Hobby Projects - Insulation tester, LED Circuits, Meters.

Saturday, March 26, 2011

LM3914 - Versatile and Easy use Display

The LM3914 is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph. Current drive to the LEDs is regulated and programmable, eliminating the need for resistors. This feature is one that allows operation of the whole system from less than 3V.

LM3914 - Versatile and Easy use Display
  • Drives LEDs, LCDs or vacuum fluorescents
  • Bar or dot display mode externally selectable by user
  • Expandable to displays of 100 steps
  • Internal voltage reference from 1.2V to 12V
  • Operates with single supply of less than 3V
  • LED driver outputs are current regulated, open-collectors
The circuit contains its own adjustable reference and accurate 10-step voltage divider. The low-bias-current input buffer accepts signals down to ground, or V-, yet needs no protection against inputs of 35V above or below ground. The buffer drives 10 individual comparators referenced to the precision divider. Indication non-linearity can thus be held typically to ½%, even over a wide temperature range.

My LM3914 Circuits

Millivolt Meter using a LM3914 LED Dot Display
Millivolt Meter using a LM3914 LED Dot Display
Circuits and Projects of LM3914


LM2941 Manual Fan Regulator & LM3914 Voltage Monitor - The LM3914 voltage monitor is also straight forward. As told I use only 6 of the 10 led outputs. A voltage divider on the input (R1-R2) decreases the 7-12V input to about 1.96-3.36V (x0.28). 

Novel white LED torch - LED bargraph readouts, here the LM3914 is used as the basis of a 10-step variable brightness current-regulated white LED torch!

Indikátor napětí autobaterie s LM3914 - This is actually a voltmeter that the size of the measured voltage signals using ten LEDs. The level of which will illuminate the first LED and the lights can be set to last.

Bauplan Schaltplan Bargraph Anzeige mit dem LM3914 - Analog displays have the undoubted advantage that you can get a reading very quickly perceives visually compared to digital displays.

Stereo Digital Camera Sync Shepherd - R7 sets the current through the LED's of the display. With R7 of 620 ohms, the illuminated display LED draws about 20 mA, which is about maximum for this display,

DIS*PLAYER: Theory and Construction -  This device drives ten LEDs in a linear display, with programmable endpoints and the choice of "dot" or "bar" modes of operation. Furthermore, it is possible to "chain" multiple devices for displays of virtually unlimited size.