Help me make an equalizer circuit connected to a LED

i want to design a circuit that will show the amplitude of a certain frequency signal just like a car audio equalizer works. the output of the circuit will then be connected to a LED that will glow weak if the signal is not strong and will glow bright if the signal of that certain frequency is strong.

can anyone help? thank you.

bar graph spectrum analyzer circuit

You can use LM3914 for LED bar gragh display. Download its data sheet, which also contain the application circuit for IC.

ENJOY!

led equalizer circuit

You can use LM3914 for LED bar gragh display

Click to expand...

It wouldn't be of much use because of it's linear scale. LM3915 with 3 dB/step is recommended for this kind of application. Also, the bargraph display is only the smaller part of the circuit, you need also suitable bandpass filters for each channel. In visualized equalizers the existing filter is used, only additional rectifiers are needed for level measurement. You can either use an individual LM3915 for each channel or only one in a MUX circuit.

guitar equalizer circuit

this circuit cellar project is a good start...

**broken link removed**

lm3914 application

The circuit is called an Audio Real Time Analyser Circuit but you wrongly called it an equalizer. Look at its correct name in Google.

guitar eq circuit

Kripton2035 said:

this circuit cellar project is a good start...

**broken link removed**

Click to expand...

This is exactly what i was planning to construct, but this project uses dsPIC to output the power spectrum. does that mean all the audio analyser even the old ones uses dsPIC in their circuits?

I wish only to display the level measurement(thanks Fvm and Awarapunshee for the driver) of a single channel by using band-pass filter like FvM mentioned, and without the use of dsPIC, to construct a circuit that can mimic the works of a dsPIC to output the frequency spectrum.

Added after 2 minutes:

Audioguru said:

The circuit is called an Audio Real Time Analyser Circuit but you wrongly called it an equalizer. Look at its correct name in Google.

Click to expand...

Yes you are correct, i'm sorry. Specifically i'm trying to work out how to make a single channel Spectrum Analyser without the use of dsPIC for FFT computation.

guitar equalizer circuits

A single channel audio spectrum analyser will show the levels at only a narrow range of frequencies.

A micro-controller is not needed. Just make a bandpass filter drive a peak detector and then an LM3915 bar-graph driver.

equlaizer circuit

Audioguru said:

A single channel audio spectrum analyser will show the levels at only a narrow range of frequencies.

A micro-controller is not needed. Just make a bandpass filter drive a peak detector and then an LM3915 bar-graph driver.

Click to expand...

i've tried using a high-pass filter on my ultrasonic sensor, the difference when viewed in time domain is that the signals is basically the same only that the amplitude of the signals is significantly lower, but when viewed in frequency domain, we can see that it has filtered the lower frequency(Figure 2 and 3).

i'm using this to process the output from an ultrasound receiver signal. in time domain(Figure 1), it's easy for the peak detector to be fooled by the echo sound and detect the wrong peak, but if we can change into frequency domain, and take the peak of the power spectrum(Figure 3), then it is much more accurate.

after some more findings, i found some circuits that is called Audio VU Meter.
**broken link removed**
http://www.talkingelectronics.com/projects/StereoVUmeter/StereoVU.html

will it work, if the output of my ultrasonic sensor first goes through the bandpass filter, then goes to the VU Meter. the final output can then be seen on the bar-graph LEDs that shows the strength of the desired frequency.

correct me if i'm wrong, thank you.

mt1750.rar

An LM3914 is a bar-graph driver with linear steps like a voltmeter.
An LM3915 is a bar-graph driver with logarithmic steps for loudness and for brightness. Each step is 3dB from the next step.

lm3915 analizer

Anyone that need basic of equalizer circuit can visit **broken link removed**

westhost equalizer

A rather poor equalizer reference, to my opinion. Better circuits have been suggested at EDAboard before. The equalizer has no clear neutral position and an almost arbitrary potentiometer scaling. It's also unusual respectively unwanted to have a down-to-zero channel control. At best it could be used where no linear frequency response is ever needed, e. g. for a guitar amp.