I like this type of the small and cute one. It only has FM stereo/AM radio, one cassette deck. The beauty of the simpleness.

In order to make this one as the Bluetooth speaker, this time I tried a different method to remove the ground-loop noise.

For the Bluetooth mod, first I need to find the signal input point, then I need to reduce the power source to 5V. And finally I need to remove the ground-loop noise.

So far I used MPOW ground-loop noise eliminator between the Bluetooth receiver and signal input point. This time I used the DC isolated converter along with 47uH inductor + 4.7uf capacitor. It simple, but worked well. I learned this method from other youtuber video.

Here is a drawing for the wiring. (I misspelled "Lenear", correct word is "Linear".)
https://goo.gl/u5f9Hn

Bluetooth 4.0 or above has the strong signal that will make a distortion to this type of small one. So I needed to adjust the Bluetooth signal input level by resistor. I used slide potentiometer to adjust the input level, then I replaced it with resistors for L and R. No need for the ground.

   • The BT input signal adjustment  

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The lists for the parts.

Bluetooth receiver 4.0
https://amzn.to/2Qn1feL

4.7uf ceramic multilayer monolythic NP capacitors
Amazon
https://amzn.to/2TPBfaX
Ebay
https://goo.gl/6ieX4F

47uH Fixed Inductor
Amazon
https://amzn.to/2r85vAT
Ebay
https://goo.gl/1FZWjX

Comidox 5PCS B0505S-1W DC-DC 5V Power Supply Module 4 Pin Isolated converter
https://amzn.to/2TLqczs

6 pins toggle switch
https://amzn.to/2PYtsZX

resistor kit
https://amzn.to/2KCbtCM

Step-Down Linear Voltage Regulator Module
https://amzn.to/2TRjbNt

Enjoy!

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Donation welcome!

I appreciate if you fund me for the new camcorder and my next youtube projects. Thanks. Teddy Hashee

https://www.paypal.me/teddyhashee358