Hey folks,
I'm one of those old folks that know a little about a lot of things, so be nice.
I have a project that requires what the title says.
"I need to turn on something when there is sound coming from a speaker."
One of the first considerations is cost, as I am hoping to manufacture a sizable quantity of devices utilizing this function.
My first thought was to utilize the speaker voltage directly, and then I turned to the sound itself being detected and amplified to the point of firing the relay.
Am I missing something ?
Is there a simpler solution that could cost less ?

Thanx,
Grampa Rich (not Rich Grampa as my kids think)

 

Hey folks,
I'm one of those old folks that know a little about a lot of things, so be nice.
I have a project that requires what the title says.
"I need to turn on something when there is sound coming from a speaker."
One of the first considerations is cost, as I am hoping to manufacture a sizable quantity of devices utilizing this function.
My first thought was to utilize the speaker voltage directly, and then I turned to the sound itself being detected and amplified to the point of firing the relay.
Am I missing something ?
Is there a simpler solution that could cost less ?

Thanx,
Grampa Rich (not Rich Grampa as my kids think)

May I (we) ask what the overall goal of this project is? Or, is it top secret?

There are approximately 298459823498 ways to do this, but your project specifications are going to narrow it down to a handful...at which point, we can do the cost-cutting.

 

Hey there PaulEE,

Yup - top secret
However, basic voltage available is 12vdc
- lookin' to keep overall device as small as possible
- will need to drop 12v to 5vdc for another little sub device (will gut a $.99 usb to 12v doodad for the 5v)
- said little sub device will have 10 second timer to turn speaker off (relay to turn off too)
- very low volume of audio is needed

HALP

Thanx,
Grampa
-

 

Anybody that likes golden's can't be all bad.

grampa

 

I just read over what I forwarded, and I need to change "I want to manufacture----------etc" to "I would like to patent the idea--------etc"

 

I just read over what I forwarded, and I need to change "I want to manufacture----------etc" to "I would like to patent the idea--------etc"

Well, if your intention is to patent the idea of:

"I need to turn on something when there is sound coming from a speaker."

You've already given it up to the public domain by posting it here! Hopefully, there is more to your invention than that, but, in the future, *be careful*!

 

There is an Instructable that blinks an LED when music plays. It was designed by a 10 years old kid so it is missing two current-limiting resistors and a diode. It is just one TIP31 transistor.

It is missing a series base resistor so its forward-biased base-emitter junction blows up and might blow up the audio amplifier. Its emitter is missing a series diode so when its reverse-biased emitter-base junction has avalanche breakdown at about 5V then it blows up and might blow up the audio amplifier.
Its LED is missing a series current-limiting resistor so the LED will probably blow up.

 

Well, if your intention is to patent the idea of:



You've already given it up to the public domain by posting it here! Hopefully, there is more to your invention than that, but, in the future, *be careful*!

Oh yeah, there is much more than this one function, and I appreciate the "be careful", but I have been down this road before and know the bumps.
Thanx----------

 

Unless you have $100 grand to spend on a patent application you might as well forget that idea. In any case, if someone knowledgeable in the field of electronics can come up with the same idea in the normal course of practice that kills your patent.

But you can still build a simple sound activated switch, just not patentable.

 

Haven't you heard about "The Clap Switch" that is being sold today?

It turns something on when you clap your hands quickly two times (or if your dog barks quickly two times). Then it turns off when you clap your hands quickly two times again (or your dog ...).

How can you patent something that is already used all over the place? How can you sell yours when everybody already has a few?

 

Oh yeah, there is much more than this one function, and I appreciate the "be careful", but I have been down this road before and know the bumps.
Thanx----------

So you are saying the sub-circuit would get power from a separate power source, you just want to switch it on and off with the speak line voltage? Do you care if this device causes issues with said speaker line? ie. does the speaker still need to work with this device inserted?

 

OK,
Let me start over here-----------
I have a neat idea for a gadget that needs the aforementioned function.
It might be patentable, it might not, I really don't care.
I just want to make one for my own use, and maybe it might interest someone who had the wherewith all to take it and run.
So, does anyone have an idea how to operate a relay with speaker audio voltage, or the sound itself ? cheap ?
thanx

 

A problem with using audio from the output of an amplifier to turn on a relay is that a relay needs a certain DC voltage and audio is AC at many voltages.

The audio must be at least 4.1W into 8 ohms for a duration a little longer than the relay's turn-on time plus the duration tthat you need. Rectify the audio then filter it. The resulting voltage will be at least 5VDC. Use a 5V voltage regulator to turn on a 5V relay.

 

WOW,
thanks for all your help !

 

Here are some example circuits of a switch activated by sound. They vary in complexity.

SOUND ACTIVATED SWITCH

AUDIO ACTIVATED SWITCH by DAVE JOHNSON

Mini Voice Operated Relay

This is clearly not patentable. It's obvious, and there is lots of prior art. Anyway, have fun.

 

Hey there PaulEE,

(will gut a $.99 usb to 12v doodad for the 5v)

-

Why 5v regulators dont cost that much to buy

 

Why 5v regulators dont cost that much to buy

Not to mention that $0.99 device is likely complete junk. Certainly poorly made with junk parts. Better to buy new parts and do it right.