The Diode, are they mostly use for safety nets?

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RyanD

Joined Jan 14, 2010
30
Most of the circuits I've been studying to learn from have diodes for two reasons. The first(most common) is to make sure current doesn't flow the wrong way and break something. The second is to drop the voltage a little(why not just use a resistor?) So, are these the main reasons to use one, are diodes necessary or just a safety precaution?
 

VoodooMojo

Joined Nov 28, 2009
495
also used for polarity protection and coil suppression.

see attached for considerations of using diode as coil suppression.
a resistor can work as well.
 

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jpanhalt

Joined Jan 18, 2008
7,697
The second is to drop the voltage a little(why not just use a resistor?)
The voltage drop across a resistor is directly proportional to the current. The drop across a diode is not and is much less affected by the current. See this graph from the 1N4148 datasheet:



John
 

Bernard

Joined Aug 7, 2008
5,228
Most usage is for one way current control, power rectfication, reverse polarity protection, implementing diode OR gates & other uses that I can not think of.
 

Wendy

Joined Mar 24, 2008
21,840
Not just OR gates, they also make AND gates.

I regularly use diodes as voltage references, similar to zeners. They are relatively stable, other than temperature. They are predictable enough to be used as temperature sensors.
 
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