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Hello guys, seeking help for W1209 Problem.
Using 2 W1209s to switch on a fan. See attached circuit.
Power supplied by solar panel (12v12w) powers up board one when enough sunlight.
When board 1 (Top) turns on it will switch relay on at 18 degrees.
This powers up Board 2 (bottom) and if temp is less than 24 degrees the fan is also powered up.
Board 2 is set to turn fan off at 24 degrees.

I tried this configuration using a 12 battery as supply. It worked but only for a few seconds.
Board 2 was flashing something and FAN seemed to stop and start.

After a couple of seconds everything went dead, Board 1 is now dead (wont power up)
Haven't checked to see if board 2 is still usable.

Is this circuit feasible or am I doing it wrong.
Any help would be much appreciated.

Sorry about poor circuit diagram - only a beginner.

Many Thanks
Ralph Walsh

Is this circuit feasible or am I doing it wrong.
Any help would be much appreciated.

I can’t see anything wrong with your schematic.

Is your battery by any chance a Lead acid? If so I would suggest checking its voltage as lead acids tend to have a voltage that is significantly higher than their nominal rated voltage when charged. For this temperature controller I would not supply it anything over 12.5V.