Re: 485 super weak brightness control


On Tue, Mar 23, 2021 at 09:27 AM, Ondrej Pavelka wrote:

Here is a odd thing I observing with B gate. Is this normal? Basically I
expect the pulse to be shortest at 1nS and gradually widen. What happens
here it basically goes in circles instead.
Looking at the width on your picture my B gate pulse width is correct at
1ns, corect at 2 and 5 but at 10ns us again the same length as 1nS and that
can't be right?
In this video I think I know what is happening. You have variable horizontal knob out (time 0:13 in the video). Your 5ns B gate is 300ns wide instead of ~ 130ns Raymond measured so this is supporting the theory of variable time scale. When you switch to 10ns it is the same RC time constant as 5ns (2x is in horizontal amp) but because variable time is disabled for B other than 1/2/5n, B-gate suddenly looks like it became shorter. If you push in the variable time scale knob my guess is you will see 5ns width same as 10ns width, not jumping to a smaller time. I tried it and can replicate what you are seeing with variable time scale set.

I don't think this behavior points to anything wrong.


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