PDP 11/24 - A Step Backwards

[Matt Burke]

On 28/03/2022 23:22, Rob Jarratt via cctalk wrote:
> Its 600mV, but it is more of a spike than a ripple. Here is a trace: https://rjarratt.files.wordpress.com/2022/03/pin-1-5v-ripple.jpg
>

I think that's just switching noise. You appear to be zoomed in on the
point where the main switching transistor is turning back on. Here is a
trace from an H7100 power supply (connected to a 70A dummy load) for
comparison:

http://www.9track.net/posts/h7100_trace.png

If you turn on averaging mode on the oscilloscope (acquire menu) then
that should filter our some of the noise and you will be able to see the
actual ripple a bit better. It should be noted though that a
differential probe is required for accurate ripple and noise measurements.

Regards,

Matt