This spectrum analyzer uses character LCD and two ADC inputs of Atmega 328.
Microcontroller converts analog signal to digital and calculates FFT. Data is displayed in vertical bars on character LCD. VU meter is planned as a horizontal bar. External connections - Your audio source and optional auxilarry controller to connect the device to Your own hardware.
Details
Main features:
Selectable frequencies of spectrum to display (512 possible frequencies)
I soldered all the parts. The layout of the board is terrible but it works.
Some notes:
LCD connector is soldered upside down due one-sided PCB. The final version will be soldered on another side of the PCB.
Trimmers are placed randomly. Not easy to find which does what. Too many trimmers and jumpers. I plan to simplify the input filters and reduce the number of these jump&trim.
Optional (and different) connectors for audio input (e.g. 3.5mm socket) and power (e.g. small screw terminal block) would be convenient.
Bad footprint of power connector.
USB->serial chip on board (e.g. PL2303) would help with the external connection
So, looks like a list of several small improvements for the next version of the PCB :)
Thanks for reply. Yes that's the way I route these jumpers. I was just wondering how to name them - "jumpers", "wire jumpers"? When I hear "jumpers" the first thing that comes to mind is these jumpers:
http://ecx.images-amazon.com/images/I/41gGJ8BjOfL._SY300_.jpg
http://ecx.images-amazon.com/images/I/41gGJ8BjOfL._SY300_.jpg