Audio Amp

ryester1120

Is there any way to amplify and audio signal with the SX chip, like an 386 audio amp chip does?

PJAllen

If you're asking whether an SX can be configured as an audio amplifier, then the answer is... sorry, no it cannot.

ryester1120

Why can't u configure the SX chip to an audio amp

Mike Green

Mostly because it's designed for use with digital information.· It's also not designed to produce significant amounts of power.· The whole internal design would have to be different.

The input and output transistors are optimized for digital use with only two states possible, high and low.· The input transistors can be forced to work in their "linear range", but they tend to waste a lot of power and the subsequent stages will force the signal into a digital state (high or low).· The output transistors are similarly designed for just two states and they're not large enough physically to handle more than about 20-30mA of current.· With a 5V supply, that's only 100mW or so.· You can't use much more than 5V since that will destroy the chip.



Post Edited (Mike Green) : 4/8/2008 1:27:42 AM GMT

Bean

You could probably use the comparitor to increase the voltage of the audio signal, but as mentioned the SX pins are not designed to output large amounts of current.

Bean.

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ryester1120

Ok does any one know how to make a good and small audio amp so I can add it to a sound level detector?

PJAllen

The LM386 you mentioned is good and small.·

How much better and/or smaller do you figure you need?

ryester1120

I have tried the LM 386 but can't find good schematics that work

PJAllen

Let's dispense with generalities and get into specifics.

The schematics / circuits·provided with the datasheet are plenty good.· Have you had a look at those?· What's the trouble?· What are you trying to amplify?·

Post Edit --

Maybe this should be continued over·at The Sandbox (What About the LM386?) instead.· This one is a blaster:



Post Edited (PJ Allen) : 4/8/2008 2:14:49 AM GMT

RobotWorkshop

The original question may not be phrased to match what you are really looking for. From your other post I would guess that you may want to connect a microphone to your SX28 chip so that you can perhaps get a reading of ambient sound levels so you can use that with your LED cube project. Is that what you are after? You should be able to use the LM386 for that purpose but the input will be the Microphone and the output will be the input for your ADC.

If so, then you'll want to look at Microphone amplifier circuits that will amplify the Microphones signal so it can generate a voltage within a 0-5V for use with either the ADC on the SX chip or by using an external ADC chip like the ADC0831 which the SX chip can read. That will turn the sound level to a number 0-255 which you can use for your display.

Robert

JonnyMac

Perhaps the attached schematic will help. I used a variation on a circuit in the book "Physical Computing" to condition audio input from a microphone or MP3 player into the SX. In a way, the circuit is like a VU meter: the louder the audio, the bigger the graph (which is laid out in the shape of a smile on the mask). This project was for a local special FX company.

Post Edited (JonnyMac) : 4/8/2008 7:01:24 PM GMT