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Maker uses 3D printing to convert 1980s Fisher Price cassette player into a Bluetooth speaker
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By Simon | 3ders.org

Although they were once considered a luxurious convenience product when they first came out years ago, wireless Bluetooth speakers have since become a go-to project for hardware hackers and developers - many of whom enjoy upcycling older products into ‘modern’ devices that are capable of connecting to any smartphone, tablet or computer.

Although we’ve seen everything from vintage radios and backpacks that have been converted into Bluetooth speakers, we’ve been yet to see the old and iconic Fisher Price cassette player converted into a device that’s capable of connecting to today’s smartphones - yet this is exactly what nostalgic and talented hardware hacker Matt Gruskin recently did.

“This is my #826 Fisher-Price tape recorder, which was manufactured on January 21, 1987 (as stamped in the battery compartment),” explains Gruskin in a blog post.

“I used it constantly when I was a kid. When I found it again in 2015, it didn’t work anymore. The problem was probably just a broken or missing belt for the tape deck, which I could have replaced. Instead, I made some deeper changes - I converted it into a Bluetooth speaker.”

– Matt Gruskin

After fully disassembling the cassette player - which was not as easy as it sounds due to the amount of mechanical assembly components - Gruskin began the process of determining what to scavenge and what to discard. In the end, many pieces were reused however it was determined that he would have to also create some new components in addition to the updated electronics, which were powered by a central SparkFun FT231X breakout board. For a power source, Gruskin used four C batteries in the original 4 battery compartment.

One of the more challenging parts of the build included implementing a PCB slot adapter, which was designed by Gruskin using OpenSCAD. The new design, which is designed to fit in the original PCB slot, is able to hold the new, smaller PCB in the correct place while also keeping it close to the volume knob slot. To print the PCB adapter design, Gruskin used an Ultimaker 3D printer - however he admits that it took more than a few prints to get the design dialed-in correctly.

“It took a few prints to get it to fit well enough - I am guilty of relying a little too much on trial-and-error when 3D printing parts, instead of measuring more carefully, as it’s so easy to make minor tweaks and try another print,” he explains.

– Matt Gruskin

Aiming to keep the updated Bluetooth speaker as similar to the experience of the original cassette player as possible, Gruskin even went so far as to modify the mechanical buttons to correspond with the controls of the digital music player - certainly no easy feat. To do this, he matched up the mechanical buttons to stranded wires.

“After some experimentation, the solution that finally worked was simply hot-gluing a stripped stranded wire to each of the vertical metal button bars. Hot glue itself didn't stick well to the metal button bars, so I wound up sticking some double-sided tape to each metal button bar, and hot-gluing the wire insulation to the tape,” he explains.

– Matt Gruskin

“When each button is pressed, its exposed stranded wire moves downward and makes contact with a horizontal metal bar that runs in front of the vertical metal button bars. By grounding the horizontal metal bar, each button's wire is floating when the button is not pressed, but pulled low when the button is pressed - exactly the signals that the RN-52 Bluetooth audio module needs for the AVRCP commands.”

– Matt Gruskin

Considering that each part of the original Fisher Price cassette player has been updated to control a modern piece of technology, this is certainly one of the more impressive Bluetooth speaker projects we’ve seen.

For those interested in hacking their own Fisher Price cassette players into a Bluetooth speaker, or to learn more about what’s involved in the process if you have an idea for doing something similar, Gruskin has supplied the necessary code and an in-depth build process journal over on his GitHub page.

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