Back EMF picture

Viewed 12 times

I want to connect power to a 3V DC motor straight from 3v3 GPIO. Is it safe or will I brick my Pi 3B+ ?

 New contributor
  • 1
    Depends on the motor and how you connect it. I wouldn’t use 3.3V – 5V is OK – Milliways 2 hours ago
  • Hello @Redlik, Welcome and nice to meet you. Ah, let me see. I think there is 97% chance you will fry the toy sooner, or later, for the following reasons: (1) Murphy’s law says “Whatever Rpi will fry, will fry”, (2) Doris Day also says “Whatever Rpi Will Fry, Will Fry”, (3) JM Keynes also says: “In the long run we [Rpi’s] are all dead”, / to continue, … – tlfong01 1 hour ago
  • (4) Lenz’s Law says: “Every motor has a back EMF to fri your Rpi”. Every motor has a start and stall current many times than the working current. Eg, if your 3V motor drinks 500mA when running, the start and stop current might be 1.5A, frying the Rpi. Eg, When you try to break/switch off the current of a running 3V motor, the motor’s inductive coil refuses to break the current passing through it abruptly, and would try to counter the current change, using whatever back EMF to maintain the current, and often many times than the supply voltage. / to continue, … – tlfong01 1 hour ago
  • So, there might be a 10 volt or higher to oppose the current change, this current, running in the opposite direction, shorts the Rpi power and signal circuit, generates heat, which happily fries the electronics stuff, and raises blue or white smoke, so get your smart phone camera ready to selfie the memorable moment of smoke getting into your eyes 🙂 – tlfong01 1 hour ago
  • In case you would like to look at the back EMF voltage pulse that might fry your Rpi, here is a scope screen capture: “5V Solenoid creates a Back EMF 25V peak to peak”: raspberrypi.org/forums/…. Good luck, good health, and God bless your Rpi. Cheers – tlfong01 2 mins ago   Edit

Categories: Uncategorized

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: