AM/FM Radio Gets Bluetooth Upgrade

For many commercial broadcast radio has lost its luster, leaving an unknowable number of perfectly serviceable AM/FM radios to lie dormant. But they don’t have to. As [Dan Gebhardt] shows in his recent hack, integrating a Bluetooth audio receiver into portable radio may be easier than you think.

For this project, [Dan] wanted to make sure no original functionality was lost. The radio still functions on the AM/FM bands, but now with the flip of a switch, he can listen to the audio coming his way courtesy of a Apt-X low-latency Bluetooth receiver. It sounds like the link is quick enough that he can even use this as a wireless speaker for watching TV, which isn’t always possible with cheaper chipsets that introduce a noticeable lag.

Isolating the audio trace.

The trick was to track down the receiver IC, a Silicon Labs chip similar to ones we’ve seen used in a few DIY radio projects previously. A peek at the datasheet told him which pins were carrying the audio signal, and after following them around the board, he found a convenient spot to cut the trace before it went into the volume control. From there is was just a matter of wiring in a SPDT slide switch that allowed him to select which device was passed through to the radio’s audio hardware.

While he had everything apart, [Dan] exorcised the Apt-X’s original 300 mAh LiPo pouch and replaced it with a DC-DC converter connected to the radio’s battery compartment. This allows him to run all of the hardware off of the same set of rechargeable NiMH cells, and also provides considerably improved runtime for the Bluetooth receiver.

Now as for physically integrating the Apt-X into the case of the radio…well, what can we say? [Dan] admits it’s a bit rough, but then the point was never to enter the thing into beauty pageants. It works well enough for his purposes, and in the end that’s all that matters.

A Field Guide To The North American Communications Tower

The need for clear and reliable communication has driven technology forward for centuries. The longer communication’s reach, the smaller the world becomes. When it comes to cell phones, seamless network coverage and low power draw are the ideals that continually spawn R&D and the eventual deployment of new equipment.

Almost all of us carry a cell phone these days. It takes a lot of infrastructure to support them, whether or not we use them as phones. The most recognizable part of that infrastructure is the communications tower. But what do you know about them?

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