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Author Topic: making a smoke unit pulse  (Read 5672 times)

andyram

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making a smoke unit pulse
« on: November 23, 2016, 06:41:43 PM »

I have a home made smoke unit using a mister unit, water tank and computer fan. It works very well and produces a constant stream of vapour. A model at Warwick show was using a similar set up but the builder had managed to fit something which made the fan appear to stop momentarily to simulate "puffing".

Can anyone tell me what is required to make this happen,in simple terms please and if possible a wiring diagram.

Much obliged to you all for looking in.

Andy.
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g6swj

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Re: making a smoke unit pulse
« Reply #1 on: November 23, 2016, 06:55:01 PM »

Do you want it to simply puff or puff faster & slower depending on throttle position?

Regards
Jonathan
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andyram

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Re: making a smoke unit pulse
« Reply #2 on: November 23, 2016, 07:03:43 PM »

A simple puff would suffice! :}

Andy.
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g6swj

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Re: making a smoke unit pulse
« Reply #3 on: November 23, 2016, 07:06:47 PM »

How many wires come out of the fan unit you have?

Regards
Jonathan
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andyram

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Re: making a smoke unit pulse
« Reply #4 on: November 23, 2016, 07:21:14 PM »

Hi,

Its a simple computer fan with two wires.

Andy
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g6swj

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Re: making a smoke unit pulse
« Reply #5 on: November 23, 2016, 07:55:57 PM »

Andy,

Sorry for the series of questions. The speed of some computer fans can be controlled by a PWM signal - the fans  have 3 or 4 wires.

The cheapest way may be to find a fan with PWM control - what are the dimesions of the fan you have? ( does it have any model number or other details on it?)

Regards
Jonathan
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malcolmfrary

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Re: making a smoke unit pulse
« Reply #6 on: November 23, 2016, 08:03:05 PM »

Fans rotate very quickly, a simple change of speed wont give visible pulses.  That would want either an extra control giving pulses of on-off power to the fan or a motor driven rotating shutter on the air input of the fan.
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andyram

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Re: making a smoke unit pulse
« Reply #7 on: November 23, 2016, 09:03:37 PM »

Thanks both for your response.Perhaps I am mis-leading you by saying I want it to pulse.Simply on off for a brief period would suffice.

The fan I have has 3 wires,Red,Black and Yellow.The only details printed on it are 12v dc  0.07A MW410L12S

I hope this is of use to you and thank you for your help.

Andy.
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g6swj

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Re: making a smoke unit pulse
« Reply #8 on: November 24, 2016, 08:13:18 AM »

Hi Andy,

I am away from home and do not have access to kit in my den.

I think your yellow wire is a tachometer - 1 blip per revolution.

I have used 4 wire fans in the dim and distant past - the fourth wire allows the fan speed to be controlled by PWM - a bit like an inbuilt ESC. Again my memory may not serve me right but I seem to remember being able to supply an external PWM pulse that allowed me to "abuse" the speed control line to turn the fan on and off. However this is all waffle as your fan does not have this functionality.

As Malcolm says - there will need to be some "control device giving the pulses for on/off power" for the motor.  I will post a solution  (<12) when I get back to base - maybe someone else will come up with a solution in the mean time as there are more than one way to skin the cat

Regards
Jonathan
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andyram

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Re: making a smoke unit pulse
« Reply #9 on: November 24, 2016, 09:12:36 AM »

Thanks Jonathan,

If it is easier for you perhaps you can give me a shopping list of parts to buy.I would then need your assistance to advise the way to assemble the unit.Bear in mind I know nothing of electronics and am just on my way to google what PWM is.


Thanks again,
Andy.
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g6swj

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Re: making a smoke unit pulse
« Reply #10 on: November 24, 2016, 09:30:04 AM »

Andy,
PWM (Pulse Width Modulation) - checkout

http://rchub.co.uk/why-connect-an-arduino-to-a-receiver/

Let me see what I have in my spares box when I get home - chances are for a donation to RNLI I can post you what you need

Regards
Jonathan
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Big Ada

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Re: making a smoke unit pulse
« Reply #11 on: November 24, 2016, 05:38:23 PM »

What about putting a rotating disc across the chimney with a section cut out so that it lets smoke pass through when the missing section is in the correct position ?.  ( well I know what I mean ).

Len.
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Re: making a smoke unit pulse
« Reply #12 on: November 24, 2016, 05:53:17 PM »

Ok interrupting the smoke delivery
but the smoke will still be produced
so where does it go?


Ned
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derekwarner

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Re: making a smoke unit pulse
« Reply #13 on: November 24, 2016, 09:03:49 PM »

Len/Ned ......I had considered the same concept and concluded it would be preferable for the rotating aperture/hole disk to be mounted on the discharge side

The fan electric motor will labour when the discharge is momentarily blanked as the fan is a [FAD] free air delivery displacement device ...not a pressure pump....however the frequency of closure [back pressure] should not be an issue

At the same time the smoke [water vapour mist] will densify <*<.......however hopefully not to the point where it condenses 

An interesting experiment ....

Would the disk be rotating at say ~~200 RPM?......a small DC speed controller for the discharge disc motor would be most advantageous
A blanking disk with two aperture/holes @ 180 degrees.....one full size & one at 1/10 size?

Lots of variables O0

Derek
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malcolmfrary

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Re: making a smoke unit pulse
« Reply #15 on: November 25, 2016, 10:15:05 AM »

Ok interrupting the smoke delivery
but the smoke will still be produced
so where does it go?


Ned
During the "off phase" the vapour flow stops.  If it stops long enough, some will condense.  A good layout will allow the condensate to return to the reservoir, otherwise it goes anywhere it wants to.  A rotating shutter in the outlet, if not sealed away from the rest of the boat, will provide a path for its escape and quite probably a surface for it to collect on.  Less of a problem interrupting the inlet. 
What sort of rate of puffing is wanted?  The original idea of pulsing the fan motor suggests quite a low rate.
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Steve Dean

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Re: making a smoke unit pulse
« Reply #16 on: November 25, 2016, 01:11:16 PM »

At the risk of spoiling the party ........ I'm sure that most of you know that ships didn't actually puff like a railway loco. The steam from the boilers (typically 'Scotch' type boilers) went to the engine or engines which were normally triple expansion  (some times with 4 cylinders, i.e. having 2 low pressure cylinders). The steam exiting the low pressure cylinder(s) then went to a condenser. By this time the steam was at a very low pressure and wasn't blasted up the chimney like a railway loco or traction engine.
What did come out the chimney (funnel) was the smoke and this could be quite dense (and black) particularly if coal was being shoveled onto a not very bright fire.
Anyway ...... please carry on with your experiments ...... it's always good fun playing with eletrickery !!!!!
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malcolmfrary

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Re: making a smoke unit pulse
« Reply #17 on: November 25, 2016, 03:44:50 PM »

..........unless its for a Puffer, which were slow revving and non condensing.
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terry horton

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Re: making a smoke unit pulse
« Reply #18 on: November 25, 2016, 03:51:02 PM »

I added a Velleman timer to the fans on my smoker. s... available from Maplins (part number VT27E )... about a fiver


Look really good on my mountfleet puffer and coaster


 Kind regards
Terry H
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derekwarner

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Re: making a smoke unit pulse
« Reply #19 on: November 25, 2016, 07:22:29 PM »

Lets just pretend the Puffer vessel was pre 1870  %).....the following courtesy of WIKI.................... Derek

"The puffers developed from the gabbert, small single masted sailing barges which took most of the coasting trade. The original puffer was the Thomas, an iron canal boat of 1856, less than 66 ft (20 m) long to fit in the Forth and Clyde Canal locks, powered by a simple steam engine without a condenser, since as it drew fresh water from the canal there was no need to economise on water use. Once steam had been used by the engine, it was simply exhausted up the funnel in a series of puffs as the piston stroked. As well as the visual sight of a series of steam puffs following the boat, the simple engines made a characteristic puffing sound. By the 1870s similar boats were being adapted for use beyond the canal and fitted with condensers so that they no longer puffed[/i]"
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Derek Warner

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Steve Dean

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Re: making a smoke unit pulse
« Reply #20 on: November 25, 2016, 10:52:59 PM »

Without wishing to hijack this thread ......... has anyone figured out a way to create smoke from a funnel that looks much darker, i.e. like it's coming from a coal fired boiler. I don't think this is possible with the water vapour style units but what about the oil burning types. Could something be added that causes it to look more black ..... without of course it being too volatile!!!!!

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g6swj

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Re: making a smoke unit pulse
« Reply #21 on: November 26, 2016, 08:33:57 AM »

Steve,

Quite a lot of interesting discussion about "Black smoke" in 2012 on forum - http://www.modelboatmayhem.co.uk/forum/index.php/topic,35772.msg379639.html#msg379639

Snippets from thread - "unburnt fuel, particulates, cancer, smuts, way to paint a model black, holy grail of modellers..."

Great Puffer > could always try and fit one of these in a model! :) - https://www.youtube.com/watch?v=MZiEt2VhAX8

Regards
Jonathan
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cos918

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Re: making a smoke unit pulse
« Reply #22 on: November 26, 2016, 08:40:08 AM »

I have made several water based smoke generators from the large to the small. I tried black food die high concentrate in water and tried that. Yes the smoke did go a little bit darker ,light grey. I put a kitchen paper towel over the out let . The paper towel went black. if this smoke landed on your model it would make a hell of a mess. I would not advise this to any one  .


john
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malcolmfrary

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Re: making a smoke unit pulse
« Reply #23 on: November 26, 2016, 08:47:29 AM »

From what I have heard on other threads, the deposits from real smoke on real ships could do exactly that.
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Brian60

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Re: making a smoke unit pulse
« Reply #24 on: November 26, 2016, 12:09:49 PM »

Lots of talk about black smoke. But what about the clear vapour seen on modern vessels? It more of a shimmering summer heat haze as seen on a road surface than smoke. Has anyone cracked that one yet?
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