Connecting relay modules

Question

Hello All,

As the title says, my goal is to control relay modules. I understand how to connect the modules directly to the mega, but I do not want to use 1 pin for each relay. Under Digital Output,Tech notes, I see a solution is provided using a DM13A... but from the reference given, I am sure I would blow something up. Can someone post a rough schematic of how I would use a DM13A to control these modules?

For my application, my first thought was to use a standard multiplexer board in an output configuration for control. However, I have not seen any examples of this for reference. Am I safe to assume, as long as the relay module has a buffered input, I can use the multiplexer board as well?

Thanks,

Jon

Answer 1

Jon,

It's described here: http://realsimcontrol.com/io_led.html
You can use dm13a outputs but see the notes below about pull-up resistor on DM13A output to create digital output.
So, simply use a resistor and connect output to your relay input.

Note, that this will be "inverted" outputs, when the output is ON it means logical "0" , when OFF - it's logical "1"

2) You can not use the multiplexer for "static" outputs because it's not "memory-type" device.
It used for outputs  only as extension for data packet-controlled devices (as MAx7219 controllers)

Vlad