Invented amplifier by chance

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When Google doesn't give you an answer: build your own!

nicolasi_ Dhal_amplifier_DTU

An unsuccessful Google search resulted in BSc Eng student Nicolai Dahl speaking at an international conference in Paris this summer.

“I’d chosen to build a class D amplifier for my course project. So I ran some searches on Google, but as I couldn’t find a drawing that showed how you actually build one of those, I designed my own. It turned out that I’d made the amplifier in an unusual way— one that captured people’s attention.”

That was how the fairytale began for 21-year-old (at the time) Nicolai Dahl, who is currently studying Electrical Engineering at DTU.“After I handed in my fourth semester assignment, one of the professors came over, almost knocked my door down and told me I needed to take a special course so I could write a scientific article about it.”

No sooner said than done … With some help from his lecturers, Nicolai demonstrated how his use of a new, self-oscillating modulator in a class D amplifier produced clearer sound than models that use different types of modulator.

A class-D amplifier is an electronic amplifier in which the amplifying devices (transistors, usually MOSFETs) operate as electronic switches, and not as linear gain devices as in other amplifiers. Despite it’s complexity, a class-D amplifier presents a few benefits: energy and cost saving, high power conversion efficiency, converting directly from analog, etc. This type of amplifier is usually used in hearing aids and cell phones, to preserve the battery lifetime. 

Invited to a conference in Paris

Nicolai’s research article was well received, and in June he walked onto the stage at the Audio Engineering Society’s annual conference in Paris to present his findings to some of the world’s leading researchers in the field.

“It was a nerve-jangling experience; even though I’d practised and practised, it was a real thrill to stand up there at the microphone and all that. I had to hold the presentation in English, and when you’re standing in front of the leading minds in the field, you know that unless everything you say is absolutely correct, they won’t have any hesitation in letting you know.”

According to PhD Student Niels Iversen, who acted as Nicolai’s supervisor, it’s not every day that a humble BSc student has a scientific article published—and is then asked to present his findings to the world’s leading researchers.

“Nicolai has been excellent in every stage of the process. He’d already done a lot of the ‘heavy lifting’ before he came to me, which meant we could immediately start giving him a special course so that he could write his article,” says Niels Iversen from DTU Electrical Engineering.

Not at all done with his studies

“I’m actually already working on another article. This one’s about class D amplifiers as well, so who knows … I might be invited back again. That’d be really exciting.”

Looking to the future, Nicolai dreams of carving out a career in the field of robot technology. He is particularly interested in advanced prosthetics and self-driving cars. But that will have to wait until he has finished studying at DTU—and there’s a long way to go there. Nicolai is not done with his education; not by a long chalk.

“I’ve just started on my MSc, and I’d love to take a PhD as well. So I’d be keen to stay at DTU for quite a while yet,” concludes Nicolai.

Adapted from article by Andreas Johansen, DTU News 

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