| abstract |
A humidity-responsive circuit consisting of a humidity-sensing element and a power supply winding in series connected through a rectifier bridge to a relay controlling an alarm or a dehumidification control device, the relay being connected in parallel with a normally nonconducting silicon controlled rectifier. The gate electrode of the silicon controlled rectifier is energized from an adjustable network arranged to trigger the silicon controlled rectifier at a preset level of conduction of the humidity-sensing element. This shunts the relay, allowing its contacts to close, thereby energizing the alarm or dehumidification control device. Any defect causing the relay to become deenergized will thereby cause its contacts to close, providing ''''fail-safe'''' operation. |