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Re: Avalanche transistor
Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
A quick search on the web would have given you all you
ever wanted to know and more:
On 11 May 2003, at 12:15, Tesla list wrote:
> Original poster: "Jolyon Vater Cox by way of Terry Fritz
> Dear List,
> What exactly is an "avalanche transistor"
> how does it work and does it any use in tesla coil work?
Being an avalanche device it exhibits a negative resistance
characteristic under certain operating conditions. It is designed
specifically for producing fast risetime pulses. If you tie the base
and emitter together and then apply an increasing voltage across the
C-E, it will break down in a non-destructive way such that Ic
suddenly rises accompanied by a fall in Vce if the power supply has
some internal impedance. There is obviously a limit on peak die
current for reliable repetitive operation. Zetex gives three curves
relating failures to currents.
Obviously, whether a particular transistor is any use in coiling
depends on its characteristics. I had a brief look at the
characteristics of a few available devices. Peak colector current for
one of them was about 60A at a breakdown voltage somewhere between
200 and 300. Check it out for yourself on the web.
> By the way, I have seen article on such a device in
> with reference to high voltage pulsers pockel cell drivers and pulsed
> radars /is the information is of any use?