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Topic: Arduino controlled Amplifier - I need ideas! (Read 2074 times) previous topic - next topic

hansibull

Hi!
I'm making an arduino controlled amplifer. The amplifer itself is a TDA7294 with a lowpass filter, so I can use it on my subwoofer.
I've implemented a IR remote control sensor, so I can turn it on and off, and I have hooked up an LM35dz temprature sensor to measure the temp.
if the temp is going abobe 55 C', a fan is turned on with a relay cooling down the heatsink if the temp is above 85 'C, the arduino turn the amplifier completly off until the amplifier have become cooler.

I still got a lot of IO pins left, and alsoa lot of space on the atmega328p, so my question is; do you guys have some ideas that I can imlement into this project? It was a great experience creating it's code, and I want to continue to add some more functions :)

Magician

- VU meter;
- volume control;
- "clipping" indicator;
- compressor;

retrolefty

Well perhaps a programmable pot controlled by the arduino would act like a bass control for your sub-woofer.

Lefty

hansibull

I've been thinking about volume control. How do I control the  volume with an arduino without using a motorized potmeter?

perhof

There are digital potentionemeters (IC:s) that you can use for volume control.
Unfortunately most digital potentiometers that I've seen have been quite expensive.

If someone can recommend a cheap one I'm interested.


perhof

Right, I forgot about that one. That price is good.
Last time I searched for digipots I looked at that one and a couple of other cheap models but I couldn't find any of them at any distributors in Sweden.
The models that did exist here were much more expensive.

hansibull

Great! I will check out the MCP4131! But for volume control, should I buy the 10K version or the 100K version?
I've also been looking at the ds1802, but with shipping to norway, that's about 26$, which is way too much for a single IC

perhof

I think the 10K version will be fine.

Let me know if you find one in Scandinavia.

patricka

Hello,

Sorry to jump in into that conversation... I'm fairly new in Arduino and electronic, so pardon me for that silly question...

My idea is to pilot the volume of a small audio amplifier with the Arduino. If I get an audio amplifier kit that uses a physical pot and I replace it by a digital pot with the same value, should it work as is? (I mean without modifying anything else in the original kit)

Thank you for the help...
Patrick

Magician

In 99% yes, if kits designer  follows common practice. To be sure, post a link to schematics of the kit.

patricka

Thank you for replying.

Kits such as these ones:
http://www.sparkfun.com/products/9612
http://www.sparkfun.com/products/11382
or (without schematics) http://www.dfrobot.com/index.php?route=product/product&product_id=165#.UPnJ7K6d58E



Magician

Mechanical pot shown in the first link has 3 leads, 1-st to input, 2-nd ground and 3-rd (wiper) to PA IC. The only difference when you replacing it with digital one, you ' d need DC offset about 2.5 V.
I'd connect PxA to input, PxW (wiper) to PA IC - similar to mechanical , only PxB instead of ground to +3.3V on board arduino (UNO or any other 5V version).
http://www.maximintegrated.com/app-notes/index.mvp/id/1828    Figure 5 or 9.

patricka

I will get all stuff needed (kit and pot) and definitely test it.

Thank you very much for the help!
Patrick

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