4x4 core memory with Fair-Rite 5952020201

I got vintage cores designed for core memory on eBay.
Left: what I have used for core memory.
Center: what I got. It's so small!!
Right: 0603(1608) SMD resistor.

Here are the schematic of the sense part and observed waveforms. There are no strong reason to use 1k ohms in the schematic, and there may be more better choice. Two 100 ohm VRs are for tuning of sensitivity.
Orange is observed waveforms between the two ends of the red wire in the picture.

Here is the schematic of the driver. I used ULN2803 instead of full bridges. Though the maximum rateting for a channel is 500mA, it exeeds the value a little. But, the datasheet of ST's chip tells that it permits 600mA, I think.
The sense amp is based on corememoryshield.com/report.html

I tried other cores. I verified Fair-Rite 5952020201 cores working in 2x2 configuration. But I have not build 4x4 configuration with the Fair-Rite cores. PCBs for 4x4 is under production.

4x4 core memory board with LCD display. The cores are available today in digikey, Laird 25T0135-60P, and are not deadstock ones.
I made the number of turns for a core two for column and row lines because coercive force Hc of the core material is high.

Flower of the week

test