There are a surprising wealth of parts inside of old laptops that can be easily scavenged, but often these proprietary tidbits of electronics will need a substantial amount of work to make them useful again. Obviously things such as hard drives and memory can easily be used again, but it’s also possible to get things like screens or batteries to work with other devices with some effort. Now, there’s also a way to reuse the trackpad as well.

This build uses a PS/2 touchpad with a Synaptics chip in it, which integrates pretty smoothly with an Arduino after a few pins on the touchpad are soldered to. Most of the work is done on the touchpad’s built in chip, so once the Arduino receives the input from the touchpad it’s free to do virtually anything with it. In this case, [Kushagra] used it to operate a stepper motor in a few different implementations.

If you have this type of touchpad lying around, all of the code and schematics to make it useful again are available on the project page. An old laptop in the parts bin is sure to have a lot of uses even after you take the screen off, but don’t forget that your old beige PS/2 mouse from 1995 is sure to have some uses like this as well.

All laptops have a working keyboard and mouse built into them, the only problem is that you can’t use these tools on other computers that don’t have them. At least, until now. [Peter] has created the KeyMouSerial in order to use his laptop’s keyboard and mouse as physical devices on his Raspberry Pi, finally freeing the bonds holding our laptops’ human interface devices back.

The software for KeyMouSerial copies keystroke and mouse information and sends this out via a serial port on his laptop (using a USB to serial adapter). From there the information is translated by an Arduino into HID commands which are sent via USB to the target computer, in this case a Raspberry Pi. It’s a pretty elegant solution to carrying a bulky keyboard and mouse along just for a Raspberry Pi, or for any computer that might not have access to a network and SSH.

[Peter] has also been working on using his iPod as a serial-to-USB converter, so if you’re a Rockbox developer and want to help out then drop him a line. All of the software is available (for Windows, Mac, or Linux) including the Arduino sketch if you want to try this software out for yourself. And, if you don’t want to turn a computer into a keyboard and want to go the other direction and turn a keyboard into a computer, that is also an option.

Lithium ion batteries are becoming more and more common these days, but some of the larger capacity batteries can still carry a pretty hefty price tag. After finding Acer’s motherboard schematics online and doing a little reverse-engineering, [Tiziano] has found a way to reuse batteries from his dead laptop, not only saving the batteries from the landfill but also cutting costs on future projects.

These types of batteries have been used for many things in the past, but what makes this project different is that [Tiziano] is able to monitor the status of the batteries and charge them using I2C with an Arduino and a separate power supply, freeing the batteries from the bonds of the now-useless laptop.

With this level of communication between the microcontroller and the battery pack, there is little chance of the batteries catching on fire when they’re used in another project. Since the Arduino can also monitor the current amount of charge in the batteries, there is also a reduced risk that they will be damaged from under- or over-charging.

This wasn’t just as simple as hooking up the positive and negative leads of a power supply to the battery. [Tiziano] also had to model the internal resistance of the motherboard that the battery expects to see, and get the supply voltage just right so the battery’s safety protocols wouldn’t kick in to prevent them from charging. After a few other hurdles were jumped, [Tiziano] now has a large capacity lithium ion battery at his disposal for any future projects.