1st shot

Blend : Barefoot slow-roller
Dose : 18g
Adding preinfusion time within 2~3bar and ramp up to 9 bar, last - ramp down
Controller : PWM Adjust
Taste : more sweet and sticky, and balanced

2nd shot

Blend : Ritual hidden cities
Dose : 18g
Adding preinfusion time within 2~3bar and ramp up to 9 bar, about last half - ramp down
Controller : PWM Adjust
Taste : reduced acidy, more balance, a little oily

both 2shots, density increased, more mellow, pretty interesting

Pwm controller v2.0 mod test

Can getting advantage of short duty time and custom preinfusion, and flowrate or pressure profiling, and quiet pump noisy sound. And so on?

Very nice.
Is this done with open loop control or is there some sort of transducer/feedback to the control system?

HI allon

it's open loop control for ulka vibe pump.
Controled by manual handling.

But vibe pump's gauge indicate the extraction pressure, so even manual system, can works pretty well

Yeah, I don't have a pump pressure gauge on my machine.
I'd imagine with an Arduino, potentiometer on an analog input, and SSR driven by a PWM output, this would be an easy addition... What's the PWM frequency on your setup?

Hmmmm. Add a separate boiler pressure gauge with a ccd looking at it, and a bit of programming and you've got a rough feedback loop. Or just buy a pressure transducer but damn those things are expensive in food-safe models.

Maybe it the board is cheaper than arduino, but with arduino can have more adventure
I don't know exact frequency in this setup.
But next week, I'll meet the circuit designer and discuss about improvement this board.

Maybe I'll make a request for adding closed loop control.
If is it possible, add LCD(for display pump power), memory bank(for preset several pump power) and so on, in that board.

And what should be needed more?

Devin Lee - (indend007@naver.com)

More clip and setup pix here

I like the pedestal in the countertop, and the integration of controls into the counter - nice job!

I've long thought of building a generic coffee roaster controller, and more recently an espresso machine controller, incorporating things like:

boiler pid
automatic shot timer display
autofill lockout while pulling shot
integrated web server offering:

- current boiler temperature
- video of last extraction (bottomless-cam)
- picture of last latte art

now I can add pressure profiling to the mix...

(obviously a little more involved than an arduino, but relatively simple using an embedded linux machine which can be had for ~$100)

I'll meet the circuit designer and discuss about improvement this board.

Now these words will reveal my lack of knowledge as regards circuit boards but . . .

I would design the board such that the potentiometer and the power switch were not soldered but had socketed connections.

Hi Eric

Maybe it's not too hard. We also unsoldered the potentiometer - it's so easy!

I wonder that your works about MGFR pump, how's your work?

I program in C, assembly language, and solder.
Solder can be a really fluid language, once you get to a few hundred degrees.....