Bit of a personal question isn't it?

> -----Original Message-----
> From: Richard Ottosen [SMTP:rottosen@IDCOMM.COM]
> Sent: Monday, January 08, 2001 7:46 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: PC Digitizing Storage Oscilliscope
>
> Dan:
>
> Do mind showing us your front end?
>
> -- Rich
>
>
> Dan Michaels wrote:
> >
> > Jinx wrote:
> > >> Does anybody have any recommendations for a PC Digitizing
> > >> Storage Oscilliscope, or just a regualr DSO.
> > >
> > >I've had my eye on the Electronics Australia Oct 1998 DSO. It
> > >has dual channel 20MSPS @ 8 bits, PC controlled timebase,
> > >vertical attenuation and vertical waveform position controls. It
> > >looks as though it could be built quite cheaply. Let me know if
> > >you want a schematic
> > >
> >
> > Thank you for the schematic, sir. I was most interested in the
> > design of the analog front-end. This is always "the" major
> > difficulty with this kind of project.
> >
> > The input amps can only accept Vin to +/-12v in direct mode, and
> > the protection for overvoltage [470ohm series R + diodes clamping
> > to +/-12v] is barely marginal. If you OV with 50v, you severely
> > load down the signal, and can drive large currents into limiter
> > resistors R20/R27 --> (50-12)/470 = 80mA --> 3W dissipation.
> > There goes your 1 Mohm input resistance down the hollow pipe.
> >
> > thanks,
> > - Dan Michaels
> > Oricom Technologies
> > http://www.oricomtech.com
> > =========================
> >
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