A digital humidity circuit diagram can be designed using EdrawMax or EdrawMax Online. The software provides tools required to create a factually correct humidity circuit good-looking chart. As shown in the below image, a wet circuit is a breathing circuit with active humidification instead of a dry circuit that uses a Heat and Moisture Exchanger. A humidity-controlled switch circuit turns on and off an electrical load depending on the moisture content of the surrounding air. The moisture is sensed with the help of a plate capacitor C2. This capacitor is similar to the old air dielectric plate capacitors in the vintage systems. When the electrical resistance between the two sensors drops below a specific value, it triggers the switches.