Zero cross detector

136

01:47:28

Detect the zero cross of a signal.

published 6 years ago

hurz

6 years ago

nice idea, but do think it does work in real. I made a very little change check it yourself http://everycircuit.com/circuit/6139051403640832

OctavioNeblod

6 years ago

Yes, this works good in real, I've used it many times for some projects. Usually adding a transformer so I can use the small voltage on the secondary to power a μC (of course adding a regulator) and the signal of the opam, while the voltage in the primary is connected to the load I want to drive. About the change you made, did you only change the source voltage value?

hurz

6 years ago

In simulation its not, you have seen. Question why?

OctavioNeblod

6 years ago

Ah, now I see the problem, sometimes a low constant voltage in the positive input of the opam is enough to solve this problem, around 100mV for the example.

hurz

6 years ago

practical a diode into GND wire of OpAmp to lift the potential a little for the input? Cant be shown here in simulation.... so can you demonstrate your solution?

OctavioNeblod

6 years ago

Done

OctavioNeblod

6 years ago

As I mentioned before, to use this you need of a continuous power source, to turn on the OpAmp and usually also a regulator to power the components that will use the OpAmp signal, so there you can use a voltage divider as shown to get the correct signal, but in general, this circuit is used with higher voltages so that connection it's not needed

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