On Dec 6, 1:27*am, tricky > wrote:
> On 05/12/11 21:32, davygrvy wrote:
>
> > Why any heater wire at all? *What if I could just bolt a 15 amp
> > (TO-3P) transistor right to the manifold itself and cook the metal
> > directly? *Hopefully there's enough material to grind a flat. *Using a
> > PNP transistor, collector is at ground potential so no need for any
> > mica insulation.
>
> >https://www.facebook.com/photo.php?f...et=a.111195867...
>
> Remember, with the transistor fully on, there will be little voltage
> drop across it. *Therefore there will be little power dissipation. ...
> Little heat .

Not true when emitter to collector is right across the battery. 10A @
12VDC = 120W

> you need to bias it half way between the rails to get the most power /
> heat, out of it.

not true at all without a load. I had nearly the same convo with a
guy I work with. Like you, he normally thinks a transistor drives a
load. What if it is the load and is operated as just a variable
resistor?

> It's early, so I might have missed something there ! ...

paradygm shift

> Like I said on FB, a plain old power resistor would be much simpler

I'll post the heat chart from the simulator now so you can see how
it'll work.

> Rich