DC rotary gap?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "G by way of Terry Fritz <twftesla-at-uswest-dot-net>" <nieporgo-at-email.uc.edu>

>The best use of async rotaries IMHO is on DC coils. On a DC coil you can get
>really neat effects by varying the break rate from less than 100 to as high
>as your little motor will spin the electrodes, and the sparks changing
>appearance all the while. On AC coils, such as NST powered coils they do not
>have much advantage, especially when you try to run a low break rate and the
>electrodes are not in the right place at the right time (especially with a
>close to resonant cap value), and your transformer and/or cap goes poof and
>lets the smoke out (all electronic equipment runs on smoke, let the smoke
>out and it stops working ;-).

Hi, I am going to be working on a DC mot-powered coil soon, what 
motor specs should i look for to power my rotary gap? I will be 
looking through a surplus shop for my motor. Do i just throttle the 
motor with a variac or dimmer, or is some electronic controller 
required? I am assuming many electrodes are also used on the disk to 
enable several thousands of bps. I seem to remember Kevin O. saying 
his rotary gap did a few bps to thousands of bps.
Here's to keeping the smoke in,
Greg
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ICQ 95403614