What do hackers do on vacation? What do hackers do whenever they have free time? What do you love to do? That’s right. But how much more fun would it be if you could get together with 5,000 other hackers, share your crazy projects and ideas, eat, drink, dance, swim, and camp out all together for five days, naturally with power and Internet? That’s the idea of the Chaos Communication Camp, and it’s a once-in-four-years highlight of hacker life.
Held not too far outside of Berlin, the Camp draws heavily on hackers from Europe and the UK, but American hackers have been part of the scene since almost the beginning. (And Camp played an important role in the new-wave hackerspaces in the US, but that’s another story.) It’s one thing to meet up with the folks in your local hackerspace and work together on a project or brainstorm the next one, but it’s entirely a different thing when you’re drawing on hackers from all over the world. There was certainly more to see and do at Camp than you could in a month, not to mention in only five days, and this could be overwhelming. But if you dig in, the sense of community that came from shared effort and shared interests was the real take-home. And nearly everything at Camp should have its own article on Hackaday.
Continue reading “CCCamp: 5,000 Hackers Out Standing In Their Field”
Here is a great introduction to a practical application of electromagnetic theory—the field telephone. It’s a training film from 1961 that covers the sound-powered, local battery, and common battery systems along with the six basic components they use: generators, ringers, transmitters, receivers, induction coils, and capacitors.
Clear illustrations and smart narration are the hallmarks of these Army training films, and this one begins with a great explanation of generator theory. The phone’s ringer uses electromagnetic attraction and repulsion to do the mechanical work of striking the bells. Similarly, the sound waves generated by a caller’s speech move an armature to create an alternating electrical current that is transmitted and converted back to sound waves on the receiving end.
In the local battery system, the battery pushes pulsating DC to carry the voice transmission. An induction coil increases the capabilities of this system, but capacitors are required to filter out the frequencies that would overload the receiver, passing only the higher speech frequencies.
In order for several stations to communicate, the use of a switchboard is required to patch the calls through. There are many advantages of a common battery system with regard to call switching: no local battery is necessary, nor is a generator needed at each station. Calls are easier to place, and communication is much faster.
Continue reading “Retrotechtacular: Basic Telephony In The Field”