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Author Topic: How to convert a servo into a dc operated point motor  (Read 4518 times)

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Offline Railwaygun

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Re: How to convert a servo into a dc operated point motor
« Reply #15 on: April 22, 2016, 08:22:09 pm »
Hi,

Bealman,
Thanks, the basic idea is of course not mine :angel:.
Just mixed some ideas together to make a design that is easy to replicate.


Nicholas,
I love to add some pictures for you but i am not really shure what you mean with "intervals of the servo".
Also saw that version on rmweb. I searched the web a few times to find some inspiration ;) for my little design.


Robert,
If you have finished one, could you please let us know if it works ok? :photospleasesign:


André

" Internals of the servo" - defishent spill chucker.
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Offline André-NL

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Re: How to convert a servo into a dc operated point motor
« Reply #16 on: April 23, 2016, 10:08:21 am »
" Internals of the servo" - defishent spill chucker.

 :laughabovepost: Now i get it.

We are leaving for a short holiday now, back next weekend.
Great weather over here next week (not  :worried:)
Shall post some pictures of the intervals internals :D of the servo then.

André

Offline André-NL

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Re: How to convert a servo into a dc operated point motor
« Reply #17 on: May 01, 2016, 04:20:11 pm »
Hi,

Made some pictures of the servo's inside.
There are more pictures like this on the internet but here are mine.

These servos are very cheap these days.
I think there is a factory somewhere making thousands of these servos.
Just search for SG90 servo on Ebay, Aliexpress or Alibaba and you can find one for less than 1 pound.
(Sorry, but you are not allowed to access the gallery)

These servos can rotate 180 degrees and have a built in end stop.
Normally this end stop is also hacked so the servo can spin continuously left or right.
But it's not really necessary for this point motor.

Just be sure the servo is in center position when attaching the servo arm.

Now lets turn this servo into a dc motor.
First unscrew the 4 small screws and off comes the bottom.


Here we find a small circuit board with 2 black wires for the motor and 3 red wires going to the potentiometer.
Don't know if they always use the same colours.


We don't need the circuit board, so just cut/desolder al wires.


Now we can solder some new wires to the motor.


Close the servo and that's it.
You can test it by connecting the 2 wires to a 1,5 battery (very shortly or it reaches the end stop and you might damage the gears).
Reverse the battery and the servo rotates in the opposite direction.




André
« Last Edit: July 03, 2016, 02:02:33 pm by André-NL »

Offline André-NL

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Re: How to convert a servo into a dc operated point motor
« Reply #18 on: May 03, 2016, 01:32:09 pm »
Hi,

Thought it might be easier to use a piece of strip board instead of the aluminium angle.
To keep it simple we don't need any measuring tool at all now :).


First pre-tin some copper strips.
You can see that in my enthusiasm i started to pre-tin the wrong strip :D.


Both pieces soldered together.


The final version (for now :)).


The DC Servo Pointmotor MK III.


André
« Last Edit: July 03, 2016, 02:42:08 pm by André-NL »

Offline Railwaygun

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Re: How to convert a servo into a dc operated point motor
« Reply #19 on: May 03, 2016, 04:27:18 pm »
If you do another one , could you use different. colours for the motor and switch and common return wiring? 

It helps the visually handicapped amongst us.

Also if you added two  hinged sidearms with Croc clips to,the wood base,  it could be be a soldering aid ( holding the 2 PC boards square)  for mass production??

Nick R
« Last Edit: May 03, 2016, 04:31:42 pm by Railwaygun »
This has been a public service announcement
It may contain alternative facts

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Offline DaveGlew

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Re: How to convert a servo into a dc operated point motor
« Reply #20 on: December 12, 2017, 09:07:15 pm »
Nice idea.

If you changed the single pole switch for a double pole, you would then have frog switching built-in too...
Neat solution!!!
Taking it one step further you could use a three pole switch to light a mimic diagram or use the dpdt to operate a mini relay for multiple uses...... pole change, signal, mimic diagram etc.
If it looks right, it probably is right.

 

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