| 摘要 |
<p>The motor driving the air blower for a bubbling water massage appts. is regulated to maintain the blown volume instead of, as previously, the pressure at a pre-set, adjustable level. The fan has an AC motor (M) which is fed through a phase-cutting circuit (PS). The air volume is measured with a temperature-dependent resistor (Rhi) placed in the blower air stream (suction side) and forming a potential divider with a second resistor (Rh2) which may also be temperature-dependent. A constant current flows through the two resistors, and the potential at their junction is compared with a threshold (given by RV, Ro) representing the desired volume of air: the output of the comparator (OP) regulates the phase-cutting circuit (PS).</p> |
