A little reconstruction here, a little reconstruction there...

... and we got sound!

Well, at least sound from one unit. The other one hasn't been ordered yet.

I had quite a struggle getting stuff to work and selecting the correct serial settings for the MP3 Trigger v2. The problem began with the first serial port occupied by one of the power boards connections. I.e trigger a sound - trigger the solenoid. Not good.

I tried resorting to using software serial communication instead...

...but after a long troubleshooting it turns out that the baud setting was not changeable in the ini file as I believed it would be. Since the baud is fixed at 9600 for software communication I couldn't use the SoftwareSerial library for Arduino to create a custom pin for serial communication. But it worked itself out alright in the end since the Mega2560 has three additional hardware serial ports that I could use instead. 


To get more than line-out level audio I had to get a small amplifier. I figure for testing purposes, a simple 7$ circuit would suffice, correct? Yes, it did. But I won't wake the neighbors with this! 

1) Cheap audio amplifier. This was gathered from a cheap MP3 speaker set that was mercilessly butchered and brought back to life by the ATX PSU. The next question is how I should mix the two sound boards' output into one stereo channel that can be sent to the speaker set...

I also spent a lot of time rewiring and cleaning up the electrics inside the cabinet. Now I got dedicated connections that I can tap +3.3V, +5V, +12V and +48V out of. Also, I rewired the Arduino and the one (later two) MP3 Trigger I got to use the computer PSU instead of a dedicated PSU for Arduino. 

2) Top: +48VDC connections, fusebox, +12VDC connections
The other top: Switchboard, temporary speakers
Center: +48VDC power boards, ground-bridge, Arduino, sound board, (cheap) audio amplifier
Bottom: +48VDC PSU, PC ATX PSU, +3.3/+5/+12V power connectors, extension cord

More power, cleaner cabling.  I like.