Measure
Calculation of current flow through LED
I would like to determine the current that is flowing through an LED, which I drive and modulate with a 50 % duty cycle square wave modulation at a modulation frequency of 1 kHz using a function generator (I use this one: RIGOL DG1022, output impedance: 50 ohm; Vpp = 10 V, DC offset: +5V). To do that, I measure the voltage drop across a 1 ohm series resistor using the NI-USB 5131 oscilloscope. Now I am a little confused about the measured voltages: voltage RMS = 92 mV, voltage amplitude: 184 mV, voltage peak to peak: 208 mV. Now I don't understand how these voltages are actually related to one another and which one I should use for my current calculation using U = Z * I? Thank you for your help. I really want to make sure that the current flow is not exceeding the maximum allowed current but still as high as possible such that the emission power is maximized.
