Controlling a Relay with a Microprocessor

August 14, 2018
Tech Tuesday

Here at FDI, we strive to provide you with a variety of logic controls for all your applications involving relays. These range from our Fan Safety Alarm Circuits, to our I/O Expanders and even our Network Compatible Devices. But what do you use when you have an application of your own? A 5V microprocessor can’t exactly drive the coil of a RIBU1C. Is there a relay that can be controlled by a micro?

The answer is yes! Or at least kinda yes…. The lowest coil voltage we offer on any of our relays is 10V like on the RIBU1C, but we do have our Low Input/Opto-isolated Relays. These relays can be found in our catalog by looking for the prefix in the part name “RIBTE” or “RIBME.” The low input relays are great because while they still require a higher voltage for the coil, they have a separate input for a control voltage ranging from 5-25Vac/dc. Which means you can now control a 1/2HP motor with your Arduino or Raspberry PI. 

Here’s a quick diagram showing how to drive a load with a 5V microprocessor and the RIBTE01B:

And that’s not the only thing the low input relays can do! For example, if you have two control voltages ranging from 10-24V, a relay like the RIBTELC could be viewed as a logical AND gate relay. That means the load won’t switch on unless both control voltages are present. The low input relays come in SPDT, DPDT, with manual overrides and with either a housing or modular version. So, a large variety of applications can be achieved with this series. As always though, if you’re not exactly sure on how to go about your application, you can always call or email us here at Tech Support!


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About the Author

Tym Moore is an Electrical Engineer who hails from the best state of Colorado.
He graduated from Colorado State University in 2017 and moved to Indiana shortly afterward to marry his now wife. Outside of work, Tym spends most of his time driving back home, and complaining about how flat Indiana is.

Be sure to give Tym a call for tech support. He will always do his best to find a solution for you.