Categories
Consulting Life Podcast

So Chris, Where Have You Been?

Well,  a lot of places.

But not around here too much. And when I’ve been here, it hasn’t been the most in-depth writing I’ve ever done (except my unusually thought out post comparing engineers to a fictional character, check that out if you haven’t, not many people noticed it). I can’t say I will be writing again full time in the near future, but maybe in the future after that. So here’s a quick rundown of where I’ve been and what I’ve been doing if you don’t already know:

The Amp Hour

Reading through a few posts or sidebars on this site and you may have noticed The Amp Hour, my weekly radio show with Dave Jones of EEVblog. It’s been going really well so far I think. We just finished episode 23 and have about 1000 regular listeners. It’s been really interesting getting my thoughts out in a different manner than writing and I’d be lying if I didn’t mention that I’m now spoiled by getting my thoughts out “Off The Cuff”. However, there is still a place for planned out articles and this is the place I intend to put those thoughts.

Consulting

Earlier this year, I started a company, Analog Life, LLC. I began consulting for projects outside of my day job (in a non-related industry, with full approval of my day job, of course). I hadn’t really mentioned it on here before, but since it’s already linked in multiple places and listed on my LinkedIn profile, I figure I can explain myself.  This has been the biggest consumer of my time lately outside of work and has been a wonderful learning experience. From the business side of things, to the work I am doing, to the juggling of tasks outside of regular work, all have been new experiences for me.

Pondering My Future

In the remaining hours of my days before collapsing into bed at night, I have been thinking about long term plans and how it might affect the path I am on currently. First and foremost are my personal relationships. If you’re working 14 hour days (effectively) and don’t think your relationships will suffer…well, you’re probably working with the other person. And even then, the relationship can be strained. So I’ve been talking over and considering how working more will cause tradeoffs in my personal life. Am I willing to give up time with my family in order to pursue work that might advance my career? Is the work I’m doing actually advancing my career or just making me money? If it’s the latter, is the money justification enough for not spending time with them?

In talking with others in my field about this subject, other questions have bubbled to the surface, some even relating to consulting. Why am I consulting and what is the eventual goal? Will I need more education to continue in a technical role in engineering? Is consulting enough of a real world education in order to not require an MS in engineering?

Onward

There is really one question that drives all other conversations: What do I want to do (when I grow up)?

I like the idea of being my own boss and owning a business and even selling some sort of product someday (aside from design services), but right now I have neither enough experience with it to say if I like it nor any idea what kind of product I might sell someday. The latter isn’t too much of a concern, but not knowing if I desire that lifestyle could influence my present day decisions.  Here’s the highest level decisions I see myself having to make in the near future:

  • If I plan on being in a technical role at someone else’s company (i.e. employed by a corporation that is not mine) for an extended period, I should go get a Master’s of Science Degree.
  • If I plan on moving into a management role at someone else’s company, I should go target an MBA or a Master’s of Engineering degree (somewhat like a combo MS and MBA).
  • If I plan on consulting for a while longer, I should continue to build relationships and seek out new clients for more work (an ongoing struggle from what I hear from my consulting friends).
  • If I plan on trying to start my own company with a viable product, I should get on my way trying and failing (believe me, I don’t expect to succeed at that at first if I do it, but I understand the value of failing in electronics). I should also begin learning to pitch to investors, as I realize this is the most critical skill of starting a business.
  • If I plan on being a technology media personality, I need to work at it more. It would involve trying to make revenue through blogs, videos, sponsorship, advertising, etc. If this is the case, I had better post more often than once a month, eh?
  • I could not worry about this for a few years, keep my head down, keep learning and hope I’m rewarded for my efforts through my day job. While this is part of any of the plans above, I don’t really feel like this is a “plan” (though I’m sure some would advise me to do just that).

I love hearing peoples’ advice and stories about their own careers, but I’m very realistic: no path is the same and what is good for someone else is not necessarily good for me. That doesn’t mean I won’t listen though, because in talking to a just a few people, I have learned SO much. So I guess for anyone else out there wondering the same things as I’m wondering, my advice would be talk to people. Weird advice from an engineer, I know, but I’m not your standard engineer, am I?

So go forth! And chattify! Or chat in the comments. Yes, I prefer that actually. Thanks for reading.

Categories
Analog Electronics

Makeshift Current Sink

I’m working on a new switcher design and need to be able to test the total current coming out of a boost converter. Here’s what I’m looking at:

  • 0-60V rails (out of the boost converter)
  • 0-350 mA
  • No access to the load that will eventually be connected to the switcher

So what do I need? I need something that can sink current and dissipate any heat that will be generated. If the load is dropping the entire voltage at the top current, that will be:

$$!60V * .350 A = 21W$$

This is quite a bit of power. I was using the TIP41A that I have on hand, a power NPN transistor in a TO-220 package. With this amount of power, a heatsink is most definitely required. Here’s the simple circuit:

In this circuit, the divider from the incoming source (the top rail) sets the current going to the base ($$i_{B}$$) and this times the $$beta$$ (in this case anywhere from 15-60) equals the current down through the collector ($$i_{C}$$). This is not the optimal way to sink current from your source, but it’s a start. The fact that I’m dialing in the current with a potentiometer in a divider that is also connected to the incoming load is not great, but again, this was a quick and dirty way to get up and running. But wait, you think that’s a makeshift circuit? Check out my heatsink:

Yup, that’s a crowbar.

Close up of the attached BJT

I didn’t have any proper heatsinks laying around, so this became my hacked version. During testing, I was looking at 30V across the TIP41A and roughly 300 mA through it. The heat was transferred well from the TO-220 case to the crowbar and the dissipation was decent (heatsinks with fins are better at dissipating the heat). Next I need to step it up and see if this simple circuit can perform under full load. If there was perfect contact between the case and the crowbar, we should see roughly:

$$!Power * R_{theta_{j}} = Delta ^{circ}C$$

$$!21W * 1.92 ^{circ}C/W = 40.32 ^{circ}C$$

I wouldn’t be putting my tongue on the crowbar anytime soon, but I think that’s reasonable enough to handle this situation.

Now, there are much better ways to do this. I really like my co-host at The Amp Hour, Dave Jones’ video about a programmable dummy load. Hell, he even has a legit heatsink! There are advantages to using a MOSFET over a BJT as well, but I went with a BJT for this situation. Mostly I was just giggly about using a crowbar and thought others might enjoy. So…hope you enjoyed! If not, check out Dave’s video below: