Sometimes, a little knowledge is a dangerous thing.
I know this one fella who knows a little something about electronics. When I say "a little something," I mean that he knows certain basics, but he fails to grasp a lot of the fundamental principles of electronic design. Now, I won't claim to be an electronics master; indeed, my practical skills could use some work. Still, I think there's a difference between needing to improve one's skills and failing to grasp fundamental principles.
For example, I once had to regulate the intensity output of a bank of LEDs. As LEDs warm up, they tend to draw more current, which in turn changes their intensity output and their color spectrum. This can be a problem if you want to use LEDs to achieve even, consistent illumination.
So I decided to build a current source -- that is, a device that would hold the current level more-or-less consistent. When I told this guy of my approach, he said, "Why bother? Just put a resistor in series with the LEDs."
I said, "No, that won't work. The resistor won't regulate the amount of current, except insofar as it will keep the current draw lower. It's a primitive approach. Besides, we don't want to reduce the amount of current! We need to keep the intensity level high, and adding a resistor will have the opposite effect."
"But you're not using any feedback!" he said. "You need to add a thermal sensor of some sort, so that when the LEDs heat up, you can reduce the amount of current!"
"Of course I'm using feedback" I replied. "That's exactly what a current source does. As it senses a change in current draw, it adjusts its voltage output to counteract this change."
"But you need to sense the temperature!" he said.
"No, you don't" I replied. "The temperature is significant insofar as it affects the amount of current that is drawn. It makes more sense to regulate the current directly; after all, that is what affects the light output."
As I said, a little knowledge can be a dangerous thing. It's dangerous when you don't have a decent grasp of the fundamentals.