Magnetic Polarity Indicator

Bring to your attention a curious device invented by me - an indicator of polarity of the magnet. That inspired me to create it: the construction of my **broken link removed** as well as the desire to practice to get acquainted with modern operational amplifiers (current does not require a bipolar power supply, which is very convenient).
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Works this device this: when power is on (battery 6F22 9 V) green light. If near the **broken link removed** no magnet, the blue and red LEDs do not light.
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When approaching the north pole of a magnet to the sensor lights up blue LED
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and southern - red.
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If you rotate the rotor brushless motor near the sensor, then the blue and red lights alternate, corresponding to passing by the poles of a magnet - it is convenient for determining the number of poles.
Circuit and photo of the PCB - **broken link removed**

what chip did you use?
what is the range? Or how strong does the magnet need to be?

Hall sensor (4 pin) from FDD 3.5''
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can replace expensive bridge VHE-101B

I checked with ferrite and

neodymium magnets ->>

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and the ring magnet of FDD motor

distance ~ 0.5 cm

comparator = LM358

cool nice project, thanks