Wave Shield Power

Adafruit Ethernet, Motor, Proto, Wave, Datalogger, GPS Shields - etc!

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VrIgHtEr
 
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Wave Shield Power

Post by VrIgHtEr »

I'm using an arduino uno r3, with the wave shield and the nfc shield.

Power consumption details of the wave shield are close to non existent.

If I connect an 8 ohm speaker to the wave shield, will the arduino be overloaded? (it has to power itself, the wave shield and the nfc shield) or do I have to make an external 5v supply for the wave shield?

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adafruit_support_bill
 
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Re: Wave Shield Power

Post by adafruit_support_bill »

You left out the most important piece of information. How are you powering the Arduino?

VrIgHtEr
 
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Re: Wave Shield Power

Post by VrIgHtEr »

12v lead acid battery (I know it seems overkill, but other, unrelated, stuff is powered by the same battery as well)

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Re: Wave Shield Power

Post by adafruit_support_bill »

The on-board regulator on the Arduino is a linear regulator, so with a 12v source, it is only about 40% efficient and the rest will be dissipated as heat. The Arduino specs say it can be run with a 7-12v DC source, but they don't warn you about external loads when using higher supply voltages.

With both a wave shield and an NFC shield, that regulator will be in danger of overload. Since the 12v SLA is your primary supply, I'd suggest something like a UBEC: http://www.adafruit.com/index.php?main_ ... rch&q=ubec

The UBEC is a switching regulator and are much more efficient than the linear regulator on the Arduino. Since the output of the UBEC is regulated 5v, you can use it to directly power the 5v pin on the Arduino. (Don't connect it to the DC jack - that goes through the on-board regulator which needs 7v minimum to work.)

VrIgHtEr
 
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Re: Wave Shield Power

Post by VrIgHtEr »

Yeah I'm aware of that. In fact, I did build a separate power supply for my Arduino in other projects. What I'd really like to know is how much power the wave shield uses. I simply can't feel confident in the system as it is. Information about this is sketchy at best. I don't think I'd have to measure the current of each component separately. Isn't stuff like this supposed to be specified?

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Re: Wave Shield Power

Post by adafruit_support_bill »

What I'd really like to know is how much power the wave shield uses.
The power consumption of the output stage depends on the recording level of the source material, your volume setting and what kind of load you connect it to. Maximum theoretical output capability is discussed in the design notes: http://learn.adafruit.com/adafruit-wave ... ino/design
The analog signal then goes into a high-output, rail-to-rail opamp. This op-amp can provide up to 100mA per channel. The two channels are hooked up in parallel for up to 200mA output (at 5V). This means it can provide 1/8 W into an 8ohm speaker (or 1/4 W into 4ohm speaker)
The power consumption of the SD card reader depends on what kind of SD card you plug into it and what you do with it. Card current loads vary between manufacturers and card-types. I have seen 'max' ratings ranging from 40 to 200mA. The peak currents are typically seen during a write operation. Read operations will draw less current.

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Re: Wave Shield Power

Post by VrIgHtEr »

Thanks a lot for your quick reply. It cleared things up for me. I must have missed that bit

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