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Chatting servos - How to shut them up...

R/C Submarine modelers

Postby Robse » Wed Sep 17, 2003 4:54 pm

Hi, fellow subbers.

I have just put all of the R/C stuff inside the WTC. There's a receiver, a regulator w. BEC, two servos, and three mini switches (Remote controlled on/off switches). The entire system is powered by the BEC in the regulator.
When the system is turned on, then once in a while the servos and the main engine starts a conversation of their own. The servos are making tiny very small steps in random direction, and just ever so often the main engine takes a few revolutions at high speed.
The system resonds 100% correct at all times to any given command. When the jittering starts, then it helps moving the antenna around a bit...BUT:

Is there a way to shut it all up, so it'll NEVER start this "small-talk" in between, or is it normal in certain radio conditions?
If that's the case, I really gotta watch out for the propeller when the whole thing is turned on... talk about nail-cutters!

I am sitting right under a bright lamp, and tons of equiptment on my desk. The noice from them will be absemt at the pond...or will it... Turning it all off does not cure the issue.

When I *really* listen to the small sounds that the system generates when this problem occurs, then I can pick a "system" in the noise patern. It's like a cycle of just 1/2 secund or so, repeated over and over, until I move the antenna, OR the nearby transmitter. I'm on the 40 MHz band.

ANY comments are greatly appreciated, thanks in advance.
Yours Sincerely, Robert Holsting, Denmark
1/81 SSBN Ohio Class scratch builder, more at www.robse.dk

"Never be afraid to try something new; remember that it was amateurs who build Noah's Ark, and professionals who build the Titanic"
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Postby JWLaRue » Wed Sep 17, 2003 10:13 pm

hi Robert,

Couple of possibilities......

- do you have capacitors installed on your motor? The general recommendation is to use three: one from each motor terminal to the motor casing and the third one between the motor terminals.

- are any of your power lines inter-twined with the servo wires? It's a good idea to keep them separated as much as possible.

- like the power lines, the antenna should be kept clear too.

Hope some of this helps!

Jeff
Rohr 1.....Los!
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Postby bo@ti » Thu Sep 18, 2003 4:38 am

And if that dossen't help. Try adding one lead from the (-) negative pole on the battery to all the motors used.

Also BEC could make some interference.
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Postby Ramius-II » Thu Sep 18, 2003 11:15 am

Hi Robert:
I agree, the capacitors on the motor are most important. In addition, be sure you have a nice heavy ground wire from the case of motor to the battery ground. Here is a place that has some info on dealing with such a problem.

http://www.veetail.com/HowRCworks.shtml

Without actually seeing the installation it is most difficult to troubleshoot by e-mail. Hopefully the info from the site will help.

Ed :)
Just one more wire!
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Postby Robse » Fri Sep 19, 2003 2:45 am

Hi all.

Thanks for all the great advice! I have played around with it now, and put a couple of 0.1 uF capasitors here and there on the main engine, and the Vcc supply wires, relocated the antenna, and added a larger capasitor at the regulator BEC output.

I also found the origin of the "pulsating" rythmic noice generated by my servos: My local area computer network switch. As soon as I kill it, I get two reactions: 1) My girlfriend and stepson sends out a we-want-the-internet-back-screem that could wake the dead, and 2) My servos goes quiet.

Now, with the added capasitors, the system is much much less sencitive to EMC noise, and can even accept my mobile phone being close by. Thanks, guys! REALLY appriciate your help and comments. :)
Yours Sincerely, Robert Holsting, Denmark
1/81 SSBN Ohio Class scratch builder, more at www.robse.dk

"Never be afraid to try something new; remember that it was amateurs who build Noah's Ark, and professionals who build the Titanic"
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