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Topic: Combining the Ampere of two voltage regulator? (Read 4 times) previous topic - next topic

dhenry

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The gsm shield required is 1.5A.


A nice heater element.

be80be


dhenry

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Here a NPN setup


The output would fluctuate with the load.

You need 1 small signal pnp, + 2 resistors.

SirNickity

The GSM shield requires 5v @ 1.5A?  Really?

I would use an unregulated PSU for the solenoids, because there's not likely to be any good reason to worry about the exact voltage going through a coil.  Same for the relays.  As long as it's rectified and filtered to remove any serious ripple, they should be perfectly happy.  A simple transistor (and protection diodes) to fire them would suffice.

That leaves the control circuitry and the GSM module.  At a load of 1.5A, you really need to move to switching regulators.  That's way, way too much current to stick with linear.  You'll be generating a TON of heat.  That means, you're wasting quite a bit of power, and you need sufficient means to remove that heat.  Those LM78xx chips say they'll drive 1.5A, but don't even think about asking them to do it IRL.

eloso

Yes, because i will use calls too.
http://tronixstuff.wordpress.com/2011/01/19/tutorial-arduino-and-gsm-cellular-part-one/

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The GSM shield can often require up to 2A of current in short bursts - especially when turned on, reset, or initiating a call. However your Arduino board can only supply up to just under 1A. 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. Otherwise there is a very strong probability of damaging your shield and Arduino. Ignore this at your own risk. 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.


I'm using linear regulator because it is easy to make and it is only a school project. So i will only use it once. I already have a big heatsink and thermal paste so generating heat is not a problem.

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