Maker Pro
Maker Pro

Lights to the beat of music.

TheRISE TheFALL

Aug 3, 2011
6
Joined
Aug 3, 2011
Messages
6
Hi guys, I'm new to this message board and was hoping you could guide me...

I have a speaker system to my computer which includes two speakers and a 80w subwoofer. My project is to hook up either cold cathodes, or just plan LED's to light to the pulse of music.

My friend and I determined that we could run the wiring from the lights, directly to the subwoofer, providing we had a way to control the power output. However-- this idea proved to be devestating as you had to have the volume just right to prevent from blowing the lights. And if the volume wasn't up high enough, you wouldn't see the lights light up at all...

My question is-- is there an easy way to regulate the power? And to make it more managable. Any thoughts or comments would be appreciated.
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
You need at least a diode (to block the negative side of the speaker output) and a resistor to limit the current in series with the LED. But this still won't be satisfactory. As you state, it will only work well at one volume level. You could make the resistor a fixed resistor and a variable one in series to allow some adjustment, but you still risk blowing it out if you forget to adjust it before adjusting the volume on the speaker.

A better way to do it is to power the LED from a separate DC supply and use the speaker output only to control a transistor to turn the LED on and off. You could use a potentiometer across the speaker as a sensitivity contol. At least this way, you could guarantee that you would not blow the LED by using a proper resistor based on the DC supply and the max current allowed in the LED.

Bob
 

TheRISE TheFALL

Aug 3, 2011
6
Joined
Aug 3, 2011
Messages
6
You need at least a diode (to block the negative side of the speaker output) and a resistor to limit the current in series with the LED. But this still won't be satisfactory. As you state, it will only work well at one volume level. You could make the resistor a fixed resistor and a variable one in series to allow some adjustment, but you still risk blowing it out if you forget to adjust it before adjusting the volume on the speaker.

A better way to do it is to power the LED from a separate DC supply and use the speaker output only to control a transistor to turn the LED on and off. You could use a potentiometer across the speaker as a sensitivity contol. At least this way, you could guarantee that you would not blow the LED by using a proper resistor based on the DC supply and the max current allowed in the LED.

Bob

Thanks for the response, I'll look into this further

Jason
 
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