Voltage / GND question

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theDVSguy

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Hello, New to teensy and I want to make sure I dont blow it up. I have a few questions.

1. I would like to further protect the board incase my voltage input goes higher. Is is ok to add a fuse for the 5v VIN ? Also Any suggest on fuse size ?
2. I will be using 6 serial ports for communication. I need to run a ground from the Teensy to all 6 of my devices. Do I have to use the one GND OR are all GNDs on the board equal ?
3. Also would like to confirm which pads to cut for voltage isolation to the USB. If I cut the pads, does that mean I can run power to +5v and keep the compter connected to USB ?

Thanks for your help.
 
A fuse won't give you the protection you want. Fuses protect against too much current. They do nothing about about too much voltage, or at least not until the voltage go so high as to cause a catastrophic failure which results in massive current.

Fuses also are generally meant to protect against starting a fire. Their main purpose isn't to protect the electronics. By the time the fuse blows, usually things have gone so badly that the electronics are unlikely to survive. Fuses are meant to save people and property by preventing really bad failures from turning into fires.

Yes, ground connections are required for serial communication. Well, unless you have a special isolated way (like MIDI inputs use), but even then a ground connection is needed between Teensy and whatever hardware sends or receives with optical or magnetic or other isolation.

The VIN-VUSB pads on the bottom of Teensy can be cut apart, to prevent 5V power from feeding back into your PC through the USB cable.

Unless you really need more power than USB can provide, at least as you start working on your project, I would recommend just using the USB power. Adding external power introduces many opportunities for things to go wrong. We've seen it over and over on this forum, where hardware gets damaged due to an accidental moment where 5V power touched the wrong place or got connected incorrectly while experimenting.

If you're worried about drawing too much power from your PC, a good compromise involves using a powered USB hub. That's how I do most things with Teensy.
 
Thanks for the advice. Makes alot of sense. So on the GND question, do I have to hook all 6 devices to the same GND pin ? or can I split them up with the other GND pins on the board ?
 
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