Basic Electronics

Ac and Dc Adapters Features

AC / DC Adapters Features:

AC / DC Adapter– The other type of external power supply, other than cells/batteries, that we will use the most for our circuits is the AC / DC adapter. It is typical function is to connect to a socket of the general electrical network to transform the elevated alternating voltage offered by it (in Pakistan it is 220 V + 5% and 50 Hz + 0.3%; if you want to know one of the other countries, you can consult in a continuous, constant and much lower voltage, to then offer this to the devices that are connected to it and thus put them into operation in a stable and safe. AC / DC adapters are basically made up of a circuit transformer, which converts the input AC voltage into another AC voltage much lower, and a rectifier circuit, which converts that already transformed AC voltage into a DC voltage, which will be the final output voltage. All adapters incorporate a printed label that reports both the range of values ​​in the AC voltage of the input with which they are able to work (in addition to the frequency of the AC signal allowed) as well as the value of the DC voltage and the maximum current offered as Exit. For example, the following image is for an AC/DC adapter that supports input AC voltages between 100V and 240V at a frequency of 50 or 60Hz  and provides an output DC voltage of 9V (and a maximum intensity of 1A).

ac dc adapter

We can classify adapters according to whether they are “regulated” (that is if incorporate a voltage regulator inside) or not. A voltage regulator is a device (or a set of them) that, being subjected to a certain voltage relatively fluctuating input voltage, is capable of generating an output voltage normally smaller, much more stable, constant, and controlled. Therefore, regulated adapters provide a very high output voltage. concrete and constant, which is the same as the one shown on its label. What can vary (up to a maximum also shown on the label) is the current intensity offered, since it depends at all times on the needs of the circuit fed. The non-regulated adapters, on the other hand, do not have any mechanism of stabilization and provide an output voltage whose value can be different by several volts from that shown on the label. This type of adapter certainly reduces the input voltage to a lower output value, but the value This specific output voltage depends largely on the electrical consumption (measured in amps or milliamps) performed at that particular time by the powered circuit. Let’s explain this: as the circuit draws more current from current, the output voltage (initially considerably higher than the nominal value marked on the adapter label) decreases more and more until it reaches its nominal value only when the circuit draws the maximum current that the adapter is able to offer, (whose value is also indicated on the label printed, as we already know). If the circuit continues to increase its consumption and exceeds that maximum current, the voltage offered by the adapter will continue to decrease and will become less than nominal, a circumstance in which there is a risk of damaging the adapter (and bouncing, the powered circuit). This behavior is easy to check it with a multimeter, as we will see in a later section of this same chapter. The main reason for the existence of unregulated adapters is their price: they are cheaper and are also available in a wide variety of shapes and ranges of use-values. Generally, the adapters that connect directly to mains plugs (in the form of a “wall wart”, or “wall-wart”) are usually unregulated. Those that, like those used in laptops, They are shaped like a rectangular box from which the cable comes out to connect to the network electric and the cable to connect the appliance, are usually regulated. Anyway, regardless of the adapter encapsulation, a rule that as a rule, The general rule of thumb is that if the adapter supports an input voltage range very wide (from 100 to 240 V, for example), then surely it is regulated. A (regulated) adapter that can be useful for our projects from Arduino is for example amazon product: it is a compatible adapter with the all country electricity grid and generates an output voltage of 9 V and a current maximum of 1 A, which makes it perfectly compatible with Arduino boards (In addition, its “jack” type plug is 5.5 mm / 2.1 mm, as is the socket said plates).

We could also use product no. 798. We can even purchase adapters that, instead of the 5.5mm / 2.1mm jack plug, offer a USB type connection, which provides 5V and a maximum current of 1A. If we needed more output voltage instead (because in our circuit we have devices that consume more, such as many types of motors), we would have to use an adapter (regulated) as per example amazon product (which offers an output voltage of 12V and 5A maximum current) or No. 658 (5 V and 10 A). You have to be careful; no However, do not use an adapter that offers an output voltage or current greater than the circuit is capable of admitting: if we connect, for example, a plate Arduino to these last two adapters, the board would burn out.

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