Full Wave Bridge Rectifier (Beginner)

Introduction: Full Wave Bridge Rectifier (Beginner)

A full wave bridge rectifier is an electronic circuit that converts an AC current into a DC current. The electricity that comes out of a wall socket is AC current, while most modern electronic devices are powered by DC current. This means that the full wave bridge rectifier is a very common and useful circuit. In this tutorial, we will build a full wave bridge rectifier using simple, affordable components. This specific version will convert 120V AC current into 6V DC current. In this case, a 1k ohm resistor is the load of the circuit, but in a practical application, the load would be some kind of electronic device. A more in-depth explanation of how this circuit works can be found here: Full Wave Bridge Rectifier. A simulation of this circuit can be found here: Full Wave Bridge Rectifier Simulation

Supplies

Breadboard (https://bit.ly/3aklJvb)

120V to 6V AC transformer (https://bit.ly/2TH8Q7V)

1 470 uF capacitor (https://bit.ly/2TeoqsD)

1K ohm resistor (https://bit.ly/2whDyw8)

4 401K ohm silicon diodes (https://bit.ly/2TvYEie)

Set of wires (https://bit.ly/2TcPYhH)

Oscilloscope

other tools potentially required (i.e. pliers)

Step 1: Understand Your Components

Before beginning the assembly, it is important that we know how are components function and the correct way to arrange them.

First, remind yourself of how a breadboard works. The two rows on either side of the breadboard (between the red and blue lines) are the power rails are electrically connected along the length of the breadboard. Meanwhile, the inside rows are electrically connected along the width of the breadboard, but not across the divider in the middle. In this design, we will use the division in the middle to our advantage to spread out the components and make the circuit cleaner.

Next, be aware that the diodes only conduct in one direction, and it is necessary that the diodes are pointing in the right direction for the circuit to function. The diodes used in this project conduct from the black side to the silver side (referencing the schematic symbol for a diode, the silver side is the side that the "arrow" is pointing towards.)

Finally, note that the capacitor is direction specific as well, and that electricity should flow from the shorter leg to the longer leg of the capacitor.

Step 2: Assemble the Circuit

Now keeping the directions of the components in mind, assemble the circuit according to the schematic and photo provided. While the specific pins in which the components are inserted need not be the same as in the photo, the components must be electrically connected in the same way i.e. the components in the same rows in our circuit must be in the same rows as in yours.

Step 3: Connect to Transformer

Using jumper wires, connect the power rails to the outputs of the AC transformer. For safety, make sure the transformer is not plugged in! For some transformers (such as the one used in the photo) it may be necessary to use a wrench or pliers to tighten nuts that connect the wires. This will power your circuit with 6V AC after it is transformed from the 120V AC that comes out of the wall. After you plug in the transformer, make sure if you smell something burning or smoking and immediately unplug the transformer.

Step 4: Test Your Circuit

At this point, the circuit should be functioning properly, but we are unable to tell unless we perform measurements. To do this, we will use the oscilloscope. Turn on your oscilloscope and connect the probe across the resistor on the circuit as shown in the photo. Adjust the scaling on the oscilloscope until you see a generally straight line at around 3.5 V with small ripples like in the photo above. These ripples are a result of the capacitor charging and releasing electricity.

Step 5: Troubleshooting/Tips

First of all, when assembling this circuit, it is recommended that all the components are fairly spread out on the breadboard. This not only makes it easier to be organized in your assembly but also makes it less likely that two components touch and short the circuit. Also, be sure to press your wires and components are fully pressed down so that they form an electrical connection with the breadboard.

As emphasized in step 1, make sure all your components are orientated correctly, especially in the case of diodes since they only function in one direction.

If the output on the oscilloscope does not look correct, make sure the scaling is correct. It is recommended that you start with the autoscaling feature and go from there. If there is no signal, measure the output of the transformer to confirm that it is functioning properly. In general, it is good practice to test the signal across each component to find where the circuit has failed.

Step 6: Your Knowledge Has Been Rectified

Congratulations, you are now more knowledgable about electronic circuits!

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