Uncrippling lower model speakers

It looks like this low-end Sennheiser HD speaker has the same internals as it’s better-brother but has been altered to reduce sound quality. It’s not uncommon for manufacturers to hobble a product in order to sell more units at a lower price that reflects less features. Linksys WRT54G routers immediately come to mind, or perhaps the more recent Rigol 100 MHz oscilloscope hack is a better example.

In this case, that black piece of foam on the left has been added to the 555 version of the hardware to decrease the sound quality you get from the much more expensive 595 model. Take it out and you’ve got an upgrade that would have cost you more than a hundred bucks. Don’t think this is the only difference? There is a bit of a difference in case design, but [Mike Beauchamp] also found that if you acquire a replacement driver for either model you’ll get the same part.

Model car additions make us hear Knight Rider theme

This collection of model vehicle hacks adds obstacle avoidance in an attempt to make them autonomous. At the front end you’ll find two PCBs which use IR approximation to monitor the road ahead. We’re not familiar with this particular use of these IR receivers (TSOP1738) which we’re used to seeing in remote control receiver applications but if recent posts are any indication we think you’ll enjoy the use of a 555 timer on each of those boards.

The rest of the hardware is pretty common, a PIC 16F628 does the thinking while an L293D h-bridge drives the motors. Alas, we didn’t find a video, or even a description of the finished project. But there are full schematics, board layout pictures, and the code for both this vehicle and a second Tank version.

[Thanks Pieter]

SMS controlled irrigation

[Mhkabir] built an irrigation system that communicates by text message. The concept is simple, sending a text message to the system will cause it to switch on the water pump.

Many times we see text message manipulation via the Internet, or using a GSM module. But in this case an inexpensive cellphone is used as the communication interface. The vibration motor has been removed and those connections are monitored to signal incoming messages. Wire leads were soldered to the keypad contacts which allow an Arduino to send out text messages when there is a problem with watering. This isn’t an iron-clad system, as any incoming message will trigger the system and outgoing messages are limited to saved drafts. But a bit of creative programming and we’re sure more functionality could be squeezed out of this hardware.

DIY PIC development board and web server


Inspired by a project featured here on Hack-a-Day, [arthurb] bought himself a PIC 24F and started experimenting once he learned the ins and outs of programming the chip. Using a breadboard and a nest of wires was fine for his first few projects, but as he advanced, he began to feel the need for a full-fledged development board. With a list of required features in mind he got to work, constructing a well thought out board as well as a handful of expansion boards that can be used for various other projects. His main development board includes Ethernet connectivity for use with his web server software, the ability to utilize an SD card for storage, and a USB port for programming. His expansion boards include a temperature sensor, a numeric touchpad, as well as a video output module. Overall it is a pretty impressive build, considering he had never programmed a PIC before starting this project. All of his boards are thoroughly documented, and he has included plenty of source code in hopes of helping other individuals just starting out in PIC programming.

You can see his web server in action here, but keep in mind that it is running off a PIC, so please be courteous in your usage.

Paper accelerometers for pennies in the works

Cheap paper accelerometers? Put us down for a dozen to start. They’re not quite ready for mass production yet but it looks like they’re on the way.

[George Whitesides] led a team to develop the new technology that uses simple manufacturing methods to produce the sensor seen above. Graphite and silver inks were screen printed onto heavy paper. The single limb sticking out from the body of the sensor is a separate piece of paper that bends the carbon area when force is applied. This changes the carbon’s resistance which is measured using a Wheatstone bridge constructed by gluing resistors to the device.

It sounds unsophisticated compared to most of the accelerometer modules we’re used to, but if you need a sensor that detects sudden motion this sounds like the perfect part. Now who wants to be the first person to replicate this in their basement?

[Thanks Fabien]