I tried it....

After the initial explosion all I could find of one of the transistors
were three leads sticking out of the breadboard!



:-0


Not really :-)

Something doesn't seem right though. Will have to look at it closer.
Rick

Olin Lathrop wrote:

> > This was done in a rush, but I think something
> > like this would work?
> >
> > Super cheap -15v smps psu.
> >
> >    +9v------------------------*----*---------------------
> >    In                         |    |
> >                               R    |  BC337??
> >                               |    C  any 200ma NPN small
> >         L is a small 1500uH   *---B   transistor  (x2)
> >         (1.5mH) prewound RF   |    E
> >         inductor.             '----|------Rx------,
> >                                    |              |
> >                                    |              C
> >                                    *----L--*-*---B
> >                                    |       | |    E
> >                                    |       | |    |
> >                            1N4148  - D1    C R1   |
> >                         or 1N914   ^       | |    |
> >                                    |  0.1uF| |    |
> >                                    |       | |    |
> >    Gnd-----------------------------|-------*-*----*------
> >                                    |       |      |
> >            (Hopefully R1 sets the  |       |      | 15v 400mW?
> >            constant current, maybe |       C2     ~ Zener
> >            5 or 10mA ??)           |  10uF |      ^ diode
> >                                    |  25v  |      |
> >                                    |       |      |
> >                                    |       |      |
> >   -15v-----------------------------*-------*------*------
> >    Out
> >
> > I think Rx may not be needed, depending how much
> > you need to keep the parts down. These inductors
> > are only slightly are only about 10mm x 5mm round
> > and not much bigger than a resistor. :o)
>
> Umm, err, you didn't actually try this, did you?
>
> ********************************************************************
> Olin Lathrop, embedded systems consultant in Littleton Massachusetts
> (978) 742-9014, olin@embedinc.com, http://www.embedinc.com
>
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