RE: [TCML] Transistor Questions (slightly O.T.)

["Gary Pedro " <kf6fpu@xxxxxxxxxxxxx>]

Why not just use the inverting output on the timer?

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Christopher Karr
Sent: Sunday, June 06, 2010 9:32 AM
To: Tesla Pupman List
Subject: [TCML] Transistor Questions (slightly O.T.)


Hello everyone,

I'm aware of the function of a transistor, though, for my purposes, an
analogy must be made:

An NPN transistor is like a N.O. SPST  push-button switch (with a diode in
series, of course). The pushing of the button is analogous to the insert of
base-current in an NPN transistor.

That being said, is there any sort of transistor which is analogous to a
N.C. SPST push-button?  Were there such a design, one could simply use a
square-wave which never goes below '0V' to drive a push-pull setup.

When the signal is high, base-current would be fed to the normal NPN
transistor(s), turning them on. Also, when the signal is high, base-current
would be (fed to or pulled from?) the 'normally-closed' transistor, turning
it off. If the on-times and off-times of these transistors were properly
matched, one could use nothing but a 555 IC (and maybe a couple signal-level
transistors) to drive medium- to high-power transistors in a push-pull
arrangement.

If such a device has not yet been invented, I claim sole rights! ;)

Thanks,

 - Christopher Karr
 		 	   		  
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