Sub Micro (Spy) Blimp Building with Hacked Servos

 by masynmachien
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Step 3: Hacking the servos

To hack each of the three servo’s start by removing stickers and the small band of shrink tubing holding it together. Remove the top part and remove all of the gears, including the pinion (if your propellers do not match the motor shaft, you can alternatively keep on the pinion and drill out the propeller to fit that). Remove the bottom part and carefully pull out the motor and pot. The motor most often comes out easy, the pot is glued in. Most often you can still pull it out by moderately pulling on the wires. I you feel unsure you can alternatively break open what is left of the servo casing, with small pliers.

Protect the circuit board from accidental short circuiting by wrapping a single layer of tape around it.
Test by connecting to the receiver with the propellers left off. Power up and trim each pot till the motor doesn’t move with the transmitter’s corresponding stick at neutral position.

Choose which motor/function you want on what stick. I usually put the up/down on what is normally the “throttle” (because a stick without auto centering is convenient here), the main propulsion on the “elevator” and the left/right on the “ailerons” (on a mode 2 transmitter).
 
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TheGreatO says: Jan 14, 2012. 9:25 AM
Great instructable! I'm slightly confused though, which is probably due to my lack of knowledge about servos, when hacking the servo, do you literally just take out all the gears so that you're left with the motor and potentiometer, and then attach the input to the servo to the throttle output of the receiver, adjusting the potentiometer to get the trim right?
Thanks
masynmachien (author) in reply to TheGreatOJan 15, 2012. 9:49 AM
Thanks!

You're close. Indeed, you take out all the gears and keep the motor and the potentiometer AND the servo electronics. The latter serves as reversible throttle output (with the potentiometer determining the middle zero throttle point). The servo's original lead is attached to any channel output of the receiver, just as a normal servo.

Some receivers have built in speed control, which you could call a direct throttle output. That is not used in this concept. It is used in the alternative shown in step 7, but then a motor (possibly also from a servo, but without the potentiometer and without the electronics) is connected to that output directly.
TheGreatO in reply to masynmachienJan 15, 2012. 12:06 PM
Ah! thus eliminating the need for ESC, that is simply genius :)
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