The USB Charger Doctor can be used to measure the working voltage and current output of any USB port and project. This blue plastic dongle connects to a USB device and allows data lines to pass through. To measure the current draw, a 0.05-ohm resistor is connected to the power pin. The numbers for testing devices such as chargers, cables, and cell phones are displayed on the Doctor's digital display in real-time.

The device has an input voltage range of 3.5 to 7VDC (although most USB devices have an input voltage range of 4.75 to 5.25) and can handle up to 3A of current. Every 3 seconds or so, it switches between voltage and current readouts. It's a very handy tool for testing USB devices, checking load levels, and debugging battery chargers and boost converters.

Specifications:

• USB 1.x and 2.x - all data speeds. Does not have USB v3 pins so USB v3 connections will automatically downgrade to v2
• Working Range: 0~3A, 3.5~7VDC
• Resolution: 10mV / 10mA
• Operating Temperature: 0-60ºC
• 21mm x 53mm x 15mm / 0.8" x 2.1" x 0.6"
• USB Plug: 13mm / 0.5"
• Weight: 16.2g