Hey everyone! I wanted to share an update on my open-source espresso machine build. All the electrical connections are finally done!

Thermal PID & Triac Control
I've successfully implemented the thermal PID control. To achieve clean sensor readings, I used a hardware RC filter with a 0.1µF capacitor, combined with a software Exponential Moving Average (EMA) filter on the ADC (using a ~20Hz cutoff for temperature, and a ~4Hz cutoff to aggressively attenuate the 50Hz vibration pump ripple for the pressure sensor).

For driving the heater reliably, I wrote a Sigma-Delta modulator that distributes power across AC full-waves. A critical trick I used here was adding a ~2.5ms delay (a quarter of a half-wave) *after* the zero-cross detection. This ensures the system toggles the MOC3042 optocoupler when the voltage is high enough (>20V), avoiding accidental single half-wave latches that could stress the components.

Surprisingly, the triac stays completely cold! I've seen other projects use huge 25A SSR blocks with massive heatsinks, whereas my 16A triac with a tiny heatsink handles it effortlessly.

Pressure Tracking & First Shots
Now I have both temperature and pressure tracking in place. Check out my sleek connection for the pressure sensor!

I pulled my first shots, and to be honest, they were quite sour and salty. I blasted through a full espresso volume in just 9 seconds! 

**The Good News:** One massive success from this test is that the temperature drop during the shot was incredibly minimal. This is achieved using a feed-forward control mechanism based on the water flow rate. By reading the flow meter, the system anticipates the cooling effect of the incoming cold water and adds a proportional power boost directly to the PID output, stabilizing the brew temperature *before* the sensor even registers a drop.

Next Steps
Without proper skills in dialing in a grinder and preparing a good coffee puck, I'm a bit stuck on the coffee side of things for now. I'll be learning that in parallel with the next major milestone: designing the custom PCB!

Thanks for reading, and I'd love to hear your thoughts or tips on dialing in shots!