Hack a pot?

[mike_cc]

Ive got some hacked servos and I wanted to ask some advice to see if I can improve their handling.

First of all, when I originally hacked them for 360 degree rotation, I adjusted the pot along with the trims on the transmitter until the trims were centred and the servo wasnt rotating.

Then I glued the pot in position so it wouldnt move any more, and did the other stuff thats necessary.

Now when Im using the servos they creep an awful lot and Im wondering, first of all WHY!

But more importantly, how I can fix this?

So here is my question, is it better to connect two resistors of equal value together and replace the variable resistor with them?

If so, whats the best way of going about this? Should I check the overall track resistance of the pot using a multimeter, then halve this figure to get the value of the resistors I must use?

Also, how acurate must they be? Should I check lots of resistors (of the same marked value) ustil I get two which are the closest to one another?

Sorry for all the questions but things like this will start to keep me up at night when it gets close to competition time!

I hope someone can help

Cheers

Mike

[blazerbotics]

Hack a pot?

theres not much you can do, even if you replace the pot they still tend to creep. Cant you just adjust your trims to stop it?

[team_ireland]

Hack a pot?

The reason is not so much the pot as it is the board over heating. You will always get creep no matter if you use resistors or glue the pot.

If you decide to replace the pot with resistors, the best thing to do is to use a 2.7k and a 2.2k. This seems to be about as close as you can get and works very well.

Regards
Ian

[woody]

Hack a pot?

May I suggest a 22-Turn Cermet 5k Trim pot

Maplins Part No. UH24B

[AndrewHibberd]

Hack a pot?

First of all what servo are you using as some have different resistors on each side, to remain stationary. I spent 3 hours removing pots yesturday from 3 diffent types of servos and they all required different circuits. Although it was trial and error.

The creep is due to warming in the system and any movement in the pot after gluing.

The resistor method means that you dont have to move your trims more than one notch.
For all my servos i used two 2k2 resistors to the middle pin form the outer ones, then adjusted the trim until it stopped, the trim needs adjusting due to the varing resitor values. If the trims then dont stop it turning then add or remove voltage from one side of where the pot was until the trims can stop it


Hope this helps

[mike_cc]

Hack a pot?

Many thanks for the advice gentlemen, thats certainly cleared up the creeping servo mystery.

What I didnt make, clear was that I feel there is an excessive amount of creeping going on, even between trim adjustments. Ill try using a pair of resistors instead.

Many thanks again

Mike

[big_nipper]

Hack a pot?

Was searching the net and found this:-

Variable Speed Control Modification
to the Futaba S3003 RC Servo
http://www.seattlerobotics.org/encod...09/S3003C.html

[woody]

Hack a pot?

UNFINISHED webpage http://www.teamonslaught.fsnet.co.uk/speedcnt.htmlhttp://www.teamonslaught.fsnet.co.uk/speedcnt.html ....It contains the above ....and perhaps some other useful type info gleaned from the web.