Android Doorbell Notifier

Breadboarded circuit to detect when doorbell rings

It’s always unfortunate to find a FedEx tag on your door saying you missed a delivery; especially when you were home the whole time. After having this problem a few times [Lee] decided to rig up a doorbell notifier for his Android phone.

[Lee]‘s doorbell uses a 10 VAC supply to ring a chime. To reduce modifications to the doorbell, he added an integrated rectifier and a PNP transistor. The rectifier drives the transistor when the bell rings, and pulls a line to ground.

An old Netgear router running OpenWRT senses this on a GPIO pin. Hotplugd is used to run a script when the button push is detected.

The software is discussed in a separate post. The router runs a simple UDP server written in C. The phone polls this server periodically using SL4A: a Python scripting layer for the Android platform. To put it all together, hotplugd sends a UNIX signal to the UDP server when the doorbell is pushed. Once the phone polls the server a notification will appear, and [Lee] can pick up his package without delay.

How to replace a Netgear router antenna

rp-sma-adapter-installed

a.ntivir.us wanted to use a different antenna for their Netgear mbr624gu WiFi router. Unfortunately, this model comes with an antenna that is not removable. As with other antenna retrofits, this involves no soldering. But because there is already a mounting area for an antenna, no case altering is needed either. After opening the router with a Torx driver it was discovered that the non-removable antenna was connected to the board with a mini rf connector (U.FL). The antenna and its mounting bracket were removed and a U.FL to RP-SMA adapter was put in its place using a washer to secure it to the rear plate of the router. Now any external antenna can be used and the router still looks brand new.

Netgear open source router


Netgear recently launched the WGR614L wireless router targeted specifically at open source firmware enthusiasts. It can use Tomato, DD-WRT, and soon OpenWRT. The core is a 240MHz MIPS processor with 16MB of flash and 4MB of RAM. You’ll probably remember when Linksys decided to dump Linux from their iconic WRT54G line in favor of VxWorks; they released the similarly speced WRT54GL for enthusiasts. Netgear seems to be arriving pretty late in the game, but they’ve set up a community specifically for this router. Time will tell whether community support is enough to make this the router of choice for hackers. We wish someone would release an x86 based router in the same price range just to make porting stupidly simple.

[via Slashdot]

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