1/31/2024 0 Comments Buy iguard voltage indicator alarm![]() In fact, we can use a popular type of IC is OP-AMP. The previous circuit used IC which May be difficult to find and expensive. # 7: Simple voltage indicator using OP-AMP 741 Besides, it can work well just 4 small parts only. This circuit uses current altogether about 7mA only. So it gives a current comes out of pin 4. But do not lower than 1.15V.Ī voltage comparator circuit within 8211. When the voltage of power supply is lower to at a defined point. It uses IC8211 or ICL 8211 (Programmable Voltage Detectors) as main parts. It can show the level voltage, the minimum of the battery with an LED display. This is another one of the low battery Voltage Indicator circuits. #6: Low Battery Voltage Indicator using IC-8211 This circuit use LM3909 and only one capacitor as an LED flasher. This is easest with a single diode for battery Charger automatically is at day time. If you charge a one 1.2V Ni-HM battery 500mAh by a solar cell charger. Because you cannot buy LM3909 in normal stores.īut we want to learn many circuits. It is necessary to turn off SCR first.īecause of the discharge of a capacitor, the voltage G-K is zero in first.ĭo you understand? # 5: Low Volt Battery LED Display using LM3909įor this circuit, I am going to show just only little ideas. The first time we connect the circuit to the battery. It needs to change a new one.Īre you wondering why the C1 across is between the gate and cathode leg of SCR? Now, the gate gets a trigger voltage of 0.7V. In contrast, the input voltage of a battery is lower than 8.4V. It appears voltage across R3 is about 1.1V compare with the ground.īut when we compare with the gate of SCR1. Some current flows through both resistors R2 and R3 are a voltage divider circuit. And it will turn on when the gate and cathode are higher than 0.7V. The SCR works are similar to a transistor. Which uses a Zener diode is a reference voltage. But you can apply to any batteries easily. You may like it too.Īn LED1 will glow up when a level voltage of 9V battery is lower than 8.3V. # 4: LED Display Low 9V Battery using SCRģ the circuit above we use the only transistor. If you try then you will get any results. According to the size of the LED and the battery voltage level.įor example, 1K for 9V battery. The RV is a limiting current resistor of LED1. We will see the flashing LED according to this status. This will continue alternately like this. The voltage at the base of Q2 is lower than the base of Q1. Then a current flows to Q1 to charge C1 slowly. It causes the voltage at the base of Q1 is lower than the voltage of LED1. ![]() Suppose that the input voltage from the battery is low. Ths voltage flows to a differential amplifier circuit. The voltage of LED1 is stable at about 2V. It is also easy.Īn LED1 is power on and LED display status. And important it makes a reference voltage, too. Is it nice? We can notice it easily.įirst, see you see 4 transistors and components more than 2 circuits above. We connect this circuit to indicate the status of the battery. # 3: LED battery status indicator circuit using 4 Transistors So, LED1 show up to alert us the battery nearly run out. The transistor Q1 will stop conducting the current. Makes LED1 go out.īut in contrast, the battery voltage is lower than 4.8V. But makes a Q2 transistor does not work.īecause no current to base of Q2. When this circuit measures the voltage level of the full Ni-HM battery.Ī current flows through R1 and R2 to bias a base of Q1. Or it indicated that the battery is running out. We use this circuit for indicating a voltage level of Ni-HM or Ni-cad battery. You can try to change any resistors as the input voltage. But the current can flow to the bias base of Q2. In contrast, the battery is lower voltage down. The Q1 runs, because getting a current bias. A current flows through 18K and VR1 to the base of Q1. Imagine you use this circuit to a 6V battery. They use a few electronics parts also just transistor BC547 and others. When the battery voltage reduces down to a set point. we can adjust VR1 to set a level of checking voltage. It can apply to an input voltage of 3V to 15V. The first circuit is the simplest battery indicator circuit. GET UPDATE VIA EMAIL # 1: Simple Battery Low Voltage Alarm Indicator
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