This button, with a few hacks, now makes it so we can open up our office with our Nexus Ones, iPhones or even SMS. Located near the reception desk, this button opens an electronic latch on the front door. Pulling the assembly out of the wall revealed the system to be about as simple as possible: the button simply connects two wires. Bridging them with a screwdriver fired
Click here to download the full size of the above Circuit.
the latch (from their small gauge and uninsulated connections, it was obvious we weren`t dealing with dangerous voltages, but please don`t start pulling cable from your walls unless you know what you`re doing). Connecting two low-voltage wires electronically isn`t a particularly hard trick, so I decided it`d be fun to spend some evenings building a system to expose that switch to our network. I`ve built a few projects in the past that make use of custom router firmwares and Arduino microcontrollers, so I decided to use those tools for the job. I`m a big fan of this approach - it`s a great, inexpensive way to add a scriptable network interface to your microcontroller projects (if you`re interested, I talk more about this technique here ). Ultimately, I ran into difficulty getting this particular router`s serial connection to work, so I abandoned the Arduino - it was overkill anyway. Inspired by the excellent new MAKE: Electronics book, I decided to build a circuit to do the job. Here`s the finished franken-router, hooked up to the switch: So how does this all work Well, let`s start with the router. It`s a Linksys WRT54GL, a still-Linux-friendly descendant of the WRT54G, the router which jump-started the custom firmware scene. There are a lot of custom router firmwares available - DD-WRT, Tomato, Gargoyle - and they can all make your consumer-grade router do some professional-grade things. For this project I used OpenWRT,...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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