# Logic gate circuit to close when sensor signal turns ON and then OFF, but must ignore another ON?

I am trying to put a permanent magnet in a transformer between both coils, so that the transformer can utilize the flux from the permanent magnet by guiding its flux periodically.

We have one primary coil that will change the direction of the flux from permanent magnet towards the other secondary coils one by one. I want primary coil to change polarity when the first secondary coil rate of change of flux becomes zero.

So I'll put a reed switch to detect the magnetic field that causes inducing of voltage into secondary coil. I want another switch named switch A to turn ON, when reed switch turns OFF after turning ON, but when the same reed switch turns ON (and OFF) again (on collapsing the magnetic field in secondary coil) the switch A should do nothing. And then how would I reset the reed switch to detect the change in magnetic field again?

Timing diagram (edited on request).

              __    __    __    __    __    __    __    __    __
Reed  ___|  |__|  |__|  |__|  |__|  |__|  |__|  |__|  |__|  |__

__          __          __          __          __
Switch A  ______|  |________|  |________|  |________|  |________|


I couldn't find it on internet, can somebody please draw the circuit to achieve the same?

• The magnet's flux will not be converted to electricity - it will just bias the magnetic field and possibly cause core saturation when the added flux from the input signal is of the same polarity. – Andy aka Aug 6 '20 at 9:07
• Good luck with it. – Andy aka Aug 6 '20 at 9:11
• I've added in a timing diagram showing the switch sequencing and reset functions but you need to edit it to clarify what you want and how to reset it. – Transistor Aug 6 '20 at 9:31
• When you use electricity to generate electricity, it's called a "transformer". The permanent magnets add nothing to the process, and you can't get more power out than what you put in -- as long as you avoid saturation, it's about as efficient as any other transformer that uses more conventional construction. – Dave Tweed Aug 6 '20 at 10:39
• For prototyping purposes, I'd just use an Arduino – user253751 Aug 10 '20 at 19:00