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Henner Zeller
Works at Google
Attended Ruprecht Karl University of Heidelberg
Lives in San Francisco
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Henner Zeller

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This looks really promising. Fusion of 3D perspectives in motion to a canonical model.
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LoL
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This is amazing!
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Henner Zeller

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This looks kinda cool - a 4 digit bubble display in a 12-DIL package (qdsp 6064).
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A bit nicer view for the board to drive three parallel RGB panel chains for the https://github.com/hzeller/rpi-rgb-led-matrix project (board is shared on https://oshpark.com/shared_projects/D2hXjnYT ).

Now time to build an aluminum frame to hold 24 panels that also will carry the 80A@5V needed to keep the LEDs happy...
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I think these look good +Antonio Diaz. You can ask them if they have the Hub75 interface, but judging from the picture, they do. You might be interested in the size also. This is a P6 panel which means that the LEDs are 6mm apart, which could looks a bit 'wide' (but is good for large outdoor panels). My panels are typically P5 (5mm). Then there are P4 panels, but I think they are more expensive (because density).
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LOL
 
I've been very unproductive this Easter. 
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Have him in circles
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Henner Zeller

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The importance of enough voltage driving steppers

For steppers, it is important to get close to the rated current, otherwise we are loosing torque and also microstepping accuracy as we can't get a proper sine curve anymore.

The first image is a DRV8825 stepper driver on a 1.8Ω/phase, 2.5mH motor. The second a A4988 on a 7.4Ω, 10mH motor. Both motors are somewhat loaded and need to do some heavy lifting.

We see the motor current with accelerating steps. Clearly visible: vignetting as with higher frequencies too low voltages can't push enough current through anymore.

Both drivers struggle to maintain the current with higher speeds, as there is not enough voltage to push it fast enough through the impedance.

Tomorrow, I'll be getting a couple of DRV8825 that allow to crank up the voltage to 45V... (right now, I am limited by the A4988 that can at most do 35V).
(Alas, I will only be able to go to 40V because of an MC34063 responsible for creating 5V out of the motor voltage on the BeagleG Bumps board).
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Yes, 24V is good, up to something close to 35V. The commonly used A4988 driver chip can only deal with up to 35V input, the DRV8825 up to 45V.

Also, these voltages bring extruder heaters into a nice Ampere range.

For bed heaters, I'd actually go directly to line voltage, as you ideally want a couple of 100W to heat up in acceptable time (but it requires more of people to know what they are doing to not kill themselves).
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Cute idea and certainly good to play around with energy harvesting circuitry at a university.

Other than that, it is as silly as solar powered roadways: don't mix two things that have different functionality - just because they have a thing in common it doesn't mean it is a good idea to build one device out of it -- which is deficient in both tasks.

A regular solar panel with the same area and a small image sensor, each optimized for their respective task would've served much better.
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Henner Zeller

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Ad-hoc bread baking with what I had at home. It is like two years since I baked my last; yeast was still good.

I didn't do anything for a nice brown crust, but still tastes nicely.

Yummy - fresh, warm bread out of the oven.
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Sieht lecker aus!
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I enjoyed the second edition for the basics, but in certain fast-moving and evolving areas, it showed its age.

Looking forward reading the third edition ...
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One of the greatest textbooks ever...
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Looks promising.
ILI9341 TFT using frame-buffer driver from https://github.com/notro/fbtft
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It is somewhat ironic how the U.S. and A. whose collective anti-communist mind comes up with the most mundane cookie-cutter housing like you would find in communist/socialist countries like you see below.

Except that it embraces greed to a point that things are not sustainable anymore. 80% of the water in California is consumed by huge farms.
A punishing drought is forcing a reconsideration of whether the aspiration of untrammeled growth that has for so long been the state’s engine has run against the limits of nature.
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Have him in circles
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Work
Occupation
Working on Google's web crawler.
Employment
  • Google
    Software Engineer, 2006 - present
  • freiheit.com
    Software Engineer, 2002 - 2006
  • Thinking Objects GmbH
    Software Engineer
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
San Francisco
Previously
Zurich, Switzerland - Hamburg, Germany - Campbell, CA - Heilbronn, Germany - Sunnyvale, CA - Earth
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Tagline
Code Poet, Photographer, Artist, Maker.
Introduction
When I was a kid, I wanted to be an inventor and making stuff. Transforming the world to a better place using the brain and other tools. And having fun doing it.

Back then, I built camera obscuras with photo paper in it and had a dark-room to develop it for my first photography experiments; now I am shooting digital pictures, but still have the fun in preserving moments and details in images.

Also, I am writing software (for fun, and even paid for it), soldering electronic circuits or building my own furniture; also I am playing the cello - I think I came pretty close to my childhood's dream.

Is the world a better place yet ? Well, while I am closer to my childhood dream, there is still a long way to get close to John Lennon's dream expressed in "Imagine" ...

Obligatory Disclaimer: This is my personal account. The views expressed here do not represent those of my employer.
Bragging rights
I download the Internet.
Education
  • Ruprecht Karl University of Heidelberg
Basic Information
Gender
Male
This ranges from more than 100 year old mechanical games and music machines to 1980ies video games or air-hockey - a cross-cut through the generations. But really, the old machines are the most interesting: well weathered but survived the times, they are still withstanding use every single day (yes, all of them still work, typically just cost a quarter). Hand-painted 'fortune teller' machines, 3D films of 1906 earrthquake, paper-roll operated pianos or a capella-singing wooden dolls - a wide range of curiosities from the last 100 years. I discovered it once by accident on a photo-walk, but now whenever someone visits the city, I take them there and they end up being as enthusiastic as me.
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Public - 4 months ago
reviewed 4 months ago
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