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Ken O wrote:
"John Popelish" <jpopelish@xxxxxxxx> wrote in message
news:C8-dnein8YsvXADZnZ2dnUVZ_sGdnZ2d@xxxxxxxxxxxxxxx
Ken O wrote:
(snip)
Actually I wanted to swap that with my 555 chip (with minor changes too)
and the output will go to my base of my 2n3055 transistor.
At first I was looking the 7555, but that seems to be too much on the
border line
I dont really want to go digital too like a vibrator.
So, are you saying you want to switch a 2N3055 on and off up to 20 million
times a second?
well the 2n3055 is only good for 3 MHz, I'll have to chosse another chip
that does faster. even that , it IS better the 555.
I think the 2N3055 has a current gain bandwidth product of between 2.5
and 3 MHz. That means that it has a current gain of only 1 at 3 MHz.
Are you planning to drive the base with the same current you hope to
switch through the collector? You also cannot produce a 3 MHz square
wave output that way, because the harmonics of a 3 MHz square wave are
9 MHZ and above, where the current gain is .3 or less. The 555 (as
slow as it is) is faster than the 2N3055.
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