Re: Vacuum tube tank cap vs. transistor fast diode

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "Craig Fuller by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <cbfull-at-hotmail-dot-com>
> 
> I came across an electical engineer's website the other day which said that
> you should always put a fast recovery diode across the primary in a flyback
> circuit, to reduce the stress on the switching device (for single transistor
> feedback circuits only, I think).  I have always wondered myself why people
> have not been doing this.

This looks very strange. A diode in parallel with an inductor that is
being switched serves just to impede the "flyback effect", clamping the
voltage over the coil to ~0.7 V when the switching device interrupts
the current in the coil. Diodes are commonly used across relay coils, 
for example, but never in a flyback.

Antonio Carlos M. de Queiroz