Unanswered Questions

25,796 questions with no upvoted or accepted answers
22 votes
0 answers
2k views

Switch from JTAG to SWD with bitbang sequence on STM32F103VB

I am trying to switch from JTAG to SWD without any external devices. Why? Because I would like to use the SWO pin to send a stream of logging information to another device. To accomplish this ...
14 votes
0 answers
770 views

What is this weird EMV pin on my credit card?

I recently got a Venmo card, which is my first card with contactless support. I was looking at the EMV pins and noticed a very weird design. In the middle of the ground pin, there is this long, thin ...
10 votes
0 answers
256 views

Speed of compound wound dc motor

This is homework. Given a 500W, 200V compound wound motor with constant shunt field and a series field that varies with armature current, how do we calculate the change in motor speed. I know the ...
9 votes
1 answer
788 views

Convert analog piezo "transition" to digital signal

I'm trying to get what amounts to a knock indication into a microcontroller input from a piezo sensor. It's looking fairly good now at the fifth iteration, and about ready to provide digital levels ...
9 votes
2 answers
4k views

Dual active bridge converter

I'm having issues calculating the power losses associated with the operation of a bidirectional isolated dual active bridge DC/DC converter. The converter is controlled using phase shift modulation (...
8 votes
1 answer
184 views

Phase noise of op-amp

Suppose I have a carrier signal with low-ish RF frequency (a few MHz) that I can reasonably amplify with an op-amp. How can I estimate the added phase noise due to the amplifier? For microwave ...
8 votes
0 answers
513 views

Looking for criticisms for a VNA-like meter I am designing

I would like some help from anyone who could let me know any flaws or improvements in my design they can find and help me reconsider any last minute design fixes before I send my new project off to be ...
7 votes
0 answers
127 views

Is birefringence exploited or otherwise meaningfully observed anywhere in electronics?

Birefringence is a property of certain materials where the refractive index of the material is dependent upon the polarization and direction of propagation of light through it. I recently learned ...
7 votes
1 answer
167 views

Why does current flow direction matter in welding?

In DC welding, there are two configurations - direct current electrode positive (DCEP) and direct current electrode negative (DCEN). When the electrode is negative, the current flows from electrode to ...
7 votes
2 answers
387 views

Rigid-Flex PCB Fabrication: Window opening vs slot opening

We had issue with one of the rigid-flex design cracking at the joint of Rigid and flex intersection. It is important to note that this is second batch of same PCB and PCB was not cracking in first ...
7 votes
1 answer
393 views

Incrementing net name for group in Eagle

I want to make 50 copies of the block below, but I need incrementing numbers on each of the net labels (these will go to a connector). I do not want each block connected to the other blocks. It would ...
7 votes
3 answers
567 views

GPS power consumption MTK3339 vs SirfIII for periodic logging application

I am currently working on redesigning a SirfIII based battery operated GPS logger. A MTK3339 based GPS module has been selected due to overall (advertised) performance. The GPS logger uses a ...
6 votes
0 answers
87 views

Burned motor controllers: possible root causes analysis

On a submarine robot we built, during an operation, we recently had 3 defect thruster motors (the internal power PCBs have many burnt components, 2 of the motors cracked open due to internal pressure)....
6 votes
0 answers
166 views

What textbook is this problem from? (circuit analysis)

A somewhat unusual question: Some years ago, the following problem appeared in a test I took during my Bachelor's in electrical engineering. Later, the professor told us which textbook he took it from,...
6 votes
0 answers
1k views

Is JTAG faster than SWD for debugging on an STM32F with STLINK-V3SET programmer?

There is a new STLINK-V3SET programmer that someone dropped off on my desk today. It supports USB 2.0. My thinking is that if SWD is the bandwidth limiter in the signal chain then a new programmer isn'...

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