Dessicant Spool Core with Hygrometer

I have been looking for a solution to keep my less frequently used bobbins dry or to dry them chemically with aggressive drying agents. I have succeeded so far with a prefabricated coil core. However, monitoring the condition of the desiccant proved to be difficult. This gave me the idea of integrating a hygrometer to save space. In order to display the correct humidity in the bobbin or the bobbin packaging, a few more tests were necessary. In the end, the best solution was to separate the hygrometer from the desiccant. Please make sure that you do not repeat my mistake when buying the hygrometers and buy the hygrometers with the large measuring range. My hygrometers show 20% as the smallest value. This already leads to increased water absorption until it becomes apparent that the desiccant has failed. In the end, I bought new hygrometers that measure from 10%. The function is great and after approx. 2 to 3 days a good desiccant starts to dry the filament. If you want very good results