Oh hey, remember me? Yeah, I'm the guy that's supposed to be running this site. Sorry for the long absence. I've been consulting, recording my electronics radio show, managing a multi-blogger engineer site and even getting married! Jeez, it's been a busy time. Anyway, things have cooled off a bit, so I've freed up some time (for now, never know what'll happen).

I decided to dive into a new project after a long hiatus from hobby type activity. I plan to put an MP3 player and output stage board into an antique radio enclosure. I also decided to document the process, specifically using the open source board layout program, KiCAD. I've been talking about learning the software and doing the videos for a while now, so here it is! The first installment is the schematic capture. I'll add more as the board gets more complex and I need to dive more into the process of actually getting a board fabbed. I'm excited! Hope you enjoy the video and the ones to come!

I was contacted a while ago and dragged my feet, like any good engineer. But today I was the "featured engineer" on EE Web! Exciting!

Aside from the fact that it was very nice of them to think of me, I'm just as excited to be featured on there along with friends from the electronics scene! My co-host of The Amp Hour (who probably won't let me forget who was interviewed first), Dave Jones has been featured in the past. My co-conspirator for the recently completed 555 contest, hackmaster elite Jeri Ellsworth has been featured. And someone else I really respect from the hobbyist scene, Limor Fried of adafruit.

If you haven't checked out EE Web, I suggest it. They have a really clean interface which I like for browsing their articles. The forums are still a bit light on participation but hopefully will fill up with knowledgeable people soon. Thanks again to EE Web for featuring me!

Aside from the 555 contest I mentioned in my last post, my February was spent building the workbench I drew in Google Sketchup. It was built partially for The Amp Hour, partially for circuits I plan on building and showing off on here and partially for my new business, Analog Life, LLC.

So for today's show and tell, I'll premier the first video ever with me in it on YouTube:

I also had a couple snapshots of the bench in progress:

So my bench is done now and I'm off to put it to good use!

I'm guessing if you follow me at all on Twitter or Facebook or just about anywhere else on the internet (I'm not too hard to find), you might know about the 555 contest. I have been talking about it quite a bit on various channels, all except here.

So I thought I'd discuss some of the aspects I might not discuss on other forums because they wouldn't be relevant. But since this site is basically about me and my interests...well I get to write whatever I want! Sweet!

First off, I thought I should mention Jeri. Honestly, I didn't know her well when we got started working on the contest. Mostly just talking on Twitter and watching her videos. It's been nice getting a chance to chat though. She's just as bright as her videos let on. And it's always interesting meeting new engineers with similar past experiences. Many of the same struggles I've gone through in the past, she has as well. Since she has more experience than me, I've been learning stuff from her. When I'm not learning from her, we usually make fun of Dave together! (kidding Dave!)

Next, I thought I should mention the spontaneity of the articles about us and the contest. Have a look at some of them:

• Jack Ganssle wrote about us on his site Breakpoints
• Mike Demler wrote about us on his blog IC Design Corner
• MAKE wrote about us when we were getting started
• Hackaday called me famous for some reason. Everybody responded, "Huh? Who?"
• Paul Rako didn't like the 555 (nor did Bob Pease) but wrote about us anyway
• A few other originals and a few that syndicated content from above.

So here's the dirty little secret: we know most of the people that wrote about us. Yup, it's true. But the interesting part for me is thinking just how often this kind of things happens. A friend/acquaintance calls up and tells you about an upcoming design contest, you might want to write about it, right? Welcome to the world of PR! I'm super happy all these wonderful people decided to write about us, and I don't think they would have unless we had something fun and intriguing; but still, I thought it was interesting and wonder if the contest could be even bigger if bigger names were setting up the contest in the first place.

And finally, I should point out that as much as I enjoy working on the contest, it's a ton of work! I'm not trying to complain but it makes me appreciate those that run other similar events (and in the past I didn't consider it). Sending emails alone and trying to coordinate sponsors across distances can really wear on you. If nothing more, it's a lot of typing! So not difficult per se, but time consuming.  Not to mention my stellar timing of jumping into this project a week after EngineerBlogs.org started; I really set myself up for a bit of time sitting in front of a computer.

So that's all from me for now. In case you've been lamenting my lax writing schedule, I'm signed up for at least one post a week over at Engineer Blogs, usually on Wednesdays. And I can continue to be heard weekly on The Amp Hour radio show. And if you really want to grab my attention, be sure to check out the 555 contest site and start your entries today!

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:

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 () and this times the (in this case anywhere from 15-60) equals the current down through the collector (). 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:

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: