Diode indicator lamp (serial resistance size selection)

For the diode indicator light (string resistance size selection) xiaobian today summarized the relevant information to share with you, I hope to help you oh.

A diode indicator lamp is a common electronic element used to indicate the current state in a circuit. When using the diode indicator light, it is usually necessary to connect a resistance to limit the current, to avoid damage to the diode caused by excessive current. This article will detail how to select the appropriate serial resistance size to ensure that the diode indicator light is working properly.

Select the appropriate serial resistance

When selecting the serial resistance, the rated current and power supply voltage of the diode should be considered. By Ohm's law, the size of the required serial resistance can be calculated.

1. The rated current of the diode needs to be determined. This information can be obtained by viewing the specification or data manual for the diode. For example, a certain diode is rated at 20 mA.

2. Need to know the power supply voltage. Suppose a supply voltage is 5V.

According to Ohm's law, the resistance value can be calculated by the following formula:

Resistance value (Ω) = power supply voltage (V) / current (A)

The obtained resistance values were compared with the available standard resistance values and the closest one was selected.

Power of the serial resistance

In addition to the resistance value, the power of the serial resistance should also be considered. Power is the heat generated when the current passes through the resistance. If the power exceeds the rated power of the resistance, the resistance may overheat or even damage it.

The power of the resistance can be calculated using the following formula:

Power (W) = current (A) * current (A) * resistance (Ω)

Based on the obtained power value, select a resistance than the calculated level.

Effect of the serial resistance

The role of the serial resistance is to limit the size of the current to protect the diode from large current damage. When the voltage is applied to the diode, if the resistance of the resistance is too large, the current is limited too small, causing the diode to work properly.

On the other hand, if the resistance value of the resistance is too small, the current will be too large, which may overload the diode and damage it. Therefore, it is very important to choose the appropriate resistance value.

An example of a serial connection resistance

To better understand how to choose the string resistance size, we look at a practical example.

Suppose we have a diode indicator light with a rated current of 20 mA and a supply voltage of 5V.

According to Ohm's law, resistance = supply voltage / current = 5V / 0.02A = 250 Ω.

Select a closest standard resistance value, such as 220 Ω.

Calculated power, power = current * current * resistance = 0.02A * 0.02A * 220 Ω = 0.088W.

Select a resistance higher than the calculated level, such as 0.25W.

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Choosing the appropriate serial resistance size is crucial for the proper operation of the diode indicator lamp. The desired resistance value can be determined by calculating the rated current and supply voltage of the diode. You also need to consider the power of the resistance, choose a power level higher resistance than the calculated result. Reasonable selection of serial resistance can ensure that the diode indicator lamp works stably and reliably.