It’s safe to say that cars are a part of life for Americans. Not only do 90% of all households have a vehicle, but 58% also have two or more.

With that in mind, protecting your car is necessary!

AOVX tracker solutions is a logistics visualized supply chain management solution provider focusing on the field of wireless communication. Included vehicle tracking solution .

In the vehicle tracker hardware, the resistors play an important role in circuits is to limit current and regulate voltage.

Let's learn about resistors knowledge systematically.

Basic resistors knowledge

In Figure 8-1(a), if there is no current-limiting resistor R, according to the volt-ampere characteristic curve of the diode, the current of the light-emitting diode LED continues to increase under the action of VCC, which will overheat and cause burnout.

The value of the current-limiting resistor is also calculated according to the current-limiting value. In the figure, the minimum current of 5mA is required to light the LED. The forward voltage drop of the LED is 1.8V, so the maximum value of the current-limiting resistor is

Of course, the value of R in the design will be smaller than this value to ensure sufficient current to light the LED. For example, a small fluctuation of the 5V power supply will make the current flowing through the LED less than 5mA.

In Figure 8-1(b), if there is no base voltage formed by the bias resistors R1 and R2, the base of the transistor cannot have a voltage sufficient to ensure the normal conduction and operation of the transistor BE.

Especially , In the initial stage of product circuit design, 0Ω resistors are often used for design compatibility for program comparison and testing. During board-level debugging, this 0Ω resistor can be disconnected for power supply and testing of some circuits, or replaced with magnetic beads and other components for power filtering and debugging.

The correct use of resistors requires attention to the requirements of resistor power and accuracy according to the actual design and application. At the same time, the thermal noise caused by the resistors must also be considered for the impact of the circuit.

Resistors  power

Sheet 8-1 shows the size and corresponding maximum power of different packages of commonly used chip resistors.

resistors accuracy

The accuracy of general-purpose chip resistors is 5%, and the E-24 standard is adopted. However, in some applications where analog signals are used, resistors with an accuracy of 1% are used, mainly using the E-96 standard, such as LDO, DCDC and other output voltage configuration resistors. There are also some occasions where higher precision resistors are needed, such as 0.5% or 0.01%, which are generally used for the detection of weak signals, such as microampere current signals. At the same time, they are also used in high-precision operational amplifier circuits. High-precision resistors.

The resistors error of different materials is also different.

The tolerance of carbon compound resistors is relatively large, and the general accuracy is 5%~20%;

The accuracy of carbon film resistors is 1%~5%; the accuracy of metal film resistors is 1%;

The precision of precision metal film resistors can reach 0.1%;

Most winding resistors have an accuracy of 1% to 5%, while precision winding resistors have an accuracy of 0.0005%.

Different precision resistors have different temperature drifts. The temperature drift coefficient is described by the number of parts per million (ppm) of the resistors change when the standard temperature (25℃) changes by 1℃. Generally, the resistors value marked by the resistors is the value under the standard temperature.

Therefore, in product design, we must pay attention to the impact of resistors changes under actual conditions, especially in projects that require high resolution of weak signals, and the errors brought about by it need to be considered.

Not only vehicle tracker , AOVX also provide the shipping / storage / tracking solution .

Feel free to contact us via : info@aovx.com