Lair Of The Multimedia Guru

April 13, 2019

Photography

Some random pictures from my cameras sd card in chronological order (this is from end 2017)


Dont focus on me.


Dont step on me.


You shall not pass.

Filed under: Nature,Off Topic,Pictures — Michael @ 12:00

February 25, 2019

Copyright EU #6

On the 20th February the EU governments approved the current text, the way i understand it, it next goes back to the EU parliament for a final vote.
I ve found a quick summary of the problem with article 13 on youtube.
There are also numerous articles from the EFF and basically everyone else about the directive. So whichever news site/creator you like, chances are (s)he said something about it. The really interesting or should i say scary part is, ive yet to find someone except the politicians and lobbyists who push this to be in favor of this change.
So who will the winners and loosers of this likely be if it passes ?
The one thing that seems obvious is that if any variant of this pass, getting some content from a creator to a consumer will involve more laws, more regulations and more risk for intermediaries. Thus it will, in two words, cost more. Increasing cost for consumers, decreasing income for creators. And consuming more paper for the extra bureaucracy. Likely less diverse sharing platforms, less diverse content. It appears that almost everyone would be loosing a bit if this passes …
Btw i almost forgot, the next EU parliament election are very soon. If you live in the EU please vote, no matter if you like or dislike the EU copyright directive, vote for the party you believe is best.
If you want to know how the members of your parties voted about the copyright directive, thats available on https://saveyourinternet.eu/act/ (currently its the previous vote, iam not sure how this page will change after the final vote).

Filed under: Uncategorized — Michael @ 20:29

February 13, 2019

Copyright EU #5

Today the EU Parliament and council negotiators have agreed on a final Text. Next IIUC are the final votes of the various institutions.
I have not had the chance to fully read the text, just 1 page that was quoted on Twitter. So iam not in a position to really say what it means but what ive heared earlier today does not sound reassuring. Nor does it feel great that the public (like for example me) seems to basically depend on “leaks” from the law makers to know what is going on. Whats in the text, and so on. The EU should make their proposed texts and _ALL_ discussions fully uncut and un-delayed public.

Some sources of information: (the full text of the proposed directive might appear on these maybe)

Julia Redas Blog
Julia Redas Twitter
A short video about the situation yesterday
WBS (German lawyer) Discussing the yesterdays situation

Filed under: Uncategorized — Michael @ 22:04

January 13, 2019

Another ARM failure

A few days ago when i wanted to run some benchmarks on my cubox, i run into some odd errors, investigation led to the micro sd card. There where several bad sectors that could not be read anymore.
Thats the first time ive myself seen a sandisk micro sd fail. ive seen transcend (really quickly) and kingston (not so quick) fails but no sandisk or samsung till now.
Another point for FATE, another disk it won against…
But how badly damaged is the sd card? ive run ddrescue on it for a few days:

# ddrescue -r 5 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7947 MB, errsize: 493 kB, errors: 217
Current status
rescued: 7947 MB, errsize: 254 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 48, average rate: 122 B/s
opos: 7389 MB, time since last successful read: 1.5 m
Finished
# ddrescue -r 20 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7947 MB, errsize: 254 kB, errors: 48
Current status
rescued: 7948 MB, errsize: 193 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 37, average rate: 10 B/s
opos: 7389 MB, time since last successful read: 7.2 m
Finished
# ddrescue -r 40 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7948 MB, errsize: 193 kB, errors: 37
Current status
rescued: 7948 MB, errsize: 176 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 36, average rate: 1 B/s
opos: 7389 MB, time since last successful read: 41.4 m
Finished
# ddrescue -r 80 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7948 MB, errsize: 176 kB, errors: 36
Current status
rescued: 7948 MB, errsize: 172 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 35, average rate: 0 B/s
opos: 7389 MB, time since last successful read: 4.7 h
Finished
# ddrescue -r 160 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7948 MB, errsize: 172 kB, errors: 35
Current status
rescued: 7948 MB, errsize: 163 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 33, average rate: 0 B/s
opos: 7389 MB, time since last successful read: 41.7 m
Finished
# time ddrescue -r 320 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7948 MB, errsize: 163 kB, errors: 33
Current status
rescued: 7948 MB, errsize: 151 kB, current rate: 0 B/s
ipos: 7389 MB, errors: 30, average rate: 0 B/s
opos: 7389 MB, time since last successful read: 4.7 h
Finished

real 1119m16.116s
user 0m1.274s
sys 0m3.877s
# time ddrescue -r 640 /dev/sdd backups/cubox-2019-01-07 backups/cubox-2019-01-07.log

GNU ddrescue 1.17
Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 7948 MB, errsize: 151 kB, errors: 30
Current status
rescued: 7948 MB, errsize: 147 kB, current rate: 0 B/s
ipos: 4393 MB, errors: 30, average rate: 0 B/s
opos: 4393 MB, time since last successful read: 15.1 h
Retrying bad sectors… Retry 375^C
Interrupted by user

real 1236m21.926s
user 0m1.383s
sys 0m4.204s

Its interesting to note that even after quite some time there are still damaged sectors which can be recovered. It was just myself loosing patience that made me stop it. Also i have a backup somewhere IIRC so this recovery was just out of curiosity. And maybe ill play more with this card in the future to see if theres anything that can be done to improve recovery.

Hopefully ill have the cubox with a new sd card up and running fate soon again … (should be quite trivial)

Filed under: FFmpeg,Hardware — Michael @ 1:21

November 4, 2018

Silencing an oil-filled radiator

The way oil radiators work is that the oil inside is heated by electricity flowing through some resistive heating element. The heated up oil then raises due to lower density and that way circulates in the radiator which then gets hot and heats the air.
Noise is produced by either mechanical thermostats or relays, so every time the set temperature is exceeded by some fixed amount some mechanical switch or relay switches which makes a click. That can be annoying if one tries to use a device like this in an otherwise silent bed room.
The Device:

To get it open one has to remove 2 screws and slide teh front down:

The top can be removed too after that and after removing the handle.

Three more screws later the next front layer can be taken off, that is as much as we need to disassemble to access all parts we need to access:

Removing the lower board is trivial, just remove screws and disconnect cables:

Next the 2 noisy relays are desoldered:

To replace the relays 2 solid state relays from ali express are added, they are rated at several times the needed current (i expected the rating to be exaggerated when i ordered and wanted to make sure they arent underrated but it seems the seller actually was honest with the rating). Careful attention is also paid to their heat-sinking requirement (which is none at the currents they would be used with).

And a quick tests shows they are working fine and also have a pretty red led indicating that they are on:
btw, they are lacking their top cover because the heater could not be closed with it on, and it serves no purpose in this case

And now i have a silent electric oil heater radiator thing … click …WTF
Was there some part expanding from the heat and making a noise ? something on the 2nd board i didnt look at ?
I had it already reassembled and had to disassemble it again to trace where that came from. The radiator is rated for 2000W, one circuit 700 W or so and the other the rest to get to 2000W. It contains a fixed mechanical thermostat that disables both heating elements in case of overheat. and the 1300W heater has its own mechanical thermostat which disables just it at 85°C. The surprising thing here (to me) was that 85°C is easily exceeded by the 700W element alone. So the heater rating of 2000W is misleading at best because the heater under normal conditions will only heat with the 700W element continuously. The 2000W will just be used for a short period. After learning about that ive checked the shop where it was bought long ago and looking at heaters rated at 700W (which they have too and which are smaller) one quickly finds customer complaints that the 700W units switch off and are unable to sustain heating at 700W. This is Europa not China :( I did not expect to find this …
Ok back to the silencing, the solution here is in fact very simple. As the 2000W and 1300W modes are fake and only sustain 700W anyway and i have to assume for a good reason. The solution is to simply disable the 1300W part.

With that change the radiator is now actually silent and also looks cooler with the relay led shining through the front. Looking at the images i regret a bit that i hadnt thought about replacing the front by a transparent polycarbonate window. it would have looked cooler ;)

Filed under: Electronics,Off Topic — Michael @ 23:04

October 6, 2018

Pandaboard 5v power supply

A few days ago i noticed that my panda-board died. This is one of the 2 ARM systems on fate.ffmpeg.org.
Resetting or unplugging and re-plugging did not help. Replacing the power supply with a random 5v supply made it come back to life.
The failed power supply is a HNP-24-050 “HN Power Germany”. This is now probably the 3rd or 4th failed power supply for my panda board. The one its running on currently is a random one from ali-express. I must say iam really disappointed by the trash that some german electronic shops sell. All the failed power supplies where bought from germany, not china. The failed supply still produces 5v but when subjected to the slightest load its output collapses to 0, even 200mA is too much.
Ive read on the net that some digikey supply is recommended but both part numbers i found are marked obsolete.
Anyone has any recommendations ? I am not too positive that the 2€ +free shipping supply its running on currently will last very long.
I know i can just run it off a brand name ATX supply or a bench supply but that is a bit inconvenient.
Also if anyone wants to add more ARM hardware to fate.ffmpeg.org, so we have a bit more redundancy, thats certainly welcome

Filed under: FFmpeg,Hardware — Michael @ 23:41

September 20, 2018

Testing high voltages

The chinese negative ion generator i used in 3d-printer-particles-air-pollution made me a bit curious about what voltage it outputs. The page from the seller mentions several different values, 2-5kv, 5-8kv, 5kv and other things. So one wonders what it actually is. This sadly cannot be directly tested by just using a normal DMM as its a bit outside the supported voltage range of the average DMM. High voltage probes for DMMs exist but even chinese ones seem to cost at least ~70€ and i wouldn’t trust them safety wise. So lets make one for 1€ which we can trust to be unsafe.
We start out with a inappropriate high voltage probe enclosure, which we disassemble and remove the unneeded parts:

The innards of our HV probe is simply a 90MΩ resistor, which will together with the internal 10MΩ resistance of the DMM form a 10:1 voltage divider, extending its input range.

Lets try:

1470V, hmm
Checking what output saftey resistance this device uses:

It seems its something around 20MΩ, maybe 2 10MΩ resistors ? Its potted so no easy way to tell exactly. But this changes our output voltage estimate as now our probe effectively is 110MΩ instead of 90MΩ. That raises it to 1764V, but it still feels a bit lowish to me. Also the 120MΩ to ground would draw 15uA, which could pull the voltage down by an unknown amount. This ionizer thing after all is not intended for producing any current.
To test for this we can use a higher value resistor. I do have a 1GΩ resistor (though it cost more than 1€), with it we get:

Aha, 4270V, so the 15uA does in deed quite significantly pull the voltage down. Now with 1GΩ we still pull 4uA here so this is likely still a too low estimate. Sadly i do not have a higher value resistor ATM.
What remains is to check that the 2 HV probe setups actually work at all, we must test this as we cannot be sure the DMM behaves as expected in this setup.

Both produce expected values at a 1kV test input, the voltage appears to be slightly below 1kV though.

at a 500V test input the value matches much better indicating that indeed the 1kV test output seems lowish

disclaimer: high voltage is dangerous, do not play with it or replicate anything described above. If you do anyway you do so at your own risk.

Filed under: Electronics,Off Topic — Michael @ 10:39

September 10, 2018

Copyright EU #4

In 2 days (on 2018.09.12) The next vote on the copyright directive in the EU Parliament will occur.
Resources about the draft, which IIUC will be voted on are available on https://www.saveyourinternet.eu/resources/. If you live in the EU and feel that this proposal is bad you can use https://saveyourinternet.eu/ to contact your representatives.
There are also 252 proposed amendments, iam not sure these will be voted on or not (i thought they would but the timeline seems too tight to really do that).
Also there will be EU parliament elections in a few months. If you live in the EU and care about this, check how the parties voted on this directive and other directives that may affect you before you vote on who you want in parliament. Politicians of all parties are very dishonest, only by looking at past actions can one with any accuracy predict what they will actually represent. No politician would ever say they intend to vote in a way that the audience of the moment dislikes.

Filed under: Uncategorized — Michael @ 18:04

September 9, 2018

3D printer particles / air pollution part2

When i experimented with measuring the amount of particles from my 3d printer, i noticed the majority originated from when the heat-bed was turned on. I had cleaned the inside of the printer roughly before, so this was slightly odd. More investigation shortly later revealed the cause though.


The use of tinned multi-core wire without ferrules. Why it was done this way you may ask? Because between the incomplete and poor official documentation, the consumer made videos of how to assemble it and my plain lack of knowledge about how multi-core wire with and without solder behaves in this case. This way of connecting the wires seemed sound enough and there also where no ferrules included with the printer kit.
That said if you did connect high current wires in a similar fashion, you probably want to consider redoing it with ferrules or in another reliable way, like directly soldering to the board or soldering a solid core wire onto the multi-core as an intermediate. Also keep in mind iam a programmer not a expert for this so do your own research if failure of a connection could have some real consequences.
My printer is fine, the heat-bed also didn’t behave erratically or anything. And i never trust/trusted it anyway in terms of safety to ever run it without someone being at home, so in my case it was impossible for this to cause any real harm. But i still didn’t expect that …

I didn’t had any fitting ferrules, so the way i fixed it was to take some terminal connector thingies, which when one cuts half of each off are basically ferrules. I also didn’t had a new terminal block that was rated for enough amps to replace the roasted one. I will properly replace these once i have proper replacement and have time. Quite likely next time that printer needs some kind of “service”.

Filed under: 3D printer,Electronics — Michael @ 17:09

July 31, 2018

3D printer particles / air pollution

A while ago i read about 3D printers spewing out nano-particles into the air, especially ABS. I was curious if i can actually measure this on my own printer and how to fix it.
My plan was to use a cheap air quality detector, that i bought previously. It has to be noted here that the device detects particles 300nm and larger while what i read seems more about 100nm and smaller particles so its not 1:1 comparable.
Before anything i used my vacuum cleaner to very roughly remove large visible crap from the inside of the printer enclosure.

First baseline measurement, with the printer on, no heating yet.


Can we reduce that particles/dust ? Lets try properly cleaning the enclosure with the vacuum cleanerto use a stream of negative ions to ionize the particles, so it sticks to something and doesnt stay in the air. As can be seen this is a effective way to clean the air, or the measurement device is affected by the ions.


There is a slight disadvantage, in that it seems the well designed printer (which lacks grounded components). Has its metal frame charged up by the ions and that then eventually discharges into something …


Luckily no permanent damage is done and a reboot of the printer clears this. Until it quickly happens again. But after a few minutes all the particles appear to be eliminated


Adding a wire between ground and the frame (with a 1k resistor between) stops it from charging up and seems to resolve this problem.


Next after heating up the heatbed to 65°C without the ions. There is really alot of particles/dust in the air of the enclosure:


After also heating up the nozzle to 215°C with PLA in it:


After finishing the print 38 minutes later


Waiting 30min (the heatbed is not disabled by the printer, the nozzle cools down), there are still significant particles in the air


Switching the negative ion generator on, 5 minutes later the particles in the air have decreased significantly


Another 5 minutes later the particles are largely gone


Now question, what happens if we try to print with the thing on?
First opening the printers enclosure brings some of our particles/dust back (from the airflow caused by the door presumably). After all it didnt magically disappear and theres nothing that would truly capture it (the heatbed is at 65°C here)


After the nozzle heated back up to 215°C the particles actually decreased


Taking an image every minute from the air quality meter shows that within about 6 minutes after the print started the particles go to 0, it does rebound slightly and fluctuate around 0 after that.


The print finishes without problems after 36 minutes. Originally i intended to repeat this with other filaments but as the biggest dust/particle creator seems the heatbed or rather air convection from its heat. This would need to be setup differently to eliminate that. As it drowns out new particles from the heated filament. But still this shows that for less than 4 euro shipped one can get a device to eliminate at least larger particles from the air within the enclosure of a 3d printer. Compared to a filter this is probably easier to setup as well. Further experimentation would definitely make sense. Though simply having an enclosure and opening it together with a window for 5 minutes probably removes most particles, if one is concerned about it.

Filed under: 3D printer — Michael @ 21:04
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