Audio spectrum analyzer - Page 1
Forum section: electronics / beginners

author: t_jason_t
author_rank: Newbie
timestamp: January 19, 2018, 12:22:17 am
content: I have a question am trying to figure the easiest way build a IN-13 spectrum analyzer. I just want to know if I use band pass filters for each stage on the low input audio then us and Inverting op on that filter single to change the level form AC to 0-5 v dc signal. Then use a MJE 340 through a 270K resistor to ground will that not work to drive this display. I have been looking around on the internet and seen some much more complicated solutions so am just asking will this work.

author: t_jason_t
author_rank: Newbie
timestamp: January 19, 2018, 12:24:30 am
content: Non inverting I mean

author: Audioguru
author_rank: Super Contributor
timestamp: January 19, 2018, 01:05:32 am
content: Your non-inverting opamp circuit will not change its AC input to DC. It is a simple AC amplifier with a voltage gain of 11 times.You need an active peak or average detector circuit instead.

author: danadak
author_rank: Super Contributor
timestamp: January 19, 2018, 02:38:28 am
content: Close to free approach -You can start with a PC sound card based scope for free. Will give you basicallyaudio rang scope, spectrum analyzer, and function generator all using yourPC sound card.https://www.zeitnitz.eu/scope_enhttp://www.zelscope.com/http://www.ledametrix.com/oscope/http://www.virtins.com/downloads.shtmlBut first build a simple circuit to protect sound card inputs so you do notruin from transients, overvoltage. Google "protect sound card input".For examplehttp://makezine.com/projects/sound-card-oscilloscope/Regards, Dana.

author: t_jason_t
author_rank: Newbie
timestamp: January 20, 2018, 06:55:37 pm
content: If there is no polarity flip how is it AC the whole wave is above 0v.

author: Michal Mytnik
author_rank: Newbie
timestamp: March 30, 2018, 10:42:58 am
content: HI t_jason_tI am basically building same thing. Have tried few approaches. Analog way with bandpass filters seems like first choice but starts to be pretty costly if you are looking for something like 22 or more bands. FFT with MC seems to be the cheapest options. I have also considered doing that with switch capacitor filter IC that is swept through audio frequency. Wondering what's your approach. I can share my design if you are still after that.

author: ogden
author_rank: Super Contributor
timestamp: March 30, 2018, 11:38:24 am
content: Quote from: t_jason_t on January 19, 2018, 12:22:17 am... then it is very hard way to build spectrum analyzer. You need loads of quite steep filters each containing at least two or even four opamp stages and capacitors/resistors which may not fall into usual "value grid" of nominals, shall be quite precise as well. Such "filter way" is crazy complex and expensive.Easiest way (today, in 21st century) to build spectrum analyzer - using powerful enough for the task microcontroller and doing FFT (fourier transform) of digitized audio. Also it is not easy to build your own design from ground-up. For beginner it is advised to copy first. When you finished copy and it works - then you can think how to improve it or make your own design.Start here for example:http://www.instructables.com/id/Arduino-Spectrum-Analyzer-on-a-10x10-RGB-LED-Matri/If it is not what you are looking for, then check this:http://lmgtfy.com/?q=fft+spectrum+analyzer+microcontroller

author: rhb
author_rank: Super Contributor
timestamp: April 01, 2018, 12:38:55 am
content: Aside from better resolution, a PC sound card & FFT will let you display a waterfall display. If you do this with a 4K TV you'll have a resolution of less than 10 Hz. It's almost hypnotic to watch.

author: MasterT
author_rank: Frequent Contributor
timestamp: April 01, 2018, 01:42:26 am
content: Arduino UNO (Atmel's AtMega328) is capable to split audio into 256 (!) bands. Done a small project a little while ago, have a look:https://youtu.be/Ra4Yx8nkENs

author: ogden
author_rank: Super Contributor
timestamp: April 01, 2018, 12:34:43 pm
content: Quote from: MasterT on April 01, 2018, 01:42:26 amVery cool project. Especially fact that you managed realtime(?) FFT256 on Uno. Could you possibly share more than just video?