> >> > >>> Have you figured this one out yet? > >>> > >>> http://s555.photobucket.com/user/panfilero/media/crap.jpg.html > >> > >>I never did. > > > >The wrong-direction spikes are from gate-to-source capacitance. > > Oops, make that gate-to-drain capacitance.ahhh, thanks, that makes sense
Opto in amplifier screws up output
Started by ●December 17, 2015
Reply by ●December 21, 20152015-12-21
Reply by ●December 21, 20152015-12-21
"Fibo" <panfilero@gmail.com> wrote in message news:fa5d0781-d941-4904-b9d3-446e4ba6fc4e@googlegroups.com...>> >> >> >>> Have you figured this one out yet? >> >>> >> >>> http://s555.photobucket.com/user/panfilero/media/crap.jpg.html >> >> >> >>I never did. >> > >> >The wrong-direction spikes are from gate-to-source capacitance. >> >> Oops, make that gate-to-drain capacitance. > > ahhh, thanks, that makes senseAlso, operation would be more obvious if you used a *much* smaller transistor, or a much lower value resistor that's actually loading the transistor to a modest fraction of its rating. Like, a few ohms I would guess? And FWIW, R2 is superfluous because SPICE voltage sources are ideal*. *LTSpice hides ESR and ESL parameters inside components, so beware if they've been set nonzero by default. Tim -- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
