Hello Again,
Still not much luck I'm afraid. I followed your suggestion Mike and I connected the circuit to a 12v transformer instead of using the wind turbine controller power supply. I then connected the negative side of the battery bank to the ground of the 555 circuit. However, when I connected the positive side of the battery bank to the circuit there was a large spark and quite a bit of smoke. It looks like the voltage division resistors have got cooked, probably not surprising since they were connected directly between the two battery bank terminals...
I reran the simulation and checked the power dissipation in R1 and R3. It is only 120mW worst case, so even a 1/4w resistor should have been ok. I suspect that the resistors you used for R1 and R3 could not stand ~240V, so here is my suggestion: Put three or four 1/4W metal film resistors in series, such that R1 totals 630K and R3 totals 590K. This will keep the voltage across each resistor to less than a hundred volts.**broken link removed**. What style of resistors did you use for R1 and R3?
The "transformer" used to power this circuit should be a mains-powered plug-in charger or power supply that puts out 15V to 20V DC. That goes into the input of the LM7812 voltage regulator to make the regulated 12V to power the 555. The accuracy of the trip points is directly a function of the voltage at the 555 pin 8. If this voltage is 3% low, then the trip points will also be 3% low, etc.
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