Relay Shield Only has 4 switches. How can I access at least 8


This is my first time posting to the spark forum. Have read a lot of other posts and really appreciated the knowledge out there.

I’m building an automated systems project for a small woodland orchard and need to control at least 8 water lines. the Relay shield that spark sells only allows for four. Any ideas out there how I can access at least 8? And if at all possible I would like to have a few lines available for input like temperature and water flow. It seems a bit sad to lock up all 16 lines for only 4 usable ones.

1 Like

If you look at the PCB files, you’ll notice that we have exposed all of the I/Os on the Spark Core via 0.1" header holes. This should allow the user to connect additional hardware by simply soldering/connecting them to these holes.

You could try something like this (I have no affiliation to this, I just searched):

This is 5V relay module so you will to either find a 3V one or also get a level shifter to convert 3.3V outputs to 5V outputs. This module looks like it has opto-isolators (which is good) and so it might just work on 3.3V.

Relays are really easy to control–the only issues with building it yourself would be separating the voltages (you didn’t say if the orchard control was 12V, 24V or 120V) and making sure the relays don’t harm the :spark: core since they can produce voltage spikes that these shields and boards usually take care of.

Good luck!

1 Like

Cool. Thanks bko. I’m new to the whole electrical side of life so I’m learning how all this works. But it sounds like its possible.

1 Like