I won’t waste much of your time so this is a no nonsense, picture full guide.
What:
This is a mod for a Spectrum +2 Issue 3 to add internal Bluetooth using a BT401 Bluetooth Module and an Audio Isolation Transformer tapped into the Datacorder to load games from a phone or Bluetooth enabled device. It’s quick , easy and costs about £5 in parts.
How?
You will Need:
An Audio Isolation Transformer : https://www.amazon.co.uk/dp/B07TLJV3WP
DFRobot DFR0781 Bluetooth Module Bluetooth 5.0:
https://uk.rs-online.com/web/p/bluetooth-modules/2473227
This is the basic wiring diagram showing the transformer /BT401 connections
This is where they go in the Datacorder:
The reason for the Transformer is because the Speccy has a common audio ground but the BT401 has an AC signal that is centered on 0v. This makes the amplifier very unhappy so to counter it, the BT401 AMP is isolated from common ground by a coil in the transformer which is then fed to the outpur on the Datacorder.
For my installation (Which I still need to tidy up) I soldered the transformer directly to the BT 401 and secured it to the transformer with some double sided tape:
Which I then tucked neatly on the inside of the Datacorder shell.
How to use?
When you power up the Speccy, if everything goes well, the BT401 Module will output a status tone and will be ready for pairing. You should check Bluetooth on your device and look for BT401-AUDIO, once paired the Speccy will output a tone and you’ll be paired.
Select the BT401-AUDIO device on your phone/tablet as the audio output and then use PlayTZX to load games onto the Speccy. You may need to experiment with volume levels but I’ve found StrangeLoop loads when the phone is at 100%. I recommend starting at full, testing Strangeloop, then dropping the volume if you need to and trying again until it works.
I’ve been using this mod for a day or so and it works really well. It’s cheap, easy and adds a great feature so I had to document and share.
Here is is in action:
JamBlog! 