Any electrical wizards care to comment?

[Tex]

I'm seeing a lot more automatic commercial espresso machines with kaput brain boxes. This presents 3 options; 1) replace the PC board ($400 - 800), 2) rebuild PC board ($200- 400), or 3) convert the machine over to semi-auto use.

#1 is very expensive
#2 is still not cheap
#3 involves a lot of work, but is often the best choice. I remove the flow-meter, PC board, and the push button dosing pad. I add a rocker pump switch, do a bit of rewiring to activate the group 3-way valve when the pump is off, and add an auto-fill circuit.

I'd like to avoid buying an auto-fill circuit box since they're $150 - 300 a pop. I've come up with this diagram of how to use a SSR in place of the auto-fill box. To do this I'll have to run one leg (neutral) of the 120 vac power through the auto-fill probe and to the input side of the SSR and feed the other leg (hot) of the wire directly to the SSR.

See the diagram for details. Any comments or suggestions are welcome!

[milowebailey]

Tex..... the Milowidget could replace the brain of any espresso machine ...... or Texan

[Tex]

Tex..... the Milowidget could replace the brain of any espresso machine ...... or Texan

Yeah, but has anyone actually seen a milowidget? Vaporware is a sin!

[milowebailey]

Tex..... the Milowidget could replace the brain of any espresso machine ...... or Texan

Yeah, but has anyone actually seen a milowidget? Vaporware is a sin!

Seriously, the Arduino is $30, and a SSR is $20.... or put a SCR circuit together for about $10..... including a momentary toggle.... and you could use it instead of your commercial PID for temp control.....  all in one.... it would let you buy more toys!!!

[Tex]

Tex..... the Milowidget could replace the brain of any espresso machine ...... or Texan

Yeah, but has anyone actually seen a milowidget? Vaporware is a sin!

Seriously, the Arduino is $30, and a SSR is $20.... or put a SCR circuit together for about $10..... including a momentary toggle.... and you could use it instead of your commercial PID for temp control.....  all in one.... it would let you buy more toys!!!

You're probably right, but I already know how to manipulate the PID programs and I'm too old to learn a new programming language.

Plus, I've got a stack of the older Cal 3200 PIDs that're perfect for this application. I just need to figure out how to use another of the $3 SSRs I already have to manage the boiler water level?

I do see one mistake - the SSR is normally open at the output, not closed. When the circuit is closed the refill solenoid opens, allowing the boiler to fill.

[milowebailey]

The Arduino is very simple... inputs and outputs....  easily monitor the boiler level and temperature.... control the pump and heater.  All that has to be done is take an input from a momentary switch (or 2 or 3 and run the pump for X seconds [or milliseconds].... could be static time or programmed (a hair more programming)).... damn... I wish I had hours or days in a clump to work on this....

I need to retire from my day job.....

[Tex]

The Arduino is very simple... inputs and outputs....  easily monitor the boiler level and temperature.... control the pump and heater.  All that has to be done is take an input from a momentary switch (or 2 or 3 and run the pump for X seconds [or milliseconds].... could be static time or programmed (a hair more programming)).... damn... I wish I had hours or days in a clump to work on this....

I need to retire from my day job.....

Sure, then you could work 20 hour days like Mrs T has me doing! Stop trying to talk me into learning the Arduino - I'm having a lot of difficulty remembering the stuff I already know.

[milowebailey]

The Arduino is very simple... inputs and outputs....  easily monitor the boiler level and temperature.... control the pump and heater.  All that has to be done is take an input from a momentary switch (or 2 or 3 and run the pump for X seconds [or milliseconds].... could be static time or programmed (a hair more programming)).... damn... I wish I had hours or days in a clump to work on this....

I need to retire from my day job.....

Sure, then you could work 20 hour days like Mrs T has me doing! Stop trying to talk me into learning the Arduino - I'm having a lot of difficulty remembering the stuff I already know.

Now I've met Mrs. T.... she is not a slave driver..... The Arduino can be programmed using basic, "C", "C++", C#.......  and the PID code is freeware.....  they say learning is life-long and you can do it!!

[MMW]

I'm no electrician Tex, but a 110V hot leg sitting in a puddle seems to be asking for trouble.  At the very least, make sure that dud is plugged into a GFCI outlet the first time you fire it up, mkay?

I recall from some reading that there are some capacitance sensors that will do what you're looking for (inside a brass boiler might be a new application, though).

I'll also second the arduino:  most of these commercial espresso machines are works of industrial art in their own sense.  Hanging a box of the side is just plain wring, IMO.  Use the arduino, tuck it away somewhere hidden and use a little LCD for the display if you must.