An automatic transistor threshold measuring circuit can include a current source circuit that can provide increasing amounts of current to a measured transistor according to current setting values. The method comprises transferring energy to an airway wall of an airway such that a diameter of the airway is increased. Other related embodiments are disclosed. The stamping stations are designed to maintain substantial alignment of the punch and die with minimal moving components. The second fixing unit is arranged at a position where a temperature of the toner of the fixed toner image on the sheet is greater than a glass transition temperature. Further, the product of the equalization errors calculated at different times is obtained, and based on the obtained product, the quality of a signal is evaluated.