Figure 9-4 Controlling Externally Powered Relays - Keithley 2701 User Manual

Model 2701 User's Manual
Figure 9-4
Controlling externally powered relays
33V
Digital Output #1
Flyback Diode
Control
Line
Equivalent Circuit
Flyback Relay
Diode Coil
Model 2701
+5V
4.75kW
Pull Up Resistor
+
External Power
(+5V to +33V)
-
Transistor Switch
Limits and Digital I/O
Pin 7 - Diode Clamp
Relay
Coil
Digital Output
Pin 9 - Digital Ground
9-9
+
External Power
(+5V to +33V)
-