Programming instructions

Variable Capacitor
 National Instruments Corporation 2-33 Multisim Component Reference Guide
2.12.1 Model
The energizing coil of the relay is modeled as an inductor, and the relay’s switching contact is
modeled as resistors
R
1
and R
2
.
2.12.2 Characteristic Equation
R
1
= 0
R
2 = • if ip ≤ ion
R
1
= •
R
2 = 0 if ihd < ion ≤ ip
where:
L = inductance of the relay energizing coil, in henrys
R
1
, R
2
= resistance of the relay’s switching contact, in ohms
i
on
= turn-on current, in amperes
i
hd
= holding current, in amperes
i
p
= current through the energizing coil, in amperes
2.13 Variable Capacitor
The variable capacitor acts much like a regular capacitor, except that you can adjust its value
using the keyboard or by hovering the cursor over the device and moving the slider bar that
appears.
 To set up the variable capacitor:
1. Double-click on the variable capacitor and select the Value tab.
2. Enter the desired maximum capacitance for the device in the Capacitance field.
3. Enter the Key that will change the variable capacitor’s value when pressed.
ComponentRef.book Page 33 Thursday, December 7, 2006 10:12 AM