Blog and progress notes,  where I keep you updated on this project’s progress

Nov 2 2025 - V1.2 design

I’ll be commencing redesign to V1.2 of the interface board soon.  I’m considering building the 4x RTDs onto the board, thereby removing the need to buy PT100 modules.  Might do the ADS1115 ADC while I’m there.  These changes will remove the pin sockets used for these sub-boards, expand the standard feature set, improving reliability and reducing overall system cost.

I have removed the relay contact snubber networks saving a lot of board space.

This redesign will be many months away, there’s a lot to learn first.

Oct 25 2025

SMD supplier is not much help.  The part is a Mysentech DS18B20U and it doesn’t talk to the Pi.  After proving it’s a part issue I test replaced one part with a UMW brand part and this works perfectly.  As I populate each board I’ll replace the faulty part.  I can now do SMD rework apparently - new skill day!

After doing a partial translation of the (chinese only) data sheet from Mysentech, the specs for the pullup seem to be different to the Maxim/AD part.  Live and learn.

Sept 23 2025

There is some issue with the onboard DS18B20 sensor, the RPi is not reading it.  The package and wiring is correct and a TO92 and cabled variant are both detected properly.  I’m waiting for the SMD supplier to advise.

In any case, I have TO92 DS18B20s and these can be installed on the board instead of the SMD device.  This will not cause any delays.

Sept 22 2025 V1.1 boards

All V1.0 boards have gone and V1.1 boards are being assembled.

These are the same with some more  SMD parts, better connectors and sockets and the addition of a I2C socket for a 2 or 4 line  display.

The board is still $125.00 AUD.  Order using the email address above.