Posts Tagged ‘remote’

How to decode infrared transmission

Thursday, April 22nd, 2010

rc5-decoding-explained.jpg

Alright, here we’re going for chapter on Manchester Encoding. Brian J Hoskins did just that when building this RC5 decoder. This protocol is widely used in television remote controls. You use them on a daily basis, don’t you think it’s time you understood what’s going on? Check out his writeup and learn the dark art of invisible light communication. Or just skip the learning and follow this how-to.

courtesy: Hack a day

Powering a switch via PoE

Wednesday, January 27th, 2010

poe-powered-switch.jpg

So the story goes like this, my roommate needed to tap some IP phones for diagnostic purposes. I found a netgear HUB that would serve that purpose. This was not ideal as the IP phone needed power from the network, or a 48V wall-wart. He asked if I could get PoE to pass through the hub. Easy, I’ll just loop the unused pair and viola! Wrong.

What really happened is I had to do a lot of reading, and found a few key things. According to 802.3 af standards, the PSE or Power Supply Equipment, decides how power is going to be sent, while the PD or Powered Device has to accept BOTH modes.

This might be a good time to explain that 802.3af can send power one of two ways. Using phantom power through pins 1,2,3 and 6 (mode A) or through the unused pairs, pins 4,5,7 and 8 (mode B). In all my testing, Cisco favors mode A power. Probably something about gigglebit standards?

[Kajer] was doing some work with IP phones that use Power over Ethernet. While trying to get this to work with a network switch he decided to use PoE to power the switch itself. The best thing about this is he managed to shoehorn all of the necessary bits into the stock case. Those bits include a bridge rectifier, transistor, resistor, and a 5v power supply. Along the way he discovered he can now power the switch off of USB if he wishes.

source: hackaday

Z-Wave Web-Enabled Door Lock

Saturday, May 31st, 2008

Z-Wave
Well-known producer of door locks Schlage is planning to add more intelligent in its products. It’s going to add Z-Wave-based looks line to provide consumers connect them to existing home automation systems or just manage them remotely via Internet.

The new product will be based on Schlage’s line of keypad locks and will have two-way Z-Wave RF technology built in. The battery-operated locks communicate with a Z-Wave gateway that connects to any broadband router. Since Z-Wave is a standards-based protocol, other Z-Wave-compatible controllers could operate the locks as well.

Remember that LinuxMCE has basic Z-Wave interface. So, you can try the new Schlage’s Z-Wave door lock when it’ll be released.