Here is a schematics of "GlueMotor Cable":
Note: C1 and C2 are not necessary for iOS devices (iPhone, iPad, iPod touch), but to avoid the risk of damaging your iOS device (most likely not, but), you should put them.
Q: What servo motor do you use at Maker Faire Bay Area 2012?
A: Futaba S3003. I bought from TowerHobbies.com Futaba S3003 Standard Servo Motor ($10.99). Also I use Parallax (Futaba) Standard Servo ($12.99).
Q: I built my own GlueMotor Cable, it works but only control +-45 degrees (total 90degrees). Why?
A: Current version 1.1.0 of GlueMotor app only generate 50Hz 1.5ms+-0.5ms PWM pulse because this is a standard specification (I guess, I could not find any official specs but several web site mention that) of the servo control signal, and I do not want GlueMotor to damage your servos with out-of-specs PWM (some miniature servos are very easily damaged in angle limiter, and causing potentiometer gets damaged). I am going to add a feature to adjust the pulse range (minimum & maximum width) so you can adjust it per servo.
Q: Did you say GlueMotor Cable works with any analog servo motors?
A: Ah, did I say that? Actually, It works with any analog servo motors that I have so far. I will put a list of servo motors that I have tried with GlueMotor cable soon.
Q: Hey! You are lier! I made a GlueMotor Cable exactly same as your schematics, but does not work with my Android Phone!
A: It is possible. Unfortunately some Android device cannot generate enough signal level to control the servos. In that case, you need to bias the input after C1 & C2. I will put modified schematics soon.
Q: I am using Android phone. How come there is a delay between swiping gesture and rotation of the servo? Are you intensionally make Android version slower than iOS version??
A: No no! I was trying to reduce the delay on Android, but so far no luck. If you know how, please let me know!
Q: Why do you hide your source code in your hard drive? I don't believe any "Not Open Source" apps.
A: I will publish the source code once I clean up the code :-)