Drawing Knots On An Oscilloscope Using Analog Means

Generating interesting imagery on an analog oscilloscope is a fun activity enjoyed by many, with an excellent demonstration by [Henry Segerman] provided in a recent video which covers [Matthias Goerner]’s demonstration. Using the electron beam, shapes can be drawn onto the phosphor of the oscilloscope’s CRT — all without touching any digital circuitry. At the core are analog components like an operational amplifier integrator, multipliers and other elements.

With just a number of these simple components in a circuit, it’s possible to draw a wide variety of shapes, all by applying the appropriate trigonometric parameters. In addition to the drawing of shapes, it is also demonstrated how these analog signals can be used for an analog audio synthesizer, and finally the image displayed on the oscilloscope is captured on Kodak (Polaroid) instant film, making the entire generating, processing and capturing chain fully analog.

While we’d be the last to campaign against digital electronics, it is fascinating to consider just how much can be done with analog electronics and a bit of mathematics. We assume that everyone did pay attention during math classes, making this a perfect chance to use all that knowledge of trigonometry.

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Eye-Catching And Crumb-Suspending

Printed circuit boards used to be green or tan, and invariably hidden. Now, they can be artful, structural, and like electronic convention badges, they are the entire project. In this vein, we find Open LEV, a horseshoe-shaped desktop bauble bristling with analog circuitry supporting an acoustic levitator. [John Loefler] is a mechanical engineer manager at a college 3D printing lab in Florida, so of course, he needs to have the nerdiest stuff on his workspace. Instead of resorting to a microcontroller, he filled out a parts list with analog components. We have to assume that the rest of his time went into making his PCB show-room ready. Parts of the silkscreen layer are functional too. If you look closely at where the ultrasonic transducers (silver cylinders) connect, there are depth gauges to aid positioning. Now that’s clever.

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Circuit Simulation In Python

Using SPICE to simulate an electrical circuit is a common enough practice in engineering that “SPICEing a circuit” is a perfectly valid phrase in the lexicon. SPICE as a software tool has been around since the 70s, and its open source nature means there are more SPICE tools around now to count. It also means it is straightforward enough to use with other software as well, like integrating LTspice with Python for some interesting signal processing circuit simulation.

[Michael]’s latest project involves simulating filters in LTspice (a SPICE derivative) and then using Python/NumPy to both provide the input signal for the filter and process the output data from it. Basically, it allows you to “plug in” a graphical analog circuit of any design into a Python script and manipulate it easily, in any way needed. SPICE programs aren’t without their clumsiness, and being able to write your own tools for manipulating circuits is a powerful tool.

This project is definitely worth a look if you have any interest in signal processing (digital or analog) or even if you have never heard of SPICE before and want an easier way of simulating a circuit before prototyping one on a breadboard.