4 replies to this topic

[luxo II]

Just purchased a heated pad 400mm x 300mm for our cats to enjoy, which turned out to be powered from a 1A DC power supply (3-12V)... out of curiousity I measured the resistance - 12.6 ohms - so 12W from a nominal 12V battery supply.

 

http://www.warmapet.com.au

 

This thing would be an alternative to a heater strap and depending where you buy it, about half the price of the larger straps, and would be compatible with PWM dew controllers.

 

The interesting thing is that because of its large area it is only vaguely warm to the touch - it doesn't get anywhere near as hot as a heater strap - and I'm curious to see how this works out on my 10".

Edited by luxo II, 29 May 2023 - 10:56 PM.

[Mossonarock]

I've tossed around the idea of using infrared LEDs to warm the corrector plate of my SCT. I use a Celestron heater ring but it struggles with getting heat to conduct through the glass all the way to the center. I have a C11. So, I wonder if infrared LEDs would do the job better since heat conduction isn't relied upon, theoretically speaking. Till then, I supplement the heater ring with an occasional blast from a 12v hairdryer. 

[archer1960]

Your infrared LEDs are likely not in the wavelength that you need to warm up anything; they are probably near IR, which are intended for communication, such as TV remotes, etc. Thermal IR is a much longer wavelength and needs a different emitter material

[gnowellsct]

I've tossed around the idea of using infrared LEDs to warm the corrector plate of my SCT. I use a Celestron heater ring but it struggles with getting heat to conduct through the glass all the way to the center. I have a C11. So, I wonder if infrared LEDs would do the job better since heat conduction isn't relied upon, theoretically speaking. Till then, I supplement the heater ring with an occasional blast from a 12v hairdryer. 

I'm not sure about the Celestron heater ring as such but that's not the way it works.  You should be heating the aluminum tube behind the front casting and the heat will rise up to hit the mirror. It is to be remarked that some people swear by reflectix as an insulating solution, I've had only partial success with that approach. The heater remains necessary.

 

Greg N

[gnowellsct]

Here's a way to install the heater internally.  I think this report inspired Celestron but that could just be wishful thinking.

 

It is to be remarked that radiative cooling is a real thing and the high heat numbers measured in my in-the-garage testing do not reflect the actual fractional degree heat effect out in the real world under the open sky. 

 

But the system works and has worked these past 15 or 16 years.

 

Greg N

 

Here's the link

 

https://docs.google....MFcL7O6dew/edit