Hey Thanks Bob!
I got it.
I'll build this up and play around with it.



wrote in message
...
On Sat, 2 Dec 2006 00:23:26 -0600, wrote:

Hey
I would be interested in looking at that if you have it handy.

RonL

OK I dug up my circuit - it's pretty simple, I should be able to describe
it to
you...

The transformer is one of those little ferrite jobs, with a small bobbin
enclosed in 2 ferrite shells. It's about 1" round and 1" high. There are 3
windings in it, all are center tapped.

The 2 transistors are NPN, I have no part numbers but you want something
rated
for higher frequencies than just audio.

The emitters go through 3 ohm resistors to ground.

The collectors go through a CT winding of 40 turns (so much for my
memory!) and
the CT goes to 12v+. There is a .047 cap across this winding.

The bases connect to an 8 turn winding, whose CT goes to a 100k pot...
this pot
is across 12v+ and ground, and was used to set the bias for proper
operation.
Once you get it working you can measure the pot and use fixed resistors.

The output winding will be as many turns as you need voltage, mine was a
few
hundred, and it had a .001 cap across it.


I found the schemagic of the circuit I used for the design, I'll post it
on one
of the electronic binary groups... look for me! You can use this circuit
for
lots of things... the original was 100 watts! Note the original was
3.5khz, I
changed it to 65k so you can't hear it...



wrote in message
. ..
On Thu, 30 Nov 2006 18:24:05 -0600, wrote:

Hi group:

Has anyone in the group found a switcher good enough for high voltage
(180
VDC), low current (.010 amps)
audio use. When I say good enough, I'm referring to noise and EMI. I've
been
looking at LT, National and power integrations
but haven't found anything yet. I also need 12V @1.0 amp for filaments.
Any ideas appreciated.

RonL


I once made a 2 transistor power oscillator, and wound the ferrite pot
transformer myself. The collectors of the transistors feed an 8 turn CT
winding,
there is another "tickler" winding of maybe 12 turns, that feeds the
bases...
and a few bias resistors, and that's it. The secondary is a few hundred
turns,
with a small cap across it ( .01 or something) it created a "sine wave"
output
due to the resonance of the output "tank", and was around 250 volts if I
remember correctly. The supply was 12vdc.

It ran at 65KHz, and produced about 12 watts, enough for a portable amp.
It
didn't create any noise at all due to the "soft" wave output. (And it
was
in a
VERY high gain circuit, 5mv input)

There are DOZENS of variations around of this circuit. I can get you a
schemo if
it interests you.

I'm going by memory of this circuit since I built it around 1985... The
transistors were "junk" in TO3 cases. If you can build the tranny, you
can
build
this circuit.