> The RMS voltage is then given by dividing the Max Voltage by=20
1.414=20
>=20
> (Square root of 2).
>=20
> The RMS Voltage is proportional to RMS current flowing in the=20
phase=20
>=20
> wire.
>=20
> This is the basic.
>=20
>=20
> 0AMy problem is to try to remove the DC voltage of 2.5V by putting=20
a=20
>=20
> serial capacitor but I like to know if somebody as the input=20
>=20
> impedance of the pin 13 to 16 (ADC Inputs) of the BX-24 for 50 Hz=20
>=20
> frequency?
>=20
>=20
>=20
> Any idea what should be the value of the capacitor?
>=20
> I put one Micro Farad (1 =C2=B5f) but when I have no current the=20
>=20
> capacitor remain charged to 5 V and when I apply a current, it=20
take=20
>=20
> very long time to reach the right value (the capacitor remain=20
>=20
> charged) .
>=20
>=20
>=20
> Thanks for your feedback and best regards.
>=20
>=20
>=20
> Patrick
>=20
>=20
>=20
>=20
>=20
>=20=20
>=20
>=20=20=20=20=20
>=20=20=20
>=20
>=20=20=20=20=20
>=20=20=20=20=20
>=20
>=20
>=20=20=20=20=20
>=20=20=20=20=20
>=20
>=20
>=20
>=20
>=20=20=20=20=20
>=20=20=20=20=20
>=20=20
>=20
>=20
>=20
> [Non-text portions of this message have been removed]
>

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Thanks for your reply.

The reason for wanting to put a capacitor was to remove the bias=20
voltage going to the ADC input.
In fact for the moment I have power the sensor with 5 V which is too=20
low according to the specification which gives 8 V Dc mini.
With 5V the sensor apparently work OK but maybe not at it best!

With 8 V DC to the sensor, it give 4 V cc Dc Bias voltage and the=20
ADC max input is 5 v which give me only 1 V of ACMax voltage.
Ok, I could use a resistor divider but this will also divide the=20
useful signal.

>From what you said about the input impedance of the BX-24 ADC input,=20
I could reduce the value of the capacitor to 1 to 10 nF and I think=20
it will work.
I have a look on this idea.

I could also put a differential amplifier but it makes the circuit=20
more complicated to make.

In term of precision, a 5 % result is acceptable to me and the=20
resolution of the AQDC is 5/1024, is that right?

Thanks and best Regards.

Patrick.
, --- In b...@yahoogroups.com, Tom Becker wrote:
>
> > ... I put 1 =B5f but when I have no current the capacitor remain=20
> charged to 5 V and when I apply a current, it take very long time=20
to=20
> reach the right value...
>=20
> No surprise. If you look at the ADC input specifications of the=20
> ATMEGA8535 processor, you'll find that RAin is ~100megohms. The=20
time=20
> constant of that in series with 1=B5F is 100 seconds.
>=20
> It sounds to me that you need do nothing but directly connect the=20
sensor=20
> output to the ADC input pin. Since it is already biased at 2.5v=20
and the=20
> maximum swing is well within the 0v and 5v rails, a direct=20
connection=20
> should work. However, 300mVRMS is only about 1vpp, so you will=20
not see=20
> the best resolution. Still, you'll have at least eight bits. To=20
get=20
> best resolution, you'll need some AC-coupled amplification - or a=20
sensor=20
> with more sensitivity, I believe.
>=20
> Tom
>

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Thanks for your reply.

The reason for wanting to put a capacitor was to remove the bias=20
voltage going to the ADC input.
In fact for the moment I have power the sensor with 5 V which is too=20
low according to the specification which gives 8 V Dc mini.
With 5V the sensor apparently work OK but maybe not at it best!

With 8 V DC to the sensor, it give 4 V cc Dc Bias voltage and the=20
ADC max input is 5 v which give me only 1 V of ACMax voltage.
Ok, I could use a resistor divider but this will also divide the=20
useful signal.

>From what you said about the input impedance of the BX-24 ADC input,=20
I could reduce the value of the capacitor to 1 to 10 nF and I think=20
it will work.
I have a look on this idea.

I could also put a differential amplifier but it makes the circuit=20
more complicated to make.

In term of precision, a 5 % result is acceptable to me and the=20
resolution of the AQDC is 5/1024, is that right?

Thanks and best Regards.

Patrick.
, --- In b...@yahoogroups.com, Tom Becker wrote:
>
> > ... I put 1 =B5f but when I have no current the capacitor remain=20
> charged to 5 V and when I apply a current, it take very long time=20
to=20
> reach the right value...
>=20
> No surprise. If you look at the ADC input specifications of the=20
> ATMEGA8535 processor, you'll find that RAin is ~100megohms. The=20
time=20
> constant of that in series with 1=B5F is 100 seconds.
>=20
> It sounds to me that you need do nothing but directly connect the=20
sensor=20
> output to the ADC input pin. Since it is already biased at 2.5v=20
and the=20
> maximum swing is well within the 0v and 5v rails, a direct=20
connection=20
> should work. However, 300mVRMS is only about 1vpp, so you will=20
not see=20
> the best resolution. Still, you'll have at least eight bits. To=20
get=20
> best resolution, you'll need some AC-coupled amplification - or a=20
sensor=20
> with more sensitivity, I believe.
>=20
> Tom
>

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... a 5 % result is acceptable to me and the resolution of the ADC is
5/1024, is that right?

10 bits, 5v/1024, yes.

5%. How can you know the sensor is that accurate if you operate it
out-of-spec?

Assuming the sensor output is offset bipolar and you remove the DC bias,
beware of negative ADC input voltages; will you ignore negative currents?

If you are able to use opamps you can solve this excessively well, but
why use hardware when a subtraction in code can do it? Why not a 7806
regulator, an input resistor, and remove a 3v offset in code?

Tom
------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... I could also put a differential amplifier but it makes the
circuit more complicated...

Well, you could build a peak detector, too, for a no-code solution.

I do not understand your rationale, Patrick. Is this an exercise or do
you need to build an instrument?

> ... too low according to the specification which gives 8VDC minimum.

No, the specs do not specify an 8v minimum.
http://www.compel.ru/images/catalog/334/CSLA2CD.pdf If you don't have a
7806 you can use a 7805 with a diode in its ground to get 5.6v, within
spec, and have a 2.8v offset.

Respectfully, I suggest that you think this through some more.
Tom
------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hello Tom,

Thanks for your reply.

I am writing on this forum because I thought it was a place top
discuss and exchange ideas on a subject we like.
Please tell me if I am wrong in my approach.

The specifications of the IC I use are at the following address:

http://sensing.honeywell.com/index.cfm/ci_id/140400/la_id/1/document/
1/re_id/0

The CSLA1CD as a minimum VCC of 8V and the CSLA2CD as a minimum VCC
of 6 V Dc.

This is a personal project that I am trying to build for my house.
I have in my house 3 phases and neutral electrical network and with
32 A max per phase.
In winter, when we use all the electric radiators, the input circuit
breaker often trip because we are over 32 A in one of the phase.
I want to switch the radiators using an X10 interface XM10E when we
reach 32 A.

I selected the BX-24 for the simple reason that he has both ADC
inputs and X10 command.

If I have managed for the moment, more or less, the AD conversion, I
have not been able to make basic X10 commands work, yet.
Now, in term of building items like differential amplifiers or peak
detectors, I have the background to do it but it is easier and
faster to put together black boxes with the proper basic function
tested by the manufacturer.

Here is the link for the LTC1966 RMS converter from Linear
Technology.

http://www.linear.com/pc/downloadDocument.do?
navId=H0,C1,C1154,C1086,P1701,D3396

Thanks for your help and suggestions.

Best Regards.

Patrick.
--- In b...@yahoogroups.com, Tom Becker wrote:
>
> > ... I could also put a differential amplifier but it makes the
> circuit more complicated...
>
> Well, you could build a peak detector, too, for a no-code
solution.
>
> I do not understand your rationale, Patrick. Is this an exercise
or do
> you need to build an instrument?
>
> > ... too low according to the specification which gives 8VDC
minimum.
>
> No, the specs do not specify an 8v minimum.
> http://www.compel.ru/images/catalog/334/CSLA2CD.pdf If you don't
have a
> 7806 you can use a 7805 with a diode in its ground to get 5.6v,
within
> spec, and have a 2.8v offset.
>
> Respectfully, I suggest that you think this through some more.
> Tom
>

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Sorry, the Linear Technology Address for the LTC1966 is as follow :

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1086,P17\
01,D3396
701,D3396>

Best Regards.

Patrick.
--- In b...@yahoogroups.com, "gouardopatrick"
wrote:
>
> Hello Tom,
>
> Thanks for your reply.
>
> I am writing on this forum because I thought it was a place top
> discuss and exchange ideas on a subject we like.
> Please tell me if I am wrong in my approach.
>
> The specifications of the IC I use are at the following address:
>
> http://sensing.honeywell.com/index.cfm/ci_id/140400/la_id/1/document/
> 1/re_id/0
>
> The CSLA1CD as a minimum VCC of 8V and the CSLA2CD as a minimum VCC
> of 6 V Dc.
>
> This is a personal project that I am trying to build for my house.
> I have in my house 3 phases and neutral electrical network and with
> 32 A max per phase.
> In winter, when we use all the electric radiators, the input circuit
> breaker often trip because we are over 32 A in one of the phase.
> I want to switch the radiators using an X10 interface XM10E when we
> reach 32 A.
>
> I selected the BX-24 for the simple reason that he has both ADC
> inputs and X10 command.
>
> If I have managed for the moment, more or less, the AD conversion, I
> have not been able to make basic X10 commands work, yet.
> Now, in term of building items like differential amplifiers or peak
> detectors, I have the background to do it but it is easier and
> faster to put together black boxes with the proper basic function
> tested by the manufacturer.
>
> Here is the link for the LTC1966 RMS converter from Linear
> Technology.
>
> http://www.linear.com/pc/downloadDocument.do?
> navId=H0,C1,C1154,C1086,P1701,D3396
>
> Thanks for your help and suggestions.
>
> Best Regards.
>
> Patrick.
> --- In b...@yahoogroups.com, Tom Becker gtbecker@ wrote:
> >
> > > ... I could also put a differential amplifier but it makes the
> > circuit more complicated...
> >
> > Well, you could build a peak detector, too, for a no-code
> solution.
> >
> > I do not understand your rationale, Patrick. Is this an exercise
> or do
> > you need to build an instrument?
> >
> > > ... too low according to the specification which gives 8VDC
> minimum.
> >
> > No, the specs do not specify an 8v minimum.
> > http://www.compel.ru/images/catalog/334/CSLA2CD.pdf If you don't
> have a
> > 7806 you can use a 7805 with a diode in its ground to get 5.6v,
> within
> > spec, and have a 2.8v offset.
> >
> > Respectfully, I suggest that you think this through some more.
> >
> >
> > Tom
>

[Non-text portions of this message have been removed]

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

> ... a place to discuss and exchange ideas on a subject...

Yes, of course, and I apologize for my style. One, though, should be
prepared for the discussion. This is a processor group so solutions
might best be focused on software solutions within the capability of the
machine, and hardware, if it is necessary, to interface the machine to
the real world. Ideally, no external hardware is ideal if the problem
can be solved with just processor resources - which is why you say you
chose the BX-24.

Your approach, from your first message, proposed and tried external
hardware to overcome the interface issue - and suggested that you had
not read the BX-24's ATmega8535 specifications and, apparently, not the
specs of the part you first said you were using, a "CSLA2CD powered with
5V". The first Google hit on that part string brought up a spec sheet
that indicated 5.4v as the minimum supply voltage, out-of-spec. Perhaps
the part has changed over time.

In any event, for your 5% accuracy tolerance and my cursory reading of
the pertinent specs, the only interface hardware required is a single
resistor, to protect the processor, if the sensor is validly powered
such that Vcc/2 and the signal resulting from current maximums of your
choice keep the swing at the ADC input above 0v and below 5v. No
capacitor is required. Your mention of opamps and differential
amplifiers indicates that you are prone toward a hardware solution - one
that is apparently unnecessary - and that, I believe, you were
unprepared to discuss.

You can, incidentally, bring the Vcc/2 zero-current bias point down with
a voltage-dropping diode or two, provided there is some small current
flowing through them, which would call for a resistance between the
diode and ground..

In code, you will need to do some peak detection and averaging over some
number of cycles, since it is unlikely the sampling loop will be fast
enough to catch fine details of each cycle.
Tom
------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hi,
I found a ac current converter that give you a proportional rms current output in dc and is self powered, You do not need to anything just read it.Attached is the link.

http://www.crmagnetics.com/pdf/an4310-1.pdf

rosarite

-----Original Message-----
From: gouardopatrick
To: b...@yahoogroups.com
Sent: Sun, 15 Feb 2009 4:29 am
Subject: [BasicX] Re: BX-24 Input Impedance for ADC conversion of small 50 Hz Voltage

Hello Tom,

Thanks for your reply.

I am writing on this forum because I thought it was a place top

discuss and exchange ideas on a subject we like.

Please tell me if I am wrong in my approach.

The specifications of the IC I use are at the following address:

http://sensing.honeywell.com/index.cfm/ci_id/140400/la_id/1/document/

1/re_id/0

The CSLA1CD as a minimum VCC of 8V and the CSLA2CD as a minimum VCC

of 6 V Dc.

This is a personal project that I am trying to build for my house.

I have in my house 3 phases and neutral electrical network and with

32 A max per phase.

In winter, when we use all the electric radiators, the input circuit

breaker often trip because we are over 32 A in one of the phase.

I want to switch the radiators using an X10 interface XM10E when we

reach 32 A.

I selected the BX-24 for the simple reason that he has both ADC

inputs and X10 command.

If I have managed for the moment, more or less, the AD conversion, I

have not been able to make basic X10 commands work, yet.

Now, in term of building items like differential amplifiers or peak

detectors, I have the background to do it but it is easier and

faster to put together black boxes with the proper basic function

tested by the manufacturer.

Here is the link for the LTC1966 RMS converter from Linear

Technology.

http://www.linear.com/pc/downloadDocument.do?

navId=H0,C1,C1154,C1086,P1701,D3396

Thanks for your help and suggestions.

Best Regards.

Patrick.

--- In b...@yahoogroups.com, Tom Becker wrote:

>

> > ... I could also put a differential amplifier but it makes the

> circuit more complicated...

>

> Well, you could build a peak detector, too, for a no-code

solution.

>

> I do not understand your rationale, Patrick. Is this an exercise

or do

> you need to build an instrument?

>

> > ... too low according to the specification which gives 8VDC

minimum.

>

> No, the specs do not specify an 8v minimum.

> http://www.compel.ru/images/catalog/334/CSLA2CD.pdf If you don't

have a

> 7806 you can use a 7805 with a diode in its ground to get 5.6v,

within

> spec, and have a 2.8v offset.

>

> Respectfully, I suggest that you think this through some more.

>

>

> Tom

>

[Non-text portions of this message have been removed]

------------------------------------



(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )

Hi,

I found an ac current
converter that give you a proportional RMS current output in DC and is
self powered, You do not need to do anything just read it and the output is compatible with BX-24. Attached is the
link.

This sensor will eliminate all his problem I think.

http://www.crmagnetics.com/pdf/an4310-1.pdf

rosarite

-----Original Message-----
From: Tom Becker
To: b...@yahoogroups.com
Sent: Sat, 14 Feb 2009 6:50 am
Subject: Re: [BasicX] Re: BX-24 Input Impedance for ADC conversion of small 50 Hz Voltage

> ... a 5 % result is acceptable to me and the resolution of the ADC is

5/1024, is that right?

10 bits, 5v/1024, yes.

5%. How can you know the sensor is that accurate if you operate it

out-of-spec?

Assuming the sensor output is offset bipolar and you remove the DC bias,

beware of negative ADC input voltages; will you ignore negative currents?

If you are able to use opamps you can solve this excessively well, but

why use hardware when a subtraction in code can do it? Why not a 7806

regulator, an input resistor, and remove a 3v offset in code?

Tom

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Am I missing something here?
As far as I can see Honeywell don't seem to know the spec of their
own parts, is the CSLA2CD speced at 5.6v or 6v who knows? And their
site is a mess I ended up going round in circles there following the
Application reports link, I guess there aren't any.
Anyway if you run the CSLA1CD at 8v then the output will be biased to
4v. If you clip +ve excursions to 5v (use a 47k series resistor and a
reversed biased diode to the 5v rail) and only measure -ve excursions
(it is a.c) then that gives you a 4v range, enough accuracy there I
would have thought.

David - robots42

--- In b...@yahoogroups.com, "gouardopatrick"
wrote:
>
> Hello Tom,
>
> Thanks for your reply.
>
> I am writing on this forum because I thought it was a place top
> discuss and exchange ideas on a subject we like.
> Please tell me if I am wrong in my approach.
>
> The specifications of the IC I use are at the following address:
http://sensing.honeywell.com/index.cfm/ci_id/140400/la_id/1/document/
> 1/re_id/0
>
> The CSLA1CD as a minimum VCC of 8V and the CSLA2CD as a minimum VCC
> of 6 V Dc.
>
> This is a personal project that I am trying to build for my house.
> I have in my house 3 phases and neutral electrical network and
with
> 32 A max per phase.
> In winter, when we use all the electric radiators, the input
circuit
> breaker often trip because we are over 32 A in one of the phase.
> I want to switch the radiators using an X10 interface XM10E when we
> reach 32 A.
>
> I selected the BX-24 for the simple reason that he has both ADC
> inputs and X10 command.
>
> If I have managed for the moment, more or less, the AD conversion,
I
> have not been able to make basic X10 commands work, yet.
> Now, in term of building items like differential amplifiers or peak
> detectors, I have the background to do it but it is easier and
> faster to put together black boxes with the proper basic function
> tested by the manufacturer.
>
> Here is the link for the LTC1966 RMS converter from Linear
> Technology.
>
> http://www.linear.com/pc/downloadDocument.do?
> navId=H0,C1,C1154,C1086,P1701,D3396
>
> Thanks for your help and suggestions.
>
> Best Regards.
>
> Patrick.
> --- In b...@yahoogroups.com, Tom Becker wrote:
> >
> > > ... I could also put a differential amplifier but it makes the
> > circuit more complicated...
> >
> > Well, you could build a peak detector, too, for a no-code
> solution.
> >
> > I do not understand your rationale, Patrick. Is this an exercise
> or do
> > you need to build an instrument?
> >
> > > ... too low according to the specification which gives 8VDC
> minimum.
> >
> > No, the specs do not specify an 8v minimum.
> > http://www.compel.ru/images/catalog/334/CSLA2CD.pdf If you don't
> have a
> > 7806 you can use a 7805 with a diode in its ground to get 5.6v,
> within
> > spec, and have a 2.8v offset.
> >
> > Respectfully, I suggest that you think this through some more.
> >
> >
> > Tom
>

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