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Spectrum analyser Equalizer project how to go about it?

Martaine2005

May 12, 2015
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so the best deal I found is 45 of the 10 led bar display's for £100 the moneys not too much of a problem but wondered if you could source some cheaper ones?
Where did you get that price from?. I’m sure I bought 10 bar graphs for around a £5 off eBay. (China).

Martin
 

Martaine2005

May 12, 2015
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If you are UK-based you can have these boards free of charge (postage only) that will give you all the LEDs you need. Sadly you'll have to desolder them yourself or, possibly, use them as-is in some fashion....

288 of each colour red, green and blue. I might have a third identical board somewhere in my 'crap hole' (as Mrs calls it).
I’d be interested in them. I can PayPal, bank transfer or any number of payment methods. If the OP doesn’t want them.

Martin
 

Martaine2005

May 12, 2015
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Of course. RS will cost a lot more but should have quality components. But they get theirs from China too. Mine are good quality as well for a fraction of the price. Just had a little wait. As they say “slow boat from China “. About 10 days really.

Martin
 

Maglatron

Jul 12, 2023
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ok can you link me to some red bar graphs on amazon please for the cheap price, how much is it to send because I would like them pm me the account no and sort code and Ill send however much you need for the post thanks
 

kellys_eye

Jun 25, 2010
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ok can you link me to some red bar graphs on amazon please for the cheap price, how much is it to send because I would like them pm me the account no and sort code and Ill send however much you need for the post thanks
I'll have to pack/weigh the boards to get a postage charge. Will be back in touch when I've sorted that.
 

Martaine2005

May 12, 2015
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You’re paying £7.20 for each set of 10.
Ebay is £3.94 for 10 sets! Including postage.
 

Maglatron

Jul 12, 2023
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that's incredible, and to say I was going to pay £100 and upwards £14.50. I'll order through a friend because I can't buy on ebay where I am.
 

Delta Prime

Jul 29, 2020
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also

where is the power for the led's on this picture
Power is 5 to 12 volts apply to pin 3 along with the anode of the LEDs connected to the voltage source. I'm probably just splitting hairs but that is not a picture.
It is a plan, drawing,diagram, diagrammatic, or schematic.
Power input is labeled on the very top LM3914 to the right just below midship or middle of the integrated circuit.
 

Maglatron

Jul 12, 2023
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Fig.2.Circuit diagram of the input amplifier, filters and envelope shapers that provide the
required PPMresponse.

so okay I still want the 31Hz to 16kHz but split into 15 channels.
how do I modify the UK version of the magaine schematic - to suit my needs?
and also want up to 30 bars in each column, how do you cascade the 4017? if I even need to. also can't find IC6 abcd anywhere in the diagram schematic anywhere. IC10 is an MC 1485 opamp
working through it slowly and im getting somewhere.
I think I need to be talked through the theory a little if any one has a minute
 
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AnalogKid

Jun 10, 2015
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The bandpass filters in the article do not have a very narrow frequency response. IOW there is some overlap between the response bands. If you increase the number of bands, the overlap will be worse. For example, if you have one band centered at 1 kHz, and you input a 1 kHz sinewave tone, it will light up the 1 kHz indicator plus a couple of band indicators on either side. The farther away from 1 kHz you get, the lower the amplitude indication, but with complex music, the overall display will become "softer" as you increase the number of bands.

If that is the effect you want, then fine. There are a couple of bandpass filter topologies used in equalizers. Whichever one is in the article, I'm sure there is a calculator for it somewhere on the innergoogle. You want the filter center frequencies to be evenly spaced on a logarithmic scale.

ak
 

danadak

Feb 19, 2021
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For future design reference, an alternative way of doing this.

I think this can be done in 8 chips total, only external passives
would be LED current limit resistors, and a bypass cap or two per
chip.

On chip there are two dig filter channels, two SARs. In addition I created a 16 bit shift reg on
the chip to drive the LEDs. So output of filter goes to code that detects peak, and thats used
to control LED shift register for that channel

1693407928787.png

Filter looks like (example at 1 Khz) :

1693408122508.png

And shift reg looks like :

1693408193665.png

So this is all on one chip, except LEDs and LED R's.

Compiler and IDE (PSOC Creator) free, boards to use for two channels and programming
it / prototype is $15

1693408384663.png

Food for thought next time you want to do something like this.

Note alternative could have done it with same board as FFT generator, and
then a chip for each 4 channels with 4 16 bits shift registers in the chip.


Regards, Dana.
 

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Maglatron

Jul 12, 2023
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what is IOW
also I want the bands to not lap over much instead of "softer" I want the responce to be quite crisp I still want 15 columns is there a way of doing it with out the op op-amps or are the intrinsic to the design I was thinking of doing something more digital that also runs from the red and white RCA jack, with the same effect with the arduino what are your thoughts?
 

danadak

Feb 19, 2021
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IOW ?

What I showed is one chip, the opamps are onchip, only one used as Vref buffer, as is the shift reg for led drive and the filer.

Regards, Dana.
 
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