Drive High-Impedance Headphones With This Stylish USB DAC

October 9, 2021 by Jenny List 3 Comments

For anyone with an interest in building audio projects, it’s likely that an early project will be a headphone amplifier. They’re relatively easy to build from transistors, ICs, or tubes, and it’s possible to build one to a decent quality without being an electronic engineering genius. It’s not often though that we see one as miniaturized as [daumemo]’s USB-C DAC and headphone amplifier combo, that fits within a slightly elongated 3.5 mm jack cover as part of a small USB-to-headphone cable.

The DAC is an off-the-shelf board featuring an ALC4042 IC, it has a line-level output and a handy place to tap off a 5 volt line for the amplifier. This final part is a tiny PCB with two chips, a TPS65135 that produces clean +5 and -5 volt rails, and an INA1620 which is a high-quality audio amplifier set up for 2x gain. All this has been designed onto a very small PCB, which sits inside a 3D-printed housing along with the 3.5 mm earphone socket. The result is a very neat unit far better able do drive high-impedance headphones than the output from an unmodified DAC, but still looking as svelte as any commercial product. We like it.

This may be one of the most compact USB-to-headphone amplifiers we’ve seen, but it’s by no means the first.

Teardown: Wonder Bible

June 22, 2020 by Tom Nardi 90 Comments

Even the most secular among us can understand why somebody would want to have a digital version of the Bible. If you’re the sort of person who takes solace in reading from the “Good Book”, you’d probably like the ability to do so wherever and whenever possible. But as it so happens, a large number of people who would be interested in a more conveniently transportable version of the Bible may not have the technological wherewithal to operate a Kindle and download a copy.

Which is precisely the idea behind the Wonder Bible, a pocket-sized electronic device that allows the user to listen to the Bible read aloud at the press of a button. Its conservative design, high-contrast LED display, and large buttons makes it easy to operate even by users with limited eyesight or dexterity.

The commercial for the Wonder Bible shows people all of all ages using the device, but it’s not very difficult to read between the lines and see who the gadget is really aimed for. We catch a glimpse of a young businessman tucking a Wonder Bible into the center console of his expensive sports car, but in reality, the scenes of a retiree sitting pensively in her living room are far closer to the mark.

In truth, the functionality of the Wonder Bible could easily be replicated with a smartphone application. It would arguably even be an improvement by most standards. But not everyone is willing or able to go that route, which creates a market for an affordable stand-alone device. Is that market large enough to put a lot of expense and engineering time into the product? Let’s crack open one of these holy rolling personal companions and find out.

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Hackaday Prize Entry: Dr. DAC

June 1, 2015 by Brian Benchoff 46 Comments

The theme of this year’s Hackaday Prize is. ‘build something that matters.’ A noble goal, but there’s also a second prize – the Best Product prize – that is giving $100k to one lucky team who can appeal to people with open jaws and wallets. It’s a fabulous prize that also includes a six month residency at the Hackaday Design Lab, but right now there aren’t many contenders for this part of The Hackaday Prize.

[drewrisinger]’s DrDAC USB Audio DAC is one of those project that’s in the running for the Best Product prize. He’s solving the problem of terrible low-quality built-in soundcards that seem to be everywhere. Yes, it’s a simple idea, but the execution is great.

The electronics for DrDAC are pretty much what you would expect for a DIY audio sound card; A PCM2706 takes USB audio and sends it out over I2S. A PCM1794 converts the I2S to analog audio, and an OPA2836 amplifies it and sends everything out through a 1/8″ jack or a pair of RCA plugs.

[drewrisinger] started DrDAC as a school project, and after receiving the PCBs, he noticed a problem. MultiSim’s footprint for a TQFP-32 package was too small, meaning the IC simply wouldn’t fit on the board. It was too late in the semester to order a new board, meaning some sort of rework needed to happen. [drew] fixed this problem by soldering jumper wires between the pads to the leads of the chip. Yes, it looks crazy, but apparently it works. You can check out a video of that whole process below.

The 2015 Hackaday Prize is sponsored by:

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An Audio Based USB Oscilloscope And Signal Generator For $20

May 27, 2014 by Nick Conn 23 Comments

SoundScope

Are you interested in building a 20kHz 2-channel oscilloscope and a 2-channel signal generator for only $20 with minimal effort? Be sure to check out [Jana Marie’s] Instructable that goes over how to build this awesome tool from a cheap USB audio card.

We have featured tons and tons of DIY oscilloscopes in the past, but this effort resulted in something very well put together while remaining very simple to understand and easy to build. You don’t even need to modify the USB audio card at all. One of the coolest parts of this build is that you can unplug your probe assembly from your USB audio card, and bring it wherever your hacking takes you. After the build, all you need is [Christian Zeitnitz’s] Soundcard Oscilloscope program and you are good to go. One of the major downsides that is often overlooked when using an audio based oscilloscope, is that it is “AC coupled”. This means you cannot measure low-frequencies (including DC signals) using a sound card. Be sure to heed [Jana’s] advice and do not use your built in audio card as an oscilloscope. With no protection circuitry, it is a sure fire way to fry your computer.

What analog projects have you built around an audio interface? We have seen such an interface used for many different applications, including a few fun medical related hacks (be sure to keep safety your first priority). Write in and let us know!