Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: StAnkys on May 20, 2009, 11:15:55 AM
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I want to use a high-torque servo to "pull" the cable to apply a manual brake. I have a DC signal that varies in level depending on input to it.
Most servos require a ~2ms square wave AC signal to apply constant maximum torque. How can I apply this torque with just my DC signal?
Ideally I want:
(small 0-2.5V DC signal) --> if it exceeds 2V, trigger relay to allow 5V higher amperage DC current to power servo --> pull cable to apply mechanical brake
What I need help with:
1) What kind of servo could be used? I need VERY high torque and cheap cost, but do not care at all whatsoever about precision/feedback/digital/etc. Should I use something else to accomplish this goal?
2) How do I set up this "gateway" that only triggers the relay if a certain voltage input is reached (it will always have *some* voltage reading, so it can't just be run straight to the relay)?
3) How do I power the servo with a DC current, as described above?
Thank you,
SOR noob
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You could feed the DC into an ADC channel to monitor the voltage and then use this to drive the servo. But servos dont tend to have a lot of torque - check the datasheet for the servos you are thinking of. Since servos are normally connected to the mcu output pin then it cant draw more than around 40mA - not a lot.
Depending on the torque required you may want to use a standard motor or stepper motor instead