I’m currently a computer engineering student from lorma colleges and we’re currently doing our design project.

Our project is called an advance helmet. A helmet that is capable on creating a communication between the helmet and the motorcycle ignition switch.

My main problem is:

I’m using 3 different sensors which fingerprint scanner uses 3.3V, ultrasonic sensor uses 5V and an alcohol sensor which uses 3.3 V. I also included a Bluetooth module (HC-05) which uses 5 V but I only have three Li-ion batteries which has 3.7 V and 2200 mAh.

Can I power up all of the components using three 3.7 V power source even if their is a difference on the voltages in each components? What kind of component should I use to regulate the voltages or boost up the voltages in every component to meet the required voltage?

I hope someone helps me to solve my problem.


1 Answer 1


You do need to provide those devices with the correct voltages. There are a couple of solutions.

You can hook the cells up in a series of 2 or 3, and then use buck regulators, but that may complicate your charging since you now need a balance charger.

Or you can hook them up in parallel, and then use a boost converter for the 5v, and some kind of LDO regulator for the 3.3v. I would go with this, because it allows you to throw in a generic 1s lipo charger without complications.

Examples of regulator boards you might use on a prototype:

Boost Regulators: https://smile.amazon.com/Crazepony-Voltage-Module-Inductris-Battery/dp/B01LW57OUM/

Charger+boost regulators: https://smile.amazon.com/Li-ion-Lithium-Battery-Charging-Module/dp/B07JNT728T/

3.3v Buck/Boost Regulator: https://smile.amazon.com/Pololu-Step-Up-Step-Down-Voltage-Regulator/dp/B01M5CRLOF/ (I will warn that these burn out very easily).

If you have trouble finding a regulator that can supply 3.3v from 3.7, you can always pull 5v from the boost reg and then step that down to 3.3. Not optimal, but should work in a pinch.

  • \$\begingroup\$ Thankyou for the wonderful answer sir. \$\endgroup\$ Mar 6, 2019 at 1:15

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