I'm currently working on three different mods for the Linea Mini:
1. Shot timer
2. Automatic backflushing - full chemical procedure (15s on, 30s off, 5s on / 5s off x 5, rinse, 5s on / 5s off x 10)
3. Flow profiling - using a new solenoid and needle valve
First I would like to thank shawndo and Peppersass who provided a lot of good information when I contacted them by PM about their flow profiling mods.
Mine is now almost ready. It is 100% reversible. I'm still waiting on a few fittings and a custom 3d printed part that I should receive next week to complete it. I'm currently still debating where to put it. The two easiest locations are at the pump and at the 3-way solenoid valve. Both locations have pros and cons. There is a third location (between the gicleur and the 3way) but removing the 3way is more than difficult so I'm not considering it anymore.
I can enumerate the pros and cons I talked about in private with Peppersass if someone is interested.
The flow profiling mod works independently from the other two mods. That said if I want to keep using the auto backflushing I will have to add a relay to control it too.
The short timer and automatic backflushing mods are implemented using an Arduino. I currently log the time and the backflush info in the console for debugging but I'm definitely planning on replacing that with a led/switch and/or a small lcd touchscreen. I just wanted to get it to work first.
That being said my knowledge about electronics is more than rusty to say the least. I noticed something off with the backflushing. There are 16 on/off cycles in total and for some of them (2-3 max) the pump is activated for 2-3 seconds, then stops, then starts again for the reminding of the flow.
I suppose something is not quite right in my circuit.
Would anyone with Arduino/electronic knowledge willing to help? I can provide a photo of the circuit with a more detailed explanation as well as the source code.
PS: It is now easy to add other options like programming the shot duration and potentially pre-brew/post-brew/pre-brew times once the flow profiling mod is added. I'm not necessarily going to add it though