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DIY Headphone Tube Amp Builds On Existing Design

DIY Tube Headphone Amp

[Simon] wrote in to tell us about a headphone tube amp that he just built. It is based on schematics at diyaudioprojects.com that were actually featured on Hackaday in the past. [Simon's] design adds an on board regulated power supply and a volume control for the input. Effort was made to keep the PCB single sided to facilitate making this at home.

DIY Tube Headphone AmpThe 12AU7 is popular due to its ruggedness and tolerance for low operational voltages. This amp design uses a plate voltage of 12, although the 12AU7 can handle up to about 330.  Since the 12AU7 is of the Twin Triode variety, one tube can be used to amplify both a left and right audio channel.

The case for the amplifier is laser cut plywood. The top piece is kerfed so that it can bend around the radii of the front and rear panels. The top also has a hole cut in it to allow the tube to peek out through.The pieces look nice but, unfortunately, he doesn’t show the case and amp in an assembled state.

If you’re interested in building one of these, [Simon] made all of the Eagle and Case files available. The total cost of the project was £25, about $43 US. To learn more about how tube amplifiers work, check out this Retrotechtacular from earlier in the year.


Filed under: musical hacks

Brighten Your Day with Studio Strobe Power Hack

large capacitor bank for flash circuit

[OiD] picked up a couple of cheap studio strobes off eBay and was not happy with the power control. So he rewired it. These lights are like supercharged flashes for professional photographers, and contain some very large capacitor banks. His first hack didn’t work out too well, and he wound up welding the innards of a switch together. He was successful however, in his second attempt to tame the large voltages.

He’s using two 1N5408 diodes, which are rated at 3 amps, for charging the capacitor bank. A massive 60EPS08 diode, rated at 60 amps with a Frankenstein worthy surge rating of 950 amps is used to separate the charge between the two capacitor banks, and allows one to discharge into the flash tube.

Consisting of just a handful of components, [OiD]‘s hack greatly improves the performance of the strobe’s power adjustment settings. He does an excellent job at documenting the hack for all to see. Be sure to check out his bog for full details.


Filed under: misc hacks

Astronaut or Not — Voter Lottery Tomorrow!

astronaut-or-not-voter-lottery

Fair warning, if you haven’t voted on Astronaut or Not you may come up short tomorrow. [Brian] will once again draw a random hacker number at 10am EDT (GMT -4).

If that hacker has voted in this round (we’re still in the first round of voting) they will win this fabulous oscilloscope. If they haven’t voted… no fancy scope for you!

We’re hoping to close this round of voting early next week at which time we’ll award prizes to the projects that received the most votes and start another round with a different theme.


Filed under: contests, The Hackaday Prize

Fail of the Week: Blown Light Bulb Controllers

fotw-nyc-resistor-chandelier-driver

We’ve been meaning to get around to this one for many weeks now. It’s been hard to find good fail write-ups… it’s as if hackers are afraid to admit that sometimes projects fail. We hope you’ll shake off that opinion as failure is the fastest path for learning and true understanding!

[xymax] was working on a control system for a chandelier with 150 bulbs which use 5 Watts each. This project was being readied for the NYC Resistor Interactive Party which [Adam Fabio] attended last month. As deadline for the show approached, the last piece was put in place late into the night… but it was connected backwards. In a tale worthy of a slapstick movie, the reverse polarity caused a chip on all seven controller boards for this module to blow like the one seen above. But that’s not all, the laptop being used during prototyping was connected by USB and started smoking!

All of us feel the pain of this type of equipment failure. Luckily [xymax] looked for lessons to learn instead of dwelling on the mistake itself. Use protection diodes, keyed connectors, and write about your failures. Hopefully reading this will help others avoid a similar equipment-destroying mistake.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story – or sending in links to fail write ups you find in your Internet travels.


Filed under: Fail of the Week, Hackaday Columns

Driving commerce with mobile: increasing savings & shortening in-store visits

Driving commerce with mobile: increasing savings & shortening in-store visits
Image Credit: The Next Web

Walmart has sought to revolutionize the in-store experience by adding navigation, voice commands, shopping lists, price comparisons, and other useful tools to its mobile applications.

At next week’s MobileBeat — July 8-9 in San Francisco — Walmart’s global head of mobile, Gibu Thomas, will talk about how those efforts have resulted in the company’s growth. He’ll also give people a sense of where Walmart is heading next in mobile and how it might drive top-line growth.

Session Speaker:

Gibu Thomas

Gibu Thomas, SVP of Mobile & Digital, Walmart

While Walmart relies on some external providers for specific functions, it has the scale, vertical integration and talent to build most of its mobile services in-house. The world’s first retailer has been early to adopt mobile technologies. While realizing that mere presence in the App Stores and even basic e-commerce features are now table stakes for the brand, they mostly focus their effort on building the blocks of a new hybrid shopping experience.

That is, Gibu Thomas and his team work on features that support shoppers’ journeys by layering the mobile experience on top of trips to the store, instead of trying to replacing it. Certainly the ability to browse items from the go creates the ability for the ubiquitous stores of the chain to act as fulfillment and pick-up centers for specific errands, but they keep in mind that a lot of the browsing will still happen in-store.

Their strategy is to provide on Walmart’s app the value customer expect from their device, be it the ability to compare prices, jot down notes of things to buy or look for product availability. By carefully listening to their customers needs and iterating on these features, Walmart is building a truly hybrid shopping experience.

Thomas will describe some of the current paradigms of their shopping assistant they hope the app will become, like how the awareness of shopper locations enables the app to switch from an “on-the-go” to an “in-store” mode automatically, surfacing the services users are most likely to need. E-receipts automatically saved also users to easily find past purchases, and will constitute the foundation for more services to come that enhance the experience of everyday shopping.

Note: MobileBeat tickets are nearly gone. Grab yours before they sell out!

Join 1,000 mobile execs, leading brands, analysts, developers, investors, and press for two days packed with high-value discussions, actionable lessons, exclusive announcements, and lots of networking.

We encourage you to secure your spot before the holiday, as tickets are very limited. You can register here.

Special thanks to the following industry leaders for supporting MobileBeat: Factual, Tapjoy, Criteo, AppLovin, Adtile, IBM and AT&T as Gold Partners; Flurry, AppMachine, HasOffers, Sequoia Capital, RadiumOne, SupersonicAds, Cirrus Insight, Tapsense, AppsFlyer and App Annie as Silver Partners; AppDynamics, BlueStacks, Upsight, Cotap, Cail, New Relic, Splunk, GLOBO, Bitcasa, Crittercism, and LifeStreet Media as Event Partners; Adenda, CommandIQ, Raw Engineering, Obelus Media, and Rumble as Nest Partners, and Bizzabo and VSC as Strategic Partners.








Facebook accepts 62 percent of applicants into FbStart developer program

Facebook accepts 62 percent of applicants into FbStart developer program
Image Credit: Brian Wilkins/Flickr

How can you leverage mobile to increase profitability for your company? Find out at MobileBeat, VentureBeat's 7th annual event on the future of mobile, on July 8-9 in San Francisco. There are only a few tickets left!

Facebook has announced the development of a program called FbStart, which will give mobile app developers access to app testing and user research. This is the company’s latest initiative to become a big player in the app market.

About 800 companies have applied for FbStart, and Facebook has accepted approximately 62 percent of the applicants for the program. Businesses that are interested in applying must already have applications that are located in the Apple and Google app stores. The goal of FbStart is to make app developers more aware of Facebook’s presence. For example, many apps now allow users to log into their Facebook account and share their activity on the website.

There are several incentives available to those that apply and receive acceptance into the FbStart program. This is what Facebook has listed on its website for those who want to take advantage of its “Bootstrap Track” offer:

 

  • Access to Facebook Start to Success Program
  • Parse credit
  • Adobe Creative Cloud
  • Appmethod app development tool
  • Appurify testing suite
  • Braintree mobile payment platform
  • Desk.com customer support app
  • Hootsuite social media monitoring tool
  • Proto.io prototyping tool
  • UserTesting UX research tool
  • Transifex localization platform
  • Workable recruitment tool

In total, the incentives are worth about $8,000. However, there is an “Accelerate Track” offer that is valued at about $40,000. Some of the companies that have partnered with Facebook for this initiative include Adobe, Salesforce, SurveyMonkey and UserTesting.

The website stated that it will continue to accept applications on a rolling basis until the program is full. Facebook first announced the FbStart program back in April.

 








Spotify’s iPhone app finally lets you see your ‘Play Queue’ & sort music

Spotify's iPhone app finally lets you see your 'Play Queue' & sort music

How can you leverage mobile to increase profitability for your company? Find out at MobileBeat, VentureBeat's 7th annual event on the future of mobile, on July 8-9 in San Francisco. There are only a few tickets left!

One of the more frustrating things about using Spotify on an iPhone was that you really couldn’t sift through your large collection of music, or see what was about to start playing. Now that’s finally changing.

In the latest Spotify iOS app update, users can now view their Play Queue on the iPhone as well as sort through music alphabetically and search for a specific song, artist or playlist. Additionally, the queue is now directly accessible from the Now Playing screen for convenience, and Spotify warns users if the song already exists in the collection to prevent duplicates.

The update, which brings the iOS app up to par with the Android version, should be well received by hardcore Spotify users, and many would likely agree this functionality should have been available on the iPhone from day one.

The streaming music service also added the ability to search through your downloaded songs offline earlier this week, as VentureBeat previously reported. Spotify listeners have been able to take their songs offline to listen to them on their mobile device in the past, but the process of downloading playlists was not always easy, according to Techlicious. The task has been streamlined and simplified for mobile users.

Currently, the Spotify app can be downloaded for free on the App Store and Google Play store. However, Spotify requires a Premium Account for those who want to listen to music without commercials. A subscription costs $9.99 per month.








Enter the ‘Custom App Challenge’ for a chance to win an app for your business

SPONSORED POST

Enter the 'Custom App Challenge' for a chance to win an app for your business

This sponsored post is produced in association with AppMachine.

Calling all VentureBeat readers and MobileBeat attendees: We would like to invite you to participate in the "Custom App Challenge" hosted by AppMachine at MobileBeat next week, July 8-9 in San Francisco.

The "Custom App Challenge" is based on AppMachine's unique code-free technology that allows businesses and individuals to build, design, and publish their own apps for iOS, Android, and Windows within hours instead of weeks.

AppMachine will be building a custom app for one lucky winner during MobileBeat. Fill out the form below for a chance to be the lucky winner!

AppMachine has over 100,000 users currently in the process of building apps and is excited and eager to take on the challenge of helping the winner build an app from the ground up in 48 hours!

Tickets to MobileBeat are limited. Make sure to grab yours before the holiday!

AppMachine is looking to expand partnerships with businesses that have a unique vision in empowering their audience with application technology.


Sponsored posts are content that has been produced by a company that is either paying for the post or has a business relationship with VentureBeat, and they're always clearly marked. The content of news stories produced by our editorial team is never influenced by advertisers or sponsors in any way. For more information, contact sales@venturebeat.com.