This is a project for alternative processes printers. It is about using an UV sensor to monitor the exposure under sunlight for Cyanotypes, Gum Bichromate, Van Dyke Brown, Carbon, Platinum, etc. The key idea is that instead of counting time, like a regular timer, it "counts energy" falling onto your print and it beeps when a preset level was reached. One can do a test strip in the morning, print in the afternoon and get the expected result. More than that, if during a print exposure, a cloud passes by, the time will be extended in order to reach the desired UV level. I developed this device one year ago and have used it ever since with consistent results. I am sharing it for free as a contribution to analog photography community. The following link leads to a video demo and detailed instructions anyone can follow to build his own Solar UV exposure meter.