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3 phase checker w/o microcontroller

Thread starter #1
Trying to simulate a 3 phase checker using multisim. i am not getting a high and low on output to change light colour. I have not included pins 7 and 14 because the simulator was putting them as inputs to the gate instead of power and ground pins. Thank you in advance.



Well-Known Member
And, what do you suppose you will accomplish with that bit of combination logic? You need to find out the timing, which phase goes follows the first one. Old meters did it basically with only one RC filter and an LED.
Thread starter #5
Well I did not create this circuit, it was online and I was trying to replicate it in real life. However, I wanted to use this model and fix it to work. At this point I am trying to get a high and low output on pin 11 of the 4011 Quad NAND Gate.


Well-Known Member
Most Helpful Member
Below is my LTspice simulation of the circuit, which appears to work properly.
V11 (orange trace) pulses low at the line frequency with the shown phase sequence (both LED rapidly blinking).
An incorrect sequence or a missing phase generates a constant high at V11 (LED D8 constantly ON).

Note the the CD4011 can't readily drive such a low impedance load, as shown in your circuit, so I modified the LED driver (makes me think the circuit was never built by the author).


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