Hi everyone!!

This is my situation:

I have servos of the following makes:

1. Yeah Racing 2.2kgf-cm and 3.2kgf-cm torques
2. Vegakit 1.2kgf-cm, 3.2kgf-cm, 5kgf-cm torques

The circuit:

I use the port 2 for this. I use pin 2.1 to give the signal to the servo motor.

The voltage to the motor is given from a 5V lead acid battery, with a max rating of 1 Amp. As servos need no drivers, this is fine. The GND line is connected to ground

The code is written to generate a non stop waveform with a time period of 20ms and duty cycle of 1.5/20



The observations:

The circuit works for 1.2kgf-cm, 2.2kgf-cm motors of both makes. The motors respond well to the signal and rotate to the desired angle

But, the circuit doesnt work for 3.2kgf-cm and above. They jerk a bit, showing that the motor received the reqd power supply. But the signal is not getting the motor to work, for some reason.

I've seen servo controller circuits which use pull-up resistors for their signal pins, but I dont know why. I see no need for it as my setup ( without the pull-up ) worked well for 1.2kgf-cm and 2.2kgf-cm


The question:

I'm totally perplexed by this behaviour of the servo motor and request u people to help me out. I dont know why things are happening the way they are happening.

I hope I cleared the situation. Please let me know if u desire anything else from me!

- Hari