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Help! LED series with Speaker Answered

I recently got a little old stereo which I've been cleaning up/painting/tuning/etcetera. To me this thing is just so darn cute and I got really excited when I noticed some LEDs under the speaker grates. However they only light up when the volume dial is up to 9 or so, and the stereo is just way too loud! 1-2 on the dial is what I would consider a medium volume level, and don't see myself ever going much higher. I would like a way to fix the dial discrepancy, but I feel that I can live with it. What I'm really after is a way to get the LEDs on at a normal volume level. Ideally pulsing with the music(like they can do now.) I've included a picture of the circuitry. Let me know if you'd like a picture from the other side and I can take it out.

I'm a super novice at this stuff. It seems like the LEDs are in a series(btw, each little circuit board is home to three leds, for a total of 12) but that the whole series is actually parallel to the speaker itself? Or is it all in series? Anyway, my first thought was to leave the blue wires going from the LEDs to the speaker, but to move the black 'power' wires to the end of the last LED series so that the power would go all the way through the LEDs before getting to the speaker. Is that a bad idea? haha. I'd rather not burn these LEDs out since they match the colors of the stereo.
What do you think?

Thanks in advance!



6 years ago

From your description the LEDs are parallel with the speakers.

Wired like that, they probably aren't intended as a "light show" feature. It's an overload prevention clipping circuit. Below their forward voltage the diodes don't conduct, and are essentially not present.

Once the amplifier output exceeds the forward voltage (2-4 volts, depending on the LED color), the LEDs conduct and create a current path around the speaker--lighting up in the process. So in addition to protecting the speaker, they're a visual indicator that the output is clipping and nearing it's max allowable volume.

Something that blinks in sync with the music will require more complexity...


6 years ago

IMHO you should remove the LEDs from the speaker. Then you need to build a simple clap circuit. This video will help you out.

Have the speaker feed in where he has the mic and add a couple more LEDs in parallel with the 1 in the video. You'll want to tie this all into the stereo's battery/power supply. But if you just want the LEDs to be on then tie it into the power supply but you'll need to know what resistors are attached to the LEDs so you don't put too much power through the LEDs.