Hi First I would like to say that I am not an electrical engineering student. I study physics, and unfortunately I lack a lot of basic electrical know-how. I know the theory behind e.g. a low-pass/high-pass filter and stuff like that, but when it comes to implementing things and - specifically - testing that my circuit works, then I fail. My wish is to get better at these things I have attached an example of a circuit that I found online. Say I have made the circuit, and now I want to test with a multimeter that everything works. 1) In the top right corner is "Supply". If I measure the resistance between "Supply 1" and "Laser diode 1", then I go through 2 resistors in series of 5.6 Ohm, 1 resistor of 39 Ohm in parallel and 1 inductor in series. Assuming that the inductor has no resistance (it is DC, so I guess I can neglegt it?), then is it correct that I would measure something close to R = 5.6Ω + 5.6Ω + 39Ω = 50.2Ω? 2) Say I measure from "Modulation 2" to "Laser diode 2". I have 1 resistor and 4 diodes in parallel with eachother + a resistor of 10kΩ in series. The arrow on the diode I guess indicates that I can't go through it. What should I expect to measure here? I would be very happy to get some feedback. Best, Niles.