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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 ...
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  • 391
13 votes
0 answers
574 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 ...
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9 votes
0 answers
185 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 ...
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  • 91
9 votes
1 answer
629 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 ...
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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 (...
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  • 91
8 votes
0 answers
448 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 ...
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7 votes
3 answers
347 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 ...
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7 votes
1 answer
365 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 ...
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7 votes
3 answers
540 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 ...
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  • 652
6 votes
1 answer
295 views

Q: Homework - Past exam solution Is this the right solution?

I am trying to find Vo but I am not sure If this solution right? Is there a shorter path to find Vo? solution
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  • 61
6 votes
0 answers
926 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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6 votes
1 answer
121 views

Phase shift near saturation mitigation in input stage amplifier -- How does this work, why does this work?

I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer. Apologies for the quality... this is the best scan I could find. The design is furnished with the ...
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  • 279
6 votes
1 answer
166 views

Beam Steering range of a phased array antenna system

What is the beam steering range of a phased array dependent on? For example, if I use an antenna array of Nx1, with a phase shifter resolution of \$\frac{2\pi}{k}\$ and the antenna elements spaced at \...
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6 votes
0 answers
287 views

Home made passive tablet pen

I have an old wacom tablet at home, its really big and I'd like to use it but I've lost the pen for it. It uses pens with passive LC circuitry. The board creats an EM-field (I can see it on my ...
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5 votes
0 answers
93 views

Why am I getting inconsistent voltages at op-amp's inputs in a simple DC amplifier?

I'm new to circuit design and am unable to figure out why I'm getting inconsistent voltage measurements under certain circumstances at the inputs of an op amp in a very simple non-inverting DC ...
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5 votes
1 answer
290 views

Reading the analog pin A0 on Wemos D1 Mini

I am doing a personal project with a Wemos D1 mini and one thing that was of interest to me was to detect a servo-motor stall. Very glad to find an useful answer to this question: How do I detect ...
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5 votes
2 answers
152 views

USB connector always reverse to connections on the IC

I'm looking to add an interface IC on to my PCB. The chip will interface through a USB B Micro connector. What I don't understand is why all the ICs I have found are designed so that the D+ and D- ...
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5 votes
2 answers
190 views

H Bridge failing under load

I have made 2 H bridges following this schematic. I have replaced TIP107 with TIP147 TIP102 with TIP142 The Opto-couplers are P785. I have not included the diodes as they are internal to the TIP. I am ...
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  • 73
5 votes
2 answers
302 views

Bridge rectifier low voltage

Power supply for headphone tube amp gives me 10-12V lower voltage comparing to the schematic (my measurements are in red for amp under load). Current under load is about 70 mA. Using simple formula : ...
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  • 51
5 votes
2 answers
545 views

How to meaningfully compare Xilinx MCS files?

Brief I have two different boards with Xilinx designs that might be the same design. I am trying to compare the different MCS files to see if the designs in them are in fact the same design. Can this ...
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  • 2,373
5 votes
3 answers
2k views

Undefined signal in simulation

I am trying to verify a design written in VHDL using SystemVerilog's assertions. I have a problem when I have a non-defined signal'X.' Just for example here is the code of a comparator: ...
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  • 51
5 votes
2 answers
3k views

How to calculate and measure motor constant for stepper motor?

I am working on a project using ST4118D30004 stepper motors and powerSTEP01 drivers. The ST4118D30004 is a bipolar stepper motor with 4 wire connection. While researching how to find the optimal ...
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  • 151
5 votes
0 answers
149 views

Frequency locking for averaging resampling

Background I've done a long one-shot measurement of a periodic signal by an oscilloscope. Thus, I've captured around 250 periods of a signal. The signal itself is a pseudo-random binary sequence at ...
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  • 57
5 votes
1 answer
748 views

Designing single fault safety into class I device

I'm trying to wrap my head around safety standards for electrical equipment. My device is medical, so for me section 8 of IEC60601-1 is what really matters to me, but it's kind of my understanding ...
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  • 111
5 votes
1 answer
278 views

DDR(2-4) Training and Length Matching

Today I learned about the concept of memory training for DDR2, 3, and 4 (I'm not sure if DDR1 has it). The purpose of memory training is to correct for skew in data, address, and command bits being ...
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  • 464
5 votes
0 answers
474 views

Understanding EGSM-900 (LTE 8 band) electromagnetic spectrum

I am trying to fully understand the physical layer of the GSM standard. For doing that I am looking at the E-GSM-900 band (mostly used in Europe). In my country these frequencies has been assigned to ...
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  • 175
5 votes
2 answers
746 views

PWM on phototransistor

I am pulsing the VDD with 50% duty cycle at a frequency of 188 Hz (PWM). I get some weird spikes on my output TP3. Am I missing something about phototransistors? Here is the picture of the IR circuit ...
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5 votes
1 answer
501 views

MCU HIB pin only pulls Buck/Boost EN pin every-other Hibernation

MCU: TM4C1294NCPDT Buck/Boost Converter: TPS63051 Hib dedicated LDO: MIC5504-3.3YM5-TR I have a LiPo battery coming into the board, feeding both the TPS63051 and the MIC5504. Tiva's HIB pin is ...
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5 votes
0 answers
152 views

Testing strategies for testing a Scheduler

We have developed an in-house Scheduler which is based on Rate-monotonic scheduling. We have 6 tasks (5 actual tasks and 1 idle task). Our scheduler works on 1msec timer interrupt. Before sending it ...
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  • 3,175
5 votes
1 answer
6k views

RGBHV (VGA) to YPbPr Converter and Waveforms?

Purely for hobby, I am working on an RGBHV (VGA) to YPbPr (Component) converter circuit for old games consoles modified to output RGBHV on a VGA cable. From the game consoles, the RGB signal is taken ...
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5 votes
1 answer
817 views

Thermal Modeling of 0805 Thick Film Chip Resistor

I recently got confronted with the question what peak/pulse power a standard 0805 thick film resistor can withstand. Background: We are designing a 2kW bidirectional DCDC converter. The Primary side ...
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  • 642
5 votes
1 answer
553 views

Charge mode piezoelectric signal conditioning

I have a charge-mode piezoelectric dynamic pressure sensor (datasheet link) that I want to read a signal from. If you look at the datasheet it says the sensor outputs are in a balanced and floating ...
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5 votes
1 answer
2k views

Current capacity of copper wires in vacuum

I’d like to know the current carrying capacity of copper wires in vacuum. The current plan (NPI) calls for sending ~3 amps through the vacuum space of a cryostat. Has anyone done this? Have any ...
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4 votes
0 answers
87 views

How to properly couple DC in this biased headphone amplifier design on power-up?

I am a self-study noob to electronics (and audio electronics) but diligently learning every day :) Some things I understand well, others I'm fuzzy on. This device is a headphone amplifier using NE5532 ...
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  • 141
4 votes
0 answers
52 views

Butterworth Filter attenuates noticeably in pass-band

The Issue: I am using a Maxim MAX7480 8th order Butterworth low-pass filter to counter any aliasing from a sensor that measures signals up to 3kHz, but I only want up to 1kHz. Thus a critical ...
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4 votes
1 answer
77 views

Solar panel for 6 V, 1100 Wh battery

I have a sensor in a remote area that draws 15 mA @ 6 V for 16 hours each day, powered by a 6 V, 1100 Wh low discharge battery. I'm trying to achieve around 2 years of autonomy. Daily consumption is 1....
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4 votes
0 answers
116 views

Custom RP2040 PCB Not Detected by PC

I designed a custom RP2040 to control some 24V LED strips. The official hardware design guide from the Raspberry Pi Foundation is what I followed for my design. It was then sent out to JLCPCB for the ...
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  • 445
4 votes
2 answers
159 views

How to fix oscillation of an 'over-discharge protection' circuit for a lead acid battery

I've created a circuit to protect my lead acid battery from over-discharging. I used the following circuit diagram. Over-discharge protection circuit for a lead acid battery: For understandable ...
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  • 706
4 votes
0 answers
194 views

Self resetting crowbar circuit for over voltage protection

I'm trying to design an over voltage protection circuit that doesn't rely on custom chips (the chip shortage has shown the danger of relying on this,) so I put together a crowbar circuit like this: I ...
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  • 195
4 votes
0 answers
138 views

Transformer saturation when current is flowing

I have a nanocrystalline center-tapped transformer with 2 turns at the secondary and 17 turns at the primary. There are 4 windings at the secondary as each leg of the transformer is parallelized with ...
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  • 1,256
4 votes
0 answers
133 views

When to use a high voltage resistor vs multiple standard resistors?

Looking for the smallest & most reliable method of dropping 360V down to ~1V for a PMIC feedback pin. Reliability is probably the most important variable here. Question: In general are we be ...
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  • 3,426
4 votes
2 answers
184 views

Problem with simple non-inverting NE5532 configuration

I am building a small amplifier which is working just fine. While experimenting I interchanged the TL072s with NE5532s and the amplifier stopped working, so I set up a simple non-inverting amplifier ...
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4 votes
0 answers
108 views

What determines the voltage rating of a cable?

I'm trying to figure out the maximum voltage of some cables in a vacuum system I've inherited, and I'm confused by the DC voltage ratings given by this supplier as they step from the 3 kV to 10 kV ...
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  • 308
4 votes
0 answers
158 views

How to understand a complex diode-resistor function generator circuit?

I'm reverse-engineering a CRT anti-pincushion circuit and it uses a complex diode-resistor circuit to approximate the function X-k×X×Y², where X and Y are the deflection voltages. My question is if ...
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  • 2,332
4 votes
0 answers
217 views

Cannot find what causes faults on DRV8353RH

I keep getting faults on a a new batch of ESC boards based on the TI DRV8353RH & Infineon IPT020N10N3ATMA1. Please consider: When starting a motor at 48V - 56V the DRV asserts a fault after ...
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  • 81
4 votes
0 answers
86 views

Why is the imaginary part absent in the BJT gain calculation?

The gain of transistor Q1 was previously calculated in this post simulate this circuit – Schematic created using CircuitLab It was found to have a gain of about 2.92. Now I change the ...
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  • 437
4 votes
0 answers
42 views

How to show opamp noise contribution in LTspice .noise calculation

When doing system noise calculations using LTspice using the .noise instruction, I can plot the total output noise and I can plot all the individual noise contributions to output noise from all ...
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  • 10.2k
4 votes
0 answers
666 views

ESD protection for ESP32 GPIOs

I want some of the ESP32's GPIOs to be accessible via 3.5mm headphone jacks or RJ11 jacks and therefore need suitable ESD protection. I wonder how much is needed for optimal protection. Conditions/...
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  • 41
4 votes
0 answers
128 views

What keeps frying my RF switches?

Short version: What might be breaking the first sensitive component connected to an ungrounded 14cm UHF dipole antenna mounted 30' above the ground? Could it be related to static electricity? I have ...
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4 votes
0 answers
230 views

Is there any specific application for an indirect band gap semiconductor?

I know that direct band gap semiconductors are very attractive for optical emission, and even though indirect band gap are used as well, I keep wondering: is there any technology that specifically ...
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