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Jan 28, 2017, 08:39 PM
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The next audio upgrade

The lion kingdom still remembers when the most $10 would get were the cheapest, tiniest, most horrible sounding speakers which plugged directly into a walkman. The sound was completely unintelligible, but what a novelty in the old days to hear a walkman through any portable speaker.

There should be no disappointment in 25 years later, what would appear in Walmart but $10, Lipo powered, bluetooth speakers which actually sound as good as a boombox did. It's not just a case of something getting cheaper by getting smaller, but a lot more getting cheaper.

The purpose of this was not the speakers, but to gain a bluetooth receiver for a lot less than $parkfun's $25 bluetooth audio module. Managing the headphone cable had become quite a chore in 6 months of driving around with it. Sadly, the new speaker would be too heavy & quiet to use intact. It would require a much bigger robot to move around a decent speaker & loudness has taken precedence over quality.

The teardown was completed & the electrical signals probed.
It uses ANT8110 class D amplifiers which take 5.5V & output 3W. The only datasheet was purely chinese except for 5.5V, chipsourcetek, 3W, & class D. Though the reduction in voltage would be a huge convenience, it wouldn't be as loud as the 6W TDA1517.

The receiver is a Beken BK3254. Analog audio comes out of 2 pins at line level.

It requires 4.2V power at the battery terminals to power the ampilifier. The receiver can work on 5V USB power only.

Had to reboot the phone when it stopped making sound once.

Volume control adjusts signal coming out of the BK3254. At maximum, it's +/- 1V.

The board also supports a microphone, for making that wireless headset with self monitoring. A 3rd board would be for the home robot, but by then there are cheaper boards in bulk.
Last edited by Jack Crossfire; Jan 28, 2017 at 10:55 PM.
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