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Hello all,

I am not sure if someone has addressed this issue before. I have
tried a search, but have not been able to find anything.

What I am designing is a video distribution box that is connected to
a surveillance system that is connected by a 30 conductor cable. In
the box is a set of batteries, that are used to power the cameras
and microphones that might be connected to the box. I need a way to
monitor the voltage and current that is being used by the box. This
information needs to be sent back to a LCD display that will be in
the van. I will also need a way to control some additional features
in the box. After the power has been sent to the box from the van I
will have 2 additional wires that I can use to send and receive
data. This means I will be using I2C to carry the data back to the
van. Any ideas on the best way to approach this.

The big thing now is the ability to measure voltage and current and
send it back to the surveillance system to be displayed on an LCD
display.

Any help or ideas would be greatly appericated.

Thanks

Patrick





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

I=92m sure there are more sophisticated ways to do this, but=85

=20

In theory you=92re supposed to be able to put a very low resistance very hi=
gh
wattage resistor, (say =BD ohm 5 watt) in series with your power feed and t=
hen
measure the voltage drop across that resistor =96 that will tell you the
current is (I =3D E/R) and because it=92s such a low value of resistance it
won=92t have an appreciable impact on the power supplied to your circuit. =
In
practice I haven=92t found this to be very accurate but math is math so it=
=92s
probably a problem with my implementation.

=20

As far as voltage you could just use a couple of resistors to create a
voltage divider to drop your voltage down to something the AD converter can
handle. So if you are running a 12v system set it up such that your voltag=
e
divider gives you just under 5 volts =96 then you can correlate that with t=
he
actual voltage.=20

=20

The rest is just a SMOP (Small Matter of Programming) :-)

=20

DougM

=20

_____=20=20

From: b...@yahoogroups.com [mailto:b...@yahoogroups.com] On Behalf Of
nuepatrick
Sent: Friday, June 30, 2006 8:40 AM
To: b...@yahoogroups.com
Subject: [BasicX] Monitor voltage and current

=20

Hello all,

I am not sure if someone has addressed this issue before. I have=20
tried a search, but have not been able to find anything.

What I am designing is a video distribution box that is connected to=20
a surveillance system that is connected by a 30 conductor cable. In=20
the box is a set of batteries, that are used to power the cameras=20
and microphones that might be connected to the box. I need a way to=20
monitor the voltage and current that is being used by the box. This=20
information needs to be sent back to a LCD display that will be in=20
the van. I will also need a way to control some additional features=20
in the box. After the power has been sent to the box from the van I=20
will have 2 additional wires that I can use to send and receive=20
data. This means I will be using I2C to carry the data back to the=20
van. Any ideas on the best way to approach this.

The big thing now is the ability to measure voltage and current and=20
send it back to the surveillance system to be displayed on an LCD=20
display.

Any help or ideas would be greatly appericated.

Thanks

Patrick=20

=20

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

=20

=20

=20


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