LTolledo wrote: ↑
Sat Jul 13, 2019 2:49 am
ok lets try first the relay without the RPi
for this "experiment" we will need a 3.3v breadboard power supply, and a breadboard.
connect the Vcc to +3.3v
connect the GND to GND
dont connect anything to the output yet.
power on the breadboard power supply
get another GND wire and touch either IN1 or IN2
does an LED on that board light up when you touch the GND wire to IN1 or IN2?
if not, then the board cannot operate on 3.3v
if it does, then connect the LED to the output (lets say on Relay 1 [IN1])
GND --- 120ohm resistor ---- NO contact
Common --- 3.3v
now try touching the GND wire again to IN1, does the LED on the relay output side light up?
if it doesn't the relay may be faulty, try Relay2 [IN2]
if it lights up then the relay board works.
one way to check if the relay is actually activating is to "feel" the relay. If you feel something moves inside then the relay activates
if you dont feel anything even if the indicator lights up, the relay is not activating due to insufficient voltage (3.3v)
most of these relays boards are "active low" meaning a GND state on the IN pins turns on the relay while a +3.3v turns off the relay.
you need to remember this when making a program on your RPi to activate the relay....
have a similar relay board and tried all of the above... so that means I know what I wrote and not just some guesswork...