On 5/17/07, Crist=F3v=E3o Dalla Costa <cdallacosta@gmail.com> wrote:
> On 5/18/07, Brent Brown <brent.brown@clear.net.nz> wrote:
> > > > If you are using a laptop perhaps the power adapter for the laptop
> > > > grounds the negative rail?
> > >
> > > Actually I've disconnected everything now, I'm testing with just the
> > > parts in the circuit I attached and it doesn't work. (I already burned
> > > the computers COM port, luckily I also have a usb-rs232 adapter).
> >
> > Oscilloscope ground clip providing the short to ground?
> >
>
> Bingo!! I wasn't even using the scope but surely the probe was still
> grounded to the circuit. Thanks, I'll sleep easier tonight :)

Oh boy. Never let software engineers doing hardware...
:)

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