Script and Tests
Ammeter Script
- Right-click ammeter_cyberscope.hex (below), and choose Save Link As…to download.
- Click the micro:bit Python Editor’s Open button, then select and open ammeter_cyberscope.hex.
- Click Send to micro:bit.
- Click the three vertical dots ⋮ by the Send to micro:bit button, and select Disconnect.
- Start the CYBERscope:
- In a different browser tab, go to cyberscope.parallax.com.
- Click the CYBERscope’s Connect button.
- In the serial port dialog, select the port with mbed in its name, and then click Connect.
Ammeter Tests
You are now ready to measure current through the LED.
- Check the meter. With a 220 Ω resistor, the current should be in the 5 mA neighborhood.
The m in mA is the metric prefix for milli or “1/1000th of”. In this case, the current measurement is 5.108 mA, or 5.108 thousandths of an amp.
Try This
- Try replacing the 220 Ω resistor in the DC LED circuit with a 1 kΩ (brown-black-red) resistor.
- Repeat this with a 2 kΩ.
- Also, try reversing the red and black probe ends in the LED circuit. Is the measurement negative?