Photoresistor Daylight Switch

oh wait - duh! I was thinking I couldn't test it until I got the photo resistors I ordered. But assuming they closely resemble the datasheet, I can emulate the photoresistor the same way I did in the simulation. I still appreciate any comments/suggestions

Might look over automotive switches, heat elements, and schematics for off the shelf module?

I already have the heat element attached to the birdbath and insulated. I got a 15C switch but ordered two more at 2C and 5C and just ordered the photoresistors. (I also tested the circuit and it appears to work, but hooked a heatsink on the mosfet to be safe at 15W)

Your photo-resistor is going to act like a variable resistor for voltage to the mosfet gate. Various gate voltages per cloud/sun is not like a straight on/off switch for your mosfet/heater (which you are simulating here with two fixed resistors). Your heater is probably not designed to work on varying voltage/current which will occur throughout each day as per this changing gate voltage, which will be reflected in the drain voltage/current to your heater load.

Being able to calculate your load drain current at any time may be something that you wish to look in to in the future. It involves the Width, Length and KP of your settings, along with the drain voltage, lambda, and Vov: (Vgs - VTO).... which can be matched to a datasheet mosfet setup, with the help there of the given Rds(on) with its matching Vov etc.... and then turn it completely on/off instantly at your chosen current or voltage point. You might want to seek a comparator circuit for now, using a 555 (or 7555) timer or op-amp with your mosfet driven heater output for your photoresistor.

I added an indicator LED to know when the photo-resistor part of the circuit/FET is active and then added a switch and LED for the power line itself as I also intend to use an NC thermal switch to turn the entire circuit off whenever the water is above freezing.

@treii28. Don't listen yo anything 2ctiby says..he is a troll,, misleading users , pretending he is an expert...lenzulz is his team mate.....they keep tslking sbout God and religeon,,, perhaps they are a pair of charlatans...just check thrir posts history and their circuit...

lol I didn't even notice as I've already tested and confirmed the circuit - now I'm just tweaking it for minimum power drain and color coding of the led indicators. I added the switch on the left side to represent a bi-metallic NC 0 degree C switch that will detect the water temperature. I also have a 5 C one if 0C is too cold to switch off. I switched the LED on the right to orange to let me know when the heating element is on (daylight and -0C)

I also found it works better with a second resistor off the bottom of the opto-resistor.

@all users ... Hurz demands subservience in every, yes every aspect of electronics. If you show signs of knowing more than him in so much as one aspect, then the trio of hurz/zorgrian/kiani will set about insulting you etc in an effort to drive you out, or force you to actively show submissive stature... If you get on ok with hurz, then you have either been seen as obviously knowing less in every aspect, or you have compromised yourself and shown him that you are submissive to him... Be honest with yourself ... Have you yielded to his imposed superiority even though you know more about a particular aspect?  No one know best about everything ... but hurz believes that he does, and you will be forced to believe that too on EC.... or suffer the consequences.

Back in October last year, kiani placed abusive lies and insults on virtually every production that I have ever placed on EC  and he continues to update that abuse recently ... eg:  http://everycircuit.com/circuit/5245744790634496     ... http://everycircuit.com/circuit/5283024345759744  ...    http://everycircuit.com/circuit/6594722429403136   ...   etc.

I do not intend to spend my life here bickering on EC with a know-all like hurz. ... Individuals must decide whether to be subservient to him or not ... Those who submit themselves to him will never be able to voice an opinion which contradicts his view. Then you must always abide by everything he says ... and that may well influence your life path outside EC, which in my opinion would be towards a hell hole, with his partner zorgrian and their puppet kiani.