Figure 99. Current sourcing from C terminals configured for control
8.2.7.2 Relays and Relay Drivers
Read More For more information see appendix Relay Drivers Modules List (p.
649).
Several relay drivers are manufactured by Campbell Scientific. Compatible,
inexpensive, and reliable single-channel relay drivers for a wide range of loads are
also available from electronic vendors such as Crydom, Newark, and Mouser
(p.
534).
8.2.7.3 Component-Built Relays
Figure Relay Driver Circuit with Relay (p. 370) shows a typical relay driver circuit
in conjunction with a coil driven relay, which may be used to switch external
power to a device. In this example, when the terminal configured for control is set
high, 12 Vdc from the datalogger passes through the relay coil, closing the relay
which completes the power circuit and turns on the fan.
In other applications, it may be desirable to simply switch power to a device
without going through a relay. Figure Power Switching without Relay
(p. 370)
illustrates this. If the device to be powered draws in excess of 75 mA at room
temperature (limit of the 2N2907A medium power transistor), the use of a relay is
required.
369
To Next Page
Loading...
Need help?
General
