12vdc solar differential controller

[EDDC]

greetings to all,

i have constructed two of these (www.TheFree InformationSociety - Di...o greater things. thanks in advance; eddc

 

[MikeMl]

Is **broken link removed**?

Try swapping the two LM34s, both where the are connected and which part the system they are in. If one has a lower output than the other, the one with the lower output should be in the tank.

Also, try increasing the 1meg resistors to 2.2meg or even 4.7meg. There may too much hysteresis.

 

[EDDC]

thanks for the reply mike;
you have the correct schematic. i swapped sensors, no change; these are normally very precise (& easy to burn up if one is half-asleep). changed one megs to 3.3meg &
unit now turns off two-three hrs after sunset. progress! oddly the LED turn-on indicator, controlled by the same signal but on a diff. quarter of the LM339 turns off at what seems to be the right time / temperature. i am wondering, as well, if the 10uf cap on the temp signal is maintaining that voltage for too long. not sure of its purpose other than a buffer, temp changes are not that fast. any other ideas will be appreciated.
ed c