View Single Post
 
Old 04-11-2010, 09:43 AM
StevanC's Avatar
StevanC StevanC is offline
Senior Member
 
Join Date: Sep 2007
Location: Serbia
Posts: 269
Arrow wondering...

Quote:
Originally Posted by nvisser View Post
Brilliant work Stevan
Parallel to series. This is way he calls it the Tesla charger
I really wonder _why_ he calls it the Tesla charger?

Is it for the sheer unidirectional pulse the battery receives, Tesla was fighting so hard to explore?

Kind thanks, but I really have little credit in this here. It's JB who fought this to public attention.

Quote:
Very clever switching using a npn on the high side instead of a pnp like in the bipolar switch.
I always wondered how to do that high side switching with npn bipolar transistors. I see now how it works as the battery + at that stage is at a lower voltage than the cap + side.
All i did is I begun to look at "what is _more_ positive and what is _more_ negative on a link connecting "two nodes".
"which side does current flow?" (we thing "poisitve to GND" or "HOT -> GND")

Luckily the BJT (MJL) is a current driven device (this is important here), but we need remember it needs some voltage to do so:
0.7V forward bias for base having current
1V for Vce flowing forward current
Then there is reverse breakdown (~16V on MJL)
But the BJT really is a "current" animal.
Quote:
Your circuit also show what JB said about using the pnp with the npn to get a faster rise time, instead of using the parallel cap and diode.
The PNP I couldn't neither confirm nor deny. I don't really know.

He notes PNP one place, and I dug PNP drive and found Sziklay pair - the "complementary Darlington" and its PRO et CONTRA vs Darlington ("Vanilla Darlington" )

I really reconsider if I need it done "Sziklay" or a "complementary Darlington" for there is a difference how the compound device acts, and how it is "fed" to do so.

The key is both the rising edge, and the FVD (Forward Voltage Drop) for the whole transition.

Sziklay provides just the most "open" on "cue" as far as I know ATM.

But then there is the SCR and the "SCR instead" with a PNP-NPN pair, that is also able to "avalanche" sheer amperes over short time periods.

Best regards,
Stevan C.

Hopefully JB comes and comments regarding this soon, so I know what I do?
__________________
 
Reply With Quote