Using a 120vac coil current relay to switch +3.3vdc

When you say the "relay latches", I assume that you are not meaning that you require a latching relay, which is a relay type in its own right. If you just require an ordinary relay, which will only keep the contacts closed while power is on the coil, check out the Omron G2R series, they have 110V AC coils available, and a max switching contact resistance of 30milli ohms, (measured at 5V, 1 amp),
cheers,
Richard

Hi yes I thought I got rid of "latch" but guess I left in there by mistake. I do not need a latching relay. :)

Thanks I will check them out. :)

Do you know if those contacts are silver? I cannot find a description in the spec sheet. Because the load is only +3.3vdc under 1 amp supposedly copper and or gold contacts will wear out due to not being able to self clean.

Hi all,

We have ancient analog/solid state equipment and are converting the equipment over to digital operation while maintaining the analog operations side as it is extremely reliable. The equipment only runs on 120vac and has several 120vac motors and solenoids that control various aspects of it's operations. 

I have designed a microcontroller that interfaces with the machine and gets certain machine vitals and run times. 

The microcontroller is currently using switches to detect the key operations it is tracking, it is OK but it adds complexity and cost for maintenance and for integration and certain employees disable the switches so it prevents the machine lockouts from functioning. This is not OK. 

So what I would like to do is use 120vac coil relays which when the AC current passes through the coils the relay closed and acts as a switch. I have a test system setup with cheap off the shelf relays but I am having trouble finding 120vac relays with switched load contacts that will handle the small voltage/current of the microcontroller reliably. Does anyone have any leads? I have tried to work with digi-key but the tech reps their get confused thinking I want to switch 120vac with +3.3vdc relays so then they talk down to me and tell me I don't know what I am doing. 

Thank you for your help. 

 

page 5, contacts, contact material, silver alloy, cadmium free.
You may find smaller relays, but voltage breakdown (creepage and clearance) may be compromised, sort of thing you need to be aware of.
Cheers,
Richard