Power-saving reminder circuit for computer

An anode of a light emitting diode (LED) and a second terminal of a third electrical switch are connected to a first power source. First terminals of the first and second electrical switches are respectively connected to a second power source and a suspend signal pin. A second terminal of the first electrical switch is connected to a cathode of the LED and an output pin of a counter chip. A second terminal of a second electrical switch is connected to the first power source through a first resistor and a first terminal of the third electrical switch. A third terminal of the third electrical switch is grounded through second and third resistors and a capacitor in sequence and a voltage pin of the counter chip.

BACKGROUND

1. Field of the Invention

The present disclosure relates to reminder circuits, and particularly to a power-saving reminder circuit to remind users to shut off commercial power after a computer is powered off.

2. Description of Related Art

In a personal computer (PC) system, power management is adopted to conserve energy while the PC is in use it can be put to sleep to save energy when not in use. System power states derived from the advanced configuration and power interface (ACPI) specification are defined as follows:S0/Working—The central processing unit (CPU) is fully up and operating; devices are powering up and down as needed.S1—The CPU is stopped; the random access memory (RAM) is refreshed; the system is operating in a low power mode.S2—The CPU has no power; the RAM is refreshed; the system is in a lower power mode than S1.S3—The CPU has no power; the RAM is in slow refresh; the power supply is generally in a reduced power mode (for example, the power supply not supplying much power and is operating in a lower power efficiency mode).S4—The hardware is completely off; the system memory has been saved to disk.S5/Off—the hardware is completely off; the operating system has shut down; nothing has been saved.

When the computer is powered off and at the S5/off state, there is still a +5 volt standby voltage (+5VSB) applied to a motherboard for driving a basic power source control circuit of the computer system during the off state. However, this means the computer still consumes energy even in the off state, thus, commercial power needs to be shut off from the computer, to save more power, but the users usually forget to do this, thus, resulting in wasting electrical energy.

DETAILED DESCRIPTION

The disclosure, including the drawing, is illustrated by way of examples and not by limitation. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.

Referring to the drawing, a power-saving reminder circuit100for a computer in accordance with an exemplary embodiment includes a counter chip U1, capacitors C1and C2, resistors R1-R7, electrical switches, such as npn transistors Q1-Q3, and a light emitting diode (LED) D1.

A base of the transistor Q1is connected to a 3.3 volt (V) power source 3D3V of a motherboard200of the computer through the resistor R1. An emitter of the transistor Q1is grounded. A collector of the transistor Q1is connected to a cathode of the LED D1and also connected to an output pin OUTPUT of the counter chip U1. An anode of the LED D1is connected to a 5V power source 5V_DUAL of the motherboard200through the resistor R2. A base of the transistor Q2is connected to a suspend signal pin S5_sleep# of the motherboard200through the resistor R3. An emitter of the transistor Q2is grounded. A collector of the transistor Q2is connected to a base of the transistor Q3and is connected to the 5V power source 5V_DUAL through the resistor R4. A collector of the transistor Q3is connected to the 5V power source 5V_DUAL through the resistor R5. An emitter of the transistor Q3is grounded through the resistors R6and R7and the capacitor C1connected in series and connected to the voltage pin VCC of the counter chip U1. A reset pin RESET of the counter chip U1is connected to the voltage pin VCC. A trigger pin TRIGGER and a gate pin THRESHOLD of the counter chip U1are connected together and then connected to a node between the resistor R7and the capacitor C1. A discharge pin DISCHARGE of the counter chip U1is connected to a node between the resistors R6and R7. A control pin CONTROL of the counter chip U1is grounded through the capacitor C2. A ground pin GND of the counter chip U1is grounded. In one embodiment, the counter chip U1is an NE555 counter chip.

In use, when the motherboard200is powered on and at the S0/working state, the base of the transistor Q1receives a high level signal from the 3.3V power source 3D3V of the motherboard200, and the transistor Q1is turned on. The LED D1is lit. The base of the transistor Q2receives a high level signal from the suspend signal pin S5_sleep# of the motherboard200, and the transistor Q2is turned on. A collector of the transistor Q2is at a low level signal. The base of the transistor Q3receives the low level signal from the collector of the transistor Q2, and the transistor Q3is turned off. The voltage pin VCC of the counter chip U1does not receive a voltage, thus, the counter chip U1does not work. Therefore, the LED D1is always lit when the motherboard200is at S0/working state.

When the motherboard200is powered off and at S5/off state, the 3.3V power source 3D3V does not output the 3.3V voltage, the base of the transistor Q1does not receive a voltage, and the transistor Q1is turned off. The LED D1does not light. The base of the transistor Q2receives a low level signal from the suspend signal pin S5_sleep# of the motherboard200, and the transistor Q2is turned off. The base of the transistor Q3receives a high level signal from the 5V power source 5V_DUAL, and the transistor Q3is turned on. The voltage pin VCC of the counter chip U1receives a voltage and the counter chip U1is powered on. At the same time, the capacitor C1is charged through the resistors R6and R7. When a voltage of the capacitor C1reaches ⅔ of the voltage of the counter chip U1, the output pin OUTPUT of the counter chip U1outputs a low level signal. The LED D1is lit. At the same time, the discharge pin DISCHARGE of the counter chip U1is turned on, and the capacitor C1discharges through the resistor R7. When the voltage of the capacitor C1is reduced to ⅓ of the counter chip U1, the output pin OUTPUT of the counter chip U1outputs a high level signal. The LED D1does not light. And after, the capacitor C1is charged and discharged again, the theory is same as above. Therefore, the LED D1is in a blinking state when the motherboard200is at S5/off state, to remind of the users to shut off commercial power from the computer to save more power.

In some embodiments, light frequency and time of the LED D1can be changed through changing values of the resistors R6and R7and the capacitor C1.

The power-saving reminder circuit100can remind users to shut off commercial power through the blinking of the LED D1when the computer is powered off and at S5/off state, to save more power.