This circuit can be used with a voltage level of about 6.1V to 18V. The LED1 will glow again, and the BZ1 will immediately emit a loud noise. On the other hand, if we moved the probes back to 7.6V or 6.8V, respectively. To be sure, let’s move the probes back to 9V again. So, the LED1 and BZ1 get a higher voltage compared to the positive voltage (+V) and the output. The internal circuit of IC1 outputs a very low voltage, sometimes even close to 0V. After that, we adjust VR1 until LED1 glows and BZ1 emits a sound.īecause when we adjust VR1, the voltage drop across VR1 or pin 5 is lowered to below 6V (the reference voltage). Then, we take both probes to an 8.3V output and ground. It will result in 9V, 8.3V, 7.6V, 6.8V, and 6.1V, respectively. We use a voltmeter to measure the voltage at each output and the ground. While the LED acts as a load and the R-resistor as its current limiter. We can make use of this situation by taking the voltage output from each diode and turning this circuit into a voltage divider regulator. Illustation: Step-down voltage regulator using diodes It will also keep 0.7V across itself, resulting in a voltage deduction at each level. The silicon diode will conduct when its forward voltage reaches the voltage threshold, which is about 0.7V. But let’s use the easiest way possible by using a ladder regulator using diodes. We would need a constant voltage level to test and fine-tune. This circuit will alarm us when the 9V battery voltage level is lower than 8.3V. We assemble this circuit on a breadboard. Perforated board, wires, 8 pin socket for IC1 Experimenting with 9V battery alarm circuit IC1: LM339 Voltage comparator IC: Buy HereīZ1: 6V-9V Active Electromagnetic Buzzer. What more? The experiment below will help us understand more. They will work at the low output voltage only. They are both connected to pin 2 (output) and positive voltage (+V). Then, we will add the LED1 and BZ1-buzzer as indicators of the output. On the other hand, if the voltage at pin 5 is less than at pin 4, Pin 2 will output almost no voltage at all. If the voltage at pin 5 is greater than at pin 4, Pin 2 will output a high voltage almost equal to the power supply. Both voltages are then compared by IC1 any result will be output to pin 2 (output). At the same time, some current from the 9V battery also flows through to a VR1 to the input pin 5 (non-inverting input), also known as a comparing voltage. The ZD1 works as a 6V Zener regulator to keep the reference voltage level at pin 4 (inverting input) of IC1. Then, R1 passes the safe current level to a 6V Zener diode (ZD1). Pin 12 is the negative power supply pin (-V).Pin 3 is the positive power supply pin (+V).There are two important pins of LM339 to see right now. This circuit consists of a few components (6 pieces without any capacitors), an LM339 Quad Comparator as the main component of this circuit, two resistors, a potentiometer, a Zener diode, an LED, and a buzzer.īy connecting both probes to a source-a 9V battery. It is a simple non-inverting comparator circuit. LED1 immediately will glow and BZ1 will emit sound. By installing this circuit to the output of the battery, if the battery voltage got to lower than 8.3V. Some circuits may misfunction when a 9V battery powering them voltage level got lower than 8V. GET UPDATE VIA EMAIL 9V Low Voltage Battery Alarm Circuit It gives an alarm when the battery voltage level is lower than the set point. Secondly, is a practical 12V low voltage battery Indicator circuit.We tried to build this circuit to start learning how the LM339 Quad Comparator works. First, is a 9V low voltage battery alarm circuit.It can sense a drop in voltage of 2 or so millivolts, for example when the voltage drops from 12.400V to 12.398V. The LM339 Quad Comparator is another type of op-amp specially designed for voltage-sensing circuits, so it is very accurate. Both circuits can be used to detect the voltage level with a comparator circuit using LM339. Another is a circuit that we currently use. The first circuit is used mainly to visualize the principle of a comparator circuit using OP-AMP. By showing on LED and with a buzzer sound alarm. It can be used as a voltage monitor for other voltage sources that might have the same problems. But it would be more convenient if we used this circuit instead. We may measure the voltage of the battery with a common voltmeter.
0 Comments
Leave a Reply. |