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Last month, I bought a bluetooth audio module on eBay. And I wonder what components are on this PCB.

  1. In the picture, what is the component in the top red box?
  2. What is the component in the bottom red box? The component marking is "DH=M6C". But I couldn't find any datasheets about "DH=M6C".

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  1. Most Likely a Multilayer Ceramic Band Pass Filter. For the Antenna Stage. (The Schematic below uses RFBPB 2012 in a 0805 sized package, but any similar Filter would be used.)

  2. Most Likely a Voltage Regulator. The IC uses multiple voltages (3.3V VDD, 1.8V, VBAT [Likely 5v]). Alternatively, it could be an opamp, but you need to trace the pins out to know where it goes. Good luck because it seems like a 4 layer PCB based on pictures on Alibaba.

Based off a schematic for the same OVC3860 Bluetooth Audio IC.

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  • \$\begingroup\$ +1 on the regulator, particularly since Pin 1 connects to the +12V edge connector on the BlueTooth board. \$\endgroup\$ Commented Aug 28, 2014 at 3:30
  • \$\begingroup\$ @TDHofstetter everything i've seen is that the edge connector is for a Lipo 4.2V battery. 12V would probably fry it. \$\endgroup\$ Commented Aug 28, 2014 at 3:43
  • \$\begingroup\$ I found that identical photo elsewhere on the Internet (can't remember where, now) along with a wiring diagram marking the 2nd pin from the bottom on the left as "+12V". \$\endgroup\$ Commented Aug 28, 2014 at 4:49
  • \$\begingroup\$ @TDHofstetter the form factor isnt unique, and some boards have regulators that accept 12V, but most do not. \$\endgroup\$ Commented Aug 28, 2014 at 5:11
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    \$\begingroup\$ The device in that schematic is primarily a balun. \$\endgroup\$ Commented Aug 28, 2014 at 8:29
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In the picture, what is the component of above red box?

This looks like 2.402 GHz chip band pass filter like the one shown in the datasheet here.

What is the component of below red box? Top of this component, It's written "DH=M6C". But I couldn't find any datasheets about "DH=M6C"

That may be 5 pin LDO for supplying the power to the module like this part.

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The ceramic part is a Balun. It's used to convert the differential-drive RF output from the IC to a single-ended 50Ω output that is suitable for feeding into an antenna (I have used similar parts when designing similar 2.4 Ghz transciever PCBs).

The balun may be specially designed to reject frequencies out of it's pass-band, but it's fundamentally still a balun. The datasheet in @Passerby's answer calls it a "filter", but I think that's a translation error more then anything.

The other part is probably a regulator, as the other answers have stated.

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  • \$\begingroup\$ It most certainly is a balun. Yours should be the accepted answer. \$\endgroup\$ Commented Aug 28, 2014 at 22:41

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