That's the problem, the little aluminum box. The power connector is 
through the box wall, and the wall wart just plugs in. I need to keep 
the heat inside the box to a minimum, and mounting anything outside the 
box like a resistor is not possible. I'm trying to keep this as simple 
as possible, and where relatively untrained people (family) can do 
something like change out a board or wall wort.

Bob Axtell wrote:
> Carl Denk wrote:
>   
>> subject=Re:[EE:] - Heat sink??
>> source= http://www.piclist.com/piclist/2006/11/23/121602a.txt?
>>
>> ---
>>
>> http://www.piclist.com/member/cdenk-alltel-
>> PIC/PICList FAQ: http://www.piclist.com
>>
>> Here's the latest on this thread:
>> Found some switching 5 volt wall warts that actually under my load are 
>> more like 5.4 volts actual. The PIC 18F1320 has 5.5 volt max. input, but 
>> the pressure sensors have a 5.2 volt max. Think I'll return the 5 volt 
>> wall warts to Digikey, and order a 6 volt switching or linear wall wart, 
>> and change the on board regulator from 7805 to a LDO LM2930T. The board 
>> is going to fabrication (quantity 3 or 4 to include spares to last a 
>> long time) with space for the TO3 regulator and a wire hole for direct 5 
>> volt.
>>
>> Comments always appreciated. :)
>>   
>>     
> Why not just increase the load, using an external 25 ohm resistor would 
> give you a constant 200mA
> load and would probably make the  wall wart switcher  fall into 5.0v 
> range. There would be some heat, but
> would be only (P=I*V; P=.2*5) or  1 watt.
>
> --Bob
>
>   
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