Wouter van Ooijen wrote:

>Shorting a modest current (a few Amps) will not produce much heat (zero
>ohms = no voltage = no power). If you would instead connect a small
>resistor (both physically small and small resistance) things will likely
>be different.
>
>
>
While the diode doesn't have an 'ohm' measurement, it still drops
voltage, and therefore consumes power.

A typical diode with a forward drop of 1.1V when drawing 1A will
dissipate 1.1W of power.  The 1n4004 has this voltage drop and is rated,
when properly mounted, to withstand 3W of current.  So it won't get very
hot very quickly.


However, on a PC power supply which can supply over 30A at 5V you'll be
dissipating 33W - Please note that most cheap soldering irons are only
15 and 20 Watts.

When combined with a current limited powersupply this is certianly a
good solution to an all too typical problem.

-Adam

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