Bernina 540 Footpedal wiring etc.
 

My 540 has speed controller electronic components built into a casing beneath the motor.
There's a larger silver capacitor (about the size of an AA battery) and 2 smaller black ones about 1/2" long that are in the motor lines. There's a separate power-in plug, and a separate footpedal plug.
I'm familiar with the old type footpedal which contains simple mechanical variable resistors, but what sort of foot control would work with this setup?

Is it so you can use the knee lever to power it? Instead of the foot pedal?

Well I don't think so Annette, because there's no physical connection or electrical connection to the knee lever.
And the machine has the 2-prong electrical connector socket in the base which obviously is supposed to connect to a footpedal (that I don't have).

This is the foot control we use, and attach to the Bernina cord at the shop. Part #072963 Singer 1116 2662 with 771 cord Here's the same foot control that's connected to the cord, at a great price. https://www.ebay.com/itm/Complete-El...-/321973575036 The cord by itself retails for $45! Last time I checked Ebay for these, they were selling for $100.

Here's a pic of my machine. Note the 2 plug sockets, on the right (rear of machine) the power cord socket, 2 flat pins male prongs.
And (I assume the footpedal) (front) socket on the left, 2 round pins - female sockets. The one you link on ebay wouldn't fit either of the plugs with the cord shown. Though perhaps you have a cord that fits the Bernina and that footpedal? Interesting! Thanks Annette.

I think it's only the capacitor that's connected to the plug socket in the machine. The carbon resistors and everything else is in the pedal. The most common replacement capacitor is a small squarish thing, but you have to check for the correct US replacement. It's probably different from the European 220 voltage. Some of the early Berninas have a small simple circuit board in connection with it, and it's easily replaced too

Here's a pic of my machine. Note the 2 plug sockets, on the right (rear of machine) the power cord socket, 2 flat pins - male prongs.
And (I assume the footpedal) (front of machine) socket, 2 round pins - female sockets. The one linked on ebay wouldn't fit either of the plugs. Interesting! Thanks Annette and Mickey.
(Btw I'm in Australia).

It looks very similar to my 730, it should look something like this.

That sure looks right Mickey. Helps to see one to know what to look for. Thanks.

Just to tie this one up, I've hotwired the 540 (made up plug adaptors to fit) and I can confirm that a good ol' fashioned mechanical rheostat type footpedal works just fine, The 540 purrs like a kitten, stitches pretty well, and has a good turn of speed too.

Yay! I'm glad you got it going!