-8

The car stereo has a USB port of 5V, 1A, and my problem is when I connect a USB memory stick it "blows" the circuits (makes the USB unreadable). It's my second USB in 8 months, so my question is can you have a USB female to male cable (that has like a resistor or something like that), that converts 1A to 500 mA without changing voltage?

Nike Dattani
  • 547
  • 7
  • 22
Cactibuddy
  • 11
  • 9
    You have misunderstood the issue, see [Choosing power supply, how to get the voltage and current ratings?](https://electronics.stackexchange.com/questions/34745/choosing-power-supply-how-to-get-the-voltage-and-current-ratings) Whatever your actual problem, it is not that the USB port is able to supply more current than the USB device will actually draw. – Chris Stratton Sep 24 '20 at 16:12
  • If there is a problem with the circuit supplying the USB port, and it sometimes jumps up to 12 V (vehicle power), that would blow a memory stick. Measure the USB output voltage while the car is in motion. – AnalogKid Sep 24 '20 at 16:15
  • 1
    Your stereo's USB port is probably "junk" and doesn't properly protect your USB stick from load dumps or engine starting events. Safer thing to do is to keep the stick out of the stereo when starting the vehicle engine or shutting it down. It's probably okay while running, though. Get a better stereo? – jonk Sep 24 '20 at 17:35
  • @Cactibuddy think of a kitchen tap ... the water pressure in the pipes is like voltage in the automobile electrical system ... when the tap is fully opened, it can fill a pot with water in a couple of minutes ... that is equivalent to low resistance, which allows a lot of current to pass ... turn the tap down to a drip, and it can take an hour to fill a glass ... that is equivalent to high resistance that allows only a small current to pass ... the flash drive is like the tap ... the only way to increase the current is to increase the voltage, which is same as increasing the pressure in pipes – jsotola Sep 24 '20 at 18:16

1 Answers1

4

There is no need to convert 1 Amp to 500 mA!

Current is only delivered to a consumer in the rate that the consumer wants to consume the current.

If you have a USB memory stick that consumes 1000mA it will consume 1000mA.

And by the way, a USB memory stick that consume 1000mA is faulty!

Mats Karlsson
  • 402
  • 2
  • 10