Quote:
Originally Posted by rcheshire
Reading an earlier post about temperature margins. It depends on how close you are to freezing. If the dew point temperature is 0 then dew point +5 is probably ideal. At 4C ice begins to form and the volume of dew droplets increases. In any case you want to avoid freezing.
At other temperatures dew point +2 is usually adequate. I found with DSLR cooling that a set point temperature of dew point +2 assured no dew formation.
There are some interesting aviation papers on ice prevention, which deals with dew formation.
My Arduino sketch just calculates dew point and adds 2. It would be easy enough to ramp that up automatically when nearing freezing - if you've ever spent an all night session at Snake Valley, you'll know what I mean.
The other thing I found with telephotos, is that dew formation inside the lens can catch you out. So I always run the dew heater if there is any chance of dew.
The native Arduino 490hz seems adequate for PWM. I run it direct to the FET gate through a 100R resistor. MOSFET is a NXP - PSMN1R1-30PL - MOSFET, N CH. You need a 750R pull down resistor from Gate - GND for top performance.
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I've forwarded your comments on to the builder as well. I've ran into what looks like my first bug and that is when the temp goes belong 0, the program spits out way too many digits after the zero.
Current tempatures are a bit extreme for out door testing as it is presently -32 with windchill and the night of course are even colder.
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