Posts from 2014-03

Deciding between a RPi colocation and hosting it yourself at home

The Raspberry Pi colocation costs 36 EUR incl. VAT per year, see here. If you spend this amount of money for energy only, it's:

Yearly Energy = 36 EUR/year / 0.27 kWh/EUR * 1000 Wh/kWh = 133 333 Wh / year
# to enter it more quickly in your calculator:
36...

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Enabling Wake on Lan on an Arch Linux Computer

https://wiki.archlinux.org/index.php/Wake-on-LAN

ip addr
su
ethtool enp1s0f0
ethtool enp1s0f1
ethtool -s enp1s0f0 wol g
ethtool enp1s0f0

What the g or the other options mean is stated here (source):

p Wake on phy activity
u Wake on unicast messages
m Wake on multicast messages
b Wake on broadcast messages
a Wake on ARP
g Wake...

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Solving NAK DHCP Problems with the Fritz!BOX 7490 router

If you encounter problems like these:

dhcpcd[13577]: eth0: broadcasting for a lease
dhcpcd[13577]: eth0: offered 192.168.1.64 from 192.168.1.1
dhcpcd[13577]: eth0: reject NAK via 192.168.1.1

Online you will find a lot of old threads suggesting things like commenting out the line require dhcp_server_identifier in the file dhcpcd.conf. Didn't help in my case.

This happened...

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19 Inch Rack Cases – General Properties

Horizontal Dimensions

The width of 19" equipment is obviously 19 inches = 482.6 mm. However, the question is: what distance is that? Wikipedia helps us: The 19 inch are "including edges or ears that protrude on each side which allow the module to be fastened to the rack frame". So for...

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Pollin Wireless Power Sockets with the Arduino

This blog post describes my project to control a cheap wireless power switch from the German electronics distributor Pollin (Funksteckdosen-Set mit 3 Steckdosen, order no. 550666, 9,95 €) via the Arduino / the RPi.

How The System Works

It uses the common chip HX2262. The RF module sends on 433.92 MHz.

The encoder...

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