dnfh1949

Even more puzzled! Surely the code and the physical connections have to match? So if the code says trigPin = 7 then the trigPin on the U/S module must be connected to digital pin 7 of the Arduino? (equally having it connected to pin 13 of the Arduino would be fine if I changed the code to "const int trigPin = 13;"). is this not correct?

I am a little puzzled. Your code has trigPin on digital pin 7 (as output) and echoPin as digital pin 4 (as Input). But your schematic shows the ultrasound module connected to digital pins 13 and 12 respectively. Can you explain please?

Interesting project!Possibly I'm a bit new, but I couldn't see where the Arduino code was. Any clue?

Ah. I'd opened the link and saw the three folders but assumed it would be in Application. Just found it in DIY_Bluettoh_Smartplug!

Sounds really interesting and I will try it . If you are interested (ignore this if not!) I think there are only two very small "errors" in your English:"1. A distance sensor have 4 pins: " '1. The distance sensor has 4 pins.' "You can just take the mine to use it." Not quite sure what you mean, but I think it is 'Use my code is you wish.'

I would like to modify the circuit with a proximity reed switch so that the LED does NOT come on (or goes OFF) when a magnet gets near the proximity switch. I think I can just put the reed switch in series with the LDR. Would that work?

That should have been "in parallel"!! So that when the reed closes it shunts the +ve pin of the comparator (pin 7) to earth. But does it need a resistor in series with the reed switch to limit any current (I assume the value would be about the same as the dark resistance of the LDR)?

Could the circuit be modified to work the other way round, so that it switches ON in sunlight and OFF in dark? I suspect its v. simple, but so am I!