The following measurement problem is associated with a high voltage (very low current) power supply. HV is around 2.5KV. The supply is charged through a 1:100 transformer by quickly completing a current path through the primary. This is a very fast operation with a very slow repetition rate.
I'm attempting to measure the two signals for this circuit - the pulse which recharges the HV, and the ripple component of the HV itself.
The pulse is a negative-going signal of about 20uS that (allegedly) occurs at a 9Hz rate. The HV ripple is a result of very slow bleed-off of the peak charge value. We're talking nanoamps here.
I'd like to get at least two of the charge pulses in one sample so I may view the dynamics associated with the HV output. I should see, for example, the HV output reaching a low-level threshold where it triggers a re-charge pulse, and then see the HV output rise until it dips once more and gets another boost.
Using the TDS744a, I'm struggling with how to set it up such that I may capture the needed data.
If I bring the sweep speed up sufficiently to see the pulse in a single X-axis division, the HV signal is all over the place - aliasing I guess. If I trigger on the HV signal at around 9Hz, I see a stable semi-sine-wave but cannot see the pulse.
I suspect this problem has to do both with my setup and possibly the amount of memory and sample rate.
Any suggestions out there?