Oct 30, 2020 Pageview：63
A power supply is an electrical device that supplies electrical loads with electrical energy. The main function of a power supply is to convert the electric current from the source to the correct voltage, current, and frequency to power the load. As a result, the power supply is sometimes referred to as a power converter. Some power supplies are standalone separate devices, while others are built into the cargo equipment in which they operate.
Examples of the latter are power supplies in desktop and consumer electronics. Other functions that a power supply can perform include limiting the current drawn from the load to a safe level, turning off the power supply in case of a power failure, conditioning the power supply to prevent electronic noise, or input spikes from reaching the load. , Power factor correction and energy storage to keep the load powered in case of a temporary power failure
A linear regulated power supply is simply a "brute force" (unregulated) power supply followed by a circuit of transistors operating in an "active" or "linear" mode, hence the name linear regulator. A typical linear regulator is designed to output a fixed voltage for a wide range of input voltages and sufficiently drop the excess input voltage to allow the maximum output voltage for the load.
This excessive voltage drop causes power dissipation in the form of heat. If the input voltage is too low, the transistor circuit will lose its regulation, which means that the voltage will not remain stable. This can only reduce the overvoltage and does not cover the voltage deficit of the brute-force part of the circuit.
Therefore, depending on the type of controller, you should keep the input voltage at least 1 to 3 volts above the desired output. This means that a corresponding output of at least 1 to 3 volts multiplied by the full load current comes from the control circuit and generates a lot of heat. This makes a linearly regulated power supply inefficient. To get rid of all this heat, they had to use large radiators which made them bulky, heavy, and expensive.
Switching the regulated power supply ("switch") is an attempt to realize the advantages of coarse force and linearly regulated structure (small, efficient and inexpensive, but also "pure" stable output voltage). The switching of the power supply works on the principle of regulating the input voltage of the AC power supply to direct current and converting it to high-frequency alternating current with a square wave through a transistor which acts as an on / off switch, if the step voltage is increased or decreased by the lamp transformer, then corrects the output.
of DC- Transformer and filter the final result. Voltage regulation is achieved by changing the inverting "duty cycle" from DC to AC on the main surface of the transformer. Apart from the lower weight due to the smaller transformer cores, switches have another big advantage over the previous two projects: The power supply of this type can be produced independently of the input voltage so that it can be operated on any electrical system. In the world; They are called "universal" power supplies.
Ripple regulated power supplies are an alternative to linearly regulated design schemes: The "brute force" power supply (transformer, rectifier, filter) is the "front end" of the circuit, but transistors are strictly current / on / off (saturation) / Interrupt Mode). ) transfers DC power to a large capacitor as needed to keep the output voltage between high and low setpoints.
Like switches, transistors in pulse regulators in "active" or "linear" mode never lose current for a long period, which means that very little energy is lost in the form of heat. The main disadvantage of this control circuit, however, is the need to have a certain ripple voltage at the output, as the DC voltage varies between two control points of the set voltage. This ripple voltage also varies in frequency depending on the load current, making it difficult to finally filter DC power.
Some batteries have a solid-state switch that is usually in the "off" position and there is no voltage on the battery terminals. Grounding or pulling the switch terminal often affects the battery. If that doesn't work, the package may require an activation code. Battery manufacturers consider this stored code a well-guarded secret that not even a service technician has access to.
Use a voltmeter to find the positive and negative terminals on the battery and determine their polarity. If there is no voltage, the semiconductor switch may be in the "Off" position and must be activated. Connect the voltmeter to the external terminals, take a 100-ohm resistor (other values ??may work), connect one end to the ground, and touch the other end on each terminal while watching the voltmeter.
Repeat this process by connecting a resistor with a positive potential voltage. If there is no answer, the battery may be dead or locked by a code. The 100-ohm resistor is low enough to power digital circuits and high enough to protect the battery from a possible short circuit.
The connection to the battery terminals should now enable charging. If the charging current stops after 30 seconds, an activation code may be required. Some battery manufacturers add an end of life switch that turns off the battery after a certain age or a certain number of cycles. They argue that customer satisfaction and safety can only be guaranteed through regular battery replacement. Note that such a policy also rotates inventory.
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