Thursday, June 17, 2010


By now many of you have seen this picture of Bob Carver floating around the net.

Rather than make my own comments I'll just point you to this DIY Audio Thread and show you all a picture of me in action in my much smaller corner where I wind.

In order to take this self portrait I needed to somehow support the camera and aim it. I tried various methods. The 75TL was too round, the 2A3 too irregular but a Cunningham CX-112A on top of a 10 pound spool of wire or two was just right.

I chose recoil for the title since that was what I was doing. I was REwinding COILS for the Lowther Field Coils. One of them took a severe hit on its way to the reviewer and the coil was damaged.

This is a closeup of the mandrel about 1/3 the way wound.

The last row of wire is on.

10 pounds of wire standing proud.

All that is left to do now is make them ugly again by sealing them off with tape to protect the magnet wire enamel and installing them in their new home for the next 50+ years.



  1. wow, cool shots - thanks for posting. You must own a tripod though I think. ;-) 112 = good choice, not too valuable if it breaks.

    Does the coil really need to be that deep? Is that to develop the gauss needed? Seems like it's deeper than it needs to be (considering how shallow the voice coil must be). Is there a reason to wind it deep vs. winding it wide (e.g. larger diameter?)


  2. Obvious answer, the backwave striking a larger diameter shallower magnet bounces back through the cone. Other reason, the mean length of turn of the motor is kept much shorter this way greatly reducing the heating.



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