Powering Class D Amp through Arduino + Wave Shield
Moderators: adafruit_support_bill, adafruit

Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Tue Apr 02, 2013 8:06 am

Hello,

I am working on a project which I expect to power through a wall socket. I am using an Arduino Uno with a Wave Shield stacked on top. The Wave Shield will run through the Stereo 3.7W Class D audio amp and playback will be controlled through presses of a single button. My question is, can I use the Arduino 5v output to power the amp if it is connected to a wall socket? I found the solution to this problem if the project is to be run off of batteries, but nothing about plugging it into the 120 in the wall.

Thanks!
Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Tue Apr 02, 2013 8:14 am

I wouldn't try to power it using the on-board Arduino regulator. It is not designed for that kind of load.
But you could use something like the 5v 2A power supply to power both the Arduino and the amp : http://www.adafruit.com/products/276
You would use an adapter such as this one: http://www.adafruit.com/products/368
and connect that to the 5v and GND pins on the Arduino - as well as the VDD and GND on the amplifier.
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Tue Apr 02, 2013 8:52 am

Thank you. Just for clarification, if I power the Arduino and Wave Shield through the VIN pin (which will have to be connected to the shield due to being stacked), this shouldn't damage either device? Also, I'm assuming that powering it in this way won't adversely affect using a button wired to the 5v and ground?

Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Tue Apr 02, 2013 9:02 am

Also, doesn't the Arduino use more than 5v to operate? The power supply I currently use outputs 9v.
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Tue Apr 02, 2013 9:28 am

if I power the Arduino and Wave Shield through the VIN pin

Not the VIN pin, the 5v pin.
Also, doesn't the Arduino use more than 5v to operate? The power supply I currently use outputs 9v.

No. The on-board regulator I mentioned in my initial response regulates the 9v down to 5v to operate the Arduino. The processor and all Arduino circuitry operate on 5v.

The on-board voltage regulator is not capable of providing enough current for both the Arduino and the amplifier. But, if you have a regulated 5v supply such as the one I linked, you can bypass the on-board regulator and supply the 5v directly.
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Tue Apr 02, 2013 9:48 am

Great! Thank you very much for this information! :)

Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Sun Jul 07, 2013 1:47 pm

My project works really well, however I find that it's being overpowered by street noise. I've seen posts for other amps asking if the outputs can be bridged. Is that possible with this one? Would that give it more output power and make it louder? I'm assuming that bridging the outputs would be simple, but I'm not exactly sure which connections to bridge.

Can you offer any advice?

Thanks!
Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Sun Jul 07, 2013 3:24 pm

Yes, the outputs are bridgeable. Tie R+ to L- and can connect your speaker to R- and L+.

What kind of speakers are you using?
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Sun Jul 07, 2013 4:55 pm

Thanks! I'm assuming the input should then reflect the modified output? How does this affect the output power? I'm using a Jensen JXHD30HPC, seen here: http://www.jensenheavyduty.com/jensen-h ... eaker.html. I chose this speaker so it would last better in outdoor conditions than a standard speaker and can be easily mounted in my project. Just for kicks, the project itself can be seen here: http://strangerreductionzone.com/?page_id=157. The one shown here is installed outdoors, however the next one will be installed indoors and can use a different speaker if needed. That being said, I do need to address the problem of the outdoor one being overcome so easily by traffic noise also.

Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Mon Jul 08, 2013 7:01 am

Those are 4-ohm speakers and when bridged, the amp will see it as a 2-ohm load. The amp is rated for 3 ohm minimum, so you really shouldn't bridge the amp with these speakers.

Even bridged, you can only expect an incremental increase in sound pressure level. To raise the level above traffic noise, you should probably look into something like a car/boat/motorcycle audio amplifier.

Nice looking project by the way :D
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Thu Jul 11, 2013 5:58 pm

Thank you again for your fabulous help! I'm not very knowledgeable about electronics especially audio, so as you could tell, I needed a little guidance. Just this morning, I got two of these little amps in and I'm very pleased with the results. Now back down to Colorado Springs next week to replace some hardware and crank it up! :)

Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Thu Aug 01, 2013 10:01 pm

This amp works like a charm! I had a 12v 1amp transformer sitting around and it worked so I ordered a second one for the second installation. Since I'm no longer powering the Arduino + Wave Shield + amp with the suggested 5v 2amp transformer, can I just plug it directly into the Arduino or are the amps too high?

Thanks!
Tim

BTW, thanks for the blog post about my project! :)
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Fri Aug 02, 2013 7:21 am

Just to be clear, you want to power the Arduino & Wave Shield from the 12v supply?

Unlike the 5v supply you are using, you cannot feed 12v to the Arduino 5v pin. That would fry both boards in an instant.
You can connect 12v DC the DC power jack, or connect it to the VIN pin.

Generally I don't like running Arduinos on 12v if they have much additional circuitry attached. The voltage regulator is working pretty hard to knock that 12v down to the 5v that the processor needs, and it will get quite warm. If you do go that route, make sure the electronics enclosure is ventilated.
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering Class D Amp through Arduino + Wave Shield

by timflood04 on Fri Aug 02, 2013 1:01 pm

I'm sorry, I should have been more clear. I'm using two different power sources now, one for the amp and one for the arduino/waveshield. I'd like to use the 5v 2amp transformer I bought and plug it right into the power jack on the arduino but I want to be sure that 2 amps isn't too much for the board.

Tim
timflood04
 
Posts: 23
Joined: Mon Nov 08, 2010 4:05 pm
Location: Denver, Colorado

Re: Powering Class D Amp through Arduino + Wave Shield

by adafruit_support_bill on Fri Aug 02, 2013 2:30 pm

I'd like to use the 5v 2amp transformer I bought and plug it right into the power jack on the arduino but I want to be sure that 2 amps isn't too much for the board.

2 amps is not a problem. The Arduino will only draw what it needs.
But it won't work plugging 5v into the power jack. The power jack will accept 7-12v. (the 5v regulator on the Arduino needs at least 2v headroom to regulate).
But since it is a regulated 5v supply, you can bypass the Arduino regulator and feed 5v directly to the 5v pin.
User avatar
adafruit_support_bill
 
Posts: 31866
Joined: Sat Feb 07, 2009 10:11 am