How can I indicate a USB charge with an LED?

I've seen some USB ports/chargers out there that have an LED that lights up when you plug the cable in.  Is there a simple way to do this?  I need the LED to light when the USB cable is plugged in, not when the charger is on.  So I could plug in the adapter and nothing would happen, but when I drew current to charge something, the LED would light up.  I can't figure out how to do it, so I'm asking you for some aid.  Thanks

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rickharris2 years ago

To check the lever of more or less anything you need a comparator. essentially an OP amp.

There should be ccts around to do what you need. Search the web fro circuits.

dudes (author)  rickharris2 years ago

I have looked far and wide for one, but still can't find anything. Do you have any idea how I could use one?

This helped me to understand how they work. Hope this helps !

www.dummies.com/how-to/content/electronics-components-how-to-use-an-op-amp-as-a-v.html

Wired_Mist2 years ago

Well I have seen many RC helicopter chargers include a LED in the male end of the USB cable. You can show it has power by simply crossing the 5v and ground across a led and a resistor(100-220Ohm)

As per Charging indicator, Have you already chosen the chips you will use to charge? I would recommend checking out this Charging IC It is one commonly used in Li-po chargers, and provides the option for a status LED ( Look at the Data Sheet) Unfortunately you are limited to 500ma charging rate; hope that's enough juice !

dudes (author)  Wired_Mist2 years ago

I would really like about an amp to an amp and a half. I'll take a look at the chip though, thanks for the idea.

Then I would Second Rickharris with the OP-Amp. Good Luck !

Hope to see what your making ! :D

well, I guess you could use some clips to use the conductivity of the material as USB input switch. I made this image, metal dashes are in own charger

Capturar.PNG
dudes (author)  ualbuquerque2 years ago

I was considering that, but that shows when the cable is plugged in, whether or not current is actually flowing through the cable. But thanks, I may do that anyway.

iceng2 years ago

Where is the LED, on the USB port ?

dudes (author)  iceng2 years ago

The LED could be anywhere, it doesn't matter, I just need it to light up when I plug the cable in.

rickharris2 years ago

To check the lever of more or less anything you need a comparator. essentially an OP amp.

There should be ccts around to do what you need. Search the web fro circuits.