About a month after I initially applied for a position as a Touch Hardware Engineer in the Touch and Sensing Group at Apple, I was contacted by an Apple recruiter. The initial phone screening was to provide more background on the position. She informed me that I would be given a skills test and, once sent, I would have 24 hours to complete it. I asked if she could send it the next day.

The skills test consisted of four questions. The first question required an analysis of a voltage conversion circuit where a 5V output was stepped down to 3.3V via a voltage divider. I was to provide an analysis of this design in terms of pros and cons. The next two questions were basic op-amp analysis questions, which were fairly straightforward. The last question involved analyzing an attached data file showing the distribution of parts on two assembly lines and making a sales decision based on the data. They requested that I complete one PowerPoint slide to present my results.

After contacting the recruiter a few days later, I had a follow-up interview via Skype scheduled for the following week. The hiring manager immediately began with technical questions. The reason they use video chat is that they draw diagrams on a whiteboard for you to analyze. There were three questions: analyze a circuit and determine its function (a boost converter), discuss the ideal properties of an op-amp (specifically, the gain-bandwidth product), and how to sample a square wave (focusing on its frequency spectrum).

After an additional week, and following up with the recruiter, I was asked to come in for an onsite interview. It was at this point that I was sent a different job description, one for a Characterization and Automation Engineer. I suspected this was a downgrade from the position to which I had actually applied. I scheduled all my travel personally through the company's travel portal for an interview date another week out. I was told to study a handful of subjects for the interviews, which were 45 minutes with each staff member from 9 a.m. to 4:00 p.m., excluding lunch. It was also at this point that I was switched between recruiters.

Meeting with nine people that day, I can say I encountered a gamut of personalities. The process was somewhat chaotic, with some interviewers not knowing the conference room we were supposed to be in. The format of each interview was generally 5-10 minutes of questions about my resume/experience, 25 minutes of open-ended technical questions, and the remainder devoted to my questions about the job. Questions about the work in the position were futile; everyone was tight-lipped about the ongoing work. The usual answer was that it was a small group that functioned like a startup. Some people were much more interactive about digging into my resume, while others jumped right into the technical questions. The assistance provided with design problems at the whiteboard was similarly varied. One interviewer was quite happy being contrary to all of my plausible answers to the open-ended problems because they weren't what he was thinking. A good strategy would be to talk through everything and be as animated as possible.

The hour-plus lunch with the hiring manager was easy, but my suspicions about this position being a downgrade were confirmed. To paraphrase, they put people in this position for 'a while' until they get used to things. This was deflating, but I continued with the interview.

Meeting with the recruiter was pointless and somewhat unpleasant. When asked about the salary I wanted, I told him I had a rough number in mind but didn't have any data on this position to compare it to. He told me I didn't have to worry because I would be compared to people coming from top-tier (read: better) schools. This didn't bode well, considering 80% of the staff I interviewed with went to Stanford. I did have one very rude interviewer. He showed up late to our meeting and was clearly uninterested in the interview. He was the only person not to have my resume available. While I was working out problems on the board, he was on his phone checking emails the entire time. In retrospect, I should have said something to get his attention.

After sending out thank-yous to the staff, I was informed that they would be making a decision in a week and that I would hear back. I followed up after a week to learn they wanted to interview one more candidate, but it was between me and him (a suspicious level of detail). They would get back to me in another week. Another week and a half went by, so I followed up again. This is when I was informed the position was a better fit for the other candidate (a peculiar way to let someone down).

Overall, it was a really good exercise in a comprehensive interview process, but the inflated egos of some employees and the hand-waving about the position did leave a bitter taste in my mouth about working at Apple.

You have a metal sphere hanging from a spring in an elevator. You would like to measure the movement of the ball relative to the carriage throughout the day.

A.) Come up with a list of devices you could use to measure the movement.

B.) Use the capacitance formed by the ball and a metal plate on the elevator floor to create a measurement device for a microcontroller.

Come up with several different circuits (block diagrams) of ways to measure a capacitor.

You have a strain gauge with a nominal resistance of 10KΩ and varies by only +/- 1% under maximum load. Design a circuit to measure this sensor with an output range of a full 0-5V.

Part 2: If you needed 1000 different levels of digital accuracy, how many bits would you need in an ADC?