Hello,
can anyone help out?
Trying to make wifi relay controle, I have connected everything correctly like schematic, Blynk connects to board, but it only light up LED in Relay module, i doesnt open relays( no clicking noise) . Same goes for 2 way relay and don't know why but sigle relay LED doesnt light up.
Please provide a schematic. How are you powering the relays ?
Ok, i would have preferred if you would have made your own schematic (copying what you have actually connected sometimes shows what is wrong) but anyway this is quite clear.
Now the nodeMCU requires up to 300mA, and the relays may use up to 75mA each. How big is your power supply ?
These type of relay boards use opto-couplers to drive the relay, and sometimes the 3.3v logic level that the nodeMCU provides isn't enough. Not only that, usually they are 'active LOW' , which means that the opto-coupler gets power from the 5v input and if the nodeMCU pin goes LOW it sinks the current that goes through the opto-coupler. But that would be 5v !! that is not good for the nodeMCU.
And the current limiting resistor in line with the GPIO and the opto-coupler may be set for 5v and therefore to big.
You need to do some testing for me.
Depending on the result of these tests, there are possible action to take.
Please provide a 'good' close-up of the relay board, without any of the wires attached, so we can read the silk-print.
No, it is actually totally necessary. Note the circuit of the opto-coupled relay module.
The voltage drop of the two LEDs prevents more than about 2 V appearing on the ESP pin.
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