Re: [tlug] GW projects

[Christian Horn <chorn@example.com>]

On Tue, Apr 28, 2020 at 03:06:04AM +0900, Benjamin Kowarsch wrote:
> On Mon, 27 Apr 2020 at 17:41, Christian Horn <chorn@example.com> wrote:
> 
> > I plan to try Fedora on Raspi4, and ordered an addon part
> > for the Raspi4 which should allow HDMI grabbing (idea from
> > this page:
> > https://mzyy94.com/blog/2020/04/10/raspberrypi-hdmi-input/ ),
> >
> 
> Interesting. What are you going to do with that?

Most importantly, I'm curious with how much latency one gets 
HDMI captured and transferred over network and displayed on a Linux 
desktop.

As the Raspi4 can also act as USB-HID, maybe it could even act as
a KVM device, translating HDMI/keyboard/mouse of a system onto the
network.
My monitor also has just one HDMI connector, so grabbing HDMI from
sources like the Nintendo Switch, I could present that live on the
single monitor.  Latency is probably not good enough for action
games, but desktop with Linux should be usable.


> Do you have an rp3, too? I would be very interested to hear from you how
> the rp4 compares to the rp3 performance wise. I have got an rp3 but found
> it wanting for the kinds of things I might have done with it. The rp4 looks
> like it is a serious leap in performance over the rp3.

Just rp4 here, also just the 2GB variant, that is what was available
last years summer when I was in Europe.

So not sure about rp3, just compared some operations with
Nintendo switch and a Thinkpad L480:
https://fluxcoil.net/hardwarerelated/raspberry_pi_4#benchmark_results


> I was thinking about building a viscometer and found a YouTube video by
> some guy in France who had done so using an Arduino as controller for the
> rpm of the electric motor, measuring the motor current and calculating the
> torque from those. When the motor is used to drive a spindle or paddle at
> different rpms within a fluid, the viscosity of the fluid can be deduced
> from the changes in torque. Unfortunately, the video doesn't give much
> detail and looking at various forums, it seems to be a somewhat complex
> undertaking that will likely require a lot more effort than a few days.
> Meanwhile I found such an instrument listed on Alibaba for 175 USD. So, I
> am not quite sure I am ready to commit to DIY. I am more interested in the
> actual instrument than the joy of building one :-)

Nice idea!
I had looked up radiation sensors, but not ordered anything.

Chris