[Dino] Tells Us About Transistor-based On/off Switches

hackaweek_transistor_onoffswitch

You know them, you love them, you take them for granted – they are single push button on/off switches. As [Dino] explains in the most recent episode of his Hack a Week series, they are typically implemented in the form of IC logic switches nowadays, but it wasn’t always that way. When they first came on to the scene in the 70’s, the single button soft switches were built using a set of transistors and a capacitor to get the job done, so [Dino] decided to research push on/push off transistor switches a bit and build his own.

After reading through a short tutorial, he was ready to go. As he explains in the video, the operation of the switch is fairly simple, though he did run into some odd issues when he prototyped the switch on a piece of breadboard. He’s looking for someone to explain why the unstable circuit suddenly performs better with the addition of a small capacitor between the battery’s positive lead and the circuit’s output, so if you have some insight, be sure to speak up in the comments.

In the meantime, check out [Dino’s] exploration of push on/push off switches below.

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Twittering Wall Switch Lets Dutch Hackers Know When It’s Time To Play

hackerspace_open_switch

Hack42, a hackerspace in Arnhem, Netherlands recently moved into some new digs, and they wanted an easy way to let their members know whether they were open or not. Fixed hours of operation typically do not fit this sort of organization, so that was out of the question. Instead, they built a switch into the wall** that will let their members know when they are open for business.

The switch separates the TX and RX pins of two Ethernet ports that reside in an old access point embedded in the wall. When the hackerspace is open, the switch is thrown and the circuit is closed. A cron job checks the state of the eth1 port once a minute, sending the “Open” status message to Twitter and IRC once it notices the status change. When the switch is thrown again and the eth1 port goes down, a “Closed” message is broadcast.

It is a simple but cool hack, and quite befitting of a hackerspace.

**No direct Google Translate link is available, though Chrome will translate it for you without issue.

[Thanks, _Danny_]