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Open and Practice Measurement with PC. |
Updated:25.12.2009
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USB devices
Wireless devices
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Wireless Voltmeter 0 - 50 V
RF voltmeter is a small module for
measuring DC voltage in range 0 - 50 V and transmitting data to the
computer. Data sent from the RF voltmeter are received with RF
receiver, which is connected to the PC via USB
cable and is also powered via this cable. Voltage values are displayed
on the monitor of a PC.
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Wireless Voltmeter
Range : 0 - 50 V
Power suply : from 2 Battery 1,5V ( or 2x NiCd 1,2V ) Sending frequency : ISM Band ( 868/915 MHz ) Paralel
connecting : up to 100 wirelles voltmeter connected is
possible |
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Wirelles voltmeter operates in free ISM Band 868/915 MHz and does not
need a license. Output power is 10 dBm. Sending range of voltmeters
depends on various factors. In the wild is at least 200m. The range is
mainly dependent on the antenna.This voltmeter uses simple wire
antenna.
Voltmeter is designed with regard to achieve good electrical parameters with the minimum requirements for hardware. It has a high input resistance and very good accuracy of measurement.
Accuracy of measurement is not dependent on the state of batteries. Even with the gradual discharging batteries voltmeter is also accurate.
Voltmeter is designed with regard to achieve good electrical parameters with the minimum requirements for hardware. It has a high input resistance and very good accuracy of measurement.
Accuracy of measurement is not dependent on the state of batteries. Even with the gradual discharging batteries voltmeter is also accurate.
Wireless voltmeter - schematic
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Voltmeter schematic
Wireless voltmeter is built
from components that
operates at low voltage 1,8 to 3,6 V. Therefore the power supply use 2
batteries 1,5 V ( or 1,2 V NiCd ). Current consumption is 12 mA/3V.
Voltage
measurement ensures a PIC16F886 microcontroller, which has an internal
A/D converter. The microcontroller also manages data transmission to PC.
At the input of voltmeter is precision operating amplifier, which ensures high input impedance. This operational amplifier requires higher voltage (3.3 V), therefore step-up DC/DC converter is used. |
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External power supply.
Voltmeter can work also with an
external voltage
+5 to +12 V. In that case batteries are not used and can be removed
from the voltmeter. Voltage from an external source is stabilized at
3,3V which is used throughout the voltmeter.
Software for wireless voltmeter
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Software features :
- shows the measured data
in PC
- RFMeasure allows to communicate with up to 100 wireless voltmeters at the same time - switches bandwidth 868 MHz or 915 MHz ( EU or US Band ) - allows to change the frequency on which voltmeter broadcasts - enables log data to file ( .csv ) - software includes API interface to build custom applications |
Software is available in the installation pack and installing is automatically. It works with Windows XP, Vista and Windows7.
Receiver for wireless voltmeter
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Receiver receives data from
voltmeter and sends
them via the USB interface to PC. Receiver is powered from a PC.
Installation is similar to the other USB devices. More about is on page
instalation.
Receiver configuration is performed in software RFMeasure. In the menu Settings/Receiver are settings for receiver. Receiver and wireless voltmeter broadcast with 10 dBm output. With this output power is the range in the wild at least 200m. |
More picture
Another voltmeters.
This page is still presented other
types of
voltmeters. It is the USB voltmeter and web voltmeter. USB voltmeter is
connected to the PC via USB cable and the web voltmeter measure voltage
remotely - via the internet.