speakers

[Burtie21]

Hi you may not think this is highly technical, but i don't know were else to ask.....so its all on you guys

I have an old 3 peice set of amplified speakers that I no longer use, I would like to add some cold cathodes to these speakers and remake the boxes in order to make the light amplify and dim with the sound of the music, kindof like an equalizer, understand?

If possible could somebody maybe show me pictures of how to do this, aswell the parts and tools I would probably need, my dad has a band saw, jig saw, skill saw, etc.......so tools shouldn't be a problem

Thanks, Graeme

 

[AyashiKaibutsu]

I don't know much about it but I imagine a sodering iron (and much skill in using it) is going to be your most important tool.

 

[Burtie21]

ya i figured that, mostly id like to know if this is possible, and if so how to go about doing it?

 

[Tiamat]

There are cold cathode sets that come with sound activation, however these merely react to sound, not specific frequencies. If you want a graphic equlizer, like one set of cathods for 40hz, one for 60hz, 100hz, 150hz, 220hz, 440hz, 880hz, etc. thats much more difficult, and you will need more professional sound equipment. As for powering them, you could use an old powersupply, ground the 2 pins on the 20pin connector and be set for that realm... Also, im not sure how you would easily force the sound activation to react only to the speakers - not to someone coughing or sneezing, or yelling.

 

[DrPizza]

I'm not much of an electrical engineer, but I don't think it'd take a whole lot to make one homemade. I'm guessing here, but cathode powered by a separate power supply, switched on and off by a relay. Use the sound signal to turn the relay on and off.

For those of you out there more knowledgeable about such things, would simply putting a variable resistor in line with the relay be enough - then fine tune when the cathodes come on by adjusting the resistor?

 

[Burtie21]

sry but i didn't understand much of that can you please elaborate dr. pizz?

 

[DrPizza]

Okay, as simple as I can make it. Hmmmmm...... A picture is worth a thousand words.
http://electronics.howstuffworks.com/relay1.htm
look at the picture. The lightbulb is in the position where your cathode will be. The lower battery operates an electromagnet. Instead of using a battery there, I was thinking that perhaps the signal in the line could be used. It may have to be amplified though - I'm not sure. A variable resistor would act as a dimmer switch in your house... but rather than dim it, you could fine tune it to a level where it's either on or off.

 

[DrPizza]

I did a really quick search... I'm sure if I looked longer (more than 5 seconds) I might even be able to find exactly what you're looking for....
But, here's one product:
http://electronickits.com/kit/complete/elec/k126.htm

 

[Burtie21]

thanks man, ill look those over after school

 

[kcthomas]

would this really work? my guess would be that because the frequency of the music changes so rapidly it would just make the lights seem like they are on full time, just a little dimmer. this sounds really cool though, let us know if it works

 

[Burtie21]

im not sure if im gonnatry it, unless i can find an easier way, because i would have to solder all of those parts onto the chip, plus i live in canada, and shipping is a pain, cause of duty's and all of that junk. im thinking now that i will just put cold cathodes in the speakers, it'll still look crazy

 

[Shenkoa]

This does work and its very easy to do, take the speaker wires and connect them to the light and run the wires from the light, to the speaker. To control how bright the light gets, run the wire to the speaker and then to the light but use a resitor to however many amps you want to kill.

 

[Burtie21]

does anybody know if i can get those resistors at radioshack?

 

[itachi]

my knowledge of electrical components doesn't go very far.. so my design is probably gonna be really shtty.

if you're trying to make an equalizer.. you could run the input of your device parallel to the input of the amp.. run the signal through a comparator (outputs logic-1 on a specific output pin depending on input current/voltage, which depends on how you configure the input resistor) then run that signal through some light-emitting diodes (led).. you'd have to do calculations though, to find out the correlation between voltage/current and db.

if you're just trying to have it react to sound.. you could run the signal through a voltage amplifier (using cascaded op-amps is the only way i know of).. run that signal through a half-wave rectifier with whatever ripple voltage you want (keeps the signal from going below the 'diode turn-on voltage'- basically a way to keep it from going below 0), connect the output of that to a first/second order filter (depending on how quickly you want it to slope out, if you want it to not react much above a specific frequency you'll want to look into higher order filters) then finally, connect the output of that to the power input of the light-emitting device.. if the power input takes ac voltage, you're gonna have to take it apart.

with that one.. the light should shine dim for low signals and bright for high signals. you'll probably also want to connect a filter between the voltage amp and input.. have that filter block voltages associated with db's that you don't want it to react to.


you don't want to connect the light directly to the amp output.. that'll mean that your amp is working harder than it needs to. it'll have to power both the light and the speaker.. you'll clip the amp at seemingly low levels and destroy your speakers.


basic electrical components like resistors, capacitors, diodes, and transistors can be bought from radioshack.. the variety doesn't go very far though. getting stuff like ic chips, comparators, op-amps, and other stuff.. you can get from www.digi-key.com

 

[kcthomas]

Originally posted by: Shenkoa
This does work and its very easy to do, take the speaker wires and connect them to the light and run the wires from the light, to the speaker. To control how bright the light gets, run the wire to the speaker and then to the light but use a resitor to however many amps you want to kill.

do not do this! if you put stuff in series with the speaker (back to back) it will change the impedance that the reciever sees. most amps are designed for an 8 ohm load (the norm for speakers) so if it sees a much higer impedance bad stuff will happen. like itachi said, it will clip. so basically it will have the same effect of turning your amp all the way to full volume, except it wont be loud at all. everything will be very distorted and your speakers will die.

 

[ecopure]

This is the kit you need

Other Kit

 

[Burtie21]

Thanks for the help guys, I'm sorry thought, I don't think I will be trying this, it seems to complicated for me, and shipping from the US too canada is a pain, i think i'll just put the cc's on a swicth and turn them on when i feel like it.................thanks alot for the help, and again I'm sorry that you all helped me and now I'm not even going to go through with the project, well at least to the same degree

Graeme