Bluetooth Module for Valve Radio

Written by Scratch on Thursday December 17, 2020

Notes on using the cheap MH-M18 bluetooth module in an old valve radio.

I used a cheap Bluetooth (MH-M18) module to turn the gramophone setting of my AC31 receiver into a bluetooth audio device.

Most of the circuit is the power supply, taking the 6.3V AC heater supply and converting it into an isolated, regulated, 5V supply for the bluetooth module.

This was designed in KiKAD and the Veroboard layout designed in VeeCAD.

Circuit diagram (link to PDF).

Circuit

The Veroboard layout is designed to fit a standard 9 strip by 25 column board (the layout shows a bigger board to allow the outline of the MH-M18 module to be shown).

Component (top) side of the Veroboard.

The Xs mark cuts on the copper side.

Veroboard component side