Hi everyone,

for the last couple of days I've been toying with the idea of adding an adjustable preinfusion system to my Elektra T1. I would probably use a PIC16 uC to implement it, with a potentiometer or a few switches as the setting point and a software timer. It should be quite easy to add it into the machine, simply by taking the cable that engages the pump, plugging it into the uC and running the cables from the uC into... and that's the question, where? The preinfusion wetting would be done by using inline pressure but I think I have to add a valve somewhere which can be triggered in order to allow water to enter the group head. Or am I messing something up? I know that the new Vivaldi has programmable preinfusion, but I don't know how it's done. Can anyone share some info on that subject?

Would there be any additional advantages of adding such a system, besides the obvious one which is decreasing the force of the water hitting the puck and slight taste changes?. When I had my Andreja running I have to say that I liked the way the preinfusion worked.

Regards,
dsc.

If it's a vibe pump, you can use thte PIC to control the pump frequency, start it off at 5hz or so for the pre-infusion stage and then ramp the frequency to 50 or 60 when it's time to start brewing. Don't know if that's the right numbers, but you have a PIC and time and it ought to be not to hard to implement. If there is an air bleed hole like my Brewtus it will be even easier.

More likely you'll find it takes a constant pulse width to drive the piston and you'll need to control the frequency of the pulses.

You could do the same thing with a rotary but I've no idea how to control those motors.

Ira

Hi again,

well it is a rotary and I'm not sure but it looks like it should be quite easy to add. I thought of using a tee connector to bypass the pump, placed just after the pump and a solenoid valve on the tee to which the inline water pipe would be connected (I will have to add another tee just before the machine water connector as well). The uC would then control the valve and the rotary motor so that I could choose what source I want to use, inline or straight from the HX (9bar). I'm guessing that a simple 8seg display and two switches would be enough to provide preinfusion settings in the range of 0-9s.

Now the only thing I need to do is find the parts, especially a solenoid valve that would work with DC instead of AC (I can use that as well but it will be a bit more complicated) and figure out what I need for the controller.

Regards,
dsc.

EDIT: I was just looking at Ken's preinfusion mod and I saw that he only used a delay relay and nothing else. Now this made me curious, will the pump let water through even if the motor is not running? Because I though that with the motor turned off it simply sits there and doesn't allow the pump to turn, thus not allowing any water to come through. Or is that a load of rubbish? If so I don't need any solenoid valves and it makes the whole thing rather easy to implement.

dsc wrote:well it is a rotary....I was just looking at Ken's preinfusion mod and I saw that he only used a delay relay and nothing else. Now this made me curious, will the pump let water through even if the motor is not running?

Yup, a rotary allows water to flow through when the motor isn't running.

If I hold my brew button just so, I get the solenoid actuated without the pump, giving me (unreliable, depending on how carefully I press) preinfusion. I thought about automating it with some kind of time-delay switch, but was unsure of which to use or exactly how it should be connected/powered.

I have thought about this, and my ideal would be a big lever on the side of the machine, connected to a bypass valve similar to the one on the pump. Up would be full bypass, down would be no bypass (9 bar), allowing me to control the pressure of the entire operation

The Vivaldi S1V2 uses line pressure for the pre infusion but all the programming is controled by new software added to the black box. The V2 Mini uses a non adjustable mechanical p/i cannister that works like the E61 p/i.

Tom: Interesting idea. You could test this by putting a switch in-line with the pump and toggle it by hand. Being able to differentiate a boiler fill and a shot could be determined by seeing which solenoid is openning.

Mark

I added a delay on make adjustable timer on my Faema to play with preinfusion a couple of years ago. I made a couple of modifications to it, things like a heater light, power light, brew light, etc... I added a small power strip off of the switch to drive the lights when the machine was powered on. I hooked the relay to the main power and the pump lead to the relay, relay back to pump. I could then dial in the preinfusion time to get full puck saturation before the pump kicked in. I think I had something like 2 or 3 bars of line pressure for the preinfusion. I was tempted to do something similar to my A3 but I don't think it will get me improvement, it is supper as is. It would be a case of a solution looking for a problem so I left it as is.

Hi guys,

I thought of using a simple switch to delay the pump start and I might try it before I add anything to the machine.

I thought about what I need and it all seems failry simple. The whole thing shouldn't take more than a day to put together and maybe half and hour to test.

I was tempted to do something similar to my A3 but I don't think it will get me improvement, it is supper as is. It would be a case of a solution looking for a problem so I left it as is.

It's not really about fixing something, more like curiosity as I would love to try some shots with preinfusion and how they compare to the great espressi I'm already getting from my Elektra.

Regards,
dsc.

Hi everyone,

so here it is, an Elektra T1 with an adjustable preinfusion system:



It's set to 3s on the video I believe.

The result is less channeling, but I will need to grind a bit finer next time, as the water passes a bit faster through the coffee when it's wetted. Will report back tomorrow how it tastes.

The controller is not finished yet and looks like a bunch of wires and PCB's, but it's enough to run some tests:



Regards,
dsc.