I’m not exactly sure what the purpose of your experiment would be. I’m not an electronics engineer. Perhaps you could clarify a bit. My fume extractor consists of a small step-down transformer, a rectifier, a 7812 volt regulator, a few smoothing caps and a 12v computer fan with a filter. I figure it’s pulling less than 1 amp. I also had my desk lamp (which draws 1.6 amps) in the master socket with no noticeable change. When it was working correctly, I could get the relay to turn on the slave sockets with just about anything. If there was something that was drawing too little current, the red LED would light up telling me to adjust the threshold trimmer, which would then turn on the slave sockets. Even if my fume extractor is pulling too few amps to trip the circuit, I would still expect some sort of reaction from the sensor. I’m actually a little surprised that there are no LEDs lighting up regardless of the condition of the sensor. Aside from the large Ohm reading, I’m not really too suspicious of the sensor. Since I know the least about that part, and everything else is testing OK, I was naturally curious to find out how I could test it. Even though the LM358 is testing good with my simple op amp tester (see attachment) I suppose it could be failing in other important areas. Other than that, I can’t seem to find any suspicious components. I suppose I could start pulling out all the diodes and testing them one by one out of circuit.
I’m a bit of a beginner regarding transformers. I have a box full of small transformers that I pulled out of switch mode power supplies. I also have a lot of inductors and chokes. My (home made) LC meter won’t go up that high in the millihenry range. The biggest transformer I have gives me a 34 millihenry reading with .9 Ohms. Of course, at such low Ohms, I might have to subtract the impedance of the test leads. Most of my other transformers and inductors are in the microhenry range, but I haven’t found one yet that tests above 1 Ohm with my multimeter. I’m assuming Ohms and Henrys don’t have a linear relationship. I was hoping I could test the sensor out of circuit because I don’t really have confidence that the rest is working properly. Anyway, back to your idea…
Measuring across the 1K Ohm resistor with the power strip on (no load in the master) I get 0v AC. With my desk lamp as a load in the master, I get .102v AC. Just for fun, I did the same thing with the fume extractor and I got .027v AC, so I guess there is a big difference. The fume extractor is grounded and the lamp is not, so that may be a factor. Needless to say, the relay didn’t switch on in either case. At least I got some sort of reading for the first time, so that’s good news.
I have some toroids here but I doubt that I could get 1000 turns on any of them. Even If I could, there would be no more room for a mains wire to go through the middle. The other toroids I salvaged are wound with relatively thick wire. I’d say the one with the most wire has about 100 turns on it. It gives me a reading of 380uH with a resistance of .4 Ohms.
I’m not sure what you mean with the series resistors connected to the 1K/47K junction. If I put two 470k resistors in series (940K) with the (230vAC) line, that should inject .24 microamps into that junction. Is that what I would usually expect from a Hall sensor? What should the result be if everything except the sensor is working? I find it interesting that there are already two 470k resistors in series (just to the right of the green LED) between neutral and the rectifier diodes. By the way, I shorted the negative of the right (24v) electrolytic cap to the collector of the c9013 NPN transistor thereby bypassing the sensor circuitry. As expected the relay switched on, the green LED lit up, and the slave sockets received 230v AC. That rules out the relay at least.