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1.0 Introduction to AVRD
The adjustable - regulated power supplies in the electronics industry are seldom available
for field applications, yet is possible to find adjustable versions, which are good for small
labs and indoor application. In these cases the voltage regulation may be good, and the
voltage adjustment may be within the range, however if AC power is lost for a few moments,
again there is certainly a loss of data as well as false readings due to the heat lost during
a brownout. Thus the best field solution is to have a battery charging source or solar panel
supplying current to a suitable battery, which in turn supplies the datalogger with a primary
(or backup) source of power, and then regulate the battery output to the sensors as needed.
In this application, the solar or battery charger source can vary significantly, the battery has
a significant reserve capacity, and yet the sensors power source is regulated and will not
fluctuate.
The new AVRD is a dual adjustable voltage regulator for supplying excitation power to
sensor heater elements. This can be used as a general-purpose regulator for powering
dc systems or for exciting sensors with voltages in the range of 1-10 VDC and current not
exceeding 5A on each channel (10A combined). Refer to specifications for more detailed
voltage and current parameters. New AVRD uses a Step-down switching controller with
external FET switch and frequency control, enabling the regulator to achieve higher current
and higher efficiency. In addition AVRD circuit is designed to dissipate the excess heat from
the switching with in the circuit thus eliminating the necessity of bulky heat sinks or cooling
systems. User can connect input source and the heater element s to the quick terminal
simply by inserting wire in the appropriate terminal slot and use screwdriver to secure the
wire properly. AVRD operates at a constant frequency of 330 KHz in the voltage range 2.5V
– 8.5V. This range being most commonly used excitation voltage for Dynamax sensors. A
constant frequency operation enables the AVRD to achieve better stability and higher input
output power efficiency.