I’m really confused and hoping someone can explain the relays to me.
Here’s what I see in my testing.
Hardware: Arduino Uno (same results with Nano), Songle SRD-05VDV-SL-C relay
Software: Only asking to turn on and off (to test):
// Turn relay on
// Turn relay off
Serial.println(" Relay OFF");
Results with multimeter:
Relay not connected (no wires, no power):
NO, C , NC; on board LED light is off (duh)
NO - no connection
NC - connected
Relay connected to power, but NOT switched at all:
NO, C , NC; on board LED light is on
NO - is connected
NC - not connected
Relay connected to power, AND switched OFF:
NO, C , NC; on board LED light is ON
NO - IS CONNECTED
NC - NOT connected
Relay connected to power, AND switched ON:
NO, C , NC; on board LED light is OFF
NO - NO CONNECTED
NC - IS connected
This is opposite of what I would expect. I assume:
if relay is either no powered or powered: the NO circuit would be unconnected and on board LED off
If relay is powered, but not switched on: the NO circuit would be unconnected and on board LED off
If relay is powered, and switched on: the NO circuit would be connected and on board LED on
Do I have the understanding correct? Am I really way off?
I can’t find any information on this on-line that talks about the various states.
My project works, but in reverse of what I want. Worst of all, if I take away the power, the relays allow power to the circuit to be ON. Not what I want.
Oh, and my relays do NOT have NO,C,NC indicators so assuming left to right: NO, C, NC
These are the symbols looking at the relay:
| | |
|_ \ _|
NO C NC
Please educate me on this. Thank you.