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I would like to make a standalone coffee grinder by reusing the grinder in an old broken down Magic Deluxe Espresso machine. My electrical skills are pretty limited but I thought I'd find an appropriate dc adapter and solder up the wires to the grinder and maybe a add a switch. However I dont know how to determine the expected input of the grinder to choose the appropriate dc adapter. It is not printed on the side.

Can anyone tell me the voltage and amperage the grinder expects?

Wiring Diagram

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closed as off topic by Niall C., auujay, Chris Cudmore, Steven, ChrisF May 25 '13 at 15:30

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I can see two motors. They have a 2A fuses on them and most likley are just normal brush motors 10vdc~15vdc I know this because there are only 2 wires to both of them. Stepper motors use 4 or more wires and need special circuits to make the motor spin. There are some that use 3 wires that might also require a special circuit.

Unfortunately there is no indication what the transformer supplies to the PCB and also there can be voltage regulators there where the big heat sinks are. So the motors could also be 24vdc motors.

You need to use a multimeter with DC and measure the two wire points on the motor when its running. That will tell you how many volts it is.

Then all you need to do is supply those motor with the DC voltage you measured, times that by 2 (2Ampers) and make sure your power supply can handle the load.

For example-

  • 24vdc * 2a == 48watts maximum power
  • 12vdc * 2a == 24watts maximum power

I really doubt the motors are AC driven.

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I think you're on the right track. I just measured my standalone coffee grinder and it uses 25 watts, so ~12VDC on a 2A fuse is totally plausible. – Henry Jackson May 20 '13 at 14:19
That is just the MAXimum rate-ting- It does not mean it IS 25Watts. It is most likely 75% of the rated fuse. But it does not have to - It might as well be 0.25A :) The protection is up to 2Amps and that gives a starting point. But the most important is is if you can measure the voltage. Later you can use the AMP features on the multimeter and see how much the grinder motor actually uses + 25% (because under load it might use more power) – ppumkin May 20 '13 at 14:38
I was just saying that I measured mine at 25 watts, so you're in the right ballpark. – Henry Jackson May 20 '13 at 14:44
Stepper motors have 4,5,6,or 8 wires. The only motors that work similar to stepper motors with 3 wires are called brushless DC motors. – Brad Gilbert May 20 '13 at 14:45
I just plugged it into a Kill-a-Watt meter, which measures all kinds of fun stuff, including watts and kWh. It's super useful. – Henry Jackson May 20 '13 at 14:49

Does the machine work at all right now? If so you could use a multimeter to at least figure out if the power is AC or DC and how many volts it requires.

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