January 10th, 2009

20 Band Audio Spectrum Analyzer

This is the final version of the spectrum analyzer, this is the version that will get shipped to buyers. The two boards can be connected either by cable or one on top of each-other trough pin headers. You need to specify the model you want on ordering. You can get the kit assembled or unassembled, for this there are two separate products in the shop(for assembly guide check the forum).

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I’ll post some of the most important features and specifications here:


  • motherboard: 8188 mm.
  • matrix: 23672 mm.


  • 7,5 V 1 A DC (the maximum current draw is 600 mA).
  • power is supplied to the board trough a 2,1 mm DC power connector.
  • you can get this type of adapter from Youritronics shop.

Dc power adapter for the spectrum analyzer

Input signal:

  • signal level 200 mV
  • Audio input is supplied to the board trough 2 x RCA connectors.
  • you can get this type of cable from Youritronics shop.

RCA-Stereo Jack 2 m cable


  • 2020 led bargraph display (red or green).
  • 9 display modes selectable trough button 2 present on the display board.
  • on/off (standby) control selectable trough button 1 present on the display board.
  • ISP (in system programming, if you have an AVR programmer that supports this feature, you can update the firmwire if new version is released)

First units were shipped,  and I’m curious about what you think related to the project so visit the Youritronics forum and share some of your thoughts also if you have any questions you can ask them there.

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You can now chose between 9 display modes and you have on/off(standby) control, My favorite is the first mode 🙂

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As you can see there are now 4 displaying modes, and on/off control trough two pushbuttons that sit next to the LED’s. In this version I used a cable to connect the two boards, but the boards can also be connected one on top of each other.

I’ve checked some shipping rates for united states and here is what I got:

Romania to USA, 1 kg:

UPS Express Saver 60 USD 1-5 business days
UPS expedited 62 USD – 2-5 Business Days
DHL – something like 110 USD with 2 days delivery time
Express Mail Service 41 USD probably 10 days
FedEx –  117 USD 2 business days

At the moment it seems that UPS, DHL and FedEx require proforma invoice for the product. Because I’m not a registered company I have no means to provide that so I’ll have to find a way around this problem.

later edit: The solution is Express Mail Service which is the cheapest and I can send the item as a gift thus avoiding any other papers. Delivery time to US usually under 10 days

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The movie shows v1.1 of the firmwire in action. Tomorow I’ll be ordering the pcbs and parts.. The final version will use bargraph LED’s for the display and it will be composed from 2 boards, the motherbord containing most of the parts and the LED board containing only the bargraphs.

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In response to the high interest shown by the readers on a spectrum analyzer posted here I decided to make a new design, that will be available in shop as a kit. The movie shows just a stage in the developing process, where the filters were being tuned. The final design will be powered by an atmega64 and will have 20 bands with 20 LED’s on each band.

I am now searching for a pcb manufacturer to get a good price on manufacturing the boards, then it will all be ready.. stay tuned.

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