Characteristics of HP-IL Transformers?

[Martin Hepperle]

I fear that a commercial quote for winding toroid cores would require an order of 100'000 and up, just for considering to set up a production run. Manual winding looks at least like a "very interesting" job.

For manual winding the split cores look much more attractive to me.

If I read the accessory list correctly, the simple split core variant with the required parts (bobbin, covers, clamp, no adjustment screw) would cost maybe 3€ for one, respectively around 10€ per transformer with 3 of them. This would be acceptable for me.

Also, for me, size would not be so important, if the end result still fits into something like a PIL box. I would not want to recreate a HP-41/71/75 internal HP-IL module, but would like to have a interface building block (hard- and firmware) for microprocessors similar to what the original combination with the HP-IL chip offered.
Similar to the PIL-box but with HP-IL frame de/encoding in the same hard/firmware so that no extra laptop or Arduino etc. is needed. Maybe with an ESP32 or similar device.

If such an interface is desired for something small, e.g. as a serial to HP-IL translator for a Swiss Micros calculator, it would have to go into an external box.