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Q&A

General Q&A about the design and function of electronic systems, electric power systems and infrastructure, their theory, and tools specific to those fields. Read these guidelines before posting.

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66%
+2 −0
Control logic for mosfet in piezoelectric energy harvesting circuit

I'm working on an energy harvesting circuit known as an in-house harvesting circuit (cc-ih) and would appreciate some guidance on implementing it in Simscape within Simulink. Circuit Description: ...

2 answers  ·  posted 6d ago by losdox‭  ·  edited 4d ago by Nick Alexeev‭

40%
+0 −1
LNA layout consideration 1-1000MHz

Mini-circuits LNA PHA-LN13+ has suggested: Eval board Layout Eval Gerber The image took from the Gerber file (3rd ref.) (Though all 3-reference mentioned containing it): There I have som...

0 answers  ·  posted 12d ago by mohammadsdtmnd‭  ·  edited 5d ago by mohammadsdtmnd‭

50%
+1 −1
What are these mystery components (one of wire coil, another labeled "100-10L A9")?

I have here an acre-counter or crop counter device like the lykketronic shown below, using two AA batteries. It arrived without working. Upon opening its case, I found that the PCB is missing tw...

2 answers  ·  posted 21d ago by Conrado‭  ·  edited 18d ago by Nick Alexeev‭

50%
+0 −0
LED driver with feedback through light. Which feedback topology is better?

I’d like to create a stable IR LED light source. I’ve read that LED efficiency changes with temperature. I’ve seen two designs which used feedback through light to correct the LED temperature dri...

1 answer  ·  posted 1mo ago by misk94555‭  ·  edited 22d ago by misk94555‭

40%
+0 −1
Determining the output swing, output common-mode range and input common-mode range in a differential amplifer

I am currently learning amplifier design, after constructing the unity gain amplifier(which is a differential-input single-ended-output amplifier) in the unity-gain feedback configuration I have pe...

1 answer  ·  posted 25d ago by aditya98‭  ·  last activity 25d ago by Olin Lathrop‭

71%
+3 −0
Step voltage 750kV lines

Some gentlemen decided to throw a hook with wire over 750kV lines in Belarus. They survived, however, I find in interesting to find out why. Assuming the connection to Earth was solid, there would...

1 answer  ·  posted 1mo ago by Elleanor Lopez‭  ·  last activity 1mo ago by Olin Lathrop‭

60%
+1 −0
Regulated charge pump design

I am working with an IC that uses a partially intergrated regulated charge pump. The circuit looks like this: It behaves like a voltage doubler. However, when looking at other regulated charge p...

1 answer  ·  posted 1mo ago by Mu3‭  ·  last activity 1mo ago by Olin Lathrop‭

66%
+4 −1
Humidity specs - is there typical reasoning for lower limit greater than 0?

Question about relative humidity specification for electronics. Industrial automation, indoors, cabinet or instrument enclosure. The failure mechanisms at the upper limit are fairly intuitive. I'm...

0 answers  ·  posted 1mo ago by Pete W‭  ·  edited 1mo ago by Pete W‭

83%
+8 −0
PCB as a wall of an underwater enclosure

Can a circuit board be waterproof enough to form a wall of a waterproof enclosure? Regular PCBs made of FR-4 with solder mask is what I have in mind. But I'm not barring less common PCB materials...

2 answers  ·  posted 2mo ago by misk94555‭  ·  last activity 1mo ago by Conrado‭

PCB
71%
+3 −0
MAX485 transceivers breaking, Pi filter generating spikes?

Problem description & speculation about causes I've having a problem with MAX485 transceivers breaking intermittently, passing our production tests but later failing. The error phenomenon is w...

2 answers  ·  posted 1mo ago by Lundin‭  ·  last activity 1mo ago by Andy aka‭

71%
+3 −0
1-wire interface overvoltage protection

I'm designing a robust 1-wire output for an IoT board. The interface should be able to withstand high voltage. Mainly the same voltage level as the board power supply. That's 12V to 36V DC. The p...

1 answer  ·  posted 1mo ago by DeadMouse‭  ·  last activity 1mo ago by Olin Lathrop‭

60%
+1 −0
MOSFET drain current ringing in saturation region

I benchtested below 0.7A constant current source circuit and observed few cycles of oscillation on drain current. With the help of bode plot analysis , I have managed to reduce the oscillations on ...

2 answers  ·  posted 2mo ago by kadamrohan16‭  ·  last activity 1mo ago by Olin Lathrop‭

66%
+2 −0
Matched transistors

There are circuits that require matched transistors. Whether BJTs or FETs. Like current mirrors, logarithmic amplifiers, etc.. There are some examples: https://www.youtube.com/watch?v=DUlugLSroN8...

1 answer  ·  posted 2mo ago by Chupacabras‭  ·  last activity 2mo ago by Andy aka‭

33%
+0 −2
Implementing local ground theory on PCB power distribution [closed]

I've tryed to implement a local ground concept told by Olin Latrop here : He have told: (What I've perceived)You should not connect every gnd point instantly to gnd plane, since it can inject HF ...

0 answers  ·  posted 2mo ago by mohammadsdtmnd‭  ·  closed 2mo ago by Olin Lathrop‭

66%
+2 −0
Why would a standby UPS fail to power devices when there's no power outage?

I have an ordinary consumer-grade standby UPS with, I believe, ample power for the devices connected to it.[1] It's five years old. For the second time in about a month, I've found my computer po...

4 answers  ·  posted 2mo ago by Monica Cellio‭  ·  last activity 2mo ago by Canina‭

60%
+4 −2
estimation of pogo pin resistance

Is there a scientific way to estimate the resistance of a pogo pin? If it was a solid cylinder or wire one could calculate the resistance: R = ρ × L / A But a pogo pin is hollow inside, the sp...

2 answers  ·  posted 3mo ago by dekker‭  ·  last activity 3mo ago by TonyStewart‭

66%
+2 −0
What type of button is this on a remote control

The remote control of my TV has two kinds of buttons. There are "normal" ones for the digits etc. which work by bringing a conductive material on the underside of the button in contact with the boa...

2 answers  ·  posted 3mo ago by samcarter‭  ·  last activity 3mo ago by TonyStewart‭

75%
+4 −0
High voltage transformer design

Suppose I have a planar PCB transformer. The primary and secondary coils are printed on different PCBs. The core is inserted through these PCBs to link the two coils. The primary is at a low voltag...

2 answers  ·  posted 3mo ago by jonathan_the_seagull‭  ·  last activity 3mo ago by Andy aka‭

75%
+4 −0
Level shifting of a 3 state logic pin

I want to design a simple battery charger using MCP73831/2. This chip has a 3-State state pin according to the table below: I have a 3.3V MCU and I want to connect this pin to a GPIO. The MCU is...

2 answers  ·  posted 2y ago by dekker‭  ·  last activity 3mo ago by Nick Alexeev‭

75%
+4 −0
Most reliable galvanic isolation technology for extreme EMI environments?

I'm working on another project with extreme EMC requirements as per various notorious military EMC standards. Civilian product but for military use, and as such subject to the toughest levels of co...

1 answer  ·  posted 4mo ago by Lundin‭  ·  last activity 3mo ago by Olin Lathrop‭

50%
+2 −2
Weird grounding on a vintage hifi sideboard

I got a vintage ('64) hifi sideboard for Christmas! It's super awesome. However, I don't understand the grounding. It has two female inputs on the backside that are labeled as "Grounding". There w...

1 answer  ·  posted 4mo ago by OddDeer‭  ·  last activity 4mo ago by Olin Lathrop‭

75%
+4 −0
Speed of EM waves from the point of view of an electrical engineer

An important formula in physics is one that relates the speed of an EM wave (c for instance) with the magnetic permeability and electric permittivity of the medium. In short: - $$c = \dfrac{1}{\sq...

1 answer  ·  posted 4mo ago by Andy aka‭  ·  edited 4mo ago by Andy aka‭

71%
+3 −0
Transformer design for a Series Resonant Converter

I am determining the Area-Product of the core required for a transformer to be used within a series resonant converter. The specifications are as follows: Switching frequency = 400 kHz Primary ...

1 answer  ·  posted 4mo ago by jonathan_the_seagull‭  ·  last activity 4mo ago by Andy aka‭

60%
+1 −0
CAN BUS monitoring with a LED

Hi, how can I use can bus monitoring through a simple led without disturbing the can line , I started with a diagram found on this forum, I need your help to correct where necessary, I want to use...

3 answers  ·  posted 4mo ago by Marian_20099‭  ·  last activity 4mo ago by Lundin‭

57%
+2 −1
Can I make an AC inductor (reactor) rated 75mH 40A from a 3-phase induction motor?

For my test bench I need an inductor (aka "reactor") that meets the requirements below. I have tried to purchase it outright as a made-up item, or the parts to make it (core and windings), but have...

2 answers  ·  posted 6mo ago by Fabio Barone‭  ·  last activity 4mo ago by TonyStewart‭

50%
+0 −0
Converting 5V to ±12V

I would like to convert 5V rail I have on PCB to ±12V. Existing solution is using boost converter 5V to 12V, and a buck for 5V to -12V. This feels bulky for what it's needed - here are the requirem...

2 answers  ·  posted 5mo ago by 2kind‭  ·  last activity 5mo ago by H_H‭

77%
+5 −0
Ceramic capacitor "memory" effect?

I have run into an interesting phenomenon related to ceramic capacitors. This question is part of the effort to understand the issue, and eventually work around it. But first, some background of ...

2 answers  ·  posted 5mo ago by Olin Lathrop‭  ·  last activity 5mo ago by TonyStewart‭

60%
+1 −0
Noise from oscillator on top layer to clock on bottom layer with VCC & GND layers between

What effect does an oscillator potentially have on a SPI clk signal if the oscillator is on the top layer, with GND and VCC layer in between on a four layer board. I know running it on the same lay...

2 answers  ·  posted 5mo ago by Hawk2020‭  ·  last activity 5mo ago by Nick Alexeev‭

71%
+3 −0
What fabrication process is being used for jellybean parts

I want to know why the top-of-the-line CPUs and GPUs from Intel, NVIDIA, and AMD are all bragging about the fabrication process (7nm and 5nm) and trying to be consistently smaller. At the same tim...

3 answers  ·  posted 5mo ago by dekker‭  ·  last activity 5mo ago by TonyStewart‭

33%
+0 −2
Beginners Guide To Power Circuit [closed]

I'm Interested In Power Circuit. What Courses/Guidelines To I Need To Properly and Effectively Under Power Circuits??

0 answers  ·  posted 5mo ago by Kalel‭  ·  closed 5mo ago by Nick Alexeev‭

62%
+3 −1
When and where to use vias in an IC design layout

I am learning IC design layouts using Cadence Virtuoso and now I got stuck with the concept of using vias. The question is when and where to use it? I am attaching the schematic of my inverter tuto...

1 answer  ·  posted 6mo ago by aditya98‭  ·  last activity 6mo ago by ErnestoG‭

60%
+1 −0
IEPE Sensor Internal Circuit

Based on reading the All About Circuits article on IEPE sensors there are two general types of circuits integrated into this class of sensors: voltage amplifier and charge amplifier. This question...

0 answers  ·  posted 6mo ago by DavidE‭

75%
+4 −0
Driving LED with NPN transistor from I/O pin

I'm trying to understand a circuit for driving a LED found on a board I purchased. Below is the circuit driven by an I/O pin (HS2) of a small 3.3V processor. The HS2 pin is driven by the I/O wi...

4 answers  ·  posted 4y ago by eric‭  ·  last activity 7mo ago by TonyStewart‭

60%
+1 −0
derating MLCC ripple current for transient current spikes

This graph - MLCC temperature rise vs ripple current RMS & frequency If I had a 10 us current spike every 100 000 us (akin to a half-sine wave and then the rest of 9999 sine waves missing), ...

2 answers  ·  posted 7mo ago by kellogs‭  ·  last activity 7mo ago by TonyStewart‭

66%
+2 −0
Will shorting a lithium ion battery cause an explosion?

I've seen batteries get shorted a few times. They heat up, and obviously the battery is not useful after, but I've never seen them explode or catch fire. I've read reports of some batteries catchin...

3 answers  ·  posted 7mo ago by matthewsnyder‭  ·  last activity 7mo ago by TonyStewart‭

75%
+4 −0
What are some best practices for library management?

Most CAD packages use a "symbol" and "footprint" library approach when it comes to designing schematics and PCBs. Some (like recent versions of Altium) have "component" libraries where symbols and ...

3 answers  ·  posted 7mo ago by Mu3‭  ·  last activity 7mo ago by H_H‭

72%
+6 −1
How to protect RF switches from ESD?

Assume that I have some generic antenna connector, followed by a pi-filter/50ohm impedance matching components, then a DC blocking cap (as per the RF switch recommendations) and then a RF switch fo...

4 answers  ·  posted 2y ago by Lundin‭  ·  last activity 7mo ago by Nick Alexeev‭

RF
71%
+3 −0
Burned Source Driver - Noise Spikes from Relay Coil

I am trying to figure out what is causing an Allegro A2982 source driver to burn up. The source driver (A2982) is connected to the coil of a Panasonic TXS2-9V relay. The source driver and coil ar...

1 answer  ·  posted 7mo ago by mrbean‭  ·  last activity 7mo ago by Olin Lathrop‭

77%
+5 −0
Soft-start circuit behaviour

Let's take a soft-start circuit that looks like this: To my understanding, the function can be described as follows: C1 charges to open the gate. Value of C1 will dictate the soft-start delay...

1 answer  ·  posted 8mo ago by Mu3‭  ·  last activity 8mo ago by Olin Lathrop‭

50%
+1 −1
Confusion about channel capacity definition and units

Why can the channel capacity C of the additive white gaussion noise (AWGN) channel be denoted in different ways and how do they relate to each other? Examples: C = (1/2) * log2(1 + SNR) [bit?] ...

0 answers  ·  posted 8mo ago by daniel_s‭  ·  reopened 8mo ago by Olin Lathrop‭

66%
+2 −0
ATX Computer Power Supply Spark in Non-computer Application

Hello! I would like to ask for your assistance with using a Silverstone DA1650 Gold computer power supply (you can find more about it here: Silverstone DA1650 Gold) for a non-computer application. ...

1 answer  ·  posted 8mo ago by Gabriel‭  ·  last activity 8mo ago by DSI‭

85%
+10 −0
Why 3.3V instead of 3V?

Usual values used in doing electronics/power supplies are almost always round numbers: 5V 12V 28V 48V 60V I understand that in some cases ICs are built to accept the voltage directly comi...

4 answers  ·  posted 3y ago by 2kind‭  ·  last activity 8mo ago by TonyStewart‭

71%
+3 −0
What is Ground Electrode in EMG?

*Learning about EMG as a part of our research. My team has at least some experience with electronics that is worth mentioning, but don't have any experience with EMG/bio-potentials. Most EMG hardwa...

2 answers  ·  posted 8mo ago by tilly‭  ·  last activity 8mo ago by TonyStewart‭

75%
+4 −0
Essential safety features of an EMG/medical grade device?

EMG consists of an electrode gel skin interface, op-amps with a certain gain and an ADC. Question is in the context of passive electrodes. What are the essential safety features of such types of h...

3 answers  ·  posted 8mo ago by tilly‭  ·  last activity 8mo ago by TonyStewart‭

75%
+4 −0
Power switches and automotive load dump, unclamped

Power switches used in automotive are usually rated to withstand clamped load dump events, of the 35 - 40 V peak variety. AFAICT there are two main clamping mechanisms - first one for the logic par...

2 answers  ·  posted 8mo ago by kellogs‭  ·  last activity 8mo ago by TonyStewart‭

60%
+1 −0
Can the corner frequency of thermal noise change with change in source impedance?

In EMG there is a certain level of thermal noise created at the electrode-gel-skin interface which depends on the skin-electrode impedance (also known as source impedance). I have been able get th...

2 answers  ·  posted 8mo ago by tilly‭  ·  last activity 8mo ago by TonyStewart‭

77%
+5 −0
Deriving resistor values for a taper pad attenuator

A taper pad is a resistive attenuator that maintains impedances on both ports and provides a specific amount of gain-loss ($A_{12}$): - I have derived formulas for each resistor (that I know to ...

3 answers  ·  posted 1y ago by Andy aka‭  ·  last activity 8mo ago by Lorenzo Donati‭

40%
+0 −1
Suggestions for projects in Embedded systems [closed]

Currently, I enrolled myself in a master's course this fall in the field of Computer Engineering. I am excited to create my microcontroller projects. I want to understand how much complexity is exp...

0 answers  ·  posted 8mo ago by aditya98‭  ·  closed 8mo ago by Nick Alexeev‭

75%
+4 −0
Disabling breakpoints in real-time section of firmware

Got a question about hazardous breakpoints in real-time firmware. Does C have a mechanism which lets me mark a section of code such that breakpoints are somehow ignored or not allowed just in that...

3 answers  ·  posted 8mo ago by misk94555‭  ·  last activity 8mo ago by Gnomo‭

75%
+4 −0
Cable loops between utility poles?

Sometimes cables between utility poles make a loop and do a U-turn. What is the purpose of such loops? The loop I'm asking about is in the lower set of wires towards the left of the picture. The...

1 answer  ·  posted 3y ago by Olin Lathrop‭  ·  last activity 8mo ago by Lorenzo Donati‭