Hi! I have a very interesting problem. I have currently wired 2 5V relay chips and an HC12 communication board to an Arduino. When I load a blink sketch and flip the 2 5V relays on for 1 second then off, everything works well and repeatable. However, as soon as I use communication over the HC12 module to turn on those same relays, they won't turn on and the LED indicator is much weaker, showing me that not enough power is getting to it. Can anyone tell me if they know of something similar happening?
This smells a typical power shortage.
Please post a wiring diagram, not any Fritzing picture.
Yes, we see that phenomenon here, at least 10 times a week.
It’s the flagellator diode on the left.
If you reverse it, most problems should go away.
Hi, @midnight1798
Welcome to the forum.
Which LED indicator?
Where is it located?
What model Arduino are you using?
Do you have a DMM?
How are you powering your project?
Thanks.. Tom... 
As good an explanation as any, under the circumstances! 
But won't that make the Tri-axial DeKerfuffle Valve work in anti-phase?
Do that and you will instantly release the 1.21 JigaWatts, Armageddon.
Tom... 
I don’t think that’ll be a problem… we’re using DC, so the phase problem will only be on the outputs.
The polarity inversion gnaffler will protect the inputs.
Ohh of course it will......
Where did you get one, they are made of hen's teeth aren't they?
No, that is just a fowl rumour! 
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