Relay and Determining the State of the Relay

[dorothymacapayag]

Hi everyone! This is a set-up for switching our relay and determining the state of the relay. The problem is that if multiple loads (2 or more) are already connected in parallel, the load (which is a light bulb) won't follow through the command, say we wanted to switch on the bulb, the light bulb won't switch on unless all relays are commanded to switch on their respective loads.

The connection from the common of the relay to the arduino analog pin is used to determine the state of the relay.

Is it possible that there is something WRONG with our set-up or the way we connected the common of the relay to the led and the analog pin? If so, what alternate routing or connection could I do? Any suggestions/advise/recommendation?

 

[BradtheRad]

Does that icon, at the left-hand of your schematic, indicate an AC power supply?

I'm running a simulation. I see something that may be unexpected.

There is a pin marked 'VIN' on your IC. Is it supposed to receive negative voltage at any time? I ask because negative polarity is applied to that pin under these conditions:

(a) one relay energized, the other relay idle, and
(b) during the half of the cycle when the AC supply goes negative.