Re: [ATM] dew heater circuit questions

[Justin Modra <nitrohepcat@yahoo.com>]

"If the heat source is in DIRECT contact with the
glass, you should NEVER need even 1 watt."

This is the best advice I've heard on this list.
Thanks for the reality check!!


--- Scott Ewart <scott.e@quicksurfer.com> wrote:

> You guys are nuts
>     I use 3 100 ohm, 1/4 watt resistors, plus a
> 1000k pot, in series, all
> glued to my 2.6" secondary.  Voltage is only 10
> volts.  And it will DRY a
> wet secondary.  Not just keep it dry, it will DRY
> it!  Not in seconds, but
> it in minutes.  How much of a hurry are you in?  A
> soldering iron is only 30
> watts, and you want to put out 5?!  Have you ever
> held 5 watts in your hand?
> It's hot.
>     If the heat source is in DIRECT contact with the
> glass, you should NEVER
> need even 1 watt.
> 
> Scott Ewart
> 
> 
> ----- Original Message ----- 
> From: "Don Clement" <clement.focuser@verizon.net>
> To: "Dave Smith" <smithersscope@yahoo.com>
> Cc: "ATMLIST" <atm@atmlist.net>
> Sent: Wednesday, December 29, 2004 3:14 PM
> Subject: Re: [ATM] dew heater circuit questions
> 
> 
> Hello Dave,
> 
> 
> 
> Heater wattage is not so critical with my dew heater
> circuit,
> http://mysite.verizon.net/res0owmd/id1.html
> 
> since the circuit automatically keeps the heated
> optics a small amount above
> ambient. The circuit automatically minimizes the
> amount of heat used through
> the closed loop control. All that is needed to
> guarantee dew is not formed
> is the optics be above ambient temperature. The
> smaller the amount above
> ambient. the better. No post regulator is needed. I
> would suggest somewhere
> from 1 watt to 5watts and adjust the wattage value
> (if needed) after trying
> it out in the field. The circuit is simple and
> almost bulletproof to make
> work. Also  the circuit works over a wide voltage
> range and regulation is
> not critical. If used near sensitive ccd imagers, I
> would take measures to
> isolate the power supply from ccd circuitry. Ferrite
> beads work well.
> 
> 
> 
> Don Clement
> 
> Running Springs, California
> 
> 
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> ATM mailing list http://www.atmlist.net/
> 



		
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