Hi, Everyone. I'm doing an AC to DC converter circuit using rectifier, filter capacitor and zener shunt regulator, to provide an output DC voltage of 4.3V. I designed the circuit in several steps, which I have attached in a PDF file. Here's the final circuit: When I do a Multisim simulation, the output voltage across the 100Ω load is 4.257V, which is a good thing anyway because the error% is small. However, when I assemble the circuit in reality on a breadboard, the output is 3.95-3.98V, which is really far less than the required output. The question is, where is the problem in the design? I hope you can check the design calculations in the attached PDF file, and I would be pleased to take your notes. Thanks.