===== Bridge Rectifier =====

==== Background information ====

Another central circuit can be created by placing two half-bridges in series and connecting both through a bridge branch. In this way, one obtains the **full bridge** or H-bridge (s. <imgref Fig-2_V3-H-Shape>).

{{drawio>Fig-2_V3-H-Shape.svg}}\\
<WRAP centeralign> <imgcaption Fig-2_V3-H-Shape | H-shape bridges> </imgcaption> </WRAP> 

From the H-bridge, many different circuits can be derived. <imgref Fig-2_V3-H-Shape> left shows the Wheatstone measuring bridge, in which the resistor $R_{\rm L}$ can be determined using a potentiometer $R_{\rm 2}$ and a voltmeter. In the right image, the switching full bridge is shown, which can, for example, drive a motor. The middle image shows the bridge rectifier, which will be described in more detail later. \\
**Always pay attention in full-bridge circuits to where the input and output voltages are located.**

==== Experimental Tasks ====
\\
In <imgref Fig-8_V3-Bridge-rectifier> the circuit of a bridge rectifier is shown. 
  - Enter the current arrows correctly. 
  - Draw the connection between the oscilloscope and the circuit in order to measure the output voltage $u_{\rm R}$ at the rectifier.
  - Explain why one cannot measure the secondary voltage of the transformer and the output voltage of the bridge rectifier at the same time. \\ \\ \\ ${\rm ................................................................................................}$ \\ \\ ${\rm ................................................................................................}$ \\ \\ ${\rm ................................................................................................}$ \\ \\ \\ {{drawio>Fig-8_V3-Bridge-rectifier>.svg}}\\ <WRAP centeralign> <imgcaption Fig-8_V3-Bridge-rectifier> | Bridge rectifier> </imgcaption> </WRAP> \\ \\
  - Build the circuit and connect the oscilloscope. 
  - Sketch the voltage curve before and after the bridge rectifier, i.e. the voltages $u_{rm Sec}$ and $u_{\rm R}$. However, note that you connect the ground of the oscilloscope before or after the bridge rectifier for the respective measurement. 
  - Give the oscilloscope settings used. \\ \\ <wrap left> {{drawio>Fig-00_V4-Screen-image>.svg}}\\ <imgcaption Fig-00_V4-Screen-image> | Screen image for uF and uC> </imgcaption> </wrap> Channel 1:  $ \frac{V}{\rm DIV} =  $ \\ \\ Channel 2:  $ \frac{V}{\rm DIV} =  $ \\ \\ Time basis: $ \frac{T}{\rm DIV} =  $ \\ \\ 
<pagebreak>
 
<WRAP clear></WRAP>

  - Connect a capacitor (electrolytic capacitor) with 100 µF in parallel to the resistor $R_{\rm L}$ and sketch the voltage curve of $u_{rm Sec}$ and $u_{\rm R}$ again in <imgref Fig-00_V4-Screen-image> with a different color. \\ **Warning: When using an electrolytic capacitor (Elko) the correct polarity must be observed!** \\
  - Measure the following values with the help of the oscilloscope in the circuit and enter the results into <tabref Table-2-Bridge-Rectifier_V3> (100 µF): {{drawio>Table-2-Bridge-Rectifier_V3.svg}}\\ <tabcaption Table-2-Bridge-Rectifier_V3 | Bridge-Rectifier measured values> </tabcaption> \\
  - Consider a measure by which the ripple voltage can be reduced. 
  - Draw the circuit with your found solution into <imgref Fig-9_V3-Bridge-rectifier-reduction-ripple> and measure the voltage curves $u_{rm Sec}$ and $u_{\rm R}$. 
  - Enter these into the screen image <imgref Fig-9_V3-Screen-image-bridge-rectifier-wo-cap> with a third color. <wrap right> {{drawio>Fig-9_V3-Bridge-rectifier-reduction-ripple>.svg}}\\ <imgcaption Fig-9_V3-Bridge-rectifier-reduction-ripple> | Bridge rectifier ripple reduction> </imgcaption> </wrap> 
<pagebreak>
 
<WRAP clear></WRAP>
 \\
  - Carry out the corresponding measurements – as above – again on the bridge rectifier. These were the secondary-side voltage of the transformer $û_{\rm Sec}$, the frequency of the secondary transformer voltage $f_{\rm Sec}$, the peak-to-peak value of the ripple voltage $u_{\rm PP-ripple}$, the ripple frequency $f_{\rm Ripple}$, the average value of the rectified voltage $|ū_{\rm R}|$ and the peak value of the rectified voltage $u_{\rm R,~max}$. 
  - Enter the results in the second free line of <tabref Table-2-Bridge-Rectifier_V3>.

==== Test questions - Bridge Rectifier ====