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Old 02-09-20, 11:14 PM   #21
NiHaoMike
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I'm still working on getting the PLC transmitter to work as I want it to. The CD4046 did not really perform that much better than the 74LV4046A since it was getting pushed close to its operating frequency limit, what performed the best was the 74LV4046A with a very carefully tuned VCO circuit. Next comes the compander circuit, which I'm going to base around photoresistors illuminated by LEDs as the basis for a variable gain cell. I'll have to tune the gain control rates to get the best overall signal. (This is very much getting up to the Jim Williams level of analog circuit design!)

To help with testing, I have built a current signal simulator by connecting a coil of wire to an audio amplifier that I can play signals through with a PC. With 100 turns, the amplifier will only have to source 2A to emulate a 200A current.

I also got a 90A contactor that will be used to connect the grid, running the coil from 240V AC as intended, it uses 12W just to stay on and buzzes pretty loudly. But if I use a 170V DC pulse to turn it on and then supply 12V DC to hold it on, it's silent after switching on and uses just 0.8W! (I selected the voltage based on the current that was drawn when powered from AC. I have found that even in its worst case orientation, it will stay on with a mere 4V applied to the coil.)

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