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The Tale of “Nitecore” Keychain LED lamps …
Once upon a time there was an overly enthusiastic browser of ebay items, instigated by “BigClive” to buy stuff. He purchased two Nitecore knock-off lights, a bit too cheap to be true!
The packaging looks surprisingly good. Guess which one is the real thing. While waiting for the stuff from China to arrive, he also purchased a set of 2 genuine Nitecore “Tube” lamps on Amazon. This will turn out to be crucial.
[…]
Several months later (sponge-bob narrator voice).
Well, I got busy. The cheap thing worked at first – until I charged it. Then it broke, not the LED, not the LiPo management chip, but the controller itself!
ON BOTH FAKE LED LAMPS. Failure by design again.
I was contemplating converting these thing to full manual mode, i.e. bypassing the controller IC with the switch, but no time once again.
What I did manage to do was to test the LED. Here I’m bridging Vcc to the GATE of the MOSFET controlling the LED. It worked. BTW, it doesn’t have a LED driver OR sufficient resistor. The MOSFET itself was abused for that – and got quite TOASTY.
So, it ends here.
Two useless LED lamps that might be abused as annoyatrons. The LiPos don’t even have a protection circuit. Shees. I did order a decent replacement battery for one, but never used it. Guess what, no time.
Conclusion:
The real NiteCore LED lamps ARE WORTH EVERY CENT. They just work, no hassle, decent battery life …
Posted in Electronics.
Tagged cheap, ebay, failure by design, keychain, lamp, LED, nitecore
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Happy New Year 2019
Created with xscreensaver‘s “fireworkx”
Forcing kdesu / xdg-su to honour ‘sudoers’
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kwriteconfig5 --file kdesurc --group super-user-command --key super-user-command sudo |
You can also just add this to $HOME/.config/kdesurc
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[super-user-command] super-user-command=sudo |
Source from 2008 :-)
VirtualBox mischief – getting rid of too many pesky users
This requires VirtualBox guest additions to be installed.
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#!/bin/bash VM_NAME="deb test" MAX_USERS=2 RUNNING_VMS=`VBoxManage list runningvms` OUR_VM_IS_RUNNING=`echo ${RUNNING_VMS} | grep "${VM_NAME}"` if [[ -z ${OUR_VM_IS_RUNNING} ]] then echo -e "VM \"${VM_NAME}\" not running...\nBye!" exit fi LOGGED_IN_USERS=`VBoxManage guestproperty enumerate "${VM_NAME}" | grep "/OS/LoggedInUsers, value" | awk '{split($4,a,","); print a[1]}'` if [[ ${LOGGED_IN_USERS} -gt ${MAX_USERS} ]] then echo "Checking VM: \"${VM_NAME}\"..." echo "${LOGGED_IN_USERS} logged in. Maximum allowed: ${MAX_USERS}" echo "Shutting down \"${VM_NAME}\" ..." VBoxManage controlvm "${VM_NAME}" savestate else echo "Checking VM: \"${VM_NAME}\"..." echo "${LOGGED_IN_USERS} logged in. Maximum allowed: ${MAX_USERS}" echo "Phew ..." fi |
Posted in Computer / Server
Tagged linux, mischief, scripting, VBoxManage, VirtualBox, virtualization
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A bit of VirtualBox scripting – NAT & DHCP
Maybe someone will find it useful…
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#!/bin/bash ISO="${HOME}/VirtualBox VMs/__stuff__/ISOs/debian-9.5.0-amd64-netinst.iso" VBoxManage createvm --name "$1" --register --ostype "Linux_64" VBoxManage modifyvm "$1" --memory 1024 --acpi on --cpus 2 --audio none --usbxhci on --ioapic on --vram 16 VBoxManage storagectl "$1" --name "SATA" --add sata --hostiocache on --portcount 2 MEDIUM_UUID=`VBoxManage createmedium disk --filename "$HOME/VirtualBox VMs/$1/$1" --size 8000 --format VDI | awk '{print $4}'` VBoxManage storageattach "$1" --storagectl "SATA" --port 0 --type hdd --medium ${MEDIUM_UUID} --nonrotational on VBoxManage storageattach "$1" --storagectl "SATA" --port 1 --type dvddrive --medium "${ISO}" #VBoxManage storageattach "$1" --storagectl "SATA" --port 1 --type dvddrive --medium emptydrive if [[ -z `VBoxManage list hostonlyifs` ]] then VBoxManage hostonlyif create fi VBoxManage hostonlyif ipconfig vboxnet0 --ip 192.168.56.1 --netmask 255.255.255.0 VBoxManage dhcpserver add --ifname vboxnet0 --ip 192.168.56.3 --netmask 255.255.255.0 --lowerip 192.168.56.100 --upperip 192.168.56.200 --enable VBoxManage modifyvm "$1" --nic1 hostonly VBoxManage modifyvm "$1" --hostonlyadapter1 vboxnet0 VBoxManage natnetwork add --netname natnet1 --network "192.168.16.0/24" --enable VBoxManage natnetwork modify --netname natnet1 --port-forward-4 "ssh:tcp:[127.0.0.1]:6666:[192.168.16.137]:22" VBoxManage dhcpserver add --netname natnet1 --ip 192.168.16.3 --netmask 255.255.255.0 --lowerip 192.168.16.137 --upperip 192.168.16.200 --enable VBoxManage modifyvm "$1" --nic3 natnetwork VBoxManage modifyvm "$1" --nat-network3 natnet1 VBoxManage dhcpserver add --netname intnet0 --ip 192.168.42.3 --netmask 255.255.255.0 --lowerip 192.168.42.100 --upperip 192.168.42.200 --enable VBoxManage modifyvm "$1" --nic2 intnet VBoxManage modifyvm "$1" --intnet2 intnet0 VBoxManage list natnets VBoxManage list hostonlyifs VBoxManage list dhcpservers |
Please note, as of today (2018-11-03) there appears to be an annoying issue with the DHCP server (5.2.20) for “NAT Network” (not just “NAT”). If you change the settings for the built-in DHCP server, you have to shut down any VM that is involved and delete the lease file (e.g. $HOME/.conf/Virtualbox/natnet1.leases).
If this is not done, the DHCP server will happily hand out old non-matching leases:
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Nov 03 20:08:10 iscsi dhclient[604]: DHCPRELEASE on enp0s9 to 192.168.16.2 port 67 Nov 03 20:08:10 iscsi dhclient[617]: DHCPDISCOVER on enp0s9 to 255.255.255.255 port 67 interval 8 Nov 03 20:08:10 iscsi dhclient[617]: DHCPREQUEST of 192.168.16.137 on enp0s9 to 255.255.255.255 port 67 ---> Nov 03 20:08:10 iscsi dhclient[617]: DHCPOFFER of 192.168.16.137 from 192.168.15.2 ---> Nov 03 20:08:10 iscsi dhclient[617]: DHCPACK of 192.168.16.137 from 192.168.15.2 Nov 03 20:08:10 iscsi dhclient[617]: bound to 192.168.16.137 -- renewal in 507 seconds |
Posted in Computer / Server
Tagged linux, scripting, VBoxManage, VirtualBox, virtualization
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Sleep is vital
Bad sleep or poor quality will do you in.
Don’t go down that path.
LLAP
Not So Half-Arsed Attempt At Aircraft Spotting — MUC Again
Posted in Something Completely Different
Tagged aircraft spotting, airport, FJS, MUC, Munich, plane spotting, weekend trip
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SuSE museum — 7.3 to 9.1
Posted in Computer / Server
Tagged good old days, historical, linux, museum, SuSE
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2017
Real fireworks this time.
Posted in Something Completely Different
Tagged 2017, fireworks, happy new year
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A Ghost from 1995 – Good Riddance
Posted in Computer / Server
Tagged 95, AOL, Certificate Of Authenticity, cleanup, trash, windows
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The worst Android tablet — Failed attempts of …
As You can see, there’s nothing of interest here. This post was cancelled due to lack of material & motivation. Please proceed to the next post in this mini-series. If you’re a user of headphones, you may want to turn down the volume a bit ;-)
In the meantime, you may find this scientific publication interesting:
“The unsuccessful self-treatment of a case of ‘writer’s block'”, J Appl Behav Anal., 1974, 7(3): 497, doi: 10.1901/jaba.1974.7-497a, [PDF][Original source]
IWATSU LeCroy 9350A — bringing back old memories…
This “beauty” appeared on my desk today. Just testing & playing with it. I used the arb sig-gen of a PicoScope 2204A for generating a unpleasant test-signal. Trying to trigger on it was “interesting” :-)
Posted in Electronics.
Tagged 9350A, amber, CRO, DSO, heavy, IWATSU, lecroy, oscilloscope
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ERSA I-Con Nano — A pico review
Well… the device I got at work was a sad case of “dead on arrival”.
Temperature regulation was totally crazy, touching the case moved the measured value from about 350°C to 60°C, with a subsequent massive overshoot.
So we have to wait until the replacement unit arrives… maybe an XMAS present.
Attempted Aircraft Spotting — MUC
Since I hear the effing aircrafts all the time, I might as well go and take a closer look at them, no?
An impromptu Sunday trip to ‘MUC’ (or FJS).
Posted in Something Completely Different
Tagged aircraft spotting, airport, FJS, MUC, Munich, noise, plane spotting, weekend trip
4 Comments
Relocating…
Still busy with stuff.
BUT, there is a functional dishwasher! What a great device !!!
Triple Teardown Tardiness — Long Forgotten Boxes Of Stuff
Moving == carrying heavy boxes, lots of them.
Suboptimal.
Getting rid of stuff is imperative!
If You’re so inclined, You’ll find sloppy teardowns of 3 devices below. Mostly images and a bit of video footage at the end.
Posted in Electronics.
Tagged HDD, Hitachi, microdrive, mp3, Samsung, teardown
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“Six Sigma For Dummies” — An attempt of a book review
To make one thing clear, I was looking for a book describing the concept, methodology and application of “Six Sigma”. So you now know my expectations: facts, recipes, some math & statistics primer, NOT a lot of prosa / wall of text without content or just stating the blatantly obvious.