Thread: servo/controller help

Tweet

Got an issue here. I have Parallax Propeller Servo Controller (USB), and VSA software. Power for the controller comes via the USB and I have a 6 volt battery hooked to the controller to power the servo motors. Here's the problem: when I hook up T Pro micro servos (SG 90 for example) everything work fine---motors respond to the VSA routine. But larger servos (T Pro SG 5010 or smaller) just sit there and twitch. If I hook up a combination of micro servos along with the larger ones the micros work fine, but again the larger one just twitches.

Baud rate on the com port is 38400.

Are the larger servos acting like this because of a power issue? Or is there some compatability problem between the Propeller and certain servos? I've tried several different servo motors with the same results.

What are the power requirements for the larger servos? They will draw more current and the 6 volt battery may not have enough to run it. Just a thought........

Originally Posted by bfjou812

What are the power requirements for the larger servos? They will draw more current and the 6 volt battery may not have enough to run it. Just a thought........

3.5 to 8.4 volts (plus the max allowable through the controller board is a little over 7 volts).

Does it list a current draw for the servos? Your voltage seems to be good. I am assuming the servos are good. I have run the T pro mg 995 without a problem. Is the baud rate set on all channels you are trying to use?

For whatever reason the servo motor specs usually don't indicate current draw, although if you have a meter you can just measure it yourself. However, I know from personal experience that the "twitching" is most likely an indication that your power supply is unable to provide enough current for the larger servos. As a broad guess, you will probably need at least 1 amp per servo for the larger ones and 500mA for the smaller ones.

Let us know what you find out as this is a problem that shows up for many of us.

Hmm. Powering a couple of servos sounds easy enough (5 or 6 volts/2 or 3 amps) but if I plan to have 12 'larger' servos hooked up to a single board, I need a power source that is approx. 5 or 6 volts and around 12 amps. Ug. What's normally used--I've seen rechargable batteries on line--- or is there a plug-in power adapter that has that kind of rating?

Am I looking at this the right way?

Sorry for the questions, just getting into this and am trying to avoid frying myself, my computer, the electronics, etc. etc.

I always use an ATX computer power supply at the 5V end. Plenty of current to drive multiple large servos, and even a wiper motor at the same time.

From what I read, you need to allot at least .5 amp for the controller unless it's using a seperate power supply AND at least .5 amps for EACH of the smaller servos. (example: 6 servos = 3 amps). I've tried to research the current draw for the larger servos without success. I'd recommend hooking one up with an ampmeter inline. Amperage may also vary with the amount of load the servo is moving.

Originally Posted by Dr Morbius

I always use an ATX computer power supply at the 5V end. Plenty of current to drive multiple large servos, and even a wiper motor at the same time.

I'll give that a shot, then. I've got one but its not ready for use yet-- I need to wire in a resistor "load" before I can use it.

Thanks!

Originally Posted by markgoodson

You might be able to get away with just connecting the green wire to a black wire and it will power up.

Yup, thats what I do. Works like a charm.