Large Scale Central

Servos and their operation

Modeling Technical Modeling
#1

I have been using servos in a most basic way. I’ have been simply operating them by rewiring them directly to the motor. Changing the polarity changes the servos throw.

I’m ready to move onto bigger and better things. I’d like to use servos in the way they were meant to be used. Trouble is, I just don’t understand what that method is.

Here is a simple log/pipe dumping car I built using one of my butchered servos. In the test video, iI simply reversed the polarity to prove it would work. In actual practice, I have separate piece of rolling stock that houses the R/C equipment and power for the servo and receiver.

http://youtu.be/HWHF-i-Ef6Q

#2

What a coincidence …this just cropped up on a UK forum about using servos for a crane.

The idea was mooted about bashing a ser vo to do the job.
A model yacht sail servo (quite powerful)would be ok for the jib of the crane…or an ordinary servo with a home made longer arm.

I found a cheapo sail winch costing under $15

#3

Good day, Dan - Servos are a really inexpensive way to animate things on one’s railroad - I use them on my G scale and HO layouts -

Here are some links that show you how servos work and some of my projects. I use either PICAXE or Arduino microcontrollers to operate the servos or you can purchase commercial controllers.

Please let me know if you have any questions

dave

Animation

This link shows how I use servos to control turnouts on a switchback modular layout.

http://www.trainelectronics.com/Module/SwitchbackController/index.html

#4

Nice modules.

They made me think it would be fun to do the same in G-scale.

Do you have plans and construction details for the modules themselves?

#5

Don - I have some notes on putting the module together here:

http://www.trainelectronics.com/Module/index_old.html

Info on the whole layout is here:

http://shmrrc.org/ModularLayout/March2010Setup/

http://shmrrc.org/ModularLayout/April_Jamboree_2010_Setup/index.html

http://shmrrc.org/Free-Mo/index.html

That should give you some idea of what we are doing.

dave

#6

I’m not sure how relevant this is to the original question but I’m working on a universal sort of wireless widget that will control servos and all sorts of other things too.

I’ve published all the circuit designs and software libraries, it’s Ardunio compatible and uses the Xbee series 1 for the wireless communications.

You can find info on it here:

http://controlwidgets.com/

Martin

#7

Martin - thanks for the link - I have been following your project with great interest and have it on my list of things to do - -hopefully early next year…

dave

#8

Thank you for the info. I will study it and see what I can come up with. As I mentioned, I have been butchering servos to operate simply on straight DC. But I think it’s not really good for them in the long term. So your info is greatly appreciated.

#9

Dave, thanks, I’d appreciate the input.

Dan, here is a link to a simple control board for servos so you don’t have to hack them-

http://www.micromark.com/dual-servo-controller,11088.html

Martin

#10

Thanks Martin. The Micro-Mark link looks simple, and I like simple. One question however. In the wiring diagram, provided by Micro-Mark, there are six terminals at the top (on the schematic drawing) marked A1, B1 and SP1. Would the servo’s three wires go directly to these terminals?. Another question came to mind, would this product operate one servo or is it meant for two servo operation only?

More questions. Should I be looking for analog servos or does it matter? What about the amount of rotation? How do I know what the range is on the rotation?

#11

Hi Dan, I have been using these http://www.pololu.com/product/1350 to control one to six servos at once. Good tutorial and down loadable software to simplify programming. All for $20.

Steve

#12

Dave,

Thanks for the module links.

All - looks like I’ve tapped into a treasure trove of links to keep me attached to the computer!