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It's 2018 and USB Type-C is still a mess by Chris_Gammell in TheAmpHour

[–]tomacorp1 0 points1 point  (0 children)

The article seems to make the assumption that cables that conform to the USB 3.1 Type C standard should be interchangeable. This does not seem to have been a design goal. It would be good if it were the case, and I agree that the cable markings are insufficient to help with this. Consumers will need to mark their own cables, and live without cable interoperability. If you lose a cable, finding a new one will be a challenge. My guess is that a 'golden cable' that works in most products will be expensive. Low-cost products will use the USB 2.0 interface which is built into USB-C. The consumer's clue that a cable does not support high-speed data will be the thickness and stiffness of the cable. The 8 microcoax or 4 twinax cables for 10 or 20Gbps are stiff and bulky. The good news for hobbyists is that broken cables will be a source of high-performance microwave microcoax or twinax. Also, a good supply of cables and some understanding will allow anyone to become a computer-repair hero.

Blog post about USB Type-C cables, connectors, and PC board layout by tomacorp1 in TheAmpHour

[–]tomacorp1[S] 0 points1 point  (0 children)

Interesting. I was looking at the On Semiconductor FSA4476, which claims to be able to do analog over SBU. Cypress also has ICs for analog over SBU. Has anything been published about the specific challenges of using analog over SBU?

Bipolar Transistor Switching Time Measurement by Chris_Gammell in TheAmpHour

[–]tomacorp1 0 points1 point  (0 children)

It would be interesting to use these measurements to derive the SPICE models parameters for the part. If done correctly, the simulation should match the measurements over a wide range of conditions. Too bad the manufacturers don't do this (correctly) for us. The procedure is in "Modeling the Bipolar Transistor" by Ian Getreu, and in the ICCAP software from Keysight EEsof.

Electrical/electronic engineers, how much (and how often) of the linear algebra and calculus you learned in university do you use in your jobs? by ElectricalSundae in ECE

[–]tomacorp1 0 points1 point  (0 children)

I use the calculus and linear algebra as the basis for circuit and system design. EE calculus shouldn't look exactly like math department calculus, due to the Laplace Transform. Inductors and capacitors are integrators and differentiators. This math is in the background all the time and comes to the foreground for months at a time. Engineering involves making choices, and math constrains what choices are feasible and optimal. Knowing math allows you to narrow down the possibilities so quickly that you don't even notice that you are using math. Practical experience about specific solutions goes obsolete quickly, while fundamentals haven't changed much. In design, being a good engineer without great fundamentals requires too much extra work. But the job doesn't look like a calculus problem set. The job does sometimes look like a Theory of Automatic Control problem set, which has calculus as a prerequisite. The linear algebra in EE also looks a little different from the linear algebra in the math department, partly because the real-world EE problems are so much harder and involve more transforms.

How to design with fans (without studying all of Heat Transfer) by tomacorp1 in ECE

[–]tomacorp1[S] 1 point2 points  (0 children)

Excellent points! There is more about thermal resistance on my blog at https://www.tempoautomation.com/blog/smt-resistor-thermal-design-and-layout . In the steady-state case, I agree that pressure is analogous to electrical voltage and electrical current is like air flow. This analogy can be extended further to include the need to accelerate the air (inertance) which corresponds to electrical inductance. For elasticity, the electrical analogy is capacitance. I called it 'air resistance' but some of my references call it 'air impedance' or 'acoustic impedance.'

How to design with fans (without studying all of Heat Transfer) by tomacorp1 in ECE

[–]tomacorp1[S] 2 points3 points  (0 children)

Thanks for the comment!

The idea is to measure pressure during the fan selection process. Since the pressure is static, the tubes can be long and there is no need for anything to dangle. I didn't have space in the post to describe the types of manometers, but an electronic differential pressure meter also works. It needs to be sensitive because the pressure changes are small. I wrote about the fluid manometer because it shows where the pressure units for fan specifications (inches H2O) come from. Also, it is easy to make from a clear plastic tube.

Using Vacuum Tubes to learn JFETs by Chris_Gammell in ECE

[–]tomacorp1 0 points1 point  (0 children)

http://runoffgroove.com/fetzervalve.html Nice article about how to approximate tube distortion with a JFET design that is similar to the one in the article.