[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Fwd: 10+MHz SSTC Gate Drive Circuit Finalized



Original poster: Kchdlh-at-aol-dot-com 

More about this...

Learning simulation as I go along, I've just downloaded some Zetex SPICE 
models & put them into SIMetrix, then put ZTX649s & -749s into my 
schematic.  I now get 100 ns rise & fall times between 10 and 4 V.  Also, 
no output-voltage overlap above 1 V, not even at the start.  So much for 
the old-timey 2N2222s and 2N2904s...

I also changed the frequency to 130 KHz (more closely matching my sec's 
Fr)& the transformer coils' inductances to 150 uH (easier to make); plus, I 
added 10 K pull-down resistors  for the loads.

Nice!

Ken Herrick
<mailto:kchdlh-at-juno-dot-com>kchdlh-at-juno-dot-com

P.S.  Juno still blocks pupman!!
In a message dated 9/22/03 6:37:24 PM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:
Original poster: "K. C. Herrick" <kchdlh-at-juno-dot-com>

Dan (& all)-

I'll prevail on Terry once again to post this revision--I hope, final--to
my suggested SSTC driver; 
<http://hot-streamer-dot-com/temp/ssdrvr-kch7.pdf>http://hot-streamer-dot-com/temp/ssdrvr-kch7.pdf.


[snipped]



Return-Path: <tesla-request-at-pupman-dot-com>
Received: from  rly-xl04.mx.aol-dot-com (rly-xl04.mail.aol-dot-com [172.20.83.73]) 
by air-xl04.mail.aol-dot-com (v96.6) with ESMTP id MAILINXL43-5d23f6fa3b01d5; 
Mon, 22 Sep 2003 21:37:23 2000
Received: from  hotlilpup.pupman-dot-com (ns2.rmpg-dot-org [63.225.119.186]) by 
rly-xl04.mx.aol-dot-com (v95.1) with ESMTP id MAILRELAYINXL410-5d23f6fa3b01d5; 
Mon, 22 Sep 2003 21:36:55 -0400
Received: from poodle.pupman-dot-com (poodle.pupman-dot-com [63.225.119.188])
         by hotlilpup.pupman-dot-com (8.11.6/8.11.6) with ESMTP id h8N2MWH22522;
         Mon, 22 Sep 2003 20:22:32 -0600
Received: (from slist-at-localhost)
         by poodle.pupman-dot-com (8.9.3/8.9.3) id TAA32396;
         Mon, 22 Sep 2003 19:36:40 -0600
Resent-Date: Mon, 22 Sep 2003 19:36:40 -0600
Message-Id: <5.2.0.9.0.20030922192930.02aea480-at-twfpowerelectronics-dot-com>
X-Sender: teslalist-at-twfpowerelectronics-dot-com
X-Mailer: QUALCOMM Windows Eudora Version 5.2.0.9
Date: Mon, 22 Sep 2003 19:29:33 -0600
To: tesla-at-pupman-dot-com
From: "Tesla list" <tesla-at-pupman-dot-com>
Subject: Re:  10+MHz SSTC Gate Drive Circuit Finalized
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed
X-DCC-SdV-Metrics: dick.jymis-dot-com 1179; Body=1 Fuz1=1 Fuz2=1
Resent-Message-ID: <fHEHTB.A.RYH.IM6b_-at-poodle>
Resent-From: tesla-at-pupman-dot-com
X-Mailing-List: <tesla-at-pupman-dot-com> archive/latest/14986
X-Loop: tesla-at-pupman-dot-com
Resent-Sender: tesla-request-at-pupman-dot-com
X-AOL-IP: 63.225.119.186

Original poster: "K. C. Herrick" <kchdlh-at-juno-dot-com>
Dan (& all)-

I'll prevail on Terry once again to post this revision--I hope, final--to
my suggested SSTC driver; http://hot-streamer-dot-com/temp/ssdrvr-kch7.pdf.
(He may also delete all the other ssdrvr-kch files to save himself some
HD space.)

In the simulation, I've followed Dan McCauley's suggestions in changing
R2 to 2 ohms & TX1's k to 0.99.  I also changed C4 & C7 to 40 nF and R1 &
R7 to 2 ohms.  Also found 220 nF better for C1, C2, C3, C5 & C6.  Also
added 470 ohms across each secondary; they were ringing a bit.

As before, in the top one of the 2 identical secondary circuits, C3
charges thru C2 and Q6 b:e while C2 charges thru D1 and Q2 b:c.  Emitter
follower Q2 is driven via D1 while e.f. Q1 is driven by Q6 via D2.  Q6
only turns on as a common-base-connected transistor when TX1's + output
exceeds C3's voltage by ~1.4 V; that's what prevents output-signal
overlap.

Because of the action of Q6, the output voltages never overlap at greater
than ~1 V except up to ~3 V during the first 3 half-cycles after turn-on.
  Rise & fall times between 10 and 4 V are a respectable 200 ns, & likely
better in real life with real & better transistors.

I've added b:e resistors here & there, also.

I realize that a plain-vanilla capacitor is a poor simulation of a
MOSFET; the MOSFET model I have with the (free) SIMetrix doesn't seem to
fully characterize the several non-linear capacitances so I don't bother
with it.

As I've said, I prefer this circuit (absent actual realization, of
course) to Dan's because a) the output signals don't overlap
(significantly) and b) no transistor zeners.

Ken Herrick