Re: 577D1 Phantom base current

Michael W. Lynch

On Mon, Oct 19, 2020 at 01:30 PM, DW wrote:

Here is a idea

If someone with a 577 curve tracer try this test, install a transitor and with
the step generator set to single and increase the collector voltage does the
display indicate some current. Does moving the step generator amplitude
proportionally effect the amount of current displayed?

I am thinking if someone could duplicate this with a good known 577 we will
see if this is by design or if it is a fault.

I tried this with my 577 and with a PNP transistor in the standard test fixture. I have inverted the display so that the traces appear first at the bottom left of the CRT. With the # steps Control set to 1 step, I increase the collector voltage and I see the first line of the trace advance across the bottom at Zero (bottom graticule line), a single step appears above the ZERO Line, at whatever the step current control is set to. So I do not have any current offset indicating on the ZERO line. The ZERO Line remains at ZERO, indicating voltage being present with no current flow. Is that what you are looking for?

Michael Lynch
Dardanelle, AR

Join to automatically receive all group messages.