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[on:]

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

[Reply #1 on:]

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

[Reply #2 on:]

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

 Lefty

[Reply #3 on:]

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

[Reply #4 on:]

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.

[Reply #5 on:]

https://www.sparkfun.com/products/10613?  $1.50

[Reply #6 on:]

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.

[Reply #7 on:]

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

[Reply #8 on:]

I think the 10K version will be fine.

Let me know if you find one in Scandinavia.

[Reply #9 on:]

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

[Reply #10 on:]

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

[Reply #11 on:]

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

[Reply #12 on:]

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.

[Reply #13 on:]

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

Thank you very much for the help!
Patrick