relay switch for 220V

HELLO ALL

I’do like to connect an AC to a 2 channels relay switch and then control it via esp8277>> —>blynk
The AC is 220v >>>—> 2 fazes 110v each

The question is: can i assign 2 relay channels into to a Single (one) Arduino pin ?
the reason for doing it is to be able to control the ac via one switch (relay& blYnk) instead of 2 switches
namely one switch for each faze, obviously i can’t put both fazes on one switch
Attachment

Thanks in advance

Yes... Maybe...

Is that a relay board with a relay driver? You can connect two relay coils together, but the Arduino can't supply enough current to drive even one relay coil.

Typically, you'd use a double-pole relay.

relay: SunFounder 2 Channel DC 5V ( link attached)

I have done completed one project with 110v Ac ( one faze) and it works
just wonder if i can do it by assigning one Arduino pin output into a into 2 relay Input channels relay
inputs (y splitter) it will enable me to create one virtual switch instead two,hence one switch for both 110v fazes instead a switch per faze

Yes, you can connect two relay driver inputs to one Arduino output so the two relays operate together.

There's a general rule (usually true) that you can connect inputs together but you shouldn't connect outputs together.

From the posted link:

5V 2-Channel Relay interface board, and each one needs 15-20mA Driver Current

30 ~ 40 mA is too much for 1 pin, I would connect each relay input to a separate output pin and switch them at the same time.

void setup()
{
  digitalWrite(relay1Pin,HIGH);
  digitalWrite(relay2Pin,HIGH);
  pinMode(relayPin1,OUTPUT);
  pinMode(relayPin2,OUTPUT);
}
void loop()
{
   relaysON();
   delay(2000);
   relaysOFF();
   delay(2000);
}

void relaysON()
{
   digitalWrite(relay1Pin,LOW);
   digitalWrite(relay2Pin,LOW);
}

void relaysOFF()
{
   digitalWrite(relay1Pin,HIGH);
   digitalWrite(relay2Pin,HIGH);
}

cheers All!

if when you say AC you mean air conditioner, then I would advise getting the full make and model of the unit so when it burns up, it will be easy to replace.

Air conditioiners use a compressor and have to run in cycles. one of the cycles is a gas eualibirum so that the refrigerant has a chance to equalize pressure throughout the entire system. for a window or wall unit, this only takes a few minutes.

But is you try to start the compressor while the pressures have not equalized, you can burn up the compressor.

On low end units there is no internal means to make that happen. The hysteresis (please look it up) of the thermostat will make it so that it will not restart shortly after finishing a cycle.

JCA34F:
From the posted link:30 ~ 40 mA is too much for 1 pin, I would connect each relay input to a separate output pin and switch them at the same time.

Many webshops seem to have copied this "30-40mA" mistake.

Those relays require 2mA drive (sink) current from the Arduino pin, and about 75mA coil current when active.
Leo..

Arrow008:
The AC is 220v >>>---> 2 fazes 110v each

AC phases don't add up like that, as they're normally 120° out of phase. You'd end up with about 180V between the two phases.

I don't understand what you're really trying to do here:

Why two relays? The only way this circuit would make sense is if there's some kind of load at the 2x 110V side, and then the relays are simply in series. A double pole relay would do the job just fine.

The relay module you linked to has a rated drive current of 15-20 mA. That's unusually low for a relay; unusually high for a signal, even if it's going through an optocoupler (a few mA should be enough here). As it's an Amazon listing, that description is probably simply wrong. If in doubt, just use two pins to control the two relays, and activate them together (two subsequent digitalWrite() calls).

Im new to Arduino as well as to programing so don’t know how to apply two subsequent digitalWrite() calls). but double pole relay .... great idea
Thanks!

Arrow008:
Im new to Arduino as well as to programing so don’t know how to apply two subsequent digitalWrite() calls).

Don’t overthink it.

  digitalWrite(RELAY1_PIN, HIGH);
  digitalWrite(RELAY2_PIN, HIGH);

AC phases don't add up like that, as they're normally 120° out of phase. You'd end up with about 180V between the two phases.

Household power here in the U.S. works exactly like that. I believe it's called "split phase".

Standard wall outlets are 120V. Half of the house is wired on one phase (with a neutral wire) the other half of the house is wired on the other phase.

240V appliances (stoves, dryers, electric water heaters) are wired across both phases.

Interesting. I never heard of that system before. I'm used to 3-phase power; 220V single phase. 380V between two phases. That's also why high voltage power lines always come in multiples of 3.

So then OP's picture starts to make more sense. The 2x 110V should be the power input side (two phases), the "AC 220V" is the load. Very confusing as AC can have multiple meanings here.

OP: do get a quality relay for this; those cheap made-in-China relays may be rated 10A but I wouldn't trust them on it. You probably have to derate them by half or more, just to be safe.