During the development of our Arduino or electronics projects, we have the convenience of using our bench power supplies or the handy USB socket from the computer that we program on, so, very often we forget about how we will power the final product once it leaves the bench to run its daily job.
Recently, I started exploring this topic where I first made a project power bank, and then I also designed a custom PCB to power NodeMCU projects but I realized that there are some basic circuits and ICs that I haven't talked about so today we will look at the step-up (boost) and step-down (buck) converters as well as some voltage regulators.
With electronics projects, there are basically three scenarios that we can face.
The first and simplest option is when we have a power source that matches the requirements of the project. An example of this is when we can power an Arduino project from a USB power adapter where the 5V output of the Adapter, matches the 5V requirement of the Arduino. In this case, we are all set and there is nothing more that we need to do in terms of power requirements for the project.
The second scenario is when we have a lower voltage from the supply than what we need in the project. With this scenario, we might need a 12V source to power a relay but the project only runs on a 5V wall adapter so we need to somehow increase this voltage.
To increase the voltage, we can use so-called step-up converters or boost converters. A boost converter is a circuit that uses a specially designed IC and an inductor to first charge that inductor and then use that energy to create a voltage spike in the circuit. Since this spike is created with a high frequency and with the help of some capacitors on the output, we can then have a voltage that is much larger than the one coming on the input.
If the project is even more complex than that and requires more than two voltages, we can add multiple step-up converters to get all the different voltages that we need from just one single power source.
In the third scenario, we have a case where we have a power source that has a higher voltage than what we need and we need a way to lower it. An example can be an Arduino project running at 5V that we need to power from a 3S LiPo battery with a nominal voltage of 11.1V. For this purpose, we can use a step-down converter or buck converter, that can take a higher voltage on the input and then again by using an inductor and a high-frequency switching of that inductor can create a lower voltage on the output.
Similar to when using more than one step-up converter, we can also have more than one step-down converter in the same project if we need to create more than one voltage source and have sources for 3.3V as well as 1.8V depending on the requirements.
In this same scenario where we have a higher voltage source than what we need in the project, we can also use a special type of ICs called a linear voltage regulator.
These components use an internal closed-loop circuit to monitor the output voltage and maintain it by basically shunting current to ground and producing a lot of heat in the process. These regulators are very inefficient when it comes to reducing high voltages but an advantage to them is that they produce really clean, stable, and noise-free voltage so they are very often used in audio projects.
There are basically two types of linear regulators, ones with fixed output voltage (ex. L7805) and ones with variable voltage output (ex. LM317).
When a regulator has a fixed voltage output, it will always output that voltage no matter how the input voltage changes and for this property, they are very useful in battery-operated circuits.
A variable regulator uses a set of resistors to adjust the output so if needed we can use a potentiometer to create a voltage source that can be adjusted on the fly while using the circuit.
This is just a quick overview of the options that we have to power our electronics projects and I hope that I was able to shed some light and clear up some confusion on what to use and when. In the links below you can find examples of such modules that I use in my projects and you can also check out the video above to see them in operation.
- TP4056 charging module - https://s.click.aliexpress.com/e/_DEe4gm7
- TP4056 with boost converter - https://s.click.aliexpress.com/e/_DEzOKxz
- Power bank module - https://s.click.aliexpress.com/e/_DEmHIVZ
- MT3608 - https://s.click.aliexpress.com/e/_Deuz1KX
- Mini boost module - https://s.click.aliexpress.com/e/_DdAHCDD
- USB Step-up module - https://s.click.aliexpress.com/e/_DdLm3Jh
- LM2596 constant current driver - https://s.click.aliexpress.com/e/_Deyafzz
- Mini step-down module - https://s.click.aliexpress.com/e/_DDvrMYr
- L7805 voltage regulator - https://s.click.aliexpress.com/e/_Dl1rIHD
- LM317 adjustable voltage regulator - https://s.click.aliexpress.com/e/_DEN5hgT
- Multimeter - https://s.click.aliexpress.com/e/_DFQ7jaR
- Riden Bench Power Supply - https://s.click.aliexpress.com/e/_DmxOw1D
- Mini breadboards - https://s.click.aliexpress.com/e/_DeeaLAn