logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

DIY Acoustic Spectrum Analyzer: Schematics & Expansion for 10+ Lines, 40-LED Video Guide

piotuś 8931 16
Best answers

How can I build an audio spectrum analyzer with 10 or more bands and 40 LEDs per band, and what circuit is needed to split the audio into separate frequency lines?

You can build it either by cascading LED driver ICs like LM3915/LM3916 for more segments, or by using a multiplexed analyzer with band-pass filters; the first approach is simple but not multiplexed and becomes expensive with many LEDs [#16734611][#16735048] The thread notes that the analyzer needs logarithmic behavior because music and speech have a very large dB dynamic range, so a linear LM324-based display is not suitable unless the signal is compressed first [#16735048][#16734742] The frequency-splitting part is done with tuned band-pass filters, and the multiplexed design described in the cited article uses LM3916 with a log-linear scale plus a multiplexer [#16735048] If you want a cheaper or simpler route, several replies suggest looking at ready-made kits or analyzer projects for microcontrollers (for example Arduino/ATmega spectrum analyzers) instead of building every filter from scratch [#16734788][#16734860][#20203648]
Generated by the language model.
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
| New topic
  • #1 16734585
    piotuś
    Level 5  
    Posts: 124
    Rate: 4
    Hello.
    I would like to build something like the video:
    https://www.youtube.com/watch?v=9SK2AxfELfw
    Anyone have schematics for something like this?
    Is it possible to do as in the movie 10 lines and later expand to more?
    Schemes of lines and this "divider" are welcome.

    If I chose the wrong department, please move it.

    Thank you in advance for any help.

    Ps. It would be good if these lines were 40led as in the video.
  • ADVERTISEMENT
  • #2 16734611
    Hektar Zahler
    Level 34  
    Posts: 2333
    Help: 230
    Rate: 526
    Series connection of LM3915 chips. Just note that the display is not multiplexed, which is terribly wasteful. These layouts cost a bit.

    Added after 31 [seconds]:

    DIY Acoustic Spectrum Analyzer: Schematics & Expansion for 10+ Lines, 40-LED Video Guide
  • ADVERTISEMENT
  • #3 16734623
    piotuś
    Level 5  
    Posts: 124
    Rate: 4
    Or do you have a cheaper and more economical alternative to this system? With this amount, a lot will come out ...
  • #4 16734632
    beatom
    Level 38  
    Posts: 3614
    Help: 420
    Rate: 853
    Kit from Chinese for $ 35.
  • #5 16734640
    Hektar Zahler
    Level 34  
    Posts: 2333
    Help: 230
    Rate: 526
    The point is, these circuits are logarithmic and I will not give you a cheap alternative. If it were linear, the LMxxx series comparators are successfully used, e.g. in LPG level indicators in cars.
  • #6 16734742
    piotuś
    Level 5  
    Posts: 124
    Rate: 4
    I was able to find the design of these lines and if I understand it correctly they are on lm324.
    http://320volt.com/en/40-ledli-op-ampli-vu-metre/
    But there is also the issue of this "filter" (excuse me, I don't know what it's called correctly) that splits a specific frequency into a specific line.
  • #7 16734788
    kotuniunia
    Level 29  
    Posts: 1315
    Help: 74
    Rate: 304
    I don't know if you want to do it from scratch. You can buy a folding kit, it looks like this:
    https://sklep.avt.pl/avt2864.html
    And big ones are a different story and costs, the worst are the filters because you have to tune each one separately.
  • #8 16734827
    piotuś
    Level 5  
    Posts: 124
    Rate: 4
    And how to make such a filter? And how is it dressed?
  • ADVERTISEMENT
  • #9 16734860
    andrzej55
    Level 37  
    Posts: 3000
    Help: 306
    Rate: 373
    Read about analyzers built on microcontrollers. Search the web, for example, "atmega arduino led spectrum analyzer"
  • #10 16735048
    Hektar Zahler
    Level 34  
    Posts: 2333
    Help: 230
    Rate: 526
    The appendix describes the multiplexed analyzer, which makes it possible to use only one VU-meter system. The LM3916 was used with a log-linear scale. The rationale for using bandpass filters is well explained, as is the principle of the multiplexer. As for the article that you provide at the link, the linear scale, as in the LM324 series connection, is not suitable for this and the circuit presented on jute would have to receive a compressed signal to show as it shows: is it with the help of a logarithm system, which I am somehow visually impaired here, or this with a dynamics compressor. So if I do not see such a system and in order to "patch a hole in the dynamics of the analyzer" a dynamics compressor was used in the form of eg a Winamp plug, then such a presentation is simply a fake. The necessity to use a logarithm system is dictated by the very high dynamics of music or speech expressed in dB. And here you need to know that this dB is not a unit, but it defines the measuring range of the VU-meter -> in this case voltage or power.
    Attachments:
    • spectrum.analisis2.pdf (547.13 KB) You must be logged in to download this attachment.
  • #11 19450725
    Pitupiter
    Level 1  
    Posts: 1
    From the AVT 2864 chip:
    Is it possible to replace the LEDs with 7 white and 3 blue ones, since their operating voltage is over 3v?
    if so :
    Do the values of the resistors change and what, can you leave the same, but you have to take into account that the diodes will, for example, "start later"?
  • #12 19450864
    zybex
    Helpful for users  
    Posts: 15889
    Help: 2093
    Rate: 2916
    I made my first analyzer on 20 UL1980 chips, 10 per channel. Red LEDs 220 pieces. The 20 extra ones were always on, i.e. even without music. I just added them. It was all housed in a large tower panel. A buyer was quickly found. The second analyzer is the multiplex analyzer from Praktyczny Elektronika (on LM) shown above. I made two plays as a stereo. I sold it without the housing.

    Here is another diagram in an old book (1986).

    DIY Acoustic Spectrum Analyzer: Schematics & Expansion for 10+ Lines, 40-LED Video Guide

    DIY Acoustic Spectrum Analyzer: Schematics & Expansion for 10+ Lines, 40-LED Video Guide
  • ADVERTISEMENT
  • #14 19451050
    zulusj23
    Level 25  
    Posts: 714
    Help: 90
    Rate: 103
    A long time ago I made a 10-channel circuit from Practical Electronics. It worked brilliantly.
    Here you have a link to a page with all the issues of this great magazine from the old days:

    http://webandy.hekko24.pl/PE/lista_pdf_Praktyczny_Elektronik_1992-2002.html

    Download and see number 3 from 1992. In the next issue there was probably a reading field for 100 LEDs.
    I recommend that you review all the issues and you will find many interesting and useful things there.

    EDIT.

    The readout field is in issue 1 from 1993.
  • #15 19451932
    zybex
    Helpful for users  
    Posts: 15889
    Help: 2093
    Rate: 2916
    You can also search for ready-made bars and add frequency filters to them. An example of bars as in the video at the auction Link . Especially this effect above (in the video) would be suitable.
  • #17 20203648
    _jta_
    Electronics specialist  
    Posts: 48808
    Help: 3198
    Rate: 4183
    And much better, you can do software on a minicomputer ...
| New topic
Report a violation of the law

Topic summary

✨ The discussion revolves around building a DIY acoustic spectrum analyzer similar to a referenced YouTube video. Users share various approaches, including using LM3915 chips for a series connection, which is noted to be inefficient due to non-multiplexed displays. Alternatives such as a $35 kit from China and designs utilizing LM324 and UL1980 chips are suggested. The importance of logarithmic circuits for accurate audio representation is emphasized, along with the necessity of bandpass filters for frequency separation. Users also discuss the possibility of using microcontrollers like Arduino for more advanced designs. Additional resources, including links to schematics and kits, are provided for further exploration.
Generated by the language model.

FAQ

TL;DR: Build 10+ band analyzers with band‑pass filters, log‑scale drivers, and multiplexing; “I made my first analyzer on 20 UL1980 chips.” [Elektroda, zybex, post #19450864]

Why it matters: This FAQ helps DIYers choose between LM391x chains, microcontrollers, or ready kits to get dense 40‑LED columns with sane cost and power.

Quick Facts

How do I build a 10‑band acoustic spectrum analyzer like in the video?

Split audio with 10 band‑pass filters, rectify each band, and feed a logarithmic bar‑graph driver. Use multiplexing to cut parts and heat while keeping 40‑LED columns bright. “The appendix describes the multiplexed analyzer,” which explains why this approach scales well. [Elektroda, Hektar Zahler, post #16735048]

Can I start with 10 lines and expand to more later?

Yes. Design the front‑end and driver for multiplexing and add more filter channels in groups. Expansion mainly means adding filters and routing those outputs through the existing multiplexer to the display. Keep the same log‑scale driver settings. [Elektroda, Hektar Zahler, post #16735048]

Is there a cheaper option than chaining LM3915/LM3916 for many LEDs?

Buy an off‑the‑shelf kit. Builders report complete spectrum‑analyzer kits from China around $35, which is often cheaper than many discrete LM391x chips and PCBs. [Elektroda, beatom, post #16734632]

Do I really need logarithmic scaling for audio levels?

Yes. Music and speech have high dynamic range measured in dB. A linear scale under‑represents low‑level content and clips peaks. A log‑scale driver (e.g., LM3916) matches how we perceive loudness and keeps columns informative. [Elektroda, Hektar Zahler, post #16735048]

What does “multiplexed analyzer” mean here?

The display is time‑shared. A multiplexer quickly scans each band’s level into one driver, so you need fewer driver chips. You still use separate filters per band; only the display path is multiplexed, cutting cost and heat. [Elektroda, Hektar Zahler, post #16735048]

Is a non‑multiplexed display a bad idea?

It works, but wastes power and parts because all LEDs and drivers are active continuously. As one expert noted, the “display is not multiplexed,” which is wasteful with large arrays. [Elektroda, Hektar Zahler, post #16734611]

How do I make the band‑pass filters, and what’s the catch?

Build a filter per band (e.g., op‑amp active filters). The catch: you must tune each one to its center frequency. On big builds, this tuning effort and cost dominate the project. [Elektroda, kotuniunia, post #16734788]

Can I drive 40‑LED bars per band?

Yes. Use a multiplexed readout and a logarithmic driver to maintain visual range without dozens of parallel drivers. Large static arrays need many chips and run hot compared with multiplexed designs. [Elektroda, Hektar Zahler, post #16735048]

Are microcontroller solutions worth considering?

Yes. Search and prototype “ATmega Arduino LED spectrum analyzer.” MCU FFT/Goertzel solutions remove analog tuning headaches and scale to more bands with code changes. [Elektroda, andrzej55, post #16734860]

Can I mix white and blue LEDs in AVT‑2864?

Builders asked about using seven white and three blue LEDs (>3 V Vf). Expect later turn‑on and the need to recalculate resistors to match brightness. Plan around higher forward voltage. [Elektroda, Pitupiter, post #19450725]

Where can I find a proven magazine project?

See Praktyczny Elektronik: a 10‑channel analyzer that “worked brilliantly,” plus an issue with a 100‑LED readout field. These articles are a solid starting point. [Elektroda, zulusj23, post #19451050]

Any other published kits or schematics to study?

Yes. Review Jabel J‑74 and Nord Elektronik NE‑091 analyzer kits for reference schematics and part lists. Studying multiple designs clarifies filter choices and display wiring. [Elektroda, jarek_lnx, post #19450977]

Can I use pre‑made LED bars and just add audio filters?

Yes. Builders pair ready LED bar modules with a filter bank for each band. This approach mimics the video effect while reducing soldering on the display side. [Elektroda, zybex, post #19451932]

What parts did classic DIY analyzers use?

Examples include 20 UL1980 bar‑graph drivers and 220 red LEDs across stereo channels. This shows the parts count balloon in non‑multiplexed designs. [Elektroda, zybex, post #19450864]

Quick 3‑step: how do I expand from 10 to 20 bands later?

  1. Duplicate the 10 band‑pass filters for the added frequency bands.
  2. Feed new rectified outputs into the multiplexer scan chain.
  3. Keep the same logarithmic driver and timing; adjust scan rate if needed. [Elektroda, Hektar Zahler, post #16735048]

Why avoid a linear LM324 bar for spectrum columns?

A linear LM324 bar needs pre‑compression to mimic music dynamics. Without a log or compressor stage, visuals misrepresent real level changes in dB. [Elektroda, Hektar Zahler, post #16735048]
Generated by the language model.
ADVERTISEMENT