Re: 555 2n3055 was:The incredible inedible ignition coil

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

555 can put out around 100 mA
2n3055 has a gain of about 10 at 5A collector current (meaning you'd have to
source 500 mA into the base)

3055's may be cheap, but they're not all that great a transistor: low gain,
low BVceo, awsome thermal runaway, etc..  There are many, many parts that
are better and still under $1.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 25, 2001 9:06 AM
Subject: Re: The incredible inedible ignition coil


> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Fucian-at-aol-dot-com>
>
> In a message dated 2/24/01 7:15:55 PM Eastern Standard Time,
tesla-at-pupman-dot-com
> writes:
>
>
> >
> > There is a problem with the 555 timer plus 2N3055 route. The 2N3055
actually
> > needs quite a bit of current to drive it into conduction, and the
standard
> > 555 timer is running at its limit, it is better to use a darlington pair
in
> > this configuration, or a power mosfet. The 555 plus 2N3055 may work for
a
> > time, but the chip may burn out at any time.
>
>
>
> WOW!!!!!!Thats the answer to my 555 ic probs!Ive been losing them in
handfuls
> with no explanation.Now i read the 2n3055 is the prob!No wonder theu all
died
> after a few MINUTES!
>
> matt
>
>
>