Welcome to the Old School: Restoring Antique Radios

Before the second world war Radio was a revolution in mass-communication much like the internet today. Fortunes were made and lost, empires built, epic patent battles ensued, all of which resulted in the world being more connected than ever before, which makes for a really great story (and a great Ken Burns documentary).

Last month we showed you how to modify a vintage radio to play your own audio source through it while re-using the existing electronics and maintaining its functionality. In this post we will show you how to restore any vacuum tube radio. You will learn basic repair/restoration procedures from a different era when it was actually worth repairing consumer electronics. Plug into history and get your hands on the most influential technology of the first-half of the 20th century!

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THP Hacker Bio: John Costik

A surprising amount of entries for The Hackaday Prize are medical devices, and the regulatory problems associated with that domain. [John Costik]’s Diabetes Data, Everywhere is one of the few projects that is perfect for a world where the words ‘hack’ and ‘FDA’ simply cannot be found in the same sentence.

[John]’s son was diagnosed with Type 1 diabetes at a very young age, and very early [John], his family, and the school nurse have had to deal with the nearly innumerable tasks that type 1 diabetes management entails. A Dexcom continuous glucose monitor is a big help, providing a wealth of glucose logging in a small, wearable device.

This monitor, however, is relatively locked down; the stock device is unable to push data to the Internet. [John] reverse engineered the protocol for this glucose monitor, enabling [John] to monitor his son’s blood glucose levels from anywhere on the planet.

There’s a huge community of people waiting for the technological advancements of the last thirty years, like the Internet and portable, networked devices, to make it into medical devices. [John]’s project has already gotten a bit of local news coverage, and is a perfect example of expanding the capabilities of existing devices to make his and his family’s life more convenient.

Bio/interview below.

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Adding I/O to the Rasberry Pi Models A & B

The Raspberry Pi has been the basis for many cool projects. Even so, Models A and B have been criticized for having only a handful of GPIO pins available. Sure, the new Model B+ has a 40-pin GPIO header but what if you want to use your old RaspPi with a bunch of in and outputs? [Steve] is one of those guys and has done something about it by creating a pretty neat solution he calls the PiMagic. It’s a Pi Plate that has an on board ATMEGA328 running an Arduino bootloader. The RaspPi and the Arduino communicate via UART as [Steve] felt it was a bit simpler than going the SPI or I2C route.

The RaspPi GPIO’s run on 3.3v and the ATMEGA328’s like 5v. To solve this, the PiMagic has a Level Shifter that keeps the I/O of the two boards happy. Older Pi’s had a problem burning out PCB traces when supplying too much current on the 5v supply line. [Steve] threw in a fuse that will burn out before the Pi does to ensure that no Pi’s were harmed in the making of this project.

Now that a bunch of I/O are available, how do you physically access them? Well, the PiMagic has female headers in the typical Arduino layout. This way any Arduino Shield will plug right in. [Steve] made all his source files available for those who want to make one themselves. Find an assembly video after the break.

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A Detailed Look at the 7805 Voltage Regulator

We’re quite sure that all hobbyists have used the 7805 voltage regulator at least once in their lives. They are a simple way to regulate 7V+ voltages to the 5V that some of our low power projects need. [Ken Shirriff] wrote an amazingly detailed article about its theory of operation and implementation in the silicon world.

As you may see in the picture above such a regulator is composed of very different elements: transistors, resistors, capacitors and diodes, all of them integrated in the die. [Ken] provides the necessary clues for us to recognize them and then explains how the 7805 can have a stable output even when its temperature changes. This is done by using a bandgap reference in which the difference between transistor base-emitter voltages for high and low current is used to counter the effects of temperature. As some elements looked a bit odd during [Ken]’s reverse engineering process, he finally concluded that what he purchased on Ebay may be a counterfeit (read this Reddit comment for another opinion).

Unbricking a BluRay Drive

All BluRay player, devices, and drives contain a key that unlocks the encryption and DRM present on BluRay discs. Since 2007, the consortium responsible for this DRM scheme has been pushing updates and revocation lists on individual BluRay releases. Putting one of these discs in your drive will brick the device, and this is the situation [stephen] found himself in when he tried to watch Machete Kills. Not wanting to update his software, he searched for a better solution to unbrick his drive.

Every time [stephen] played or ripped a disc, the software he was using passed a key to the drive. This key was compared to the revocation list present on the drive. When a match was found, the drive bricked itself. Figuring the revocation list must be stored on a chip in the device, [stephen] broke out the screwdriver and started looking around inside the drive.

There aren’t many chips inside a modern BluRay drive, but [stephen] did manage to find a few Flash chips. These Flash chips can be dumped to a computer using a BusPirate, and comparing the dump to a publicly available ‘Host Revocation List Record’, [stephen] was able to find the location on the Flash chip that contained the revocation list.

The next task was to replace the revocation list currently on the drive with an earlier one that wouldn’t brick his drive. [stephen]’s MakeMKV install made this very easy, as it keeps a record of all the revocation lists it runs across. Updating the Flash in the drive with this old list unbricked the drive.

This is only a temporary fix, as [stephen] still can’t put a new disc in the drive. A permanent fix would involve write protecting the Flash and preventing the drive from ever updating the revocation list again. This would be a very complex firmware hack, and [stephen] doesn’t even know what architecture the controller uses. Still, the drive works, saved from terrible DRM.

A Tale of Two Ring Boxes

This is a tale of two hearts, two engagements, and two ring boxes. About a couple of years ago, [curtisabrina] proposed to his girlfriend. Rather than just hand her the ring, he placed it in a locking ring box [imgur link] he custom-made. The box seems normal at first glance, but lifting up the first drawer reveals a complex and ornate gear system. The gears can only be turned by a pair of interlocking heart-shaped keys – a gift [curtisabrina] had given her months earlier. The mechanism is nothing short of stunning – planetary reductions drive a spring-loaded iris which opens to reveal an engagement ring.

[curtisabrina] built his ring box after hours at his signmaking job. The job gave him access to some incredible tools, such as the MultiCam 3000 series CNC. The box turned out great, and he showed his work off in a Reddit thread.

Fast forward two years. [joetemus] was getting ready to propose to his girlfriend, and wanted to do something similar. He didn’t have access to high-end shop tools, but he did have a Shapeoko 2. Using the original box as inspiration, [joetemus] started designing. Over time, trial, and error, a second ring box emerged [imgur link]. Like the original box, [joetemus] started with a rough cut board. Nearly every part, including the aluminum gears, was cut on the Shapeoko 2. [joetemus] also celebrated his accomplishment with a Reddit thread.

[joetemus’s] ring box isn’t quite as complex or polished as [curtisabrina’s], but he was working with a machine that cost much less than the equipment [curtisabrina] was using. We think both of them are great, and are happy to report that both of their girlfriends said, “Yes!”

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Upgrading the Battery In a Wrist PDA

No, your eyes do not deceive you. That’s a wrist-mounted PDA. Specifically, a Fossil Wrist PDA, also known as an Abacus, that was sold from 2003 to about 2005. Yep, it’s running PalmOS. [mclien] has had this watch/PDA for a while now, and found the original 180mAh battery wasn’t cutting it anymore. He made a little modification to the watch to get a 650mAh battery in this PDA by molding a new back for it.

The original PDA used a round Lithium cell, but being ten years old, the battery technology in this smart watch is showing its years. [mclien] found two batteries (380mAh and 270mAh) that fit almost perfectly inside the battery.

The new batteries were about 3mm too thick for the existing case back, so [mclien] began by taking the old case, adding a few bits of aluminum and resin, and making a positive for a mold. Two or three layers of glass twill cloth were used to form the mold, resined up, and vacuum bagged.

After many, many attempts, [mclien] just about has the case back for this old smartwatch complete. The project build logs are actually a great read, showing exactly what doesn’t work, and are a great example of using hackaday.io as a build log, instead of just project presentation.