Relayboard

[kwame]

Hi
folks, i have bought an optico isolated relay board for a project.The relay is going to wired to thermostat.I done majority of the work.What is left now is how to wire the alarm.I want the alarm to sound when tempereture rises too high or goes too low and when there is power failure.
The problem is the alarm uses 12VDC (it runs on car battery)whilst the output of relay board (fitted with general purpose relay)is 240VAC.I am the 240VAC will damage the alarm .I have seen this type of thing work somewhere else some years back.I heard it is called 'battery backed control circuit'.
I do not know how wire to leads and whether to use 'NC' or 'NO' contacts.
Any questions welcome!

 

[Reloadron]

One problem you will have is what is going to happen while whatever you are heating is coming up to temperature? You will have a LOW ALARM. What is this thermostat controller and what outputs does it have? You really aren't giving us much to work with.

Ron

 

[kwame]

When that happens the temperature can take care of that automatically.That sholud not be a problem at all.All i want is for the siren to sound.The thermostat is multi stage digital thermostat 12VDC.

 

[kwame]

When temperature rises too high beyond set point/value the 'high temperature alarm' should sound.Conversely when temperature falls below the set value/ range the 'low temperature alarm' should sound.When there is power failure too the siren should sound.

 

[Reloadron]

Does the controller have an output for O/T (Over Temperature)? Can you provide a schematic? Multi-Stage digital thermostat doesn't tell anyone much. The temperature will be blow set point till it gets to setpoint so logically you will have an alarm until you exceed whatever the lower limit is.


Ron