I am using a regulator to regulate 12v to 3.3v for my digital camera.
The regulator is rated to 1.5A, however the DC adapter for the cam is rated for 2A. I was just wondering if you can exceed the current limit for short periods such as taking photos because i dont think the camera will draw much current while idle.

Also what happens when you burn out a regulator? Say i drew too much current and it burnt out, can the input power short?

 

You are playing a very dangerous game. In some conditions your cam must be fed with a higher current than 1,5A. For ex. when you use the FLASH. Then the power supply (PS) of 1,5A is overloaded. If the PS has an overload protection build inside, then it will cut off the current. In this case the cam can't work correctly or it switching off. Without overload protection the PS can be burned down. The destroyed PS can supply the cam with a higher voltage then 3.3V, and the cam can burned down too. What type of regulator do you use?

 

The whole point of this is for aerial photography. The cam will be mounted on an RC plane so there will be no need for flash or even the LCD if i can get it to disable. The regulator is LM1086CT-3.3

 

:!: The LM1086CT-3.3 regulator has current limiting and thermal protection. So you can't destroy it. The drop voltage in your circuit is 12-3,3=8,7V. The maximum power dissipation is 8,7Vx1,5A=13,05W. In other words the regulator needs a good thermal cooler.

 

i don't expect your RC plain will carry car battery or pack of them.
any small 12V source will not last very long if load draws 1.5-2A
why an't you use pair of large 1.5V batteries? is there anything else
that needs to be powered by 12V (maybe the plain onboard radio
and servos) and how much current does it need?
btw. power supplies for cameras and similar devices are often
oversized so that they can be used while the built in battery is charged.
there are also very simple circuits using external transistor to increase
current capacity of the voltage regulator. personally i would be looking
into switching regulators to reduce heat and get longer battery life.

 

Weight is the key to this application therefore AA batterys are out of the question. The plane is powered by a 12v (11.1v) lithium polymer battery which can handle up to 12A constant current and 18A burst for 10 seconds i think.
Providing the cam only draws the large current when taking shots it should be ok? Im assuming the current draw will be small for most of the time while not taking pictures so the regulator shouldnt have to get rid of much heat?

 

Like Edmond said, the Regulator has built in over current protection, so if you try to draw too much current, (say the camera does need 2 amps to take pictures) it would shut itself down and you would possibly lose power to the camera.

Chances are, the 2 amp powersupply is sightly higher than what is needed, so you may be ok.

on the heat subject, any heat disappated by the V-reg is power lost from the batteries which means shorter battery life. If your flight time is very dependent on your battery life (you cant fly as long because your batteries run out, then you should look into a switching regulator

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Jeff
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