Circuit for Flashing Lights With Music





•These instructions will show you how to build a simple circuit that controls any kinds of lights (That plug into the wall) and will flash them along with the beat of music

•Only simple soldering skills and a bit of electronic knowledge are required for the completion of this project along with the materials.


•Soldering Iron and Solder

•120V AC Plug (Male)

•120V AC Plug (Female)

•Speaker Wire

•Solid State Relay

•(2) 3 Amp Switches



(Links to these items will be at the end of the instructions)

Step 1: 120V Cable to SSR

•The first step in this project is to solder the 120V AC cable to two sets of speaker wire. (I cut mine off of an old laptop charger)

•The next step is to solder the ground wire from the 120V AC (male) cable to the 120V (Female) connector. The positive wire from the 120V AC (male) cable is soldered to two separate sets of 20g wire. I used red because it is the positive connection. You need to have two sets of wires coming from the positive because it will be connected to two separate places as shown in the schematic. •You can connect one of the 20g wires that is coming from the 120V AC (male) cable to the ~2 connection on the SSR (Solid State Relay). This is shown in the picture.

Step 2: 120V Cable to S1

•The next step is to solder the second 20g wire from the positive wire on the 120V AC cable (male) to on of the switches. This will be S1. S1 will bypass the SSR and turn whatever is plugged into the 120V AC Connecter (female) on all the time.

•You then solder a 20g wire from the other connection on S1 to the positive connection on the 120V AC Connecter (female). These connections are shown in the picture.

Step 3: S2 to SSR

•The next step is to solder a 20g wire from the 120V AC connect (female) positive connector onto the first connection on S2. This switch will NOT bypass the solid state relay and allow the lights to be turned on and off for flashing with music.

•You then solder a 20g wire from the other connecter on S2 and connect it into the ~1 connection on the SSR. You do not need to solder this connection. These steps are shown in the pictures.

Step 4: SSR to Speaker AMP

•The next step connect the two speaker wires from the SSR into your speaker amp. One wire ill be connected to the +3 connection, and one wire will be connected to the -4 connection on the SSR.

•The wire coming from the +3 connection is connected to one of the positive ports on the speaker amp. The -4 wire is connected to the ground port on the speaker amp. This is shown in the pictures.

Step 5: Final Testing

•The final step is to connect some music to the speakers and turn S1 off and S2 on. This will enable the circuit to flash the lights with the music. A demonstration of the circuit working is shown in the video.

Step 6: Links for Materials



    • Arduino Contest 2019

      Arduino Contest 2019
    • Trash to Treasure

      Trash to Treasure
    • Tape Contest

      Tape Contest

    6 Discussions


    3 years ago

    You should be using a transistor to add actual DC power to the relay input. A tip122 or similar Darlington transistor with a small DC voltage from collector to emitter with the audio sine waves at the base.


    3 years ago

    dude, good call. this guy knows what hes talking about^^^^^


    3 years ago

    This could easily be expanded to have band-pass filters triggering separate circuits. I've had 6 of those SSRs sitting around for more than a year just itching for such a project.

    1 reply

    Reply 3 years ago

    I've also thought about rigging up such a setup through my Arduino to use PWM for varying (apparent) brightness.


    3 years ago

    This is SO cool. I can trash all those audio output transformers I've been saving. :-)


    3 years ago

    Really fun idea! I love the look of it on your tree!