I have been prompted by fellow Weather forum friends and local friends too, to try and eliminate the temperature spikes on a partly cloudy day, or excessive temps on a sunny day.
I have the La Crosse 2310 type with the equipment all split up and spread out - the only two close together are the rain gauge and the hygrometer/Temp/field hub. From the field hub to the house there is a 20m extension getting the signal to the console. This is buried in 40mm plastic conduit - its a heavy duty underground two pair telecom cable. Perhaps it should have been shielded Cat5e… and so probably more likely should have been the anemometer cable from up on the roof to down on the fence to the field hub - that cable is about 30m long. It also travels through the conduit to get to the fence posts.
For a while, I had an upturned 3L plastic container with top cut off as a sun shield - it had 1" holes all through it but I was still getting sun strike spikes. Then the idea of a solar driven fan as per the Davis unit and a friend has trialled a DIY made up kit as well using plumbing pipes as ducting out the top and over discharging downwards.
I finally managed to get all things together tonight as a rough draft of the final installation. Installed in the dark at 9pm…
The solar panel is 3 x 1.5V to make 4.5 volts high sensitivity low current, or a higher current 1.5V system for the 1.0 - 3V motor and fan. It was part of an educational solar system science or home teaching kit for $28.
The clamp for the motor is a SS muncing ring and a S/S 3/8 UNC stud cut shorter and two nuts. It fits neatly inside a reducing bush (80 x 65) and the rest is MF elbows and about 200mm/8" of pipe going down in and over the sensor unit itself. I have taken the “shroud” shield off it to give more direct access to a draught to be puilled directly over the device. I may add a length of 65 (2.5") pipe directly around the fan and make a discharge duct downwards too. I also need to add a circular bush and seal off the bucket hole to the pipe and fittings - rain can get in through the gaps at the moment. It is all just lubed and fitted without glue - it seems stiff enough at the joints, and it also needs supporting on the downward discharge fan section.
I double checked the cables with a battery to ensure correct rotation of the fan. I will upload more photos to my photo account later in the weekend and reference them from here. The solar sensor panel is facing due north with an approximate angle of elevation to match the path of the sun at midday… (guess)
Hopefully my spiky temp curve today will be more smooth tomorrow - clear skies continuing, perhaps a few clouds - I hope!!
I have now modified the Hygro into a truly 24hr FARS with a PC power supply fan running at 7.5V and have much better temp results!!Also added a link to a table of my photos.
http://www.inmanavenue.com/sitephotos.html
Cheers! (March 21 2008)