|Home > Circuits > Light/Laser > 3 Channel Spectrum Analyzer|
This 3 channel 15 LED spectrum analyzer is the perfect addition to any audio amp project. It produces fantastic displays on three LED bars that can be individually adjusted for any particular frequency range. The circuit will take line level output from most any audio source, and operates on 12V DC. This means that it can even be run in a car.
|Add A Comment|
|I appreciate all of the work that went into this; could I take out the led drivers without messing with the rest of the circuit? Also, what is the value for capacitor18?|
|Hello peoples, I was wandering if this circuit would work well with LM3915 instead of AN6884. I think it would be neat to have 10 LEDs per channel.|
|Error in my last message-- I did not meant LM3900 but those led drivers. @Audioguru: About LM3900, that can be replaced with any quad (or single op-amp). About rare led drivers concern is the same thing -- whichever comparator or opamp will do in this schematic. there are possible to make with widely available components. When replacing OP amps, just pinouts needs to be checked. And LED Drivers... its easy to convert it for opamps/comparators (in that case couple ref-level resistors needs to be added only).|
|Nice. instead of LM3900 can be any cheap quad op-amp or also quad comparator in this schematic (though with some minor modifications in schematic - resistors for ref levels).|
|can i add another 2 channels for this project to make it 5 channels? how to do it?|
|can i add one led on each ouput from AN6884 ? so it will be 2x5 LED in each collum is it posssible ? thanks|
|I found this reading the forum.. FROM: audioguru Posted - Jan 02 2011 : 10:18:10 PM If you add more frequency bands then you need to re-calculate the bandwidth of the existing bands to make them narrower. The "multiple feedback bandpass filter" design is in Google but uses a "normal" quad opamp instead of the weird LM3900. C18 is simply a supply bypass capacitor. Its value depends on how much ripple is on your power supply voltage. If your power supply already has a big filter capacitor or you are using a 12V battery then C18 can be from 10uF to 100uF. I think the CanaKit is the same circuit.|
|What is the value of C18? --Thanks|
|hey i got two question...im noob at this but, how do you connect audio input to this????? and what is the value of C18?? i really want to know how to add input though, like an aux cable from an ipod, or something like that.|
|firstly, thanks for this useful circuit. i saw its schematic but there is not value of the c18. i think it might be between 100-1000 microfarads|
|I will believe it works when I will try|
|where can I get a board to make a 10 LED analizer?|
|Good. The errors are fixed. Nobody said they were fixed. It is too bad it still uses the obsolete LM3900 quad Norton amp. The Japanese LED drivers are hard to find.|
|You said " ...It produces fantastic displays on three LED bars that can be individually adjusted for any particular frequency range " I would be interested to make it for 16, 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000 and 16000 Hz (ref. http://zone.ni.com/devzone/cda/tut/p/id/101 ) by adding 8 more lines but the problem here is to calculate those new values. My question is could you make one of these and post it here? I am deeply interested. Thank you.|
|i like your analysis but theres a something wrong to your design...|
|Your Schematic for this circuit is not correct. You do not have Pin 5 of the Bar Graph IC's grounded in any way, as it should be. Instead you have the output of the center amp stage connected to all of the Pin 5's that SHOULD BE GROUNDED. You have pin 8 ( The Input ) of the center Bar Graph IC grounded, and it should clearly be connected to the output of the center stage amp. You also have Vcc connected to the Bar graph IC thru a resistor, and no current limiting resistor for the LED's, as the LED's are connected directly to Vcc. Vcc should go directly to pin 9, and the resistor's (26,28 & 30) should be used as a current limit for the LED's from Vcc to the LED banks. With the circuit as it is shown, the bar graph part will not work. Without having hooked the amp part up, I do not know if there are mistakes there also or not. Hope this helps those that may be trying to make this circuit work..
(Editor's notes: I'll fix the diagram next time I update the site.)
|is there any pcb? Oscar, Chile|
|l like the analysis|
|thank u very much for all this good crt and all the website memeber thank u|
|All comments are being shown. Show Only Last 10 Comments.||Add A Comment|
If you would like to leave a comment, you can do so using the form below. Comments can be things like suggestions, successes or failures, improvements, similar circuits, error reports, an answer to a previous commenter's question, or anything in between. However if you would like to ask a question it is suggested that you use the forum instead. The forum provides a more robust environment for discussion.
Important: If you post a technical question here, there is no guarantee it will be answered. All technical questions should be posted to the forum. The owner of this site generally does not answer questions in comments.
All comments are subject to approval before they are displayed here, so your comment will not appear immediately. This is done mainly to prevent spam and other abuse. If you wish to remain anonymous, simply enter "anonymous" for your name and/or email.
Back To Circuits Page | Mail Me | Search