As I’m hosting my blog on a Raspberry Pi, I did some research on the web about it’s performance as a server. I started this site with Apache and migrated after a while to Lighttpd which already reduced server response time (3.6 seconds, according to Google’s PageSpeed Insights it reached 72/100 points) and improved performance. With an DSL upload speed of only 676 kbit/s one shouldn’t expect miracles anyway. Google’s PageSpeed results, which suggested to make a couple of changes to my site, and a comparison of Lighttpd vs. Nginx convinced me to migrate to Nginx.
So far I’ve attached devices to my Raspberry Pi or Arduino Uno with ratings less than 100 mA. These devices were connected to the output pins through a transistor or optocoupler. However, for heavy load currents a relay must be used. As a noob, it is somewhat difficult to chose parts with the right specs for driving a relay — so here are some hints.