The NTE1509 is a monolithic integrated circuit in an 18–Lead DIP type package that senses analog voltage levels and drives 10 LEDs, LCDs, or vacuum fluorescent displays, providing a logarithmic 3dB analog display. A single pin changes the display from a bar graph to a moving dot display. LED current is regulated and programmable, eliminating the need for current limiting resistors. The whole display system can operate from a single supply as low as 3V or as high as 25V.
The circuit contains its own adjustable reference and accurate 10–step voltage divider. The high impedance input buffer accepts signals down to GND and up to within 1.5V of the positive supply. Further, it needs no protection against inputs of ±35V. The input buffer drives 10 individual comparators referenced to the precision divider. Accuracy is typically better than 1dB.
The NTE1509’s 3dB/step display is suited for signals with wide dynamic range, such as audio level, power, light intensity, or vibration. Audio applications include average or peak level indicators, power meters, and RF signal strength meters. Replacing conventional meters with an LED bar graph results in a faster responding, more rugged display with high visibility that retains the ease of interpretation of an analog display.
The NTE1509 is extremely easy to apply. A 1.2V full–scale meter requires only 1 resistor in addition to the 10 display LEDs. One more resistor programs the full–scale anywhere from 1.2V to 12V independent of supply voltage. LED brightness is easily controlled with a single pot.
The NTE1509 is very versatile. The outputs can drive LCDs, vacuum fluorescents, and incandescent bulbs as well as LEDs of any color. Multiple devices can be cascaded for a dot or bar mode display with a range of 60 or 90dB. NTE1509s can also be cascaded with NTE1508s for a linear/log display or with NTE1549s for an extended–range VU meter.
NTE Electronics NTE1509