
Inside a Poundland computer mouse [video] - bane
https://www.youtube.com/watch?v=NwfZBRTqXFY
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edent
Big Clive's videos are always informative and invariably entertaining. He goes
in to so much detail, and often includes little circuit sketches. Perfect for
casually learning about electronics.

Without a doubt the funniest is the teardown of South Park's Nosulous Rift
device -
[https://www.youtube.com/watch?v=Ucymk0q70aQ](https://www.youtube.com/watch?v=Ucymk0q70aQ)

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benj111
Entertaining? Yes. _Always_ informative?

[https://m.youtube.com/watch?v=n2ZZbuOeNmw](https://m.youtube.com/watch?v=n2ZZbuOeNmw)

~~~
jrockway
Probably educational in the sense that V = IR rather than "for mysterious
reasons you must connect a 120V appliance to 120V and not 240V".

~~~
teh_klev
Oh hai....would you prefer a 470ohm or 1k ohm hotdog for lunch?

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rasz
On the shoulders of giants. This single chip mouse has its origins in HP, they
needed precise paper tracking for big format printers. HP spun it off to
Agilent, who spun off Avago Technologies, current optical mouse sensor giant.

Interview with Optical mouse inventor: Oral History of Gary Gordon
[https://www.youtube.com/watch?v=TxxoWhCzIeU](https://www.youtube.com/watch?v=TxxoWhCzIeU)

~~~
londons_explore
Ironic that this tech is actually pretty bad for precise tracking.

As the paper thickness varies, or the paper roughness varies, the distance
between the paper and the lens goes up and down, effectively zooming the image
in and out.

Since the focal length is so small, even a surface roughness of a few
micrometers can have a 1% change in the measured distance travelled from the
sensor.

In the case of an optical mouse, you can test this out. First turn off any
"pointer acceleration" by your operating system, so the cursor position
represents the actual movement of the physical mouse. Now move the mouse to
the left, push down on the body of the mouse, while moving it back to the
start point in the real world. Notice the cursor isn't at the screen start
point?

That's because pushing down very slightly changed the optical distance, and
the mouse thought it moved further than it really did.

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rasz
It worked great for its intended application. You dont have to worry about
paper thickness/distance in a commercial machine using high quality source
materials. I dont even think it would play major role, measurement is done by
correlation, moving closer/further only scales the picture.

Commodity mice are terrible as distance meters tho
[https://www.youtube.com/watch?v=CIRKRzw54Zs](https://www.youtube.com/watch?v=CIRKRzw54Zs)
because you cant completely turn off acceleration/interpolation inherent to
particular sensor package. It would require low level access to sensor
parameters/options, something only available to clients doing xx thousand
units per month volume from vendors like Broadcom.

~~~
avian
> I dont even think it would play major role, measurement is done by
> correlation, moving closer/further only scales the picture.

Scaling the picture is the problem. What parent is trying to say is that the
distance the physical paper has to move for the sensor to see 1 pixel of
movement depends on the height of the sensor above the paper.

If you want to know how many millimeters the paper moved based on sensor
input, this is important (especially if you want precision on the order of dot
size in high-dpi printing).

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bigtrakzapzap
Big clive on HN. Hurray!

He earned my respect from a video on a USB charger with an electrocution risk
and why you should never buy cheap USB chargers.
[https://youtu.be/3Hdn0MuCK_0](https://youtu.be/3Hdn0MuCK_0)

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bemeurer
This video of his made laugh for about an hour straight. I must've rewatched
it at least a hundred times by now. [profanity warning]
[https://www.youtube.com/watch?v=QLWKNTUHiEU](https://www.youtube.com/watch?v=QLWKNTUHiEU)

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Zenst
I got one about a year ago as a backup (thought why not), actually works
rather well, small, but perfect for laptop bag, cheap enough to not stress and
small enough to not take up much space. Not pondered scrapping one for parts,
but certainly something I've become more mindful of since Maplins closed.

~~~
Theodores
I own one too! Very happy with mine, I have also loaned it to people with
small hands, RSI and other reasons to use it.

The scroll wheel is not to my liking but otherwise it is a very useful mouse.

I did actually try to buy another but they had a different design to the one
shown here and not as good. Maybe stocks vary by outlet or it is seasonally
available.

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rkachowski
For US viewers - Poundland is basically a dollar store.

~~~
DominikPeters
In Poundland, all but a few items cost £1. In U.S. dollar stores, prices vary
a lot, and most items cost >$1.

