Hi i am bigginer about electronic.question about sound detecting.

i am wondering if i could make cirkit which will light LED When they detect specific sound frequency.

i would like to put 5 LEDS. And it connected with input sound cable which play specific frequency.

the sound cable will give 5 kind of hertz(100,150,200,250,300)and it will make sound one kind of hertz at one time.

the LED shoud be lighting by DC suply( i think i could use electrolytic condenser)

I dont know what kinda electric part i can use for detecting specific herts.

could you give me some ideas?

those frequencies are kind of close together. In order to discriminate between them you will probably need some circuitry that might be beyond 'beginner' type. The simplest approach is to create 5 filters which will each pass only the desired frequency. When the signal out of a particular filter is high enough, it can cause a comparator to switch, turning the LED on.

[Merged] thanks for answering

could you explane more about filters?
do you mean the filters will turning on the comparator swich?
and you said that frequencies are kind of close together..
so what kind of frequncies could i use?

i just wanted to test my LED lightning from specific sound gernerating program from computer. so i can set the frequencies.
could you give me some idea?

Make sure that you answer in the same thread instead of starting a new one.
I have moved your answer here, where it was meant to be posted. [alexan_e]

Click to expand...

As I said, maybe this is not a beginner project. You need to learn about filters; searching the web will give you lots of information. What you need for your application, I think, is a BANDPASS filter, a filter that blocks signals outside a specific range. The problem when the frequencies are close together is that a real filter will pass some signals outside the desired range; for instance your 100 Hz filter will pass some 150 Hz signal. This means that you need a more complex filter to reduce the amount of unwanted signal getting through. But, as the frequency gets farther away from the passband, the amount of signal getting through is less. In other words, a given 100Hz filter will pass less 400Hz signal than 150Hz signal.

Agree w/ barry on the subject matter to study. However, I have a broader question... what range of sounds are you trying to detect and indicate? 100-300 Hz is very much in the range of bass frequencies, when you talk about the range of human hearing. Typically, the human ear can detect from 20-20,000 Hz (20 Hz - 20 kHz). If you are trying to make your LEDs light up to music, then you'll want a much wider range of frequency coverage than 100-300 Hz. In that case you'd want something more like an audio equalizer (several bandpass filters, in parallel) that connects the output of each filter stage to an audio detector. Each detector, in turn, is connected to a circuit that enables the LED for each frequency band.

Here's a link to a 10-band equalizer that uses active filters (uses op-amps) to filter and amplify each frequency band.
**broken link removed**

In this circuit, the outputs are summed together and put back onto one signal line (the purpose of an eqaualizer), but you could remove the final sum-and-amplify stage and connect the output of each filter/gain stage to their own detector and LED driver circuits (one for each frequency band).

Ideally you want a Goertzel filter. But that is not for beginners.

Goertzel algorithm - Wikipedia, the free encyclopedia

Let us assume you like to get 5 outputs for 5 audio frequencies.
I suggest using the restricted audio spectrum which is from 300 Hz to 7000 Hz (as of my tape recorder in the 70's)
This means the lowest frequency to be detected is 300 Hz and the highest 7000 Hz.
Let us calculate the remained 3 frequencies...

The ratio is 7000/300 = 23.333 which is 2.2^4 (approximately, to get the 5 frequencies).

What I am trying to do is to select 5 audio frequencies that are not high (for the opamp) and spaced well to ease the filtering.

F1 = 300 Hz
F2 = 300 * 2.2 = 660 Hz
F3 = 660 * 2.2 = 1452 Hz
F4 = 1452 * 2.2 = 3194 Hz
F5 = 3194 * 2.2 = 7027 Hz

Is this ok so far?

dselec said:

u need a hobby electronic lab for a beginner it will cost u a min of 2 thousand dollars , buying used instrument so u need to be rich or dedicate your life to electronics.

Click to expand...

Pardon my flaming, but that's ridiculous and not the least bit helpful.

You can buy cheap or used test equipment pretty inexpensively; you don't need to be rich, nor do you need to 'dedicate your life'. For a couple hundred dollars (or less, depending on how resourceful you are) you can get a scope, signal source and power supply.
And buying a ready made kit kind of defeats the purpose, don't you think?

I had about $100 only when I started my private business (though relatively small) in designing/producing electronic products for the local market... but this was in the 70's
I started with a multimeter, a home-made power supply and audio generator. Naturally, I couldn't design serious hence profitable circuits before buying an oscilloscope though it was just 10MHz analogue. (Now after 35 years, things have changed a lot ;-) )

Hello Barry
dint mean to put him down .
i envy you USA citizens .
really used equip.. is dead cheap out there.
we have been exposed u ebay for no more than 5 years and we can see things are cheap still the transportation to israel is expensive , and any body selling parts or elec. equipp. makes 200-300% on what he buys from u.
i myself started in 1973 with about 1500$ worth equip. at that time when i started my business.I was poor and had to work odd jobs to buy all that stuff giving up going to the movies or eat /drink at the pub or other activity that come easy to today's children or teens.
all the best
shimon

Hi Shimon,

Sorry to go off like that; I must have been having a bad day Anyway, I would have thought that with all the high-tech in Israel, there would be lots of used/surplus equipment around. And I'm not sure where the original poster is living--Maybe in China where you can get very inexpensive test equipment.

LM567 is a tone decoder ic. When certain tone is present, it gives an output. Frequency can be set from less than a hertz to more than 500KHz with a singe resistors. It is an old ic. It was widely used cordless telephones to decode dialed numbers.
LM567 - Tone Decoder [Discontinued]
LM567 Tone Decoder Calculator

No harm done Barry.
Next time ill be is mass.. ill buy u a beer .
i have been in mass 4 times the last 9 years buying lot of stuff from usa.
About the high tech it started to bloom in Israel after six day war. when companies saw our potential , security and industrial,but the real break thru was after YOM-KIPPUR war.

K sorry big boys above but above a beginer OKkkkkkkkkkkkkkk where do you suggest some one would start........a comunications satelite, or maybe a new set of brains for the now defunct appolo space rocket.??????
In answer to the first post which NONE of you have picked up on is the fact he is asking for a colour organ or spectrum analyzer allbeit on 5 channels maybe ambitious agreed but one channel 100 channels when you get the circuit right just add to it to get to the right number

Try this
3 Channel Spectrum Analyzer

Good old arron cake to the rescue.

With a little be of pen and paper math (or look at post above) it can be worked to give what you want. couple TWO side by side and you have SIX channels.

Failing than google spectrum analyzer LOADS of simple circuits out there using easily obtainable parts
That was one of my sons first projects when he was 6 that was ten years ago......... so if a six year old can do it thn its not outside the scope of a begginer.
Or have you all forgotton that a high and low pass filter is basically two capacitors and two resistors ( even my cat could do that with a bit of help from my new hotair solder wife station)

Sorry to sound like I`m having a pop I`m not but sometimes there are simple answers that just dont need over complicating