Featured Engineer

Interview with Todd Harrison

Todd Harrison

Todd Harrison - Database Admin by day; Hobby Physicist and Electronics Engineer by night (genius for short)

How did you get into electronics/ engineering and when did you start?

I knew I was destined to be an engineer when at the age of 6 my father gave me a football for my birthday. I still remember going outside to play with it, but within minutes I was back in the house getting a steak knife because I couldn’t untie the strings on the football to see what was inside. I was quite surprised to find cutting the strings off didn’t open the ball. A couple of jabs did eventually get it open. My father was very upset, but I never saw it as a negative. I found out what was inside; a black rubber bladder that held the air and I learned how the fill valve worked without a cap or stopper to keep the air in.

As I got older, I took apart everything, even if I got into trouble. My sister would always get a new music box for Christmas but it would be completely disassembled before New Years. Did I say I got into a lot of trouble? She loves me now, however, because I fix everything for her including cars, dishwashers, computers you name it. She says having an Engineer for a brother is the best if you can keep from killing him while growing up.

For me electronics started with a 6v lantern battery, 6v flashlight bulb and a few bits of wire. I couldn’t believe how simple it was to make a flashlight work. That is when the magic veil covering electronics lifted for me. By age 10 I had built a telegraph system between my sisters’s room and mine following a diagram I noticed in an old encyclopedia set. Using bits of cut tin, wood, screws, magnet wire from an old toy and my model train transformer I was learning and sending Morse code.

How did you go from studying Engineering Physics to programming?

My transition was purely economic. Fresh out of college in 1993 I had little engineering experience but years of experience hacking out code. My first job was an engineering position but the pay was so low I couldn’t support my family so I had to look for other work. At the time there was a lot of buzz and dollars in computer programming so I fell back on my high school programming skills and got paid 3 times as much as I was being offered for entry level engineering jobs. The rest is history, but I still love engineering and have a nicely outfitted electronics lab and welding workshop in my garage. I share my hobby work and whatever I think is fun on my blog.

What are your favorite hardware tools that you use?

Number one would be screwdrivers of all sizes and I even find myself fabricating my own screwdrivers sometimes to get into stuff. After that I enjoy my Fluke multi-meters, I have several for different usages. I do have other brand multi-meters but they seem to always give me problems and I don’t trust them.

I had to work for years in my garage lab without an oscilloscope but my wife gave me a nice Tektronix TDS2012B for Christmas a few years back and WOW I can’t count the number of times that has helped track down problems faster. In college you learn about scopes a bit and you use a few for some labs but you never get the time to appreciate one until you have one.

I fabricate a lot of projects like vacuum chambers, Van De Graaff generators and redneck pool heaters from scrap metal so a must have for me is welding, cutting and drilling equipment. I have a MIG welder, plasma cutter, midsized Oxygen – Acetylene torch set, two drill presses and a hand held band saw. A Dremel tool with lots of cutting, grinding and sawing tips is also a must. Without these tools I wouldn’t have the freedom I need to fabricate and/or fix a great many things and I would be so sad!

What are your favorite software tools that you use?

At my day job I’m an Oracle Database Administrator so I use a lot of software tools but my go to program is always TOAD by Quest software for Oracle and MS SQL Server. I recommend the Professional suite with DBA module and lots of time to learn all the great stuff it can do for a DBA. Once you know how to use all its features it magnifies your skills by 3 to 5 times over where you would be using Oracle tools or command line scripts. You still have to know the command line interface for emergency control but for day to day tasks it is a must have tool for any company that maintains such databases.

What is on your bookshelf?

When I was young I amassed all of Forrest M. Mims III engineering mini-notebooks from Radio Shack and his book “Getting started in Electronics”. Those are the best books for learning electronics in high school and early college years. You can’t get the mini engineering notebooks anymore but thankfully they are being republished in a 4 volume collection which is on Amazon and I have seen them at Radio Shack lately. Even though I have the dozen or so little mini notebooks I have since purchased the 4 volume set and find them much easier to lookup circuit examples than shuffling through all the old mini notebooks plus I have verified the content is the same. I have links to these and other “Books you should get ASAP” on my blog bookmarked “Beginner in electronics.”

What challenges do you foresee in our industry?

Getting young kids interested in engineering in our country again. I think the engineering bug is partly born in someone out of the desire to know how things work and because they are bored and want some stimulation. There are two main things working against kids in our country now days. One is that kids have all the stimulation they could hope for from home video games, internet gaming, cell phones, TV, movies, facebook, email and texting 24/7. They are never bored enough to wonder about the world around them. They never have to improvise a toy or invent a game to play. If they want something they are raised thinking all you can do is buy something at a store. The second reason is that everything that is around them is locked up in black boxes that either can’t be opened or is extremely difficult to open without damaging the content. Because of this, safety and the fear they might damage something kids are never encouraged to examine or understand the devices they use on a daily bases. Even when I was a kid I got in trouble for breaking a lot of stuff I took apart but I pushed on. Others succumb to the punishment and stopped. Because of these reasons the magic veil never lifts in their mind and they go on living happily never knowing or caring how things really work. This maybe why we already have a shortage of engineers in this country and it is destined to become much worse in the coming generations.

What has been your favorite project?

When my daughter was 13 she wanted a pool party for her birthday. Her birthday is in February and our pool is much too cold to swim in that time of year. She asked if we could heat it but the cost of a commercial pool heater and the gas line installation was prohibitive. I suggested we could try building a pool heater I had in mind but it would take a lot of work and time. She was all over the idea and jumped right on board. We started by building a small prototype that had just one copper pipe going through our gas grill with a garden hose on either end. It heated a 5 gallon bucket of water quite fast so the numbers looked good enough to continue. We spent the next 40 hours of our free time over the week soldering all the copper we could fit into our gas grill and still close the lid (180 feet). When we finished we connected the garden hose feed lines to the pool filtration pump and let it run. About 4 tanks of propane and 3 days later the pool was warm ~89F! I have a site dedicated to the build here and it has inspired many others to build pool and hot tub heaters which are showcased under the “more photos” section.

Do you have any note-worthy engineering experiences?

Back in 1993 in my last year of college at NDSU I worked on a free space laser communication system for the Air Force. Free space laser communication was nothing new but our design requirements were quite radical for the time. The device had to be very portable, run on 9v batteries, using only a 5mW pen laser and send voice communications over 1 mile! We looked a bit funny shooting a red laser around campus every night especially during fog or snow. We used a rifle scope to align the source and target so you can imaging the funny looks we got aiming the laser down the sidewalks and from building to building through open windows. Great fun and we did workout all the issues ending with a portable free space communicator that work at 1.5 miles. It might have worked even farther but lining up a collimated beam at 1.5 miles was quite a challenge being the collimated beam is only 3 feet across at 1.5 miles and that translates into an absolute split hair adjustment on the source. To even get the alignment to work we had to scavenge an x-y micron adjustment stage from an old microscope. During the prototyping I learned that 9 volt batteries only work for about 3 minutes at -25F unless you insulate them somehow and those carbon resistor trim pots crack from the cold. Most of the trouble came from environmental conditions and us not being familiar with such impact to product design.

What are you currently working on?

I’m working on several projects almost perpetually. Getting the time to complete one project before being distracted by another is the real trick. My most current project which is almost done is running my bicycle tire in a test rig using a scavenged AC motor. The test rig is so my daughter can work on her SpokePOV kit from Adafruit at the lab bench and the motor will make it easy to spin up the wheel to check the image and/or animation. It takes longer for these projects because I document it all and shoot video for my ToddFun blog. This build includes welding, repairing the scavenged motor and building a 120v AC to 15v DC power source to run a cooling fan to cool the AC motor. The cool part is I built the 15v DC source using only a light bulb, diode and capacitor and showed the viewers how to correctly calculate the required wattage light bulb and what is important to get it right without getting into too much engineering.

What is the hardest/trickiest bug you have ever fixed?

I can honestly say I’m still working on that. See my “Power Supply Repair” blog posts parts 1 through 5.

I still haven’t figured out what is wrong with this power supply and I keep putting it on the back burner, but I promise you I will find the problem and when I do I can assure you it will qualify as my hardest/trickiest bug ever Ha.

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