An acquaintance of mine made this sensor about 10 years ago as a side hobby and had passed away and I’m trying to re-create the sensor. I’ve been tasked with taking over sunshine records and need to replace the pre-historic sensor the local National Weather Service office is using before that one fails. The NWS no longer is interested in recording sunshine minutes but the media and other news outlets like to use the data.
So, I’m trying to determine parts. Here is what I know from the manual he had informally produced:
- Dual hermetic sealed planar silicon photovoltaic sensors with translucent diffusion lenses.
- Spectral response: 400 to 1100 nanometers
- Operating range: 0 to 1500 watts per square meter
- Operating threshold: 50 to 400 watts per square meter (via adjustable control knob)
- Output signal: +9 VDC (battery voltage) to Ground (during sunshine)
- The signal went to a Veeder-Root totalizer to record sunshine by seconds, minutes, etc.
- The sensor was supplied with an internal 9 volt lithium battery which needed replacement every 30 days (if operating from only that power source).
- During sunshine conditions, the signal is at ground (0 volts). During non-sunshine conditions, this signal is pulled up to approximately 9 VDC (battery supply voltage) through a 1 megaohm resistor.
When correctly installed and aligned with the solar ecliptic, the signal output generated by the amount of sunlight falling on the lower exposed sunshine sensor is compared with the signal output of the sensor positioned under the shadow band. During conditions of sunshine, there is a differential signal between the two sensors, and the sunshine display will count and totalize elapsed time in seconds.
During the night, or when the sky is obscured, or when clouds cover the sun, the differential signal is greatly reduced, and the sunshine display stops counting seconds.
Thank you for any help you can provide - I’d be most grateful!! : )