I screwed up the measurements in the message I just sent. With the room (and the trace) dimmed for photography, I messed up getting the trace properly aligned for risetime measurements. I didn't notice until too late. There won't be a major difference in the results, but I'll remeasure (and rephotograph) later today.
Sorry about that. John ---- John Ackermann N8UR said the following on 04/09/2006 11:14 AM: > This morning I took 'scope shots of three 74AC04 gates paralleled > through 47 ohm resistors, and of a single gate through a 47 ohm resistor. > > There's very little difference in rise time -- 2.5ns (10% to 90%, using > the post-ringing high level as 100%) for three gates, and 2.35ns for a > single gate. As expected, the output voltage using a single gate was > significantly lower; the three-gate voltage was 3.56v p-p while the > single-gate voltage was 2.32v p-p. > > The test setup was an HP 5363 time synthesizer set to generate a 1MHz, > 50% duty cycle square wave through a 4 foot RG-58 cable driving a TADD-3 > board set for 50 ohm input termination. The TADD-3 output went through > a 4 foot HP 50 ohm test cable (the ~RG-58 thickness, highly flexible, > gray jacket type) into a Tek 2465B 400MHz scope with 50 ohm internal > termination. > > John > > > ------------------------------------------------------------------------ > > > ------------------------------------------------------------------------ > > > ------------------------------------------------------------------------ > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
