Relay basics
Each relay has three corresponding terminals: NO,
COM, NC. This means Normally Open, Common,
Normally Closed. When the input signal
corresponding to the relay is low the COM terminal
will be connected with the NC terminal. When the
input signal corresponding to the relay is high the
COM terminal will be connected with the NO
terminal.
The board is equipped with 4 high quality Schrack
general purpose relays from TE Connectivity. These
are rated 250V AC 16A and tested 25V DC 10A (non-
inductive; operating DC loads may shorten lifespan
of the relays and is not advised for prolonged
periods).
Never touch the relay module when
connected to high voltage! Potential damage
by electric shock depends on the human body
resistance. Generally up to 36V is considered to be
safe for the human body. A voltage of 50V and above
is considered hazardous and can already be life-
threatening!
