Many times you need 3.3V from 5V power supply, so here we show are some simple ways to convert 5V to 3.3V using diodes. You won’t learn this in electronics engineering schools or courses. So this is after electronics engineering degree you will learn all these.
But before showing you the circuit you might wonder where and why the circuits are so useful. The primary reason for this is that many microcontroller pins and IC operates on 3.3V and many times you also have 5V devices in the same circuit. So you want to use a single 5V supply and convert 5V to 3V. There are number of techniques which are used to get 3.3V from 5V supply. Some techniques includes voltage divider, using voltage regulator etc. Note that voltage is not the only issue you have consider for applications. Current magnitude issue has also be taken into account. So voltage divider might not always be fruitful.
Here we show some ways you can get 3.3V from 5V as we show.
The first one uses the popular 1N4148 diode. The circuit is shown below.
The circuit uses three 1N4148 diodes. They together produces a voltage drop of 1.8V. At the end we get 3.2V regulated voltage. Note that the 5V must also be regulated.
The next circuit uses 3.3V zener diode,
The Zener diode is a 3.3V zener diode such as 1N4761A or any other. Or you can use voltage regulator zener diode such as BZX284C3V3. The 47Ohm resistor will limit the current. At the output you can expect 3.3V output with current of 30mA.
Try this and let us know whether it worked or not. Hopefully this will be useful to you and add up to your electronics engineering classes.