Hello friends! It’s the end of my seventh week of work at Columbia University’s Plasma Physics lab and the end of the project is very much in sight. This week, since the part I needed to program the microcontroller did not come in until Thursday, I spent much of the week trying to create an array of inverters and mixers so that my phase shifting circuit could cover more of the angles in a circle. The original plan was to have it shift the incoming signal anywhere from 0 to -90 degrees, but with the array that I put together this week, it will be able to cover any angle in a circle through the use of three switches and four operational amplifiers.

I also soldered most of the circuit together this week, so the board has come together quite nicely. I’ll try to post a picture later in the week or definitely by the end of next week to show you all how I am progressing, but it is safe to say that a good portion of the circuit has been completed and is on an actual circuit board.

However, there still remains a significant final step to be taken. The voltage controlled resistor that I have been trying to make with a frequency-to-voltage converter, a microcontroller, and a digital potentiometer has not yet materialized. When the programmer arrived on Thursday afternoon I tried to upload the code I had written to the microcontroller and (big surprise), nothing happened. I have since tried two simpler versions of the code to no avail. This is the area of the project that I have the least experience in, so I’m not surprised that it’s not working yet. However I only have two weeks before I go home to San Francisco, and I’d like for the project to be done by then. I’d be lying if I said I didn’t feel any pressure, as this really has been my first research experience and I’d love to end it on a high note. However I’m confident that if I try hard and keep my focus, I’ll be able to figure out how to program this chip before I go home. If I don’t, I’ll have two weeks in California to let it stew, and then I have an extra week to work before I get back and school starts. I’d like it to not have to come to that, but you never know.

On Monday I hope to finish soldering the analog portion of the circuit and test it to make sure it works. Then all that will be left is the coding. Once that’s done, the circuit will be completed and hopefully I’ll get some good results.

That’s all for this week!

Scooby doo

L

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