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Speaker headphone disconnect for mP3 player with amplifier and headphones Answered

Hi, I am working with a Flyron FN-M16 MP3 player module which has both output for headphones (pins 4,5, and GND = 7), and a 3-watt amplifier for speakers (pins 6 & 8).  The problem I am having is that I am unsure of how to disconnect power to the speakers when headphones are plugged into the jack.  This is easy when you have a separate amplifier circuit, but here the amplifier is built in. The easiest solution would be to find an audio jack with an isolated NC (normally closed switch) to disconnect the speakers.  They do not seem to make them in SMD packages.  I have found a 3.5mm stereo audio jack with an isolated NO (normally open) switch from Technik.HK.  Is there a mosfet type circuit that I can use to disconnect the speakers when the NO switch is closed without introducing any distortion to the speaker sound?  Any advice for an electronic disconnect?    P.S:  The manufacturer has stated that if I ground the speaker outputs for the 3-watt speakers I will blow out the internal amplifier on the flyron Mp3 player board.


You can just add a DPDT switch between the wires going to the speakers so that you can just open and close the circuit which would allow you to control the sound source according to your choice.

I can find the sockets everywhere, even on Ebay:


If you want to go electronically you need a trasistor in the ground line for the speakers.

A second transistor is in the headphone output and whe it senses a current it switches the speakers off - big downside is that you switch between speakers and headphones every time there is a period of silence, so I would stick to the socket solution.

If you have a few old mobile phones around you can salvage suitable sockets from them too, but they usually are in the 2.5mm layout and not the 3.5mm standard.