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Servo rotation

Non standard use

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Peter Russell 306/12/2018 15:58:19
8 forum posts

Hi

I have a DX6 and want to get the servos to go 180 deg not 90

Any sugestions as to how to do it?

Nigel R06/12/2018 16:08:03
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1969 forum posts
366 photos

The obvious answer is to buy a 180deg servo.

https://hobbyking.com/en_us/turnigytm-tgy-180d-180-degree-digital-servo-2-2kg-0-10sec-12g.html?___store=en_us

Peter Christy06/12/2018 16:19:21
1124 forum posts

How is your soldering? You are unlikely to be able to increase the throw at the Tx end sufficiently to get 180 degrees from a standard servo.

It is theoretically possible to modify the servo amps to achieve 180 degree travel, but it is not a job for the faint hearted or inexperienced! There are many pitfalls.awaiting the unwary. It might be easier just to try and get some 180 degree servos - if anyone sells them any more....!

--

Pete

Chris Bott - Moderator06/12/2018 16:26:36
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6424 forum posts
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1 articles
Remember that many 180deg servos are not proportional. They don't move until your stick passes centre position, at which point they go straight to the other extreme.
Don Fry06/12/2018 16:56:52
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2886 forum posts
35 photos

I think the units Nigel R pointed out are proportional, used as pan motors for a camera.

Gary Manuel06/12/2018 17:34:26
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1760 forum posts
1507 photos

If you use a programmable servo and a compatible programmer, you can extend the "out of the box" end-points.

As an example, the Hitec HS-5245MG can be extended from the default 118 degrees to 199.5 degrees.

Servo spec databases you can find online don't always show the full details. I have found that Servo City show more data than most. Here is their data for the HS-5245MG as an example.

Here is a suitable programmer.

Peter Jenkins06/12/2018 23:35:27
1034 forum posts
32 photos
Posted by Peter Russell 3 on 06/12/2018 15:58:19:

Hi

I have a DX6 and want to get the servos to go 180 deg not 90

Any sugestions as to how to do it?

Peter, what are you trying to achieve? You will get more focused answers if you tell us that.

Peter Russell 307/12/2018 13:35:23
8 forum posts

Peter.

I am using a servo to open a steam valve in a model locomotive.

Ive used a toothed belt and two pulleys of equal teeth with one pulley on the steam valve the other I have mounted on the servo.

If I can get a half turn of the servo giving me a half turn on the steam valve using the throttle channel on my Tx with the stick going from full down to full up I will have achieved my object only mini servos will fit ie 12 x 23 x 21 mm.

Hope this helps

Pete Russell 3

Kim Taylor07/12/2018 14:13:12
222 forum posts
53 photos
Posted by Peter Russell 3 on 07/12/2018 13:35:23:

Peter.

I am using a servo to open a steam valve in a model locomotive.

Ive used a toothed belt and two pulleys of equal teeth with one pulley on the steam valve the other I have mounted on the servo.

 

Pete Russell 3

 

Is it possible to get different sized pulleys, i.e if the pulley on the servo is twice the dia of the one on the valve, you'll get the same effect as twice the angular throw.

Kim

Edited By Kim Taylor on 07/12/2018 14:14:00

The Wright Stuff07/12/2018 14:17:06
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1362 forum posts
226 photos

Any idea how stiff the valve is?

If you double the throw, you'll half the torque of the servo. I think this might be a big ask for a mini servo.

Mike Blandford07/12/2018 17:35:48
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430 forum posts
14 photos

I have some code for a small Microchip PIC processor that extends a servo pulse to give a 180 degree rotation for using a normal servo to drive mechanical retracts. It does also slow down the output change to give a realistic retract operation.

Mike

Don Fry07/12/2018 18:38:35
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2886 forum posts
35 photos

Peter, to clarify, you need something to open or close a valve? You are not interested with the intermediate positions? Or are you interested in the intermediate positions?

Martin McIntosh07/12/2018 19:50:53
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2591 forum posts
963 photos

Please see my post on `Don`t just stand there, get one up!`

If the servo has wiring to the potentiometer , `pot`, and to the motor as opposed to ones which are directly soldered to the PCB then you can add resistors to each end of the pot. Try values from 1K0 to 2K7 (1000 to 2700 Ohms) which will extend the travel. For flaps I have used TGY 180D`s to great effect.

Don Fry08/12/2018 11:38:28
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2886 forum posts
35 photos

Couple of thoughts. The proportional servos with 180° rotation are used by the flying cameras people, and the robot builders. They have their own websites.

One which has the dimensions you need is on the HobbyKing site, is a analogue servo, cheap. SKU is 9399000001. If you want to up its power a bit, run it on a 2s LiFe battery, 6.6 volts. But you may need a charger for this battery. I did see they were selling a B6 charger for a small price on special offer the other day. But that's about the end of the knowledge tree for me.

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