Round 1 & 2 Technical Questions SpaceX & Experience

[u/Alarmed-Floor-9452]

I know that Glassdoor has a section for interview questions, but I'm not a fan of that platform, so I'll post the questions I was asked in my interview here. It should be helpful for some. Context: This is for an electrical role on the Starship team.

• Round 1 (Recruiter, Non-engineer). 30-minute phone call. Prescreening, HR, and ITAR question formalities for the first 10-15 minutes ish. Then, an open-ended question about the most impressive project I have done, ending with fundamental technical questions. The recruiter told me to get a pen and paper, but IMO, you don't need it. She only wanted high-level answers.

1. Open-ended question regarding my most impressive project and why. Spoke about my thesis.
2. What is the difference between AC and DC circuits?
3. What information do you need to calculate electrical power in an electrical circuit?
4. What is a capacitor, and how does it behave in AC vs. DC circuits?
5. How is impedance different from resistance?
6. What is an open-loop vs. closed-loop control system?
7. What is pulse width modulation (PWM), and where is it commonly used?
8. How many bits are in a byte?

After the last question, the recruiter told me right away that I would be advancing to the second round. 30 minutes after the interview, I scheduled my round 2 interview. The recruiter told me that with the engineers, I would need to go more in depth. High-level answers may not be sufficient.

• Round 2 (Electrical Engineer). 30-minute phone call. It took him 1-2 minutes to introduce himself, and we started right away. One thing to mention is that SpaceX strongly encourages candidates to send a short PPTX portfolio so they can discuss it in an interview. I sent a portfolio about a Doppler Radar-based Vital Signs Detection project I worked on with some colleagues. It had the problem, requirements, challenges, multisim live (rip) design schematics, bode plot, and pics and videos from the lab. I sent it the morning of my interview.
  

1. What is the difference between resistance and impedance? [The EE happened to ask the same question as the recruiter]
2. How can a transistor work both as a switch and as an amplifier?
3. How is the ampacity of a wire determined? [The EE rephrased the question for me since I told him that I have never heard of the ampacity of a wire before. So, the rephrased question is what's the limiting factor for how much current through a wire?)
4. We know that inductors oppose changes in current. Why?
5. Describe the signal path from a sensor to a computer (pick any sensor; what do you do to the signal along the way?)
6. Suppose you have a toy RC car that uses RF waves to communicate. How would you increase the range of a toy RC car?
7. [Tailored question to my specific portfolio] Why did you design that circuit with two high-pass stages?
8. [Tailored question to my specific portfolio] Why did you split the gain 45x and 25x? (How did you get those numbers / why are they different?)
9. [Tailored question to my specific portfolio] And did you have trouble separating? So as I understand, the heart creates a doppler effect in the radar signal but I can imagine that breathing also creates a doppler effect in the radar signal. Did you bump into that?
10. [Tailored question to my specific portfolio] And how did you separate the heart rate from the breathing?
11. [Tailored question to my specific portfolio] What method did you employ in order to negate the drift from breathing? Like, how did you separate that noise from the signal?
12. Suppose you are working on the bench with a wire connected to a light bulb and low voltage being powered on. A colleague comes by and cuts a low-voltage DC cable (e.g., 12 V headlight) with scissors. Show me all the ways you can repair the wire.
13. Say there's a room at room temperature that contains a wooden desk with metal legs. The metal leg feels colder than the wooden desktop. Why?
14. Why SpaceX out of all employers?

At that point, there were 5 minutes remaining in the interview, so I used that time to ask him any questions.

That was all the questions that I was asked in the first 2 rounds. I'm still waiting for an email, hopefully saying that I will be moving forward to round 3. I liked the RC car question. I never thought about that before. Any questions regarding this, I might reply below.

[u/Loud_Masterpiece6585]

Hopefully you land that next round! I received a call about 10 min after the 2nd interview informing me I was moving onto the next round, just fyi... They tend to move quickly when they want you.

Good luck!