Abstract: A precision control device generally includes a current-limiting resistance, a voltage control unit, and a feedback voltage regulation unit. The current-limiting resistance has a grounded end and is serially connected to a DC load. The voltage control unit includes a microprocessor, an ADC, and a DAC. The feedback voltage regulation unit includes at least one operational amplifier and a transistor having a control input, a collector, and an emitter. The transistor is configured to operate at an unsaturated region, wherein the control input thereof receives a signal sent from an output terminal of the operational amplifier. The precision control device enables a power supply to smoothly adjust a predetermined output voltage set value for the DC load in response to a deviation of a voltage applied to the DC load. As such, the current flowing through the DC load and the current-limiting resistance can be regulated at a stable level.

Abstract: A low-glare fluorescent-powder LED light device includes a shell, a multi-frequency directional light source, a high-frequency directional light source, and an electrical control circuit. The shell has a surrounding wall, which defines a front opening and a rear opening and has an inner surface extending along a central axis. The multi-frequency directional light source, including at least one fluorescent-powder LED, is disposed at the inner surface of the shell. The high-frequency directional light source, including a plurality of high-frequency LEDs, is disposed at the inner surface of the shell such that the high-frequency LEDs are arranged in radial symmetry about the central axis. The electrical control circuit can drive the multi-frequency directional light source and/or the high-frequency directional light source. The central light beams emitting from the high-frequency LEDs do not reach the fluorescent-powder LED, so that the fluorescence interference of the fluorescent-powder LED can be avoided.