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Topic: A few questions about supplying 5V, 2 amps for SM5100B GSM module (Read 1 time) previous topic - next topic

tobek

Hi everyone - I'm using an SM5100B cellular shield (http://www.sparkfun.com/products/9607) for Arduino. The module apparently can draw up to 2 amps or even 2.5. However, I'm fairly new to electronics, so I'm not sure what the best way is to achieve this.

From one tutorial (http://tronixstuff.wordpress.com/2011/01/19/tutorial-arduino-and-gsm-cellular-part-one/):
Quote
It is highly recommended that you use an external 5V power supply capable of delivering 2A of current – from an AC adaptor, large battery with power regulator, etc. ... When connecting this supply DO NOT use the DC socket on the Arduino. Instead, connect the 5V (positive) from the supply to the 5V pin on the GSM shield, and the negative to the GND pin.


Here are my questions:

  • Why not supply this power from the DC socket?

  • What is a good rechargeable and portable power source for this? I read somewhere that a regular 9V battery won't cut it because the voltage will drop quickly. Is this the case? Not to mention the fact that I imagine a 9V battery can't supply 2 amps.

  • Any recommendations on an AC adapter that would do the trick? I'm not sure where to begin.

  • Is it correct that I can use something other than a regulated 5V power supply as long as I connect it to the VIN pin instead of the 5V pin?



There are likely some other things I'm missing, so I welcome any thoughts on this.

Thanks a lot.

CrossRoads

1. 5V regulator is only good for 800mA, not 2 to 2.5A.  That must be external.
2. Big ass LiPo battery pack & 5V switching regulator. How big depends on how long you want to draw 2A for.
3. www.mpja.com has 5V, 4A walwarts for $6-7.  http://www.mpja.com/5VDC-4A-Regulated-Plug-Supply-Openpeak/productinfo/18520+PS/
4. Yes. Not for 2A tho. That must still be external.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

MarkT

Question 2: 4 x high-spec NiMH AA cells.  Must be NiMH (which are about 1.3V each, so provide around 5.2V or so).  Beware cheap brands of NiMH that won't be happy with the high current.
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MarkT

Actually that shield takes its power from Vin by the look of it, so it will need more like 6.5 to 7V in order that the Arduino gets enough volts on Vin...  Alternatively I think you could common Arduino's 5V and Vin busses and power from 5.2V batteries.

The good news is the 2A peaks are only a small percentage of the time (a GSM transmit slot) so the average power isn't too large.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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