Now it was time for me to do a little homework because the motor needs about 20V DC at around 8-9 Ampere.
I first looked at variable digital power supplies from the lab equipment stores but one that's capable of 10A is quite huge & heavy and Cees at Muco electronics in Amsterdam told me that the sensitive electronics inside these lab DC supplies can't cope with the peak startup-current of the short circuit motor I want to drive it with.
He advised me to build my own instead. A heavy toroidal transformer and a massive rectifier should do the job he said. "It won't give a fart for the startup current of your motor and just keep working" he told me.
So I got the material and a hard plastic box to build it in. At home I do not have the equipment for drilling things to size like Tije has so I used an awl, two metal reamers and little files to get the right holes.
The first tests gave me only fireworks so eventually I decided to look again at the diagram for the connections and sure enough, I had made short circuits of both secondary 22V 5A windings.
Very happy that the fuses took these blows for me! No need to replace the transformer.
The thing is ready to try on the motor now. The box weighs 2800 grams! It could crunch some coffee beans on its own if necessary.
|DC power source plus tools|
|Just a handful of fuses blown|