What Are the Different Types of LED Resistors?

LED digital displays (LED Segment Displays) are composed of multiple light-emitting diodes packaged together to form an "8" -shaped device. The leads have been connected internally, and only their individual strokes and common electrodes need to be drawn. The nixie tube is actually composed of seven LEDs in a figure of eight, plus eight decimal points. These segments are represented by the letters a, b, c, d, e, f, g, dp.

LED digital tube

Specifications: (round, semi-circular, D-shaped);

The diameters are: 30mm, 40mm, 50mm, 80mm, 100mm, 110mm;

Color: single red, yellow, blue, green, white, colorful;

Shell color: milky white;

Performance: waterproof, dust-proof, UV-proof, pressure-resistant, rupture-resistant, high- and low-temperature resistant, flame-resistant, super impact-resistant aging;

Protection level: IP65

Working voltage range: 24V-220V;

Working power: 8-12W;

Working environment: -40 degrees-+75 degrees;

Normal life:> 80,000 hours.

1. According to the control mode: it is divided into internal control mode (there is a single-chip microcomputer inside and it will automatically change color when it is powered on) and external control mode (external controller is required to change color).

2. Divided according to the change mode: fixed color and colorful, full color; fixed color is used to hook outlines, full color can be hooked outlines, can also be composed of tube screen display text, video, etc.

3, according to size: D50, D30, this is the diameter; the length is basically 1 meter (can be customized); this needs to be selected according to actual needs.

4. According to the internal controllability: there are 1 meter 6 sections, there are 1 meter 8 sections and 1 meter 12 sections, 1 meter 16 sections, 1 meter 32 sections. That is to say, there are several sections in the 1-meter tube that can be controlled independently; the more the 1-meter sections, the better the video effect. If the density is low, or do some chasing effects, you can do 1 meter 6 sections.

5. According to the number of LEDs: there are 96 lights at 1 meter and 144 lights at 1 meter; the more lights, the better the effect. Generally, 144 lights are used to make full color.

6. According to the power supply: It is divided into high voltage power supply (direct 220V power supply) and low voltage power supply (12v power supply, 220v power supply needs switching power supply conversion); generally, low voltage power supply is selected, which is more reliable and stable, and high voltage power supply is easy to burn.

7. Divided by pixels: A 16-meter lamp with 1 meter has 16 pixels with a 1 meter lamp. Generally there are 6-segment digital tubes, 8-segment digital tubes, 12-segment digital tubes, 16-segment digital tubes, 32-segment digital tubes, etc. There are more 16-segment tubes. Such as 6-segment digital tube is generally used on contour items.

For the LED digital tube to display normally, it is necessary to use a driving circuit to drive each segment code of the digital tube to display the number we want. Therefore, according to the driving mode of the LED digital tube, it can be divided into two types: static and dynamic. .

1.Waterproof

If asked

1. Static real pixels (equal and non-equidistant are the same): 16 * 8 real pixels single module maximum power consumption 16 * 8 * 3 * 0.02 = 7.68 1616 pixels wide; 88 pixels Point height; 3-three currents per pixel; 0.02-estimate the size of each current.

Note: Two red LEDs of 2R1G1B real pixels connected in series together only count one current.

2.Static

1. Display effect: Since the LED is basically a current-sensitive element, its forward voltage drop is highly dispersive, and it is also related to temperature. In order to ensure that the digital tube has good brightness uniformity, it needs to have a constant work. Current, and should not be affected by temperature and other factors. In addition, when the temperature changes, the driver chip must also be able to automatically adjust the output current to achieve color balance temperature compensation.

2. Safety: Even short-term current overload may cause permanent damage to the light-emitting tube. The use of a constant-current drive circuit can prevent large-area damage to the digital tube caused by current failure. In addition, the ultra-large integrated circuit we use also has cascaded delay switching characteristics, which can prevent the reverse peak voltage from damaging the light-emitting diode. The ultra-large integrated circuit also has a thermal protection function. When the temperature of any one piece exceeds a certain value, it can be automatically turned off, and the fault display can be seen in the control room.

The first step: punch holes in the wall, install expansion screws, and then install

To find the common common yin and common common yang, first of all, we find a power supply (3 to 5 volts) and resistors of different specifications. VCC is connected in series with a resistor and GND to any two pins. There are many combinations, but there are always It is enough for one LED to find one, and then use GND without moving. VCC (string resistance) touches the remaining pins one by one. If there are multiple LEDs (usually 8), it will be negative. On the contrary, if VCC is not moved, GND touches the remaining pins one by one. If there are multiple LEDs (usually eight), it will be common. You can also use a digital multimeter directly. The red test lead is the positive pole of the power supply, and the black test lead is the negative pole of the power supply.

LED digital tube does not light up

The cause of this failure may be:

1) The transformer is damaged, the leads are disconnected or the solder is soldered. If the transformer is damaged, it should be replaced or re-wound; if the lead is broken or soldered, it should be reconnected or soldered again.

2) + 5V power failure. Should check the display circuit power voltage and digital tube power is normal (normally 5V DC voltage). If the two are abnormal, check whether the 7805 three-terminal regulator has a 5V voltage output. If the three-terminal voltage regulator has a 5V voltage output, the connection lines of the circuit board are damaged, or the furnace is not turned on or short-circuited. If it is open, it should be reconnected; if it is short-circuited, the short-circuit point should be cleared. If the three-terminal regulator does not have a 5V voltage output, check whether the 8805 input terminal has a voltage of about 8V. If 8V is present at the 7805 input, the 7805 is damaged. If there is no 8V voltage at the 7805 input terminal, check whether the bridge rectifier circuit has a voltage output of about 8V. If there is no 8V voltage output from the entire circuit, check whether the 220V AC power supply is normal. If the AC power is abnormal, check the AC power. If the 220V AC power supply voltage is normal, the transformer should be damaged and replaced if the connection line is normal.

3) There is no + 5V voltage on the common anode (or common cathode) of the LED digital tube. Such failures are often caused by false soldering of the current-limiting resistor or improperly printed conductors. If there is no 5V voltage, check it according to the method of checking the power supply voltage described above; if the current limiting resistor is open, it should be replaced; if the circuit board is soldered or the printed wires are not connected, you must reconnect or solder:

4) If the digital tube is damaged internally, it should be replaced.

LED digital tube only lit by decimals

This phenomenon indicates that the ± 5V power supply is normal. The reasons for this failure may be:

1) If the A / D converter does not work properly, the A / D converter should be replaced.

2) If there is a fault in the digital tube, the digital tube should be replaced.

3) If the connection between the A / D converter and the digital tube is open, it should be reconnected or newly welded.

4) If the integrated components of the A / D converter are damaged, the integrated components should be replaced.

5) If the A / D converter pin is not in good contact, it must be re-soldered.

LED digital tube missing pen segment

For the instrument with A / D converter 7107, you can check the voltage of each corresponding output pin of the 7107 for display output and the + (positive power supply pin) brake (that is, use the multimeter's black test lead to connect the corresponding output pin and red test lead Voltage point of the positive terminal connected to the power supply), if it is always a few millivolts, it means that the 7107 is bad and should be replaced; if there is about 4V (the digital tube pin end is negative), the LED does not light, then the 7107 output is normal when the meter Then, you can check the voltage between the corresponding pin of the digital tube and + (the black test lead of the multimeter is connected to the corresponding digital tube pin, and the red test lead is connected to the positive voltage point of the power supply). If there is also about 4V, it means The LED digital tube is bad. The digital tube should be replaced; if there is no voltage, it may be that the 7107 pin is not in good contact, or the connection line from 7107 to the digital pin is not connected, and it should be reconnected and resoldered. If the two voltages are different, check the circuit board for corrosion or oil between the 7107 and the digital tube. If it is, you must clean it and do insulation work; if not, the internal short-circuit of the digital tube must be replaced.

LED digital tube is not bright enough

The cause of this failure may be:

1) The LED nixie tube has been used for too long and the luminous efficiency has been reduced. It can be replaced with a new nixie tube.

2) The resistance of R9 is too large, it can be replaced or adjusted again.

3) Circuit board leakage, discharge the capacitor on the circuit board or clean the circuit board, and dry it before wiring.

4) If the power supply is insufficient, check whether the connection resistance of the power supply circuit is changed. If it is changed, it should be replaced; if the load power of the voltage regulator decreases, it should be replaced; if the filter capacitor is leaking, it should be replaced; if rectified If the diode is damaged, it should be replaced; if the transformer load power drops, it should be replaced; if the power supply is still insufficient after routine inspection, check all load circuits for short-to-ground components, and if short-circuit components are detected, they should be replaced. replace.

5) The output voltage of the A / D circuit is insufficient, first check the peripheral circuit for short-to-ground components. If there is a short-to-ground component, it should be replaced; if the inspection is normal, the A / D conversion integrated circuit is damaged and should be replaced. replace.

LED digital tube display overflow

(When the A / D converter is 7107, "1" or "-1" is displayed) or the range is very small: This phenomenon is mostly caused by the absence of a reference voltage. During the inspection, the input terminal of the instrument can be short-circuited. If "1" is still displayed, the voltage between pins 35 and 36 of the 7107 should be checked. First measure the meter to measure the full-scale voltage (can also be calculated) between 30 and 31, and then take 1/2 of the full-scale value to be the normal voltage value between the 35 and 36 feet. If it is abnormal, check whether the pull-up resistor and the adjustable resistor have changed value (the resistance value becomes larger) or are soldered. If the value is changed, replace it; if it is welded, replace it.

Positive display of LED digital tube-

The display shows a positive value, but displays "-XXXX". The cause of this failure may be:

1) The input signal is reversed, then the input signal should be reconnected.

2) The connection resistance is soldered, and the adjustable resistance is invalid. You can check the voltage between the 31 (IN +) and 30 (IN-) pins of the 7107. Its normal voltage range is about 0 to 2V (the 31 pin is the + terminal). If the voltage between the two pins is negative, It should be checked step by step. If the connection resistance is soldered, it should be soldered again. If the adjustable resistance fails, replace the adjustable resistance.

3) Check whether the pull-up resistor (resistance to the positive terminal of the power supply) is normal, and whether there is open circuit and false soldering. If the value is changed or open, it should be replaced; if it is welded, it should be re-welded.

LED digital tube display value is seriously low

The displayed value is severely low, and the displayed value does not increase after adjusting the range potentiometer. The display frequently flickers. The reason for this failure is likely to be: the sampling period is too short, and the resistance between 39 and 40 is incorrect. If the resistance value is incorrect, you should readjust the resistance value or replace the corresponding resistance. If there is a short circuit or an open circuit (open resistance or short circuit of the capacitor) between pins 38, 39, and 40 of 7107 (see Figure 1), they will all increase the oscillation frequency of the A / D converter, resulting in excessive sampling rate. If this happens, replace the faulty capacitor or resistor.

In addition, the rise of the reference voltage will cause the displayed value to be too low, and the too high reference voltage is often caused by the resistance of the voltage divider circuit or the potentiometers being soldered or changed. In particular, the adjustable potentiometer is most likely to have an open circuit or change in value. After a faulty resistor is checked, it should be replaced.

"1999 LED digital tube always shows "1999"

"1999" is always displayed, and the decimal point shows that the original prisoner who normally caused this failure may be:

1) If the + 5V power supply fails, check it in accordance with the method for checking the power supply circuit described above.

2) If the A / D converter is damaged, replace it.

LED digital tube jumps seriously

The cause of this failure may be:

1) If the A / D converter is broken, it should be replaced.

2) If there are interference factors introduced from the input side, after the interference source is found, if the interference source can be eliminated, it should be eliminated; if the interference source cannot be eliminated, it should be far away from the interference source and shielded as much as possible .

3) If the sampling rate is too high, check for short circuit or open circuit (open resistance or short circuit of capacitor) between pins 38, 39, and 40 of 7107. For the corresponding treatment method, please refer to "Severely low displayed value. The displayed value is not too high, and the display flashes frequently.

4) ± 5V power supply ripple is large, often accompanied by insufficient voltage, the value is unstable. If the power filter capacitor fails, it should be replaced; if one of the rectifier diodes is broken down, it should be replaced.

5) There is leakage between circuit boards or interference between lines. The main reason is that the line is wet or there is a conductive impurity in the line, or the insulation treatment is not done after maintenance. The circuit board should be cleaned and insulated.

6) If there is a false weld in the input or reference line and power line or the power of an electronic component is reduced, after the faulty component is checked, replace it and re-solder each solder joint.

LED digital tube shows large drift

The cause of such a failure may be:

1) 7107 circuit is not good and should be replaced.

2) 7107 is hot, it may be because the LED digital tube current is too large, you can increase the current limiting resistance and then test.

3) The drift of the reference voltage is mostly caused by the failure of the adjustable resistor or the decrease of the power of the pull-up resistor or the replacement of the resistor power is too low. If this happens, the corresponding resistor should be replaced.