The choice of MOSFET can be tricky. Seems that irlz44n was discontinued so you may need to find one adapted to the voltage and current you want to handle. In all the cases you need to get a logic MOSFET too, meaning that they are fully open usually around 1 to 3V. Also I'm sort of confused as it seems to me that L7812CV is a Voltage regulator, not a MOSFET. So if you are actually using that in the MOSFET spot it will definitively not work. Especially if you are handling high current or voltage I would recommend using one from a reputable source for your MOSFET, I recently switched from mouser / digikey / aliexpress to mostly use http://www.arrow.com as you get free regular shipping, event if you order a couple of components (no affiliation to them whatsoever).

@Yveaux I have 34 of 80k RAM used for this sketch, so 128 bytes looks like "a bit more". You can not use progmem with ESP and mysensors now because PSTR redefined as PSTR(x) (x) so all strings are really in RAM

@Fabien: Thanks!

@Gambituk I believe you can force the parent ID like this: "gw.begin(NULL,22,false,0);". The last number is the parent ID. Looks like I misread the original issue as in my mind I saw 255, not 25 Cheers Al

If you use the MySensors provided functions (saveState) you can store 256 bytes without overwritnig anything.

thanks, i'll give it a try.