| 摘要 |
A dimmer circuit for controlling the light intensity from a lamp by adjusting the firing angle of a silicon controlled rectifier (SCR) or like control element supplying ac power to the lamp. The circuit comprises a firing angle function generator which produces, in sync with each ac half cycle, a signal f( alpha ) monotonically related in amplitude to SCR firing angle. Comparator circuitry triggers the SCR's when the signal f( alpha ) crosses the level of a light intensity control signal linearly related e.g., to dimmer control handle position. In one embodiment, the function generator includes a capacitor charged at preselected rates during portions of each ac half cycle. The firing angle function thereby synthesized is programmable to implement any desired dimmer response.
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