Heating tubes / rods

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harlequin2902
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Joined: Tue Sep 30, 2003 11:04 am
Location: Singapore, Sengkang

Heating tubes / rods

Post by harlequin2902 »

Hi all,

Can those who were involved in the past discussion over at the Singastro Yahoo! Groups regarding the use of heating tubes / rods or those who are currently using them yourself, kindly share your knowledge with us here again ? e.g How it works, how well it works, where to find them etc...

Thanks :D
Samuel Ng
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weixing
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Joined: Wed Oct 01, 2003 12:22 am
Favourite scope: Vixen R200SS & Celestron 6" F5 Achro Refractor
Location: (Tampines) Earth of Solar System in Orion Arm of Milky Way Galaxy in Local Group Galaxies Cluster

Post by weixing »

Hi,
I got make one to counter the dew problem on my observation session. But I found out that I still have to cut short my observation, because the rest of my "equipments" (eyepiece, star chart, and etc) still fall into the victim of dew, except my scope... :P

Anyway, making one is quite simple. Buy a suitable resistor, connector for your power adapter, two wires and solder them together. Below are some required formula:

Current(A) = Power(W) / Voltage(V)
Resistance(ohm) = Voltage(V) / Current(A)

For example: If I need my resistor to produce 1 Watt of heat and I got a 12VDC power adapter:
Current(A) required = 1W / 12V = 0.083A
Resistance(ohm) = 12V / 0.083A = 144ohm

So what you need is to get a 144 ohm resistor that has a power rating of 1Watt or greater. By the way, you won't be able to find a 144ohm resistor, they don't come in such values... just get the nearest value. Any value greater than 144ohm will give you less than 1 Watt of heat and any value smaller than 144ohm will give you higher than 1 Watt of heat. Also, make sure your power adapter can supply the required current.

By the way, I thought your MN is a close tube scope, so how are you going to insert your "heating rod"???

Have a nice day and happy Chinese New Year!!
Yang Weixing
:mrgreen: "The universe is composed mainly of hydrogen and ignorance." :mrgreen:
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kayheem
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Joined: Tue Sep 30, 2003 9:59 am
Location: Sennet Estate

Re: Heating tubes / rods

Post by kayheem »

harlequin2902 wrote:Hi all,

Can those who were involved in the past discussion over at the Singastro Yahoo! Groups regarding the use of heating tubes / rods or those who are currently using them yourself, kindly share your knowledge with us here again ? e.g How it works, how well it works, where to find them etc...

Thanks :D
Hi Sam,

The heating rods come in different lengths with different heating capacities. Mounting brackets are included. I have a 3ft rod and it is keeping my scope storage at about 52% RH.

I bought it at a DIY shop in Centrepoint and this shop is situated along the row of shops perpendicular to the main concourse area and is on Level 3 (I think).

The label gives an idea of the length required based on the size of your cupboard.

HTH

Kay Heem
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harlequin2902
Posts: 744
Joined: Tue Sep 30, 2003 11:04 am
Location: Singapore, Sengkang

Post by harlequin2902 »

Thanks, Weixing and Dr.Chan for your replies.

I do have an empty cupboard that may fit the MN56, so I will look into the mounted heating rod method first.
Samuel Ng
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