LED digital tubes are commonly used electronic components for simple displays in devices. Below, we will introduce their performance characteristics, simple testing methods, and application precautions.
1. Performance Characteristics
The main features of LED digital tubes are as follows:
(1) They can be driven to emit light under low voltage and small current conditions, and are compatible with CMOS and ITL circuits.
(2) The response time of light emission is extremely short (<0.1 μs), with good high-frequency characteristics, good monochromaticity, and high brightness.
(3) Small size, light weight, and excellent shock resistance.
(4) Long life, with a service life exceeding 100,000 hours, even up to 1,000,000 hours. Low cost.
Therefore, they are widely used as numeric display components in digital instruments, numerical control devices, and computers.
2. Simple Performance Testing
LED digital tubes should have uniform color, no local discoloration, and no bubbles. Under amateur conditions, dry batteries can be used for further checks. Here, we take the common cathode digital tube as an example to introduce the inspection method.
Connect the negative lead of a 3-volt dry battery to the common cathode terminal of the LED digital tube. Then, sequentially move the positive lead of the battery to contact the positive terminals of each segment. When this lead contacts the positive terminal of a particular segment, that segment should light up. Using this simple method, you can check whether the digital tube has broken segments (a segment cannot display), connected segments (some segments are connected together), and compare the relative brightness of different segments. If checking a common anode digital tube, simply reverse the polarity of the battery leads, and follow the same method.
LED digital tubes have a working current per segment ILED of approximately 5-10 mA. If the current is too high, it can damage the digital tube; thus, a current-limiting resistor must be added. Its value can be calculated using the following formula:
R value = (U - ULED) / ILED
where U is the voltage applied across the LED, and ULED is the voltage drop per segment of the LED digital tube (approximately 2 volts).
Using a digital multimeter's hFE socket can conveniently check the light-emitting condition of the LED digital tube. When selecting the NPN range, the C hole is positively charged, and the E hole is negatively charged. For example, when checking the LTS547R type common cathode LED digital tube, insert a single-strand fine wire into the E hole, and connect the wire end to pin 9 (pin ③ and pin ⑧ are internally connected, choose one as needed). Then, connect another wire from the C hole to each segment electrode in sequence, which will respectively display the corresponding segments.
3. Usage Precautions
(1) If the light is dim during inspection, it indicates that the device has aged and its luminous efficiency is too low. If the displayed segments are incomplete, it means the digital tube has been partially damaged.
(2) For LED digital tubes with unknown models and no pin arrangement diagram, the hFE range of a digital multimeter can be used to perform the following tests: ① determine the structure form of the digital tube (common cathode or common anode); ② identify the pins; ③ check the fully lit segments. Assume a certain electrode is the common electrode, then verify based on whether the segment lights up or not. When the segment electrode is reversed or the common electrode is incorrectly identified, the segment will not light up.
The body and cover of the digital tube lamp have both the dynamic brilliance of neon lights and the softness of daylight, capable of producing various colorful lighting effects, achieving 31 kinds of changing effects such as synchronous seven-color three-color gradient, jump change, flow, chase, scan, etc. The product can be widely applied in gardens, stages, overpass guardrails, building outlines, landscape lighting, signboards, and urban brightening projects.
The body and cover of the LED digital tube are made of imported PC material or PMMA material. The LED uses computer programming to control digital circuits, with high-brightness LEDs as the light source. Utilizing red, green, and blue primary colors, through microcomputer controllers, multiple tubes combine to form a color-changing light belt in the night sky, achieving various color changes such as color gradient, jump change, color flicker, random flicker, gradient alternation, color chasing, flow, scan, rolling, pattern compilation, etc. It is a new type of advanced decorative lamp.
Company Name: Jinan Light Electronic Technology Development Co., Ltd.
Factory Address 1: No. 103 Xishilihedong Street, Shizhong District, Jinan City
Factory Address 2: Opposite the Meteorological Bureau, Wuyinshan Road, Tianqiao District, Jinan City
Company Phone: 0531-87960001 85909001 55500501 55500502
Company Fax: 0531-87960001 85909001
QQ Customer Service: 342098054 1365924577
Company Website: http://www.001led.com
Email: [email protected]