AGC Help (Please)

Hi All,

I Need some input. I am working on a Visual EQ. I have a thread going here. ATTiny2313 Pin help - Programming Questions - Arduino Forum But I am now stuck. I am trying to incorporate a AGC circuit so the LEDs don't max out when the MP3 player is at high volume.

My plan is to split the Left and Right channels two ways. L/R to the AGC and L/R to a LM1036 amp with V/B/T control.

The Issue I am having is finding a AGC that will fit my needs. As I am still learning I not sure what AGC circuit would work best. I also have no clue how to test the output of my MP3 player so I will be able to figure out the best sustained Gain. I hope I am saying all this right.

Well I found this Mic Preamp with AGC, but as I intend to use and Audio Jack I am not sure if it will work. Any input will be welcome.

Thanks

The Issue I am having is finding a AGC that will fit my needs. As I am still learning I not sure what AGC circuit would work best. I also have no clue how to test the output of my MP3 player so I will be able to figure out the best sustained Gain. I hope I am saying all this right.
Well I found this Mic Preamp with AGC, but as I intend to use and Audio Jack I am not sure if it will work.

You have described very little about your needs, specifically what does the output of the AGC PREAMP drive? Headphones, another pre-amp/amp, etc. What I do know is, " I intend to use and Audio Jack" and this represents approximately a 32 Ohm impedance per channel. Line inputs/outputs are around 600 Ohm nominally. So your design/purchase will need to deal with this electrical characteristics.

Building a generic AGC is not too difficult, the Internet has examples... Such as:
http://www.wiringcircuit.com/audio/Automatic_Gain_Control_Pre_Amplifier_Circuit_Diagram_1528.html

I'm sure that your MP3 player has some AGC already... Maybe your recorded MP3's are in need of amplitude leveling - especially if they are DVD rips. There is free software that will take and amplitude adjust your original music file.

Personally, I would find an audio/electronic forum to quiz about AGC builds.

Ray

Sorry for the limited info. I will elaborate .

I am making a Visual Eq ( Light organ). I am trying to keep the Led’s from Maxing out when the volume is set to high.

I am using a atTiny 84 and MSGEQ7. Because I am new to all this and I am not familiar with the terminology I may of missed spoke.

I may be looking for a gain limiter.

AGC using an LED and photocell as a gain control element. If you wish to turn down the gain for a Line Level input, increase the 12k resistor on the left.

http://www.techlib.com/electronics/audio.htm

AGC using a 2N7000 as a variable attenuator, however the incoming signal must be small enough not to turn on the intrinsic body diode parameters. Just mentioning that in case you use this circuit and modify it.

Thanks for the post. Ill give it a go.