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Author Topic: Operating a servo with an on/off power signal  (Read 229 times)

McGherkin

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Operating a servo with an on/off power signal
« on: October 12, 2017, 02:12:10 PM »

Hi all.


I've got a Beier USM-RC-2 on the way for the Tamar, but I do have a slight problem.


The Beier has 2 servo outputs, but I want to control more servos than this. Fortunately, I only need to control 2 of them proportionally, the others are simply switching from one end of their travel to the other.


The Beier can output a switched voltage, so is there anything out there which will move a servo to two seperate positions based on whether it gets a signal or not? Preferably it should have the ability to set the speed at which the servo moves as well.


Thanks!
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C-3PO

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Re: Operating a servo with an on/off power signal
« Reply #1 on: October 12, 2017, 02:18:14 PM »

Hi,

Do you need the 2 pairs of servos' running at the same time? If not I can think of a way to do it all from your USM RC2 (I  think!)

I have several USM RC2 and think they are great!!

C-3PO

Quick update - I think I misread your post. The 2 servo's you want to control proportionally will be controlled from your radio TX and direct connection to your RC RX?

The 2 servo's you want to move from position X to Y as Z speed is a easy one for the USM RC2 to achieve
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McGherkin

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Re: Operating a servo with an on/off power signal
« Reply #2 on: October 12, 2017, 02:48:29 PM »

No, I'll try and explain,


All the channels of the reciever are feeding into the USM-RC-2. The USM RC will be controlling 10 outputs.


6 will be purely voltage outputs, and therefore will just use the switching outputs as per normal. (Lighting, radar via a relay etc)
2 will be proportionally controlled servo type outputs (cooling water and smoke unit fan, these will use the USM's servo outputs)
2 are actions powered by servos which need to be switched from one end of their travel to the other. (Transom, masts)


These all need to be controlled by the USM RC 2, but as it only has 2 outputs that feed a servo signal, I need to find a way for 2 servos to be operated purely by recieving an on/off voltage output through the USM-RC's output switches.
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C-3PO

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Re: Operating a servo with an on/off power signal
« Reply #3 on: October 12, 2017, 03:41:54 PM »

Hi,

Quote
2 will be proportionally controlled servo type outputs (cooling water and smoke unit fan, these will use the USM's servo outputs)

What control do you want over and how do you want to control them ( what will change their status)? In what way will they be proportional?

What is your reason for using the USM RC2 servo outputs for these? (Water cooling and exhaust smoke?)

There is no direct link from "input" to "output" proportionally for the USM RC2 servos outputs. They:

Quote
There are two different ways to control the servo outputs:
1. Driving to fixed positions
2. Running through a programed sequence

The USM RC2 is a complex and very capable beast as I am sure you are aware and the functionality can be leveraged in many ways.

C-3PO
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McGherkin

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Re: Operating a servo with an on/off power signal
« Reply #4 on: October 12, 2017, 05:31:32 PM »

The smoke generator fan is controlled as 'smoke generator on' in the USM - it will spin the fan up during starting then back off to idle, and increase with revs (You can change the values of what it will do)

The water cooling pump is on a proportional channel as I can then programme its speed in a sequence. Even if I put it on a non-proportional channel running at full tilt 24/7, the Masts, Transom and Smoke Generator fan add up to more servo outputs than the USM has.
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C-3PO

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Re: Operating a servo with an on/off power signal
« Reply #5 on: October 12, 2017, 05:46:54 PM »

Hmmm...

Confused I am - have you direct experience of the USM RC2?

From my experience it makes more sense to put the water pump and smoke generator on the same channel as the throttle and use separate "ESC"'s to control their speed directly linked to the throttle channel signal (Y Lead split). Not sure how you would get a "Puff" at start-up though from smoke generator.

You would then use the elegant servo sequence to slowly and smoothly control the Mast, Transom to exact positions - the sequence being triggered by the RC TX and then running by itself.

C-3PO
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McGherkin

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Re: Operating a servo with an on/off power signal
« Reply #6 on: October 12, 2017, 06:31:56 PM »

It's OK, I know what I'm doing when it comes to the USM. The smoke and cooling is all part of a function sequence for starting the engines. It's very elegant.


First the +24v is applied to the mister, this fills the mister unit with smoke. A second later the USM plays the engine start sound, followed quickly by the second start sound, and the fan is buzzed up to push all the accumulated smoke from the mister out from the exhaust in a plume. A moment later the cooling water pump starts up and begins pumping water overboard too.


All I need to know is how to operate servos from one end of their limit to the other by making or breaking a circuit with the switching output of the USM.
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C-3PO

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Re: Operating a servo with an on/off power signal
« Reply #7 on: October 12, 2017, 06:51:16 PM »

Hi,

I would suggest this is your best bet - EXM2 - https://www.beier-electronic.de/modellbau/produkte/exm-2/exm-2.php - It will give you another 2  servo channels you can apply sequences to.

I fully understand the elegant switch on sequence, but if only using one USM RC2 then I would have gone for the elegant control on the transom/masts etc over the startup

There is not elegant way control a servo from specific points X to Y at speed Z without additional circuitry at the flick of a switch/switcher.

I know some people have used hacked servo testers - but do you really want your transom/mast raising at full servo speed without a soft stop!

Another suggestion could be a Pololu servo controller - you can program the sequence, speed etc an then trigger with switch - https://www.pololu.com/product/1352

Or you could use an Arduino or 2 - you could have the sequences for the transom/masts running triggered from the USM RC2 directly for less then 5

C-3PO

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McGherkin

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Re: Operating a servo with an on/off power signal
« Reply #8 on: October 12, 2017, 07:19:48 PM »

I was hoping to avoid the extension module as it adds a lot of channels I don't need... but looking now, it includes a speed controller as well, so that could control the watercooling pump without me needing to buy another ESC. I'll take that!

Cheers.
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C-3PO

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Re: Operating a servo with an on/off power signal
« Reply #9 on: October 12, 2017, 07:36:29 PM »

Hi,

It's certainly a great product  - good luck with the implementation.

You could use some of the other switched outlets to do some nice lighting effects / strobes / blue flashing light etc

One suggestion - if you are using the sounds files direct from the CD they can benefit from some "cleaning up" to get rid of some hiss/ EQ etc - the free utility Audacity is great for this.

C-3PO
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McGherkin

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Re: Operating a servo with an on/off power signal
« Reply #10 on: October 12, 2017, 08:01:23 PM »

I think I'll be paying a visit to the station with a microphone and a healthy amount of alcoholic and financial bribery  :-))

I have a blue flashing LED already, otherwise I'd have coded that, but otherwise it'll have all the bells and whistles  ok2
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