USB Port Protector/Isolator for Arduino & Electronics Hobbyists
The user's Arduino fried their laptop's USB port, and they're asking, "How do I prevent that?" While there are guides out there, it really shows the need for a physical protective device. A USB isolator or a current-limiting adapter, specifically designed for Arduino and electronics hobbyists, would offer a real safety net to keep computers safe during experiments. This is a big concern for both beginners and experienced users. Such a product would protect expensive computer hardware from common mistakes in DIY electronics projects, saving users a lot of money on repairs and reducing stress. For a business, this is a chance to tap into a large niche market with a low-cost, high-value solution, potentially leading to significant sales.
Origin Reddit Post
r/arduino
My Uno R3 fried my USB-A port on my laptop, how do i prevent that?
Posted by u/Early_Hawk_5249•05/28/2025
I made a light-sensitive LED circuit with my Uno R3 using an LDR + 10kΩ voltage divider feeding into A0. Based on the value, it lights up one of 3 LEDs (red/yellow/green) through 220Ω resisto
Top Comments
u/ClassyNameForMe
You expressed concerns with USB over current. The forward current for your LEDs is high IMHO and is easily measured by measuring the voltage drop across each current limiting resistor. You sh
u/No-Information-2572
Although be aware that you might fry the hub then. The 10 bucks isolators will keep working.
u/Early_Hawk_5249
Sure i can try 490 or 1000 ohm, that gives me more "headroom". I am not planning on getting high efficiency leds anytime soon as the cheap ones seem to do the job fine now, except this time o
u/Early_Hawk_5249
Just uploaded a crumb circuit which looks like the one i used, and the code.
Will take a look at the wiki, thanks.
u/Early_Hawk_5249
Yeah id be scared to even come close to using external sources right now, im too big of newbie lol.
Diligency about wiring, youre right, i just cant understand what and how it happened thoug
u/gm310509
No guarantees, but you might find our [Protecting your PC from overloads](https://new.reddit.com/r/arduino/wiki/guides/protecting_pc_from_overloads/#wiki_protecting_your_pc_from_overloads) gu
u/j_wizlo
Diagram and code look good. Probably a wiring mishap
u/j_wizlo
The real bad one is when you put voltage from an external source onto the USB ground /shield. Now you get current in your laptop’s mobo that may not be detected or the laptop may not have the
u/Early_Hawk_5249
Its a little bright, but 220 Ohm resistor is fine no?
Max per digital pin is around 20 mA, all three of my leds probably use each around 4-5 mA each on the three digital pins, way under thr
u/ClassyNameForMe
Why are you running the LEDs so hard and bright? Increase the current limiting resistors to lower the forward led current.
u/gm310509
No guarantees, but you might find our [Protecting your PC from overloads](https://new.reddit.com/r/arduino/wiki/guides/protecting_pc_from_overloads/#wiki_protecting_your_pc_from_overloads) gu
u/Early_Hawk_5249
Will definitely try to find a usb hub after this
u/No-Information-2572
Cheap USB hub.
If you are doing more nefarious stuff, there's also opto-isolators available starting at 10 bucks, depending on what speed you need.