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Pure Resistance Cirtuits

Electronic components are the basic elements in the circuit, with two or more pins or metal contacts, with specific functions. Electronic components include resistance, capacitance, inductance, potentiometer, electron tube, radiator, connector, sensor, power supply, switch, micro motor, electronic transformer, relay, integrated circuit, etc. The most common components in circuits are resistors, capacitors, diodes, triodes, chips and connectors.

With the progress of science and technology and the demand of the society, in order to meet the requirements of an equipment with more functions, the development trend of the PCBA contains variety components. But some simple circuits are still has their value for our daily life.

What is the pure resistance circuits?

In AC circuit, resistance (R), inductance (L) and capacitance (C) are three basic circuit components. If there is only one kind of the components in the circuit is called a pure circuit.

There are three kinds of pure circuit, namely, pure resistance circuit, pure inductance circuit and pure capacitance circuit.

Resistance is represented in a circuit by "R "plus a number. The main functions of resistors in circuits are current shunt, current limiting, partial voltage, bias, etc.

The pure resistance circuit is a circuit that has only resistors except for the power supply; or even have the inductors and capacitors, their impact on the circuit is very small thus can be ignored. Resistors convert all the energy obtained from the power supply into internal energy (thermal energy). This kind of circuit is so called the pure resistance circuit.

To be precise, all variations of Ohm's law and Joule's law (Q=U^2/R* T, Q=W=Pt=UIt, etc.) can be used in pure resistance circuits.

The difference between pure and non-pure resistance circuits

The non-pure resistance circuit is one in which Electrical energy is converted into internal energy and other forms of energy. Among them: internal energy should only account for a small part.

From the perspective of energy conversion: The main difference between it and a pure resistance circuit is the energy transform. Pure resistance circuit can only convert into heat energy, while non-pure resistance circuit can convert other energy besides heat energy, such as wind energy, optical energy, etc. The common seen equipment--hair dryers, for example, convert electricity into wind and heat to dry out hair. For circuits containing motors, other forms can be mechanical energy; for circuits containing electrolytic cells, other forms can be chemical energy

The characters of the pure resistance circuits.

In the pure resistance circuit, the voltage and current have the same frequency and copper phase, and the maximum value, effective value and instantaneous value of the voltage and current comply with Ohm's law.

Resistance effects the same way on DC and AC. When both pass through the resistance, the current has to do work to convert electrical energy into heat energy. So resistors are energy-consuming components;

The average power of a pure resistance circuit is equal to the product of the effective value of the current and the effective value of the voltage at both ends of the resistance.

In a pure resistance circuit, the electric power is equal to the thermal power, i.e P=UI=I²R=U²/R

The common seen pure resistance circuits in daily life.

Basically, as long as there is no conversion of electrical energy other than heat energy, the circuit is a pure resistance circuit.

Common products in daily life are incandescent bulbs, electric kettle, electric warming treasure, electric soldering iron, electric stove, iron, electric rice cooker, electric blanket, etc.

Incandescent bulbs convert more than 99 % of electricity into heat and very little into light.

Therefore, the incandescent bulbs can be regarded as a pure resistance circuit product.

CFLS or LEDs, on the other hand, convert most of their energy to light energy, so CFLS and LEDS are an impure resistance circuit. That is why incandescent bulbs consume far more electricity than CFLS and LEDs.

The inspects and solutions to common malfunction

The resistance changes

This kind of fault is quite common. Due to the temperature, voltage and circuit change exceeding the limit value, the resistance value increases or decreases. When checking with the multimeter, it can be found that the actual resistance value differs greatly from the nominal resistance value, and the resistance value generally increases.

This type of fault, where the resistance changes, can only be eliminated by replacing the resistor.

Open circuit

The so-called open circuit is the resistance is infinite, the circuit is blocked. Sometimes the fault can be checked out by the eyes; sometimes it is necessary to measure with a multimeter, that the pointer indicates infinity.

This type of fault also needs to replace the resistors.

Poor contact

Soldering defects and loose wires can cause poor contact. For example, after the device is energized, the power indicator lights up but does not heat. In this case, you can check the welding condition of the components and repair the defective position with add tin.

Other problems of pure resistance circuits products

In addition to the above fault problems, pure resistance circuit products in daily use due to improper user operation will cause some safety problems. Because this kind of products is to use heat for us, their fast heating characteristics is both an advantage and a hazard.

Fire hazard: To folding or extrusion the circuit, circuit burn-in and long-time continuous energizing is easy to cause fire accident. In order to avoid the occurrence of fire, it is necessary to set the circuit overheat protection and automatic power off device.

Uneven heating: Electric blanket, electric hot-water bag is very popular in winter, the improper usage will easy cause scald. The gear of electric blanket is little, the temperature is not stable or comfortable; electric hot-water bag is not able to control the temperature, after charging, the temperature is too high, and the holding time is relatively short, so it needs to be charged again soon.

In terms of heating products, Jia Yuan Electronic has done a lot of research and development.
We fully consider the advantages and disadvantages of pure resistance circuits in the market. Our products include heating clothes, heating pants, heating belts, and other heating products for pets. All products are in third gear, controllable constant temperature. And we also designed mobile charging, to ensure comfort at any time. Besides, our products are collapsible and washable. After fully drying, there is no safety hazard. In addition, when the temperature inside the clothes reach the maximum temperature limit, it will automatically stop heating, so as not to scald users.


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