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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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Things are not usable yet, but at least in Y-direction I have more definition now, by replacing the laser driver that came with the laser with my own.

The next issues to address is mirror start point drift and jitter with a feedback photo diode, and making the laser focus point actually sharp (right now, it is a diagonal oval as can be seen in the circle).

#ldgraphy
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Henner Zeller

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First exposure with my Direct Laser Imaging experiment.

Left is the output, on the right is how it should look like.
The lines are 0.25 mm thick, the distance of the narrow lines is 0.5mm.

Focus: needs tweaking, but the crappy lens in that laser makes that hard. Something I worry once the other problems are solved.

Distortion: Looks like the PLL in the Polygon mirror was drifting initially. I am probably driving this at too low speed. To be able to go faster, I have to replace the laser driver to provide for higher bandwidth.

Also part of the distortion is that I still have to exactly determine the radius I am working with, right now it is just roughly estimated.

X-axis is not properly mounted yet, so that is as well something known.

Total exposure of this 30mm x 30mm patch was about 90 seconds. And it looks like this is sufficient for the resist.

Anyway, given all the known deficiencies, the first result is actually not too bad.

More to come.

#ldgraphy
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Playing with the idea to create a direct UV exposure for circuit boards. Polygon mirror from an old laser printer, 405nm laser.

If I don't make an attempt to 'straighten' the projected laser, then I can always be in focus, which simplifies the whole set-up because I don't need an expensive f-theta lens or equivalent mirror. The circular projection line can easily be corrected for in software.

However, hitting the surface at an angle will create an oblong laser dot. Maybe I need to play with an astigmatic lens.

Anyway, early stages.

#ldgraphy
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Stephen Cameron's profile photoHenner Zeller's profile photoBranko Badrljica's profile photo
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Great. I planned to play with it myself. But I had more in mind to f**k around with Einstein & his photoelectric effect in the sense of optically assisted etching.

If it's about using paint/lacquer, I'd go for reworking cheap A3 inkjet like WF-7110, which allegedly has a bit oily inks that look interesting. And a resolution of 4800x2400 isn't half bad either.
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Henner Zeller

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A view over Seattle.
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Watching a +Micah Elizabeth Scott stream on a RGB matrix[1] with FlaschenTaschen-protocol[2] which is a supported video network protocol by the git version of VLC[3].

This 160x96 LED matrix operated by a Pi3 is leaning against my fireplace and I use it often to simulate some crackling fire. But it also works as Saturday afternoon entertainment display.
Looks better if a little blurred..

[1] https://github.com/hzeller/rpi-rgb-led-matrix
[2] https://github.com/hzeller/flaschen-taschen
[3] https://wiki.videolan.org/UnixCompile/
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Henner Zeller

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Retrofitting an old amplifier with a remote control.

Goal was to have a tiny remote control sender that essentially is the size of a knob controlling an old amplifier that didn't have a remote control.

Remote control is made from an Attiny44, a FET, two infrared LEDs and a rotational encoder with monentary switch option. Operated with a CR2450 battery. The final housing is in a cylinder made of laser-cut round acyrilic slices.

The amplifier itself got its mechanical pot replaced by an electronic pot (Dallas/Maxim DS1882, dual log pot), and a 32 detent optical rotational encoder (which feels close to the original potentiometer in that amplifier). Also, it has a momentary switch, which is used for the mute function. Everything controlled by an Attiny48.

To get user-interface feedback, there is an LED ring with 30 charlieplexed LEDs around knob on the amplifier, moving the dot where the knob on the amplifier or the remote control sets the volume. Being outside the case, it also has the TSOP75338 receiver. Connected with the inside of the amplifier using a flat-flex 0.5mm pitch cable.

I am quite pleased with the result. Things worked out of the box even though the original potentiometer was 25k and this is more like 47k.

There are little things to do, such as covering the LED ring in a contrast-enhancing grey foil. And maybe a next hardware version will have the negative supply just generated from 5V with a MAX1720 instead from a linear regulator from the (luckily available) negative supply of the amplifier (right now, there are three supplies +6V, -6V, +5V; in the future, that would only be one).
Also future todo would be to have a bunch of tantalums to provide the energy for an IR burst, so that the remote control could be operated with a CR2032 even if its internal resistance increases over time.

https://github.com/hzeller/DerKnopf
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One of my supplies is not like the others. And it cost me some debugging time this night.

Is Power Supply Shaming a thing ?
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New Year's Eve project.

Was designing and laser-cutting a couple of parts today at +Noisebridge.

A couple of us were hanging out there tonight and making cool things.

#ldgraphy
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+Henner Zeller and +Ben Kochie made this Flaschen Taschen driven sign work for you. #33c3
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The electoral college was supposed to be a safeguard to prevent unfit candidates. But even in this grossly obvious case, they didn't do what they were supposed to do and were locked into their track.

Partially, this was probably because there was never a proper process defined as this was never had to put to practice, so the legal grounds were hand-wavy and shaky.

This is one point to address after this democracy falls entirely to ashes within the next four years and needs to be re-constituted. Maybe the new country will choose to have the Phoenix as the new national emblem.

But for now, we have to endure the Machtergreifung and the years to come.

https://upload.wikimedia.org/wikipedia/commons/4/43/Phoenix-Fabelwesen.jpg
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Wolfgang Rupprecht's profile photoThantiK's profile photoBen Walton's profile photo
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Democracy needs DiRT so it's prepared for real emergencies.
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Henner Zeller

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538 EUR. Is this thing made of Rhodium foil, rolled up by Astronauts living on Mars, delivered back in single units back to earth ?
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Stefan G. Lesser (wharrgarbl)'s profile photoBranko Badrljica's profile photoHenner Zeller's profile photo
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I have read more the details of the page. Looks like this is for a package with 700 of these. In that case, the price is actually acceptable.

This is also part of the headline - but the headline is soo long, that it gets truncated.
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Henner's Collections
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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
Story
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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reviewed 2 years ago
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