[sdiy] Yet another about AN299

[Motohiko Takeda]

Hi, list and flightofharmony

In last September, I had got LM431 for cheap price, so I tried AN299 again.
I had omitted thermal loop and only tried to do oscillation.
and I had got around 1.9kHz as same as you.

my friend living in tokyo 'PCM1723' (it's his handle) analyzed AN299.
In High frequency, there is less current to drive switching transistors.
So 1.9kHz is max for this configurations.
And he had proposed this this methods for faster switching.
http://www.aleph.co.jp/~takeda/radio/takedanote/img/an299/an299-test-schem.gif
Check the diode around Q1 and Q3. I had got 2 more octave with this.
(there is something mistake in memo on the schem. never mind it! 0.7V is
ref for thermal loop.)

it's just like this.
http://www.aleph.co.jp/~takeda/radio/takedanote/img/an299/an299-wave2.jpg

AN299 said 15KHz in documents, 2 times. but it should be 1.5kHz or so.

cheers!

Motohiko Takeda
Tokyo, Japan.