Script and Tests

Ammeter Script

  • Right-click ammeter_cyberscope.hex and select Save link as… to download.

ammeter_cyberscope.hex

Ammeter Tests

You are now ready to measure current through the LED.

  • Go to cyberscope.parallax.com and click Connect.  
  • 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?