# All Questions

25,269 questions with no upvoted or accepted answers
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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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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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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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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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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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### 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 ...
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 ...
• 383
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 ...
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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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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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'...
• 63.3k
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 ...
• 279
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 \...
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 ...
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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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 ...
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- ...
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 ...
• 73
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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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 ...
• 2,373
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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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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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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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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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 ...
• 464
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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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 ...
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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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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### 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 ...
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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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 ...
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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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 ...
• 141
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 ...
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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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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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 ...
• 706
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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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 ...
• 1,256
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 ...
• 3,426
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 ...
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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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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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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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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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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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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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 ...