User`s guide

309
Chapter 7 Tutorial
Actuators and General-Purpose Switching
4
7
Using Attenuators
Provisions have been made on the 34903A circuit board for installing
simple attenuators or filter networks. An attenuator is composed of two
resistors that act as a voltage divider. A typical attenuator circuit is
shown below.
To select the attenuator components, use the following equation:
One typical use for the shunt component is with 4 to 20 mA transducers.
A 50, ±1%, 0.5 watt resistor can be installed in the R2 location. The
resultant voltage drop (transducer current through the resistor) can be
measured by the internal DMM. Thus, the 50 resistor converts the 4 to
20 mA current to a 0.2 to 1 volt signal.
R1
R2
V
signal
V
att
HI
LO
V
att
V
signal
R
2
R
1
R
2
+
--------------------
=
34970A Refresh UG.book Page 309 Wednesday, February 17, 2010 12:34 PM