Working With Servos

[Madman]

I've played around with servos in the past. I would like to make more use of them. There is an article in Classic Toy Trains about using servos to animate various things on our layouts.

I don't quite understand how to activate the servo without using R/C. The article talks about a servo driver. but how's the servo driver controlled ?

 

[Paul M]

I'm not sure, but I'm going to follow this thread. I do know not to use cheap servos in locations you can't easily get to!

 

[dunnyrail]

Typically Servo drivers use a simple toggle switch. Have a look at MegaPoints downloads.

Documentation – MegaPoints Controllers

 

[PhilP]

Hi Dan,

Look at the Servo Tester here:

RC Trains RC Trains - Accessories

Electronic and hardware accessories for battery powered, radio controlled model railway / railroad locomotives

www.rctrains.co.uk

There is an underlined 'see more' link.. Follow that for more info on the tester.


The servo drivers in the article, have push-buttons on the board. With a little bit of delicate soldering, you can extend these to a convenient position for you to operate.

PhilP.

 

[The Shed]

Dan, great article.

Leuchtturm Garten Bahn

Leuchtturm Garten Bahn

www.theshedrailway.co.uk

 

[The Shed]

Leuchtturm Garten Bahn

Leuchtturm Garten Bahn

www.theshedrailway.co.uk

 

[a98087]

THe item that’s PhilP LinkedIn to is what you need, it needs an external power supply 5v I think, and then it becomes the servo control box.


Twist the knob and the servo moves, or reset the servo, or make it continuously move.

What are you actually trying to achieve?

Dan

 

[Madman]

Hi Dan,

Look at the Servo Tester here:

RC Trains RC Trains - Accessories

Electronic and hardware accessories for battery powered, radio controlled model railway / railroad locomotives

www.rctrains.co.uk

There is an underlined 'see more' link.. Follow that for more info on the tester.


The servo drivers in the article, have push-buttons on the board. With a little bit of delicate soldering, you can extend these to a convenient position for you to operate.

PhilP.

I found a picture of a servo tester like the one in your link. I can see where to connect the 4.8-6 volt power. But what is the third pin used for ?

 

[Paul M]

Looks like the outer works has several uses other than a servo tester, all they do is change the bits inside.

 

[Michael]

You will probably find that this doesn't move the servo to it's end points without adjusting the resistor values so I wouldn't recommend it. You really need a microprocessor based one.

If you search for "servo controller model railway" you will find that there are many controllers designed for indoor model railways to drive points for instance. Here's a UK based one but I'm sure there will be similar US based ones too. It's designed for the popular 9 gm servos which are the ones I use on my steam loco.

 

[PhilP]

I found a picture of a servo tester like the one in your link. I can see where to connect the 4.8-6 volt power. But what is the third pin used for ?

It is not used.. For speed, they are using a standard 3-pin servo connector..

PhilP.

 

[GAP]

You will probably find that this doesn't move the servo to it's end points without adjusting the resistor values so I wouldn't recommend it. You really need a microprocessor based one.

If you search for "servo controller model railway" you will find that there are many controllers designed for indoor model railways to drive points for instance. Here's a UK based one but I'm sure there will be similar US based ones too. It's designed for the popular 9 gm servos which are the ones I use on my steam loco.

View attachment 269283

The servo tester most certainly does move the servo to it's end points using the variable control knob.
I have one and for manual control I connect the power to the pins labelled + and - Feed and the servo to the Servo Signal Output and it will move to a position corresponding to the knob position.
This is a very simple manual servo controller that can have as many a use as the user can dream up.
To get fancier with R/C and microcontroller control I would use another driver depending on what is desired to be achieved.

 

[a98087]

This is my servo test set up,

It’s nice and simple,
All you need a-power supply
Ubec- produces 5v dc for the servo tester
Servo tester

By extending the wires you could fit it into a model if you wish

 

[Michael]

The servo tester most certainly does move the servo to it's end points using the variable control knob.
I have one and for manual control I connect the power to the pins labelled + and - Feed and the servo to the Servo Signal Output and it will move to a position corresponding to the knob position.
This is a very simple manual servo controller that can have as many a use as the user can dream up.
To get fancier with R/C and microcontroller control I would use another driver depending on what is desired to be achieved.

That's interesting. I use the same SG90 9gm microservo that is in this video and it appears to only travel through 90°.

When I drive the same servo with an Arduino, I get around 160° of movement.

 

[Dan]

In digital (DCC) engines, some decoders have servo capability. Zimo largescale decoders have 4 programmable servo outputs, and the smaller scale decoders (MX645) have 2.
I use these and add remote uncoupling via a standard servo, chain, Kadee coupler. Others have used the servo outputs to animate a arm waving or door opening on the loco.

 

[The Shed]

Leuchtturm Garten Bahn

Leuchtturm Garten Bahn

www.theshedrailway.co.uk

 

[Madman]

This is my servo test set up,

It’s nice and simple,
All you need a-power supply
Ubec- produces 5v dc for the servo tester
Servo tester

By extending the wires you could fit it into a model if you wish
View attachment 269291

Well, once more electronics proves too much for my pea brain. I set up the servo tester with a brand new servo. It's wired exactly like the one in your photo. Voltage supply is around 5 plus DC volts. No matter what I do the servo will not budge.

 

[Michael]

You have the servo cable the wrong way round. Brown is ground.

 

[PhilP]

Wot Michael say's...

 

[Tony Walsham]

Tell me about it.
Bit of a b....r being red - green colour blind isn't it!!

Except for some no longer available old AM equipment, the middle wire is always positive.
The lightest colour wire is usually the signal wire. White, Yellow & Orange.
That makes the opposite wire Negative (-).