The plot thickens with MAX31865

Sun, 11 May 2025 00:00:00 +0000

My max31865 story is still ongoing. I managed to find a PT100 sensor to pair with my accidentally obtained boards. It worked in testing, but once I hooked up to the power supply I was using for my solar interface board all along, it doesn’t work! It complains about “over/under voltage” and can’t calculate the resistance. I thought it’s because the power supply is weak, so I added a 6300uf capacitor to the 5v line. It didn’t help. I still haven’t figured out what is happening, in the meantime I just powered it from USB-C 5v PSU. At least I have some temperature measurements; also, there’s apparently a PT1000 variant of the breakout somewhere in the mail, destined for my postbox. We’ll see if that one will be twitchy too.

On a completely unrelated note I find it increasingly hard to do anything useful nowadays. I don’t know if that’s some new form of burnout, but I’m trying to find an interesting project to do and can’t. Everything is no fun. I should try what always helps - making a list of things to do.

MAX31865 conspiracy

Sun, 20 Apr 2025 00:00:00 +0000

I’ve finally decided to install solare electrical (photovoltaic) system. Unfortunately this means I need to get rid of existing solar heating system. Not a big deal, except I’ve used the data from the controller to track the hot water temperature. So, naturally, the idea was to put together something which can take existing PT1000 leads in.

ESPHome has a component, so naturally I went to aliexpress.com and ordered 2 breakouts which look the part. Unfortunately, these ended up having 430 ohm ref resistor, which means that they can only be used with PT100. Now, it doesn’t seem to be possible to know if the breakout offered on aliexpress has 430 or 4300 ohm resistor in it. So I ether need to find 4300-ohm breakout, or I need to unsolder the resistor and solder another one in place.

Max31865 on Think before you push the button

The plot thickens with MAX31865

MAX31865 conspiracy