If the pin is connected either to ground or is left unconnected floating , then the chip is in dot mode. We place a toggle switch on this pin so that we can switch between the 2. Here we have used 9V to power the IC to monitor an analogy voltage of V. As the resistance increases, the voltage increases, so the LEDs begin turning on. How to use a LM? Using the resistor R1 value we calculated before of 1.

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How to Build an LM3914 Dot/Bar Display Driver Circuit

So uses such as this are many times what LED bar graphs are used for. It’s not a big deal. The LM is an pin chip.

If 1 or no LEDs are lit, it can mean lm391 battery is dead. Since we are using LEDs with such long leads, we simply connect pin 4 to ground. An LED bar graph is a device that can be a visual indicator of voltage output.

LM Dot/Bar Display Driver IC | NightFire Electronics LLC

Always note that the voltage used to power the IC here 9V should be at least 1. This circuit can be modified to create almost any type of measuring device.

Or for every 0. As we turn the potentiometer, increasing its resistance, more and more LEDs will be turned on until a full 5V is fed into pin 5, in which all the LEDs will be on.


As you might have noticed we have connected all the 10 LEDs directly to the IC without any current limiting resistor this is because the IC has an internal current limiter and the value of current can be set by using the pin VRO pin 7. The advantage of using LM is that it requires minimum hardware and can be easily set up. Depending on the its resistance affects the voltage directly.

LM3914 Dot/Bar Display Driver IC

At 2V, 4 LEDs turn on. With this circuit, you can develop a number of VU volume unit or SVI standard volume indicator devices. In this circuit, we will be using the same for both. The below circuit is a typical application circuit for LM We can put in a force-sensing resistor that measures the amount of force applied to the sensor and then the value proportionately on the LED bar graph. This includes the pinout and all the details of how to connect the LED Bar graph.

Pin is the mode pin. Pin 9 is the mode pin. Since we are monitoring V here, the low reference voltage pin 4 is set at 0V and the high reference voltage pin 6 is set to 5V.

Here we have used 9V to power the IC to monitor an analogy voltage of V. Meanwhile, in bar mode, all eight LEDs will be on. As we turn the potentiometer so that its resistance, and, therefore, voltage increases, the number of LEDs that light up on the bar graph increase proportionally. If you are using LEDs with pins 6″ or longer, then you would place a capacitor in parallel to this pin.


The other formula is to calculate the second resistor value R2. With varying voltage, we get varying LEDs lit.

We simply have to connect the 10 LEDs to the IC, set the reference voltages for input voltage and limit the current through the LED and we are all set. The formulae to calculate the current is given below, where I is the current through each LED and RL is the resistor connected to pin 7. The pinout of the LM is shown below. This varies the voltage that is fed into the LM Pin 5 is a very important pin. You have the choice: Next in pins 6,7, 8, we place our biasing resistors R1 and R2 to doy the current of 10mA.

These are the pins where the LED bar graph connects to.