Andy Howards' idea is great <G>

I can receive faxen & translate 'em (I'll work on getting a SPICE faq
together, I think.)

(360) 802-2558 Fax, hit 'Send' when the stupid old thermal paper fax
machine answers the phone (I'll get the Fax Server up, some time, then
it'll just be Fax modem tones if someone calls <G>)
(360) 802-2557 Voice (Please don't send Faxes to there <G>)

I don't guarantee to be THE fastest person to get to these, if you want
speed, someone else might be a little faster.

  Mark

Donald L Burdette wrote:
>
> The reason I used the transformer secondary for an inductor is that this
> design requires a huge inductance - around 100mH, rather than 100uH.
> That is so I can keep the frequency low, which is what makes the design
> so easy to implement.  You could push the frequency of this design to 50
> or maybe 100 kHz, with proportional decrease in the inductance, but the
> higher you make the frequency, the more attention you have to pay to the
> layout, transistor switching speeds, diode reverse recovery time...
>
> It is quite possible that the 2000 Hz ripple will get into the audio.
> You'd have to know what it's used for, or just try it and see.  You could
> set the switcher for 14V and use a 7912 to remove the ripple.  You could
> increase the frequency.  You could improve the output caps.  But maybe
> you don't need to.
>
> As for the gory details, I'll have to apologize.  I forgot who I was
> talking to.  Since the schematic is too detailed for ASCII art, I'll have
> to try to figure out how to get it into electronic form.  If someone
> would be willing to receive a fax, scan it and post it, that would be a
> lot easier for me.  I'm still in the pre-scanner dark ages.  If you'd
> like to volunteer, e-mail me off-line since I don't get the digested
> piclist until after midnight!
>
> Don

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