Sound-sensitive switch

[Rankenphile]

I am looking for a sound-sensitive switch - one that would increase the output according to the volume. Basically, what I want to do is string a series of nine LEDs in sequence, connected to some sort of sound-activated switch, so that they will react to the volume. For instance, a very quiet noise would only light the first one or two, music playing would keep the lights "jumping" and a very loud boom would light them all up, for a second.

I figure I can string them all to the switch in series, with varying resistors in front of them to regulate the current that gets to them. Correct?

It has been about ten years at least since I've taken any sort of electronics class.

Thanks in advance.

[wingman358]

Hey Rank. I know Antec makes some cool "Cathode" tubes (which are really just tubes made of acrylic with LEDs shoved in the ends) that are sound reactive. The device consists of a USB plug, control thinger (which has a knob to increase or decrease sensitivity), on-off switch, and then the actual light. I had one of these a while ago and they work amazingly well. I had the sound activator on my sub, so the light pulsed to the beat. It was cool. Check them out here (http://www.amazon.com/exec/obidos/tg/detail/-/B00008VF7U/002-5352574-3864835?v=glance).

I also found some sound reactive cathodes (real cathodes) here (http://www.xoxide.com/sounaccat.html).

For what you'd be using them for (the arcade thing, I think) you could always hack off the light stick part (of course saving it for some other mod) and hook up your own LEDs.

[snefan]

I figure I can string them all to the switch in series, with varying resistors in front of them to regulate the current that gets to them. Correct?
no, that wont light them at all, or very little (depending on how many ohms in total), im afraid

[snefan]

i guess you want a resistor that act like this:

http://grossdachshund.gotaweb.com/TEF/images/circuits/circ01.gif
the higher volume the more output you get :)
ohms cus you could probably convert volume into that, and it would ease the rest

wiring each LED to an input on something (microprocessor?). then have this thing light as many LEDs you want, depending on how much gets through from that resistor through coding the thing

i just dont know what components you need.

[Rankenphile]

I really have no idea how to work with microprocessors, so I am hoping to brute-force my way to an analog solution.

My over-all goal is to have a light bar (two, actually) that looks like this, only mounted vertically.

http://rankenphile.com/images/lightbar.gif

As the volume gets louder, it start lighting the red, and then jump up to the green.

I really don't have a lot of experience with electronics, but understand mechanical theory, to an extent. Here is what I have envisioned in my head right now, but I realize I may be off the mark on this.

http://rankenphile.com/images/lightbar_diagram.gif

The mic detects volume, and the regulator tells the power source how much power to put out (somehow). Then, each of the LEDs are wired to the same strip from power source, and have a resistor, or some other current switch, that only fires if the current reaches a certain point. They would be in sequence, 1 being the most sensitive, 9 being the least, so it would take more current to fire 4 than it would to fire 2, etc.

Does this seem realistic? I appologize if I'm way off base here, I'm just trying to get these to enhance the overall look of the arcade cabinet with a sort of retro analog sound bar.

Wingman: Yes, I'm aware of sound-activated lights like that, and have ordered a pair of sound-activated CCFL blacklights for the cabinet. I just need these to fire in sequence - to be a bit smarter than jsut "on/off" like those. Thanks though.

[crazybillybob]

Rank,

here is a one chip solution to the sound meter it drives 10 LEDS. This one runs on low level input (rca connections....input voltage 1.3vpp) would work with a mic, but NOT speaker or headphone output from anything.

Hope this helps, Sound Level Meter Circuit (http://www.aaroncake.net/circuits/vumeter.htm)

If you want to look at some other circuits do aGoogle Search (http://www.google.com/search?hl=en&lr=&q=led+bar+graph+sound+level+circuit&btnG=Search) on led bar graph sound level circuit There are abunch of diffrent designs out there, some work with powered amps (head phone, speaker output!)

Your on the right track, Keep it up!

Crazybillybob

[Rankenphile]

I knew you'd come to the rescue, Billybob. :p Hehe, thanks. I'll look into this. My friend at work is pretty good at electronics, adn even designed a working chip in college, but that was many a year ago. I've been talking about this project with him today, and he suggested finding a chip like the one you pointed me to. I'll show it to him and see what he says.

[Guttenaffe]

Don't use a LM3915, those are crap for PCs. Use the LM3916 driver, will work WAY better due to the 3915 is 3dB steps and it will hardly change. For the low output of a PC the smaller scaleable 3916 is 1000x better.

[Rankenphile]

Appreciate the input, but you're a little late, lol. I already ordered the parts.

For what it's worth, it's not going in a pc.

Thanks though!

[Guttenaffe]

Well, I've been so busy of late not had time to hang around here like I used to.
To bad I wasn't able to post sooner :D
not for a PC? hmm sorry missed that it wasn't for that. Ohwell still the 3915 would work ok if your wanting to connect it to a strong siginal source. The 3916 is wonderful because you can scale it from a referance voltage and is able to have a display of 70dB :D

since you ordered the parts already no biggie, hope it works out for ya :)

[Rankenphile]

I'll be doing the initial assembly tomorrow, and will post pics as I can.

Thanks for the input, it is much appreciated.