Selecting the Correct Pulse Frequency Width Modulator

[JHC2]

Hope that you can help.

I have a Lelit Elizabeth espresso machine and need to accurately control its vibratory pump. To do so, I will likely buy a High Frequency Pulse Width Modulator (PWM).

Any suggestions on PWM specs and settings?

And specific PWM suggestions?

I just want a PWM with a rotary knob, as distinct from a Raspberry computer.

Here are some specs for the pump that I wish to control:

Voltage, frequency and pulse shape are ‘as provided by mains voltage’ i.e. for US/Canada 120V 60Hz full sinewave. The pump (as per Olab description) includes an integrated rectifier which feeds only the ‘positive’ half of the sinewave to the coil. There is no indication of the characteristics of this rectifier, or of the mechanical circuit in the pump (which is likely to be the limiting factor in terms of frequency response).

Other pump specs:
ED: 2/1 minute
CI: 155
Tf: 35C

The 230/240 volt version of the pump is 35 Watts.

My Lelit E espresso machine is a 110v machine.

By my math, the amperage is 0.1489.

Calculated as X amps X 235 volts = 35 watts

35 watts / 235 volts = 0.1489 amps

Hope you can help, as soon as convenient.

 

[rjenkinsgb]

The only pumps I've seen that work in a similar way to that are mechanically resonant; ie. a relatively heavy mass and a spring that build up to a good amplitude vibration when the applied power frequency is correct.

If it is that style, it can only work at the rated frequency, or within a few percent of that.

 

[JHC2]

These are very very small low mass pumps.

I welcome any further guidance from anyone.

 

[Nigel Goodwin]

These are very very small low mass pumps.

I welcome any further guidance from anyone.

Controlling the speed of a motor depends entirely on the type of motor, and how it's connected, and we've no idea of either.

 

[danadak]

Any markings, part number on the pump in the machine ?


Regards, Dana.