sound to light

C

craig008

New Member
I am looking at making a divice that picks up sound and than convertes to a lights output, ie through a pwm, i am guesing it will be hvae to work from a ADC input, any ideas on what sort of programme, and the best PICAXE to use, i would have thought that a 08m would be enough to do the job, but not sure, also some circuit ideas if any body has done this before.

my first idea was a mic passed through band pass filter into the ADC and then the pwm = the adc, seems pretty sound (get it pretty SOUND!!).
________
Ladder Day Saints - Mormonism Advice
 
Last edited:
B

BeanieBots

Moderator
Reading these two threads would be a good start:-
http://www.picaxeforum.co.uk/showthread.php?t=7990
http://www.picaxeforum.co.uk/showthread.php?t=7989

Essentially, you just need to select the frequency of interest for each channel of your sound to light.
Filter that frequency, rectify and smooth to DC, read with ReadADC and turn on output accordingly.
Unless you will be using a fixed volume, you will also want auto level control. There are chips that will do that for you but it is quite easy to do yourself.
Op-amp circuit with FET in feedback path. Output of op-amp controls FET gate, FET is lower part of potential divider on input level.
Works quite well with just one master agc (automatic gain control) but might be better with one on each channel. Then you would not need to worry about getting the gain of each channel spot on.

Or use google. There are countless sound to light circuits out there.
 
C

craig008

New Member
i was no going to worry about 2 channels, just on, if i were to do every chaneel coming ou of my pc it would be a rather large and complex affair for 7.1 audio, one chanel is enough at the mo

i found an op amp circuit for 100hz cut of, different to what yu were suggesting it has no FET and only uses 2 capacitors and 2 resistors, hooked up to an lm102. the lm102 no longer seems to be availible not even the data sheet, but i have found what should replace - hopefully a ne5532 which does leave the scope for 2 channels as well if required
________
Daihatsu fellow max history
 
Last edited:
B

BeanieBots

Moderator
By 'channels' I was referring to frequency. ie bass, mid & top or more if wanted. That's what most commercial units have.
Just about any op-amp will be fine but I do strongly suggest an agc circuit. Without it, the smallest variation on your volume control will result in either fully on or off. Even the difference in recording level could produce such a result. You'll spend so much time manually adjusting the levels that people will think it's you turning the lights on and off rather than the music!
 
C

craig008

New Member
have not come across one of those, cant find one in my recources either, or even wht they do, gonna have a look on google to see what i can find out
________
How to roll joints
 
Last edited:
D

Dippy

Moderator
If BB's suggestion for op-amp+FET for AGC is too difficult I would suggest the SSM2167 from Analog Devices for the AGC. It is superb but SMD only so may be fiddly. And i is specifically for companding signls from a mic.
From the SSM2167 you could have a simple op/amp buffer/filter then rectifier to the PICAXE ADC.

Get some info on op-amp techniques for filtering and amplification, then you'd understand what BB was on about for making your own AGC.
I've got an ancient book called Practical Electronic Filters by Owen Bishop from the Babani publishers. Shows all sorts of filtering techniques.

But I guess you want someone to post a circuit for you?
 
C

craig008

New Member
no now owrries about the circuit have been finding loads of stuff on AGC from google, but one of the first circuits i cam across was transistor driven, no op am in sight but it did have alot of extra components
________
Ferrari F355
 
Last edited:
B

BeanieBots

Moderator
Op-amp is not essential, just easier. It's no different to, for example, if you just wanted a single NAND gate. Single tranny, two diodes and a few resistors makes a NAND gate. An analog amplifier is quite simple too but using op-amps saves having to do lots of maths. I use them for most things because I'm lazy.;) Most engineers are. They will spend hours trying to save a few minutes:eek:
 
You must log in or register to reply here.
Top