Classic Analog Spectrum Analyzer for Your Desktop
Introduction: Classic Analog Spectrum Analyzer for Your Desktop
This is a spectrum analyzer that visualizes 10 audio frequency bands. Although it might look like just another FFT ESP32 project, it is most certainly not! This design uses a PCB that I designed and build and although it involves an ESP32, it doesn't involve FFT. ( A digital way to determine what frequencies are embedded in a signal). The analysis of the input signal is actually done by 10 good old fashion opamp driven, band filters.
An ESP32 is used to host a webserver for visualization and to drive all the leds on the acrylic display.
Here are some of the specifications:
* 10 Opamp based band pass filters
* Onboard Power supply 12V input/4A to onboard 5V/3.3V
* Microphone and Line input
* Onboard multiplexor to switch between audio signals
* Onboard Analog switch to toggle between input signals
* Operating panel with 3 potmeters and 2 switches
* Onboard pre-amplifiers
* Onboard input protection against wrong polarity and over-current
* All hardware and software are open source
Supplies
You Need the following materials.:
* PCB buy here ( pre assembled including smt components )
* or bare PCB without components @PCBWAY.com
* LEDSTRIP 74Leds / Mtr ( Ws2812 or simular, Other size possible if you deviate from my housing design)
* Acrylic 5mm black ( or other color is you prefer)
* acrylic 10mm transparent to create the tiles.
* ESP32 DevKit1 ( you can use other ESP32 but I wrote the firmware for this one)
* Some wire and connectors for audio and power
* A power switch to your liking
* A power supply 12V / 4 A
Also you will need some tools skills:
* Soldering skills to hook up some wires
* advanced soldering skills if you decide to assemble the PCB yourself (not recommended)
* You'll have to glue together the parts of the housing if you decide to stick with my acrylic design
* In that case, you'll also need a laser cutter of know someone who can cut the acrylic for you.
* And finally, you'll need to be able to install the ESP32 libaries and boards and for that you need to know your way around Arduino environment. Although, all of that can be done using some tutorials because it is not that spectacular if you have the right guidance
All sofware ( sketch) hardware design, schematics, pcb layout etc is available at my Github:
Github for Analog Analyzer
Step 1: Assembling the Housing
To glue all the parts of the housing together, I used this glue: Evonik Acrifix 1R0192
Other glue for acrylic might also work fine.
step 1: I started with the backplate and glued the inside spacer plate on top. This plate has a zig-zag cutout where the ledstrip can be placed.
Step 2: Internally wire up the LED strips. Take note that you line them up properly. There can be a diviation in size and LED spacing, depending on who manufactured it. 382
That's why I cut my strips into sections of 6 leds and line up each one individually. The design files for the backing plate includes some engraving to help you line up the LEDS.
Step 3: If you have the possibility, try out the leds before you glue on the top plate. You can also decide to glue the top plate later.
Step 4: connect the connection wires to the first ledstrip because you won't be able to do this later.
Step 5: glue on the top plate. Make sure it lines up with the other plates
Step 6: assemble the bottom housing. I used a L shaped rules to help me line up all at a 90° angle. Don't use to much glue! If you do, you might end up with glue on the outside of the unit and you don't want that!
The bottom plate is not glued but attached with little screws later.
Step 2: Placing the Tiles for the LEDS
I used the same glue to attach the tiles, however, I only attach 2 dots of glue on the side of the tile that goes into the backplate. One dot to the left and the other to the right.
I used a L shaped ruler to make sure the tile is place under a right angle. Also, my advise is to glue one row at a time to make sure the tiles line up. When applying glue, work in pairs of 3 or 4 because the glue hardens rather fast.
If you won't more visibility of the tiles when the leds are on, glacing them will help. 276