Right. I should be seeing ~11 volts, not 6, after the triangular spike. The 17 volts is unregulated - but I can't see 15K knocking it down. I'll test that - just connect the 15K directly between ground and 17V and measure with the DMM.
Ed
Here are my latest and probably last test results:
BTW, it's possible that on some of my earlier tests, I had accidentally set my home-made power supply to its lowest current limit (about 25 mA).
-- Terry Pinnell Hobbyist, West Sussex, UK
Here are my latest and probably last test results:
BTW, it's possible that on some of my earlier tests, I had accidentally set my home-made power supply to its lowest current limit (about 25 mA).
-- Terry Pinnell Hobbyist, West Sussex, UK
The zener I was using is no good and now resides in the trash can. With a properly working 6 volt zener, I get the same waveforms as you. The expected ~11 volt level is there, the spike is there, and the mystery is solved. Damn thing tested good in series with 1K at 9 volts.
Ed
Great - glad we sorted that puzzle .
-- Terry Pinnell Hobbyist, West Sussex, UK
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