On Monday, April 16, 2012 12:05:22 AM Jon Elson did opine: > gene heskett wrote: > > Looking at the scope traces, either the probe is way out of > > calibration against the scopes own test square wave, or the 540 has a > > low value series resistor, 33-120 ohm range, with several hundred pf > > on the other side of the resistor as a noise filter on that input, > > and likely on all inputs since engineers have a tendency to 'step & > > repeat' for that stuff. > > It was described earlier that the charge pump input to the G540 is > capacitively > coupled, and apparently has a large coupling cap. If it is driving the > base of a > BJT with the cap, that would require a pretty big one. > > Jon Gee Jon, its been yonks, as in 2+ decades since I last played with a BJT. Do I properly recall that the triggering voltage is more than a normal NPN transistor would have?
That could also explain the remark Kirk made about the first 2 volts, then a knee, like the load of the BJT's Junction loading kicking in as it switched on. > ------------------------------------------------------------------------ > ------ For Developers, A Lot Can Happen In A Second. > Boundary is the first to Know...and Tell You. > Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! > http://p.sf.net/sfu/Boundary-d2dvs2 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> "Not Hercules could have knock'd out his brains, for he had none." -- Shakespeare ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
