Friends, Romans, Countrymen, and internet hooligans: the third week of my work at Columbia University’s Plasma Physics Laboratory has come to an end, and with it, my hopes of completing this circuit without doing any programming at all. Last week I informed my cherished readers that I was hoping to utilize a scheme created by Iranian Electrical Engineers to make a frequency dependent resistor without using any digital components. While I was (finally) able to make their design function the way they said it would, the circuit they proposed was fairly limited in its frequency range and didn’t give the resistance decay that I needed in my own design. Long story short: I’ve ruled it out as a viable option. I get my digital components in tomorrow, which is exciting because I’ll hopefully get to start looking at existing code and seeing for myself what needs to be done in order for this digital business to work correctly. The idea was actually proposed by Professor Volpe, the principle investigator who I am working under and involves three components: a frequency to voltage converter, a microchip, and a digital potentiometer.
The frequency to voltage converter has a name that accurately explains its function. The chip takes in voltage and determines its frequency and then spits out DC voltage that is directly proportional to that frequency. Higher frequency incoming voltage gets you higher output voltage from the chip. Next, the microcontroller digitizes the voltage and outputs a number to the digital potentiometer. The digital potentiometer takes this incoming number and adjusts itself to a particular resistance, so effectively these three chips will (hopefully) give me a fairly accurate frequency dependent resistor when they are strung together and coded correctly. I had a chance to talk with one of the graduate students who works with the lab about this and he said that the decision to go digital was most likely a good one, which made me feel a lot better as I’m getting into unfamiliar territory.
My week took a different turn on Friday when Professor Volpe asked me to build a prototype for permanent use on one of the machines in the lab. Even though the circuit isn’t functioning exactly the way we both want it to at this point, he’s still interested in the applications that could be observed when it gets tested out. This means that I get to build something, which is pretty cool and that, even after I’m done this summer, something will stick around the plasma lab that I made. Again, hopefully it will work a lot better than it does now, but the fact that Professor Volpe asked me to build something this early on indicates to me that he’s interested in my project and is happy with the work that I’ve put in so far. My main plan for the beginning of this week is to produce, on a real board, the circuit that Volpe needs and get it to him by Tuesday, then begin working with my digital components on making the same design more broadband and more dependable. That’s all for now lovelies, I’m off to enjoy what remains of my weekend.