headphone jack

3 Articles

Google Home Mini Gets A Headphone Jack

June 11, 2019 by 19 Comments

The Google Home Mini can be a useful home assistant device. It can set reminders, tell you the weather, and even play you music. [Brian] had a few lying around, and decided he wanted to hook one up to a beefier set of speakers. Thus, he installed a headphone jack into the Google Home Mini.

The quick and dirty approach to such a task is to solder a jack to the speaker connections. However, this is an amplified signal, rather than a line level signal suitable for feeding to an amplifier. It’s also mono only. The Google Home Mini uses the TAS5720L mono digital amplifier chip, and some investigation with a logic analyzer and a datasheet allowed [Brian] to figure out the format of the I2C digital audio signal.

With this knowledge in hand, [Brian] hacked in a PCM5102A digital amplifier chip to the Google Home Mini. It can accept audio data in the same format as the TAS5720L, and is readily available on eBay for use with the Raspberry Pi and other maker platforms. With a 3D printed baseplate and some careful soldering, [Brian] was able to integrate the stereo amplifier and a headphone jack neatly into the Google Home.

Unfortunately, the audio output is only two mono channels rather than true stereo, as the device outputs the same data on both left and right  channels in the I2C data. Regardless, the hack works, and [Brian] now has a high-quality voice assistant that he can hook up to a decent pair of speakers.

8-track player turn into a Walkman

Turning 8-Track Player Into A Walkman

April 19, 2018 by 21 Comments

Following time backward, for portable music we’ve had iPods, CDs, and cassette tapes which we played using small Walkmans around the size of a cigarette box. And for a brief time before that, in the 1960s and 1970s, we had 8-track tapes. These were magnetic tapes housed in cases around the size of a large slice of bread. Car dashboards housed players, and they also came in a carry-around format like the one [Todd Harrison] recently bought at a Hamfest for $5 and made more portable by machining clips for a strap and adding a headphone jack.

But before hacking it, he wanted to try it out. Luckily his sister had hung onto her old tapes and after plugging it in and sliding in a tape, it worked! Opening it up he found that the contacts for the batteries were rusted but the mechanical components and electronics inside were very clean. Though he did add glue to a crack in the plastic read-head support, cleaned out some grease, did some lubricating, and cleaned the contacts in the volume control’s potentiometer. Check out his teardown video below for those details or if you just want to see how it all works.

Then came making it portable so that he could embarrass his kids by carrying it around the mall. The shoulder strap didn’t come with it, so he machined some clips out of steel and snapped on a strap. It didn’t have a headphone jack and he didn’t want to embarrass his kids too much, so he added one.  You can see that hack in the second video below, including how his repurposed jack automatically disconnects the speaker when the headphone plug is inserted. Personally, we think he looks pretty spiffy carrying it around wearing his Hackaday T-shirt.

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Bringing Back The IPhone7 Headphone Jack

September 7, 2017 by 96 Comments

Plenty of people bemoaned Apple’s choice to drop the 1/8″ headphone jack from the iPhone 7. [Scotty Allen] wasn’t happy about it either, but he decided to do something about it: he designed a custom flex circuit and brought the jack back. If you don’t recognize [Scotty], he’s the same guy who built an iPhone 6 from parts obtained in Shenzhen markets. Those same markets were now used to design, and prototype an entirely new circuit.

The iPhone 7 features a barometric vent, which sits exactly where the headphone jack lived in the iPhone 6. The vent helps the barometric pressure sensor obtain an accurate reading while keeping the phone water proof. [Scotty] wasn’t worried about waterproofing, as he was cutting a hole through the case. The vent was out, replaced with a carefully modified headphone jack.

The next step was convincing the phone to play analog signals. For this, [Scotty] used parts from Apple’s own headphone adapter. The hard part was making all of this work and keeping the lightning port available. The key was a digital switch chip. Here’s how the circuit works:

When no headphone is plugged in, data is routed from the iPhone’s main board to the lightning port. When headphones are plugged in, the data lines are switched to the headphone adapter. Unfortunately, this means the phone can’t play music and charge at the same time — that is something for version 2.0.

The real journey in this video is watching [Scotty] work to fit all these parts inside an iPhone case. The design moved from a breadboard through several iterations of prototype printed circuit boards. The final product is built using a flexible PCB – the amber-colored Kapton and copper sandwiches that can be found in every mobile device these days.

Making everything fit wasn’t easy. Two iPhone screens perished in the process. But ultimately, [Scotty] was successful. He’s open sourced his design so the world can build and improve on it.

Want to read more about the iPhone 7 and headphone jacks? Check out this point and counterpoint.  we published on the topic.

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