[Dan] had been wanting a pair of Bluetooth headphones for quite a while. Most of the reviews for wireless headphones in the $50-$80 range complained of tinny sound and dropped bass. Nevertheless, he stumbled upon a $20 pair of headphones with similar reviews and realized that he could switch out the driver and make a decent pair of cans.
The donor drivers came from a pair of Sennheiser HD 540 headphones. These are very respectable headphone speakers that cost about what you would expect for pro audio gear. To to get Bluetooth working with the Sennheisers, [Dan] removed the PCB and battery enclosure and attached them to the headband with velcro.
For his build, he had to cut the cable on the Sennheisers and solder them to the Bluetooth board. There was never any danger of ruining a good pair of headphones, though. If he screwed up he was only out a headphone cable. Now [Dan] has a nice pair of Bluetooth headphones that can reproduce bass. Not a bad deal for a $20 pair of headphones.
Baby, it’s cold outside. But that doesn’t stop [Grissini] from listening to some tunes when not indoors. He added headphones to a pair of ear warmers. We guess you could call them ear muffs, which is where the name comes from. But these are the newer type that wrap around the back of your head.
[Grissini] picked up a set of headphones that similarly wrap around the back of your head. After pulling the speakers out of their plastic enclosures he needed a way to soften the sharp edges when they’ll be pressed against your ears. Sugru once again shows its versatility by providing a soft, self-bonding, and moldable surface. The last step is dead simple, as the ear warmers already have a fabric pocket by each ear perfect for accepting the speakers.
Now we need this to go one step further, by making them wireless. We figure hacking in a bluetooth headset board would make it work with your cellphone. Or you could roll your own minimal MP3 board and house it in the part that wraps around your neck.
[Reginaldo] purchased a cheap Bluetooth headset adapter, and while it worked well with all of his devices, he was disappointed to find that the battery life didn’t quite live up to the manufacturer’s claims. Advertised as capable of operating for 10 hours, he discovered that the device would typically die after only 7. He wanted more from the headset, so he took things into his own hands and replaced it with a much larger battery (Google Translation).
His goal was to keep the modifications as cheap as possible, so he repurposed a lot of items he had sitting around the house. He used a battery out of an old cell phone, with a capacity over six times greater than that of his original headset battery. He built a charging circuit using a MCP73863 microchip, specifically designed for managing Li-Ion/Li-Poly batteries. The Bluetooth headset was dismantled and repackaged in the shell of a cheap “audio amplifier” that he had on hand, along with the new battery and charging circuit. A nifty Hackaday logo was included on the outside of the new battery case, and the project was deemed complete.
[Reginaldo] reports that he is quite happy with his battery retrofit. The new power brick only takes about half an hour longer to charge, but can now be used for approximately 44 hours before requiring a recharge – not too shabby!
Here’s something we haven’t run across before. We’re familiar with proprietary battery shapes (we’re looking at you, digital camera manufacturers), or custom recharge connections (look of death directed toward cellphone manufacturers), but using electrical tricks to force AAA brand loyalty is a new one. It seems that’s exactly what is happening with [OiD’s] wireless headphones which were manufactured by Phillips.
The headphones take AAA sized batteries and can use either disposable or rechargeable varieties. There is a warning label advising that only Phillips brand rechargeables should be used, and sure enough, if you try a different brand the performance suffers both in charging time and in battery life. The original batteries are labelled as Nickel Metal Hydride at 1.2V and 550 mAh, which falls within common specs. But [OiD] noticed that there is an extra conductor in the battery compartment that makes contact with the sides of the battery case. Further inspection reveals that a reverse-biased diode makes contact through this conductor with a portion of the battery which has not been painted. This is not true with other brands, allowing the circuit to distinguish between OEM and replacements.
[OiD] shorted out that connection and immediately saw a performance boost from his replacement batteries. It’s hard to know exactly what’s going on here without a full schematic for the circuit, but we’d love to hear your speculation on this setup in the comments. Is this a low tech version of the identity chips that camera batteries sometimes hide?
If you are in the market for a nice pair of Hi-Fi headphones, it is not uncommon to to find price tags in the range of $300-$500. [Stacy] loves her music, but she had no desire to pay that high a price for a pair of good portable cans. Instead, she upgraded a set of cheap, knock-off headphones to near-audiophile quality for less than $50.
She starts off by explaining the technology behind the expensive headphones you see in stores, and why the sound quality is so much better. She says the orthodynamic drivers used in these products produce far better sound due to the placement of the voice coils, and their lack of delay when producing sound.
She found a pair of orthodynamic drivers for $30 and fit them into her knock-off headphones with a reasonable amount of effort. A bit of insulation and supporting plastic was added to ensure proper mounting of the drivers, then the headset was painted and reassembled.
[Stacy] claims that the end result is easily comparable to far more expensive headsets, especially when connected to a proper amplifier. If you are looking to step up your audio game on the cheap, here’s your chance.
One complaint we hear about often is ear-bud’s cables getting tangled within backpacks. [Andrew] was having this “spaghetti” wire problem, and also wanted to listen to his music with ear protection on – where ear-buds are usually uncomfortable. The latter problem is fixed by placing speakers inside of folding ear protectors, and the cable is managed with a 3.5mm disconnect.
For those who can’t make disconnect-able headphones but still suffer from tangled headphone wire, we recommend proper wrapping technique for your wire, and a small carrying pouch. With the combination of the two, we’ve never had a tangled cable.
The headphone remote for the third generation iPod shuffle has a special chip that identifies it to the iPod itself. [David Carne] posted an in-depth report about the process he used to reverse engineering that protocol. He’s discovered that the remote uses a peculiar signal to identify it as authentic when the device powers up. We’ve talked about Apple’s use of peripheral authorization before and it seems this is no different. [David] did manage to emulate the authentication using an ATmega88. If you’ve got a shuffle 3G sitting around this info will allow you to operate it with a microcontroller in your next project.