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At present, in remote mountainous areas and rural areas of China, the power grid voltage is extremely unstable and generally low, and some power grid voltages are only about 120V. In such a power grid, televisions and other household appliances cannot be used normally. Although there are many voltage stabilizers on the market, the effect is not very good and the price is high. In order to solve this problem, the author has specially designed a voltage stabilizer with low cost and easy-to-buy components, which is suitable for radio enthusiasts to make by themselves.
Circuit principle: The circuit principle of this voltage stabilizer is shown in the figure below. It is mainly composed of several unit circuits such as power supply, reference voltage, voltage sampling and comparison. The mains is input from the transformer’s 1 and 2 terminals, 3 and 4 terminals are auto-voltage regulator taps, and 5 and 6 terminals are the control circuit’s power supply and sampling taps. When the mains voltage is normal, because the voltage at point C is always 3V (i.e., the voltage obtained by R1 stepping down and DW stabilizing the voltage), points A and B are both greater than 3V, so A1 and A2 output low levels; when the mains voltage drops, the voltage at terminals 5 and 6 also drops, and the voltage at point A also drops. When the voltage at point A drops below 3V, A1 outputs a high level, saturating the transistor V1 and conducting, and relay K1 closes, adjusting the output of the voltage regulator to terminals 1 and 3; when the mains voltage continues to drop, similarly, when the voltage at point B is lower than 3V, (VA
On the contrary, if the voltage rises, the voltage at point B also rises. When the voltage at point B is higher than 3V, A2 outputs a low level, V2 is cut off, H2 is released, and the output is adjusted to terminals 1 and 3. Head; when the mains voltage continues to rise, the voltage at point A is higher than 3V, A1 outputs a low level, V1 is cut off, K1 is released, and the output end is adjusted to heads 1 and 2. A1 and A2 are operational amplifiers, used here as voltage comparators; IC1 is a three-terminal voltage regulator block, which provides power supply for the operational amplifier and relay; VD5 and VD6 are protection diodes.
Selection of components: IC1 uses LM78L06. A1 and A2 use LM358. V1 and V2 use 9013. Relay uses 4123, and the voltage is 6V. DW uses a 3V voltage regulator tube. VD1~VD4 use 1N4007, and VD6 uses 1N4148. The core of the transformer can be adjusted according to the stability. The power of the voltage stabilizer depends on the voltage. The author has selected the E-type 24 iron core, and the coil parameters are: 1~2 is wound with 0.22mm enameled wire for 1800 turns; 2~3 is wound with 0.27mm enameled wire for 400 turns; 3~4 is wound with 0.27mm enameled wire for 850 turns, and 5~6 is wound with 0.21mm enameled wire for 145 turns. The parameters of other components are selected as marked in the figure.
Installation and debugging: This voltage stabilizer should be installed in a metal case with good heat dissipation holes. After the circuit is assembled, adjust RP1 and RP2 to the maximum resistance, use the voltage regulator to adjust the input voltage to 180V, and then adjust RP1 to adjust the voltage at point A to 2.9V. At this time, A1 outputs a high level and V1 is turned on. , relay K1 is energized, and the output terminal is automatically adjusted to terminals 1 and 3, and the output voltage is about 220V; then the voltage regulator is adjusted to make the input voltage 140V (the output voltage is 180V at this time), and RP2 is adjusted to make the voltage at point B 2.9V. At this time, A2 outputs a high level, V2 is turned on, and relay K2 is energized, and the output terminal is automatically adjusted to terminals 1 and 4, so that the output voltage is raised to about 220V again. According to the data given in the figure, when the grid voltage is as low as 120V, the TV can still be watched normally. It should be noted that: because the pull-in current of the relay is greater than the release current, the output voltage will have a certain error, and RP1 and RP2 need to be adjusted repeatedly to achieve the best state.
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提升卡
变色卡
千斤顶
京公网安备 11010802033920号
