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FET threshold tests with Bitscope
Some of you may recall my complaining about the lack of USB oscilloscopes for the Mac a couple of years ago, when I bought myself a used Kikusui COS5060 analog oscilloscope. In the comments for my...
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Negative resistance oscillator
In More mess in the FET modeling lab, I reported observing an S-type negative resistance in the nFET that I had not expected: Negative resistance 12mA and 50mA. (click to enlarge) I decided to see if...
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Tenth day of circuit class
In today’s class I had originally planned to cover the following topics: RMS voltage. I keep putting off a discussion of the 3 different systems for reporting AC voltage (amplitude, peak-to-peak, and...
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Inductance of large inductor summarized
This post summarizes my inductance measurements, some of which I did with my son, some independently. The goal was to determine the inductance of the large inductor that my wife found lying in the...
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Pressure sensor with air pump
I’ve been thinking of expanding the pressure sensor lab for the Applied Circuits Course to do something more than just measure breath pressure. Perhaps something that conveys another physics or...
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FFT on ATMega and BitScope
Yesterday, my son was thinking of adding a microphone to the design he is working on, and was considering adding a fast Fourier transform (FFT) to detect pitch. He spent a few hours after his 10 a.m.–5...
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Logarithmic amplifier
My son wanted to design a circuit to convert microphone inputs to loudness measurements usable by an Arduino (or other ATMega processor). We discussed the idea together, coming up with a few different...
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Logarithmic amplifier again
Yesterday, in Logarithmic amplifier, I ended with the following plot: (click plot to see larger version) The cloud of points is broad enough to be consistent with slightly different parameter values. I...
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Precision rectifier
The log amplifier that I’ve spent the last several days understanding (posts a, b, c) is not the only non-linear circuit needed for a loudness detector. We also need to convert the audio input signal...
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Improved rectifier
In the Precision rectifier post, I gave the simplest circuit for making a precision rectifier: This circuit is both a log amplifier and a precision rectifier. If Vb is set to a constant voltage, then...
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Improved rectifier with Schottky diodes
In the Improved rectifier post, I gave the following circuit for an inverting rectifier and showed traces of its performance using diode-connected S9018 NPN transistors as diodes: Only one of D1 and D2...
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First blogging swag
One hears about bloggers making money off their blogs from advertising (I get nothing from the ads that WordPress.com puts on my blog—it just pays for the free blogging service). One also hears about...
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Bitscope differential probe
In First blogging swag, I mentioned getting a pre-production prototype of the Bitscope DP01 Dual Channel Active Differential Probe: The probe PC board is about 6.2cm long and 2cm wide—8cm long with the...
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Wire loop vs. twisted pair try 1
I was thinking about things we might do in the first lab day for the Applied Circuits course next quarter, now that I have 2 lab sessions a week. The first, obvious thing is to unpack the lab kits and...
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Hysteresis lecture
Today’s class started with feedback on their second design reports (the electret mic lab). Everyone in the class got a “redo” on this assignment. Some of them actually had pretty good write-ups, but I...
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Hysteresis lab ended well
Today’s lab went well, with very little intervention on my part. Students finished up their RC calculations, picked their resistors and capacitors, and got their relaxation oscillators working. They...
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Last day of class for Spring 2015
Today was the last day of class, and I covered almost exactly what I proposed in last night’s blog post: one-transistor amplifiers, a review of the goals of the course, and getting suggestions for...
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Bitscope jitter and nFET Miller plateau
I got a little less than half my grading done this weekend (all the lab reports for the final lab, but not the redone reports from earlier labs, and not the 2–3 senior theses that had to be redone from...
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Update for nFET Miller plateau
In Bitscope jitter and nFET Miller plateau, I gave a nice super-resolution plot of the gate voltage on an nFET using the Bitscope and subsequent dejittering of the trigger: Here is an example of the...
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More on nFET Miller plateau
In Bitscope jitter and nFET Miller plateau and Update for nFET Miller plateau I talked about using the Bitscope BS10 USB oscilloscope and post-processing to remove the trigger jitter to get a better...
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