Working With Servos

Madman

Madman

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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 ?

IMG_1385.jpgIMG_1386.jpgIMG_1387.jpg
 
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!
 
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 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 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
 
PhilP said:
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 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.
Click to expand...


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 ?

Image 6-30-20 at 11.11 PM.jpg
 
Looks like the outer works has several uses other than a servo tester, all they do is change the bits inside.
 
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.

Servo-Controller-600x618.jpg.png
 
Madman said:
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 ?
Click to expand...

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

PhilP.
 
Michael said:
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
Click to expand...

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.
 
GAP said:
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.
Click to expand...

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.
 
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.
 
a98087 said:
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
Click to expand...


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.

IMG_1498.jpg
 
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 (-).
 
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