Hello, I'm planning to use diodes to drop down some voltage. It's in a tiny RC airplane. I got some super duper teeny tiny servos which I realized too late are made for a single lipo cell around 4V. The planes speed controller is for a 2 cell lipo pack for the motor, and a regulated 5V output for the electronics...so a diode or two should drop .6 to 1.2V off the 5V if my memory serves me correctly.
Here's where my limited knowledge stalls...I got a 5v Radio Shack diode (I wasn't sure if I should have gotten the 12v diode?) and alligator clipped it into the positive lead to a tiny motor and connected to 8.4v source to see which way it was biased. I ran fast in one direction and slow in another...but shouldn't it have not run at all in one direction? I seem to remember if a diode gets too much reverse voltage it would open up and allow flow? Is this what is happening with the higher voltage source?
The voltage drop across the diode was 5v, and across the motor 3V while motor spinning slower. So I assume it was wired backwards? Then I realized that I was using a full 8.4v instead of 5v, so now wondering what would happen if I kept it wired the same, would it not work at all if not over-voltaged?
So long story short, given the 5v source with a 3-4V servo, am I correct in assuming two "proper" diodes in series in the proper polarity would drop the voltage down to proper range? Secondly, would the "proper" diode be a 5v or 12v?
Sorry if it sounds confusing, but to those smart folks here, I'm the dumb azz.
Edited... here's the servo in question: http://www.hobbyking.com/hobbyking/s...c_0_075kg.html