Plug a wall wart right into Elk Analog Input ?

[shenandoah75]

I don't think there's any reason i shouldn't do this (just looking for clarification), i have a couple of 12V warts lying in a box. Was thinking i could use this on one of my expanders where i have no power supply, just 120V wall outlet. So i can chec output every minute or so, and use value < 9V or something this to trigger counters/rules when power goes out, such that i can get an email and see a dispay on the keypad with the total time it was out whn i get home.

That way i won't need a relay...

Will fast loop/slow loop apply on a type 34 zone?

-brad

 

[shenandoah75]

well - that didn't work...

Looks like the elk provides the 12V to the chennel... So whether or not a wart is plugged in, status is open with 13+ volts... Looks like i'm stuck using a 12v driven relay

-brad

 

[upstatemike]

well - that didn't work...

Looks like the elk provides the 12V to the chennel... So whether or not a wart is plugged in, status is open with 13+ volts... Looks like i'm stuck using a 12v driven relay

-brad

Even nice relays with screw terminals and LED status lights are only about $7. so why agonize over using a relay? I use at least 45 wall-wart/relay combinations to track the status of various things.

 

[shenandoah75]

Ya no big deal at all - just don't have the time to grab one before i head out for a couple of days...

-brad

 

[BraveSirRobbin]

well - that didn't work...

Looks like the elk provides the 12V to the chennel... So whether or not a wart is plugged in, status is open with 13+ volts... Looks like i'm stuck using a 12v driven relay

I think the pull up resistor may be biting you here!

Hmm, maybe series a resistor to get a voltage smaller than 12??? Just not sure.

 

[rocco]

Hmm, maybe series a resistor to get a voltage smaller than 12??? Just not sure.

Good idea. The pullup is 2k, so if you put a 1k resistor across the zone input, the analog voltage (without the wall-wart) will be between 4 and 5 volts. You can then use a wall-wart to bring the voltage up near 12 volts.

A 12 volt wall-wart (make sure it is DC) will push 12 milliamps through the 1k resistor, dissipating about 144 milliwatt, so make sure it's at least a 1/4 watt resistor.