360 servo creeping

[sleepiejay]

So I have converted my first servo ( hitec 325hb) to 360 rotation by taking out the pot and replaced it with 2 resistors of the value. It works well but a little hard to center or stop, I can deal with that. The problem is when I turn it off and then back on to use it again it starts turning slowly. I can us the trim to stop it but just wondered if I missed somthing ?

[sleepiejay]

Nobody has had this problem ?

[Exclusive RC]

perfectly normal.... especially under load of any kind.. I have a Digital Hitec servo in my front loader and at idle it shakes like its a diesel..... wont harm it at all, just have to learn to live with it..

[gismow]

Hi,

I've not yet had exact this problem, but I think I can explain what's happening.

I don't know how many knowledge you have regarding the steering of servos. The position is defined by HIGH signals in a defined length in milliseconds. In general you have 1100ms for complete left, 1900ms for complete right. All signals in between are the positions in between.

If a servo gets a command, it calculates the actual position from the potentiometer. Depending on that value the servo drives the arm left or right until the value from the potentiometer fits to the requested value.

Now your problem. You added the capacitors and by doing this it you defined a situation that will always be calculated to the same value, e. g. 1513ms.

As long as the center value of the receiver fits to this fix value the servo will stay in that position. If the center position differs slightly, e. g. 1528 the servo will identify this as a difference that needs a small correction. The arm will start to move. Because of the fix capacitors the requested value will never be reached and the arm will move continously.

A solution is a bit complicated. First you must find the ms value that keeps the servo quiet. Than you can program e. g. a ATTiny85. It must read the value from the receiver and as long as the difference between the receiver value and the found out value is smaller than a defined threshold, the chip sends out the fix servo value. If the difference is higher than the threshold the receiver value is passed to the servo.

That's it...

Even if I do not have an ad hoc solution I hope I could help to find out the reason. This might help finding a solution.

[cosworth34677]

Originally Posted by sleepiejay

So I have converted my first servo ( hitec 325hb) to 360 rotation by taking out the pot and replaced it with 2 resistors of the value. It works well but a little hard to center or stop, I can deal with that. The problem is when I turn it off and then back on to use it again it starts turning slowly. I can us the trim to stop it but just wondered if I missed somthing ?

what i did was just take the esc out of the servo and used a small 1/18 scale esc. the reason was the creep on my track loader was so bad it was almost un-driveable but also i've found that some companys servo are better then other at 360 converts futaba's work better the hitec and both work better the traxxas and china brands

[sleepiejay]

Thanks for the help and it all makes sence. I will leave it as is and see how it goes and if it don't like it I think I will go with the esc.