What is a Voltage Level Indicator?

A Voltage Level Indicator is a simple electronic circuit that can indicate the voltage level between any two nodes in a circuit. It is a simple yet crucial electronic circuit that later becomes the basis of many advanced testing equipments. It is easy to design and is relatively inexpensive. So, In today’s article, we will learn how to design a basic Voltage level Indicator circuit using an LM3914 Dot/Bar Display Driver IC & a small number of other components.

LM3914 is an analog controlled LED driver IC. This IC eliminates the need for programming a microcontroller and also reduces the hardware required to control 10 LEDs. For LM3914, the input voltage can vary from 3V to 18V. The IC has two operating modes DOT mode and BAR mode, also more than one IC can be cascaded to control up to 100 LEDs. Since the LEDs can be controlled without any flickering and perform flawlessly with equal brightness these IC’s are commonly used in visual alarms and other metering or monitoring applications.

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Step 1: Useful Steps

1) Solder the LM3914 IC on the veroboard. After that, Solder the -ve
terminals of the nine LEDs with pin 1, 18, 17, 16, 15, 14, 13, 12, and pin 11 of the LM3914 IC

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2) Solder the -ve terminal of the 3V piezo buzzer with pin 10 of the IC. After that, Solder the 18KOhm between Pin 4 & Pin 2 of the IC.

3) Solder the middle pin (variable end) of the 10K preset pot with pin 5 of the IC & one of the fixed ends with pin 2 of the IC.

4) Solder a 56KOhm resistor between pin 3 of the IC & remaining fixed end of the preset 10K pot.

5) Now solder the 4.7KOhm resistor with Pin 6 & 7 of the IC & short the other end of the resistor with pin 2 & 8 of the IC.

6) Solder the cathode of the 1N4007 with Pin 3 & 9 of the IC. After that, solder the anode of the diode with the +ve terminals of all the LEDs & the buzzer.

7) Solder the -ve terminal of the block connector with Pin 2 & 8 of the IC & the +ve terminal with pin 9 & 3 of the IC.

8) Power up the circuit using a variable DC supply & test the circuit.