Opencircuits

Paul was a self proclaimed expert in three different areas. The funny thing was that he was ‘expert’ in those areas one at a time. If someone asked him about high voltage, he claimed his expertise was in resonant flyback circuits. If someone asked him about resonant flyback circuits, he claimed his expertise was in magnetics. And of course if someone asked him about magnetics, he claimed to be an expert in high voltage. He got away with that for over two years and basically got no work done.

I was given design responsibility for a project and my boss wanted to assign Paul to my team. I resisted and said we needed competent people who could get work done and not a talker who deflected with his claimed areas of expertise. I was told in no uncertain terms that Paul was an asset and that he would design a resonant flyback circuit for my project.

Paul got to work by immediately heading for the copy machine with a schematic for an old project. He was going to take something that already worked and tweak it for a new application. I was skeptical but was told to let him work. Paul got his circuit board layout done in drafting and a couple of initial prototypes were assembled. During this time, I was designing a couple of other circuits for the project as and was helping out other members of the team. I was analyzing my circuits and doing some testing, so my circuits took longer to get into layout. My boss let me know that Paul was ahead of me. It wasn’t going to do me any good to point out that there were problems on the horizon.

Paul got his circuit ‘working’ in the lab and went to the boss and bragged that his circuit was ready to be proclaimed finalized. My boss went to the lab and saw that the circuit did indeed work after which we came to talk to me and gave me the business about how Paul completed the first circuit board on my project.

I let the boss finish talking and calmly asked him how long he saw the ciruit operate. He said he watched for about a minute. I suggested he go back and see if he could watch it operate for ten minutes or so. When he asked why, I told him that if he waited that long he would see a good show. There were two diodes on the board that would get so hot that they would melt the solder holding them in place and would fall off of the circuit board.

The boss thought I was joking, but I was not. When he realized that I was serious, he went and had Paul demo the board again. After a couple of minutes, Paul turned off the power. My boss told him he wanted to see the board operate for a while and Paul admitted that there was a problem. When asked whether there were diodes that self-unsoldered, Paul confessed that it was true.

Paul got fired a few days later. I heard later that he got a job with another company that made similar products. I never did hear how long he was able to keep up his facade of triple expertise at the new place.

Einar ‘The Insulting Engineer’ worked for some interesting companies. One of his most interesting adventures was when he was called in at the eleventh hour to try and rescue a project. The company had a very innovative design concept but just couldn’t get things completed. Einar was very good at problem solving, so they contracted him for a few weeks.

Einar started out by asking lots of questions and gathering all of the documentation available. Once he had a pretty good understanding of things, he sat down and did some analysis. The management wasn’t happy with that kind of work, because they were expecting instant results. Einar assured them that he would let them know when he had some meaningful input.

After a few days, Einar gave a presentation and a detailed report. He regretted to inform them that the concept that they were pursuing was fatally flawed and would not work and could not be made to work. He also outlined a revised concept that would work and offered to implement it. Needless to say, that’s not what they were hoping to hear. They meekly thanked him for his report and said they would get back to him with some kind of answer within a day.

Sure enough, a day later they called a meeting. They started out by telling Einar that they had reviewed his report and agreed with everything he said. But then they told him that what they really wanted was for him to try to fix up what they already had and complete the flawed design.

Einar had quite the explosive temper. He pointed out in no uncertain terms that they could not possibly have agreed with his report and asked him to fix what they had since his report explicitly stated that their design could not be made to work. Within a few minutes, he packed up all of his belongings and left. He never expected to hear from that company again.

Six months later, they called and asked Einar to come back. He told them he was disinterested in the work they were doing. They assured him that at that time they really did understand that their design could not be made to work and asked him to implement the concept he had proposed. Einar agreed to do so and he went back and successfully implemented the design they turned down. They finally got a good product, but they never did recover the lost revenue from the time wasted trying to implement their original idea. They did manage to save some money by not paying the salaries of the fired engineers who came up with the original concept and were no longer around when Einar reappeared.

Einar was a consulting engineer from Norway who specialized in power electronics. He was a brilliant guy who had consulted at over 175 companies. He had a lot of funny stories about morons at plenty of those companies. He had three rates for his services depending on what someone wanted to accomplish. His lowest rate was for interesting work that he hadn’t done too many times. His medium rate was for work that he had done multiple times and his highest rate was to come in and solve problems for someone’s disaster project. He didn’t take too many of the disaster projects even though he had offers for 10x more of that work than for the other categories.

Einar was consulting at a place where I worked. Some people didn’t take him so well as he could be pretty impatient. He didn’t like the slow pace and casual attitudes of some of the engineers. It wasn’t a common characteristic for a consultant in my experience, since most consultants billed by the hours and didn’t care if things took too long. Einar was into getting things done and move on to the next interesting project. He was definitely an engineer’s engineer.

We had a department meeting where we welcomed a couple of new employees and the boss went around the room and introduced everyone and said a few words about what everyone did. When he got to Einar, he said, “And this is Einar…the consulting engineer……or as some people say, the insulting engineer.”

Einar didn’t find it at all funny and immediately came back with, “Watch it. I’d rather be an insulting engineer than an insult to the engineering profession like a couple of people I can name in this group.” It got pretty quiet, mostly because everyone in the room knew that Einar was right. It was all I could do not to laugh out loud.

John was a real good engineer. He was easily one of the best I’ve ever worked with and one of the hardest working. One of the things about John was that he was unafraid to build and/or modify circuits no matter how many times he got made fun of for his soldering. His techniques with a soldering iron were as bad as his circuit designs were good. Solder blobs, burn spots, etc. were like John’s trademark. Anyone who worked with him for any length of time could recognize his soldering immediately.

Anna was an assembler in manufacturing. She’d help out in engineering pretty regularly and was one of the very best with a soldering that I’ve ever seen. Her skill level was impressive. She could fix just about anything and on multiple occasions got the honor of fixing up one of John’s solder jobs. The company started a program of IPC certification for everyone in manufacturing who soldered. Anna was selected as the trainer and person who awarded certifications within the company as she was easily the most skilled.

One day Anna went to John and asked him to solder a couple of parts for her. John had taken so much grief for his soldering from so many people that he was a little curious but honored to be asked by Anna. He soldered the parts and gave them back to her. When he gave them back, he asked why she had asked him for help. Anna got a little embarassed and told him that she was teaching the IPC soldering class and needed some examples of how not to solder. Everyone got a pretty good laugh out of that including John.

Don’s boss was losing patience. He couldn’t find work to assign to Don that Don wouldn’t completely mess up. He kept simplifying the assignments, but no matter what he gave Don to do, he’d end up having to re-do everything himself. At the same time, Don was complaining that he wanted to work on designing more complex, new circuits.

One day during all of this, the phone rang. It was the production people letting Don’s boss know that they had problems with a switching circuit. It wasn’t turning on like it was supposed to do. The production building was a few miles away. Don’s boss let him know that this was his chance to solve a real problem and show what he could do.

Don happily drove over to the other building and got to work. He verified that the circuit was indeed having problems and that the switching transistors were not turning on. Don sat down and drew out the circuit and somehow determined that the switches weren’t being driven hard enough. He grabbed some resistors and a soldering iron and did his thing.

It took a few days, but Don finally called his boss and declared success. He was able to get a half dozen boards to work by driving the switching transistors harder. Don’s boss hoped for the best and jumped in his car to check things out. When he showed up a few minutes later, Don eagerly handed his boss one of the reworked boards with the changes installed. The boss looked at the board for a good 2-3 seconds before his face turned a bright red. He pointed to the switching transistor and said, “Don, the transistors are installed backward.”

Sure enough, that was the only problem. The switches were the old TO-46 cans, which weren’t hard to install backward, but it was quite a bit harder to get them to switch when they were installed that way. Don had redesigned the circuit to drive the daylights out of those poor little transistors to the point that they switched. They wouldn’t have worked for very long like that.

They reworked the boards back to their original designed configuration and had the transistors put in the right way. Everything worked fine. Don still argued that he needed to work on more complex circuits.

Pete had quite the history of failure when it came to designing circuits. He never learned anything useful from his failures. He’d draw a conclusion, but it never was the correct conclusion. He designed a power converter that somehow made it to production. He saw plenty of failures during development, but that never stopped Pete from pushing bad circuits into production. The failures during early production testing should have been enough of a red flag to take a better look at things, but Pete’s answer to the manufacturing folk’s complaints was that they were obviously building them wrong.
The biggest issue with that particular circuit was catastrophic failure of some tantalum capacitors. Had Pete done his job correctly and calculated the ripple current and compared to the ratings of the parts he specified, he’d have known he had a problem. The correct conclusion should have been to make sure not to operate the capacitors above their rated ripple current spec.
Pete came to a different conclusion. He declared that tantalum capacitors were no good. He moved on to the next project where he somehow got say-so over all of the circuit boards in the final product. He declared that nobody was allowed to use tantalum capacitors and that ceramic capacitors were the answer. The power supply for that project looked downright silly. It had a little auxiliary board that piggybacked on top of the main power circuit and contained nothing but ceramics placed in parallel to get to the desired capacitance.
It wasn’t such a great idea. Pete did not understand and nobody could convince him that it wasn’t possible to get the same performance from ceramic capacitors as they were resonant at the same frequency and the overall impedance wasn’t low enough across the frequencies to get acceptable system performance. Pete was unfazed as usual. There were noise problems all over the place. Pete didn’t care and was very proud that none of the ceramics had the ends melt out of them like his previous circuit did after violating the ripple current limits. What’s a little noise problem compared to that?
They still had issues in production due to the noise problems. They would call Pete and ask him to look at that. Pete told them they obviously weren’t building them right.

Pete liked to design control loops even though he never could get one to work reliably.  No matter how many times and no matter how spectacularly he failed, he was fearless when tackling his next control loop design.  He did the bulk of his research with a soldering iron tacking capacitors in random spots in the circuit.  As soon as he’d get one to sort of work, he’d break out the champagne and declare the design done.

One of the worst circuits Pete designed was a control loop inside of a control loop.  He had some crazy explanation of how that was a great idea, but it was a fatally flawed concept.  Sure enough, Pete got one prototype sort of working and he declared the design done and signed it off.  The manufacturing department couldn’t get anything to work.  They’d call Pete and ask him to help troubleshoot, but he gave them his standard answer that they obviously weren’t building them right.  It didn’t take too long for the pressure to mount and Pete was getting a little nervous about his “design.”

Around that time, a state university was offering design analysis services to private companies.  They had some real circuit experts and some high powered computer analysis tools.  They offered to analyze some circuits to demonstrate their ability to solve complex problems in the hope of getting more of that type of work.

Pete decided to let the university folk have a go at his control loop.  He gave them the schematics and a brief description and they said they’d do their best to offer some help.  They worked on it for almost a month and responded with a brief report.  Their report stated that the circuit did not lend itself to be analyzed and they recommended that it be completely redesigned.

Pete was unfazed by the report.  As a matter of fact, Pete was extremely proud of that report.  He showed a copy to almost everyone in the company and bragged.  He said, “My circuits are so complex that they can’t be analyzed.”  I’ve thought about that situation a lot of times over the years.  I’ve tried to decide which was crazier between making a control loop inside of a control loop or bragging that your circuits cannot be analyzed.  I’ve yet to reach a final verdict.

I’ve heard that said over and over for a lot of years. People take power supplies for granted way too much. Power supplies are supposed to work under all conditions, take up almost no space, and are supposed to be cheap. In reality, power supplies are vital to working products and systems and are among the hardest circuits to design. The late Jim Williams wrote a classic application note that is available here:

http://cds.linear.com/docs/Application%20Note/an25fa.pdf

The first page of that app note should be required reading for anyone who uses the line, “It’s Just a Power Supply.”

Todd got moved into an engineering management position and took over some products that had a lot of circuits that I originally designed. He wanted to impress his higher ups by doing some cost reduction and improving profits of the product line. Todd quickly deduced that the quickest way he could save some money was to get a cheaper power supply.

Todd and his crew started out by locating cheaper supplies. It was a triple output supply and their search focused on meeting the voltage and current requirements while being substantially cheaper than what I had designed. I was oblivious to their efforts until they asked me to review specs on some supplies they were planning to test. They let me know that they had promised some big cost savings and were almost halfway there with the supplies they had found.

After a quick review of the supplies they were considering, I let them know that the supplies they chose would not work. They completely neglected to look at the cross regulation requirements of the supply. They were disappointed and said they’d keep looking. For the next couple of weeks, they came back and asked me to look at other supplies. I let them know again that the supplies they were looking at would not work due to cross regulation.

A couple weeks later, they sent the most junior guy in the group to ask me some questions. After asking some irrelevant questions, he let me know he had another question. He said, “What’s cross regulation.”

It was difficult for me not to laugh, but I patiently explained things to him. The power supplies output +5V, and +/- 15V. The heaviest load was the +5V output, which the supplies regulated closely. The +/- 15V outputs were not tightly regulated. In our application, the 5V output was used to power a thermoelectric cooler circuit. At room temperature, the current was very low and was much higher at the temperature extremes. The +/-15V outputs powered some amplifiers with very tight input voltage requirements. The supply that I designed had separate regulators for all three outputs and would work regardless of load on any output. A supply with poor cross regulation would result in non-compliant performance at several temperatures at which it was guaranteed to work.

Todd and his crew were disappointed, but they didn’t want to go back to the upper management types and tell them they weren’t going to come through with the promised cost savings. They went ahead and specified a new supply even though it would likely result in disappointed customers. They did all of the harness and mechanical drawings and scheduled a product review. Shortly before the review meeting, they discontinued the project to cost-reduce the power supply. It turned out that when they had the mechanical parts all built up and went to assemble their test units, they neglected to figure out that the cheaper supply was too big and it didn’t fit into the product enclosure.

It was impossible for me not to laugh at that one.