Hello Arduino fans.
Looking for some guidance in regards to using a 220V AC relay in a 120V AC home. Its just that these 220V AC relays are less expensive and wondering if they will work with 120V AC. Just to note that it is AC currrent that activates/deactivates the relay in question.
Thanks for taking the time.
What makes you say it is AC current that activates the relay?
I think you will find it is a 12V or 24V DC signal that operates it.
As long as you are not putting more than 10A through the relay it will work fine switching 220VAC or 120VAC.
It is an electomechanical relay. You might want to look at optoisolated solid state devices.
This is the kind of relay that take 220V AC to activate the circuit. This is not a DC activated relay.
This is why I am asking. I am looking to make a circuit that will activate/deactivate a relay or switch in response to a general AC power failure. I wish to activate a DC battery operated light probably at 9 Volt DC.
I am also considering using a 5 volt DC relay powered via an AC wall USB charger.
No, the coil requires 220VAC to operate.
It's not hard to find relays with 120VAC coils, but I recommend buying from a reputable/reliable supplier that gives you a manufacturer & model number and a link to the manufacturer's datasheet.
The [u]datasheet[/u] for the Omron LY series says the "must operate" voltage is 80% of the rated voltage.
DVDdoug:
No, the coil requires 220VAC to operate.It's not hard to find relays with 120VAC coils, but I recommend buying from a reputable/reliable supplier that gives you a manufacturer & model number and a link to the manufacturer's datasheet.
The [u]datasheet[/u] for the Omron LY series says the "must operate" voltage is 80% of the rated voltage.
Great info. Thanks
Hi opale7000.
You had this same line of thought going on another thread.
12 Volt car battery emergency light
Why have you started another on what looks to be the same topic?
opale7000:
I am also considering using a 5 volt DC relay powered via an AC wall USB charger.
Would be my preference.
If the circuit is low voltage simply operate direct.
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op's
If you use the Golden Rule of application-application-application
you do not start at cost, you start at need.
what is the power/current/voltage you need to SWITCH
and what is (are) the most available power sources that do not need alteration such as transformer or power supplies.
and of course what do you have to switch them.
if you are doing the EM ergency light, you only need a 120V coil and nothing else.
if you happened to look up emergency light schematics, you would have found it is just connecting the relay to the lines voltage and nothing else. an indicator light adds a nice touch.
Op's line voltage is 120vac.
12v not much use.
bluejets:
Op's line voltage is 120vac.
12v not much use.
That depends on the application, now doesn't it.
It is much more useful than a 220v relay with 120v
If, for instance, the OP wanted to have a relay that was powered all the time.
all that is needed is a simple wall-wart to the relay.
and, if for example, then there is a loss of power, the relay fails to the un-energized state and the battery is now connected by the contacts to the LED lights.
When power is restored, the wall wart will recive power, then energize the coil and the relay contacts will open and the LED battery will be disconnected.
by connecting the battery charger to the same relay, the battery would be charging when there is mains power, and then light the LED when there is a power loss.
in the above example, the 12V power could be the source for the battery charger as well.
opale7000:
This is the kind of relay that take 220V AC to activate the circuit. This is not a DC activated relay.This is why I am asking. I am looking to make a circuit that will activate/deactivate a relay or switch in response to a general AC power failure. I wish to activate a DC battery operated light probably at 9 Volt DC.
I am also considering using a 5 volt DC relay powered via an AC wall USB charger.
Sorry, my mistake. The page you originally linked to does say "Control Voltage(V) :220VAC".
The partumbers are quite complicated, I did not find a full datasheet.
Even in the datasheet quoted by @DVDdoug I cannot see LY2NJ
dave-in-nj:
That depends on the application, now doesn't it.
It is much more useful than a 220v relay with 120v
If, for instance, the OP wanted to have a relay that was powered all the time.
all that is needed is a simple wall-wart to the relay.
That was my suggestion in #6.
this is such a long project for something that is sooo simple.
120V relay, on 120V line. end of story. spend the extra 30 cents.
switching the battery pack to turn on the LED lights is also a no-brainer.
no capacitors, no resistors, no microcontrollers. just one relay and some wire and Bob's your uncle.
well, SAVE 54 cents !!
if this project takes you more than 5 minutes, you are missing something very-very simple.
with the 120 to the coil, the relay is activated.
with the relay activated, the contacts are on the N/O output
when there is a power failure, the relay changes state to the non-powered condition and the N/C normally closed terminal will have the battery power.
the LED connected to the battery and the relay.
the battery connected to the LED and relay.
if you do not have a 120V relay now, but you do have a 5V DC, then get a phone charger and power the relay.
this is how it is done in every commercial building in the USA.
required over each exit door, and every so many sq feet for emergency lighting as required by fire code.
the EXIT or EMERGENCY lights also have a battery charging circuit that is connected when there is power, but that is easy enough if you use a DPDT relay and use the relay to also isolate the battery when there is 120V power.
remember, there is no direction on a relay, you can connect one wire to either comm or NC, or to NC or comm, whichever is easier or offers you the most benifit.
with a DPDT relay, the other pole can be how you connect the charger to the battery when 120V is present.
