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 Robotics / 19022
19021  |  19023
Subject: 
Re: Voltage Sensor
Newsgroups: 
lugnet.robotics
Date: 
Mon, 16 Sep 2002 17:03:35 GMT
Viewed: 
604 times
  
Are you powering the RCX from this battery?

If so you can use the RCX it'self to monitor the battery.

task main()

{

while (true)

{

SetUserDisplay(BatteryLevel(), 3);

}

}

I use this to detect if my 1.0 RCX is plugged in or on batterys.

Hope that helps.

Dean

"Tom Beattie" <tom@magneticpie.com> wrote in message
news:H2J17p.Ior@lugnet.com...
Hello fellow Mindstomers,

I am seeking some direction in the development of a Voltage Sensor I wish • to
use with my RCX.

I have solar cell connected to a 12Volt (1.3A) sealed lead acid battery • via
a small trickle charger PCB (bought as a kit). The solar cell charges the
battery when sun permits. Connected to the battery I have a voltage
regulator (again, bought as a kit) to bring the output of the battery to 9
Volts, which I then feed to various lego components. i.e motors, lights,
RCX, etc. This works well.

What I want to do is to be able to monitor the batteries voltage via a RCX
sensor input
I have made the following assumptions
1    Sensor type should be a "Light sensor"  - In order to monitor a 0V - • 5V
sensor input reading
2    Use a General Purpose Analog Interface as per Michael Gasperi's fab • web
site http://www.plazaearth.com/usr/gasperi/gpa.htm
3    Use some sort of 'resistive divider' setup to bring the monitored
battery output voltage within the 0V - 5V input range of the sensor.
http://news.lugnet.com/robotics/?n=18648
4    Convert the sensor reading within a RCX program to bring it back to • the
0V - 12V range


My questions are:
1    Is this the 'right' way to go about this sort of thing?
2    What is the arrangement of the resisters in a 'resistive divider' • setup
relative to the battery and the analog interface.
3    How might these affect the reading generated in the analog interface
given that it also has a resistor (R1 @ 2.2K)?
4    By reducing voltage am I going to overload the sensor input on my RCX
(i.e fry it with too much current)
5    Am I reinventing the wheel here, and a simpler way already exists to
measure voltage through a RCX on external battery sources.

Thanks for your time

Tom Beattie



Message has 3 Replies:
  Re: Voltage Sensor
 
Hello, (...) This idea, while in itself interesting, will not work when the 12V battery gets regulated down to 9V. This is because these 9V will barely vary across the regulator's permitted input range. If of course the regulator is specifically (...) (22 years ago, 16-Sep-02, to lugnet.robotics)
  Re: Voltage Sensor
 
(...) Thanks Dean, I had some thought in monitoring the battery level directly through RCX. But potentially I wanted to monitor multiple battery sources so I thought I might as well as develop an external sensor. Another thought was that the same (...) (22 years ago, 17-Sep-02, to lugnet.robotics)
  Re: Voltage Sensor
 
Tom, it is possible to also buy ready made voltage sensors for the RCX, see (URL) have used a most of the sensors from this company for data-logging purposes, but have not yet used the voltage sensor. If you would like more info, I can probably try (...) (22 years ago, 18-Sep-02, to lugnet.robotics)

Message is in Reply To:
  Voltage Sensor
 
Hello fellow Mindstomers, I am seeking some direction in the development of a Voltage Sensor I wish to use with my RCX. I have solar cell connected to a 12Volt (1.3A) sealed lead acid battery via a small trickle charger PCB (bought as a kit). The (...) (22 years ago, 16-Sep-02, to lugnet.robotics)

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