Inspired by an Instructable project

https://www.instructables.com/id/LED-VU-Meter-With-Arduino-UNO

Started the project with Arduino Uno.

Found that power it with the barrel plug made audio input stable

Tested this theory by using USB power

Suspect this was due to grounding not being as good with the USB

This caused LED's to light even without an audio input

Ended up using an generic Arduino Nano to control the project

Modified an audio mic preamplifier from Amazon to condition the output from the laptop music source

Ran the output from this to A0 on the Arduino

Split the signal out to an external speaker

Used digital outputs listed in the sketch to power the LED indicators

For reference, a sketch is the program that the Arduino runs through a loop.

Used pins 10 to 12 as AnalogWrite pin to provide the power to the solid state relays.

Used a dremel to separate the power to the hot side of the two power outlets

Used three of the outlets to power three strings of Christmas tree LED lights.

Used the other outlet to power the Arduino

Bonus

Using these particular solid state relays, there is still a 10Vac output in off state. It actually worked for good, as the lights are at a nice brightness without a music input.

Kindly leave a note in the comments if this is common to Solid State relays.

Links:

GY-MAX4466 Electret Microphone Amplifier

https://www.amazon.com/gp/product/B07C3HXPJ9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Solid State relay on Ebay

https://www.ebay.com/itm/25A-40A-SSR-25DA-SSR-40DA-250V-Solid-State-Relay-Module-Alloy-Heat-Sink/401478280169?hash=item5d79f863e9:g:dkwAAOSwiqFaX3f8

ELEGOO for Arduino Nano V3.0

https://www.amazon.com/gp/product/B0713XK923/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

AnalogWrite

https://www.arduino.cc/en/pmwiki.php?n=Reference/AnalogWrite

https://www.arduino.cc/en/Tutorial/AnalogInOutSerial

My video

Sound

Reactive Christmas lights on Archive.org

Edit:

Here is the song I meant to add, to see if it matches my video of the lights.

It is the Trans Siberian Orchestra, Carol of the Bells.

https://m.youtube.com/watch?v=sCabI3MdV9g