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cooling fan


Bottletopburly

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i'm thinking of fitting a fan on the primary of the 200pds and i see you can buy them with a usb lead so no hassle wiring does it matter what fan i use or do i need to buy a really good quiet one , i thought i would chuck one on the 200p too as they are cheap and im selling that in the near future anyway and it`s flocked and bobs knobs too so may as well put a cooling fan on , or do i need to limit the rpm as i read somewhere once ambient temp attained you can slow fan down so do i need some sort of switch adding to it ,and is it worth adding a fan to the 130pds or could you use a heat sink fan instead of a 120mm fan  .

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I did a guide. Link is in my signature. I used a super low vibration fan that was recommended to me by @Tweedledee.

I used a variable speed controller but found that the fan has a whine to it when I slow it down. You can't hear it in the day but it's annoying at night so I just leave it on full.

 

Is it worth bothering if you're going to sell it?

Edited by tuckstar
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Its an inexpensive mod David so why not.

Fitting one with a speed controller is benificial.

 

Theres much debate about whether a fan should draw air up the tube from behind the primary mirror.....or

whether it should suck air down the tube from above, over the primary, around it, and out at the bottom of the tube.

 

And i'm a firm believer of the latter idea. Simply because if you go for the first option, you'll be cooling the back of the mirror

rather than the bit that NEEDS cooling - its surface.

 

Heres a video that Dion Heape did a few years ago. Theres others like it if you look on YouTube.

HTH, Rob.

ps. please share some pics of you mods. Its always fascinating to follow progress in these things.

 

 

Edited by Bino-viewer
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The mirror will cool just as quick from either side, but having the air flow directed at the font of the mirror breaks up the layer of air on the mirror surface, can't remember what it's called. Which should improve the seeing. The problem is fitting the fan so that it is directed at the front.

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29 minutes ago, tuckstar said:

The mirror will cool just as quick from either side, but having the air flow directed at the font of the mirror breaks up the layer of air on the mirror surface, can't remember what it's called. Which should improve the seeing. The problem is fitting the fan so that it is directed at the front.

i think for now  i will just stick it on like dion did ,some air is better than no air 

Edited by Bottletopburly
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I got my fan from Dion, it came with a variable switch on it and wired it up to my Baz battery.

 

Had it a number of years and it still works a treat.

 

Regarding which direction you should blow / suck the air, I don’t think it really matters but some people’s train of thought is that if you suck it down the tube, your pulling moisture down onto your secondary.

 

Also, by blowing up from the back, the train of thought is that you are creating a layer of air just above the primary, and that it is keeping the moisture off.

 

I can only talk about the blow up from the back option, it has worked for me and my primary has never due’d up since fitting.

Edited by Daz Type-R
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Blowing from the rear is how mine works as well. It does work not only to cool the mirror to ambient, but steadies the view as well, I have turned it off and get a "scooby doo" effect, turn the fan back on and it steadies again.

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One other thought - use a potentiometer so you can vary the speed of it and tune out any vibration if necessary. I start mine on full speed for a few mins then turn it down to a gentle blow once the mirror is clear just to keep it from misting up again. :)

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Another thought on the blow or suck debate. 

Sucking air down the tube also sucks dust into the scope. 

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4 hours ago, Brantuk said:

One other thought - use a potentiometer so you can vary the speed of it and tune out any vibration if necessary. I start mine on full speed for a few mins then turn it down to a gentle blow once the mirror is clear just to keep it from misting up again. :)

Theres sooo many on eBay does it have to be a particular type

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I use one of these to control my fan, they can be taken out of the case, put into a smaller one with the wires being soldered directly rather than using the plug.

 

https://www.ebay.co.uk/itm/DC12V-8A-LED-Switch-Dimmer-Controller-White-For-Led-Strip-Single-Color-Universal/112788578642?hash=item1a42b92152:g:fxQAAOSwubFacr12

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19 minutes ago, BAZ said:

I use one of these to control my fan, they can be taken out of the case, put into a smaller one with the wires being soldered directly rather than using the plug.

 

https://www.ebay.co.uk/itm/DC12V-8A-LED-Switch-Dimmer-Controller-White-For-Led-Strip-Single-Color-Universal/112788578642?hash=item1a42b92152:g:fxQAAOSwubFacr12

Nice one cheers 

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My fan has a fwm connector so has 4 wires , I want to connect it to a dimmer do I cut the fwm connector off and just use the pos and neg to connect to dimmer or do I need the other wires or are they needed if only using on a pc 

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What colour are the wires. 

You may need a 5 volt supply on the sensor wires to make it work. 

Edited by Graham
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3 hours ago, Graham said:

What colour are the wires. 

You may need a 5 volt supply on the sensor wires to make it work. 

They’re all black but on back of motor they are marked neg , pos, F,P I assume I only need pos and neg , it has a 4 pin  pwm connector I could just cut connector off and strip wire back connect to dimmer then use a usb lead cut off end and use pos and neg to connect to dimmer that way will power off usb plug 

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I assume that F is frequency and P would be pulse. 

Wiring just the positive and negative might work. 

Only one way to find out. ;)

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Dimmer switches arrived via China and Hong Kong , the Hong Kong one is better as its more compact but both work in controlling fan , so I’m thinking of housing in the power box and connecting via some sort of jack lead just to make it easier for storage no trailing leads , what type of jack lead will I need is it just a standard 3.5mm jack lead and plug?

Cooling fan dimmer120 mm cooling fan

 

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