texts: Can USB PD pass-through charging deliver different voltage settings than it consumes?

texts:
I'm trying to understand USB PD pass-through charging and what charger/dock/host combinations would be compatible or how much power would actually be passed through. I have a MacBook Pro 2017 which does 60W USB PD, and just bought an Aukey dock for $60 which says it can pass through 60W. Now I'm wondering, since third party chargers have historically been regarded as not trustworthy, if this is still the case for USB PD charging, or whether I can mix and match these days. It would be nice if docks supporting USB PD had their own power conversion circuitry, so I could buy any charger that does 60W USB PD (let's say the dock negotiates 20V 3A with the wall charger), and the dock would consume that but convert it to whatever the attached host wanted (let's say 9V 3A if I happen to attach a fast-charging phone, or 15V 3A for a laptop that only charges at 45W). However, given the size and price of these dinky little docks I don't imagine they do. But maybe the big >$250 ones can?
Now, afaict this is kind of a moot point for most laptops, since 20V is the only allowed voltage for 60W and 100W anyway, and after negotiation both dock and host would share the same 20V bus for power, right? At that point the only remaining concern would be the safety of the charger, but I would still like to understand whether the pass-through power feature has the dock and host sharing a single negotiated voltage, or whether this is a two-stage process with 2 negotiations and 2 potentially independent voltages. I do think that the dock will need at least some power conversion, because it presumably needs to feed power to a bunch of attached devices that will likely all run on 5V, which it would have to step down from 20V if that was the negotiated voltage, correct?
TL;DR can I stick any old 3rd party 60W wall charger into a 60W capable dock and expect the host to get whatever power it likes? Or do I need to make sure that the wall charger and host are compatible in the first place? And how exactly is that implemented?


texts: Is it possible to rapidly bring a cell back to equilibrium after charging/discharging by applying a current flow in the opposite direction?

texts:
This is an example electrical model of a generic Li-Ion cell.

Image credit-
https://www.researchgate.net/publication/260712260_Simultaneous_Fault_Isolation_and_Estimation_of_Lithium-Ion_Batteries_via_Synthesized_Design_of_Luenberger_and_Learning_Observers
After stopping charging a cell, we expect a high voltage that slowly decays down to the OCV.
After stopping discharging a cell, we expect a low voltage that slowly decays up to the OCV.
The question is, right after stopping charging/discharging for example, can we apply a known current flow in opposite direction for a predetermined duration to rapidly bring the cell back to equilibrium & be able to measure OCV at the terminals? (instead of waiting for hours)
If this is possible, is it possible to work out the required opposite current and time reliably for a ?


texts: What's the name for a switch that opens its contacts when pressed?

texts:
The title is probably already enough info. Just an example:

Imagine a power button on the front of a computer that is always connected except when pressed, it disconects for a brief moment.


texts:
I have a need for a FAST linear actuator of which I may control position and speed reliably. I have already been looking into pnuematics, however it does not seem that this will fit my needs (I am open to suggestions though).

Currently my wanted motor specs are:

>16"/sec
about 1lb of force
Position control
Speed Control

It seems that I may be able to make a DIY linear if you will, however I wanted to ask the forums for a sanity/experience check.

Below is a rough drawing of what I was thinking to create.

Assumptions:

I am able to close the loop with position (looking at hacking a caliper for this or maybe even some Linear Pots in parallel, Source Link to Calipers for positioning data)
I have a micro controller fast enough to process this position data (I believe I will be using a STM32F series but sill up in the air on this)

See the picture below for a rough outline of how I am hoping to accomplish this:

I will be controlling this with an off-the-shelf ESC.

In addition to the ESC, I will also be buying a ball screw assembly to be used as seen here - Lead screw assembly

I want to get feedback for this idea and anything that experience has shown may not work. This will be my first stab at this sort of project, so while doable it does seem like it can get big quick.

I am worried that I might be attempting to reinvent the wheel here, so what I was hoping to get is feedback on this idea or an alternative.

Thank you all in advance.


texts:
I have parallel Inductor and Capacitor like below. This is a one part of the circuit.

simulate this circuit – Schematic created using CircuitLab

I want to have sinusoidal current on waveform. Everything is ok. But in the circuit, @ the output of the capacitor voltage is changing, it is like fallowing sine wave. Cap input is fixed and 12V, so that capacitor getting too hot. Is there any additional circuit to prevent it. Full circuit diagram and its' explanation is below.

9837 is a Sinewave generator and connected to Nano 1 to set frequency. It's output goes to LM358 to amplify it to desired voltage level. And with 4131, i am playing with digital potentiometer that is directly connected to LM358(U1) amplifier circuit to obtain desired gain. At the end I have pure sinusoidal waveform that i can play with its' peak voltage which goes through the IRF3205 gate pin. So with this sinusoidal waveform, i have sinusoidal magnetic wave on inductor.And these capacitors will be parallel with inductor for some frequency range to get close pure sinusoidal magnetic waveform. Each capacitors working with its' frequency range. For example, if i choose to work with 2500Hz, 1uF will be choosen only. Controlling relays with Nano 2, actually doing that. Almost everything working fine. However, @ the choosen capacitors' negative side, there is a voltage changing that fallowing the gate of the tranistor. Positive side is fixed and 12V. It causes current flow from - side to the + side of the capacitor. So capacitor getting too hot. I couldn't solve this issiue.

NOTE:

I am using electrolytic capacitors.

2500 - 2000Hz << 1uF
2000 - 800 Hz << 10uF
800 - 500 Hz << 47uF
500 - 300 Hz << 100uF
300 - 100 Hz << 220uF

'-' side of these capacitors are connected directly drain of IRF3205 Do you think sin wave on gate has any effect @ - side of capacitors ?


texts:
This is not about debugging the actual hardware/software on the board...

I had my first 6-layer PCB made recently, it's a 50mmx50mm board with the following stackup:

Signal
Ground
Signal
Signal
Power
Signal

The actual signal types are irrelevant to this question, the problem that I found is that the 3.3V and GND are shorted together. At first I thought that some component on the board was shorting, so I went through the entire board with a microscope looking for shorted/skewed components and could not find any. Finally I took one of my blank PCB's and found that it too showed short between 3.3V and GND.

I went through my PCB tool and could not find any shorts between 3.3V and GND, even checking 0R resistor jumpers. I can't visually see anything that is wrong.

What are some methods that I can identify the problem area? The only things I'm left with are bad manufacturing (10 board copies, 2 of which are populated), such as a shorted via. How would you go about finding the short? If it's as simple as a bad via I might be able to drill it out.

I had thought of plugging in the PCB and letting it heat up and finding the hot spot, but the on-board regulator has a shut-down feature for shorted outputs. The only other thing I can think of is x-ray, but aside from being inaccessible to me, I'm not sure it would work through a solid ground plane or power plane to see the internal layers.

How do I do a "post-mortem" analysis of multi-layer PCB's to find the fault? Should I take the board and cut it into ever-smaller pieces until I isolate a small enough section?


texts: Is there any current gain in a FET amplifier?

texts: I have seen many books, but no one gives any information of the current gain parameter in a FET amplifier (low signal analysis). So I was wondering is there any current gain in FET amplifiers or not?


texts: Circuit design - Measure power supply and detect power failure

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I have an idea to measure separately power supply and battery voltage. I am not so sure if going with following design is good idea (my apologies.. using MS paint).
Some external chip in LOAD should measure PSU_VOLTAGE and BAT_VOLTAGE separately. On power outage I expect PSU_VOLTAGE = 0V. During battery charging (e.g. battery voltage 3.4V) I expect real battery voltage. Not 4.2 from TP4056 charging.
Q1 is MOSFET-P which should disconnect battery from LOAD if PSU is live.

How should I change design to measure real BAT_VOLTAGE? (I dont know how to)
Is rest of design proper or what should I change?


texts: Adjusting LED currents same level for different voltage levels

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I have different voltage levels 1 V, 1.2 V, 1.8 V .. 5 V, 12 V and I want to connect a led each of them to see the voltages are clearly set. In this case, I want same brightness for each LED. I can do this by using simple resistor for each voltage level but low voltage sides (1 V, 1.2 V and 1.8 V) aren't efficient. So I thought maybe there is some voltage shifter that accepts different voltage levels as input, fixed voltage level for the output that I can use. Anyone know anything like that? or some other suggestions to handle this?

Thank you


texts:
Since it's not possible to know with 100% accuracy about what's going on in a circuit and its components, and I have to trust my multimeter on measurements, what's the usual approach to managing errors?

Let's say I want to build a simple device or a circuit, and I know what materials I'll be using, how do I find out in what range my measurements for things like resistance or current can be off, to reduce the chance of damaging components?


texts: Detect multiple corn bags through wood with a sensor

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I'm working on a project for school, and wondering what options I have for detecting the corn bags through a piece of wood.

More specifically, we are creating an automated cornhole scorer.

Sources of images are those: wood and scorer.

We have chosen to some sort of load sensor for the bags within the hole, but still looking for options to score the bags that lie on top of the board. We have looked into some openCV application, which is most likely what we are to use.

Being an electrical engineer, I am still trying to figure out different ways we can detect the bags without a camera. Accelerometers have crossed my mind, but the angle due to the ground can be compromised easily. Having PCBs in every bag can get quite expensive since they will also have to transmit the data wirelessly.

Is there any sensor that can detect multiple objects with just magnets inside of each bag?


texts: How to output signal though SMA connector in Spartan 3E Starter Kit

texts: I want to output a signal through the SMA connector available on the Spartan 3E starter kit board. Can someone guide me as to how to do it?


texts: What does the third wire on this speaker do?

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I salvaged two large speakers from an old iPod player/alarm clock device. Each of the speakers have three wires tied to it. There is a positive and negative and a third which I assume is ground since it is tied to the thick metal casing.

I understand how a two-wire speaker works and is used but I haven't encountered a three-wire speaker before. I don't see the point to the third wire besides it being a ground.


texts: I think I am failing to understand how a zener diode works. Please let me know what you believe will happen if I were to make this circuit.


texts: control four motors with Motor Driver 1A Dual TB6612FNG

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I know I can control 2 brushed DC motors bidrectionally with the Motor Driver 1A Dual TB6612FNG, but can I somehow control 4 brushed DC motors with the Motor Driver 1A Dual TB6612FNG, NOT BIDIRECTIONAL? (I thought I might be able to because i don't need direction control, so I thought to connect each output to each motor and their ground to the chip ground and also send PWM signal to the direcion pin)

Would this work? (I don't have one to test it)


texts:
I'm currently working with embedded system implemented on SMT32F103C8T6 Blue Pill microcontroller based on FreeRTOS. I want to control the velocity and position of DC motor using PID controller. For the position control, i got no problem at all. But, for the velocity control, i'm confused on how do i get the time difference for calculating the sum of error (for integral controller) and delta of error (for derivative controller).
sum_error += current_error * delta_time;
diff_error = (current_error - prev_error)/delta_time;

In most applications, we could use time = millis() - prevMillis;. But in FreeRTOS, we shall not use millis, as it would disturb the task schedulling of the RTOS.

So, is there any other way to get the time difference? Notes: I've tried using a constant value of 0.01 (ms), but it doesn't work (the PID controller seems not working).


texts: Modelling transformer voltage drop in LTspice

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I read that a transformer has a rated secondary voltage at a rated load current. So open-circuit voltage and any secondary voltage at different loads will be different.

When modelling this in LTspice should we than add a series resistor next to secondary windings(inductor)? Is that something similar to output impedance of a power supply?


texts:
I am building my first arduino uno project to control a small motor, using the following guide as a reference http://learn.adafruit.com/adafruit-arduino-lesson-13-dc-motors?view=all

It says the following:

  The motor that comes with Adafruit Arduino kits does not draw more
  than 250mA but if you have a different motor, it could easily draw
  1000mA, more than a USB port can handle! If you aren't sure of a
  motor's current draw, power the Arduino from a wall adapter, not just
  USB.

I have a motor with the following specifications:

Operating voltage 1.5 - 5Vdc.
Rated load 8 g.cm.
Speed@rated load - 13000rpm
Current@rated load - 1A.
No load current - 350mA

What would happen if the motor couldn't draw enough current - would anything break, or would it just not run at maximum speed?


texts: Which pins are required when reading and writing NAND flash?

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I plan on reading and probably writing NAND flash on some embedded devices or USB flash drives.

I did not come across many examples for in circuit reading though I'd give that a try at first if possible. Otherwise I'm going to desolder the NAND flash. For reading I want to use a FT2232H board. I was wondering which of the 48 pins are really required to be connected. Sure there are the obvious ones which are labeled DNU or NC on the spec sheet.

But could I omit connecting some of the ground or voltage pins or some of the IO pins? There are multiple of the latter ones and maybe connecting just one or two of those would be sufficient though maybe reducing the read and write speed.


texts: Choosing a touch screen type for a project

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I have a project that I have to choose a touch screen for. I have done some studies on the different type of touchscreens. I would like the screen to be:

Multi-touch capable: So a resistive touchscreen doesn't work. I need it to support multitouch because users will most likely "write" on the touchscreen. The screen needs to be able to detect the difference between the palm and the finger. (Palm rejection)
Any input devices will work: So a capacitive touchscreen won't work because it won't interact with gloved hands or a regular ballpoint pen.

As far as I can tell, there's still no technology out there that can satisfy both criteria. But maybe I'm missing something. Or maybe there're some software workarounds to make either a resistive or a capacitive touchscreen to work.


texts: Alternative to alternating relay? or help?

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I'm using a littelfuse relay shown in the link to switch motor directions. I'm sending a pulse to the relay switch of 0.02s in order to switch between the L1 and L2 contacts. The pulse seems to be too short and the relay picks up on the pulse sometimes, not always, which is a major problem for me. If i increase the time of the pulse duration, the relay works perfect but the accuracy of my project reduces, so the shorter the time the relay picks up on the pulse, the better. What are some alternatives to this relay, or how can i improve my design to make sure the signal is picked up by my relay? Thicker wire, shorter wire, caps? I dont know. I'm only knowledgeable in the basics plus just a tiny bit extra and i can't figure this one out. Thanks in advance for your time and help!

edit: I've included a wiring diagram with part numbers available. The counter is counting up to a pre-set number XX. Once it gets to XX, counter sends pulse to Relay #2 and reverses motor through the speed control. The pulse duration needs to be AT MOST 0.02s in order for my accuracy to be sufficient. I was thinking if there were some kind of solid state alternating relays? The motor is a 90V DC from Dayton.

I hope that's a little more information. I didnt want to add too much so that you all didn't have to do all the work, but any and all suggestions are welcomed.

LittelFuse Relay

Diagram:


texts:
When using a hall effect sensor like this one, naturally, it will be pretty close to a rapidly changing magnetic field.  This means that the analog signal line coming out of the sensor will also be close to a rapidly changing magnetic field.  I'm concerned about shielding this analog signal from the very field that the hall effect sensor is trying to measure.  According to my back-of-the-envelope calcs, I shouldn't have to worry about this... can someone confirm my calculations?

I know that Lenz's Law tells us that induced voltage due to a changing B-Field is given by

and of course

Given the strength of the magnets in my physical setup and their position relative to my loop, I expect a maximum dB/dt of about 10Tesla / second.  My pcb is the standard 0.1524mm trace/space, so I could conservatively have the loop of "analog signal + return path" be on the order of 10^-5 square meters.

All of this suggests that even with a rapidly moving magnetic field, I will have less than 1 milliVolt of noise in my (very delicate) analog signal.

Is my analysis sane, or is EMI protection a problem when measuring a rapidly changing B-field with a hall effect sensor?


texts: I am having a bit of difficulty generating the power contours at a Pin where Pout  is 17dBm. I am doing a PSS analysis in Cadence Virtuoso. I am sweeping the phase along with a parametric sweep of the magnitude to generate the power contours. Initially I did a small signal match to verify all parameters it was found that 17 dBm was achieved at around Pin = 9 dBm. When I try the large signal setup, the power contours seem to give a completely unexpected output as seen in the attached image. But when I try for a different power at an arbitrarily negative value, say -30 it seems to be alright. I have attached screenshots of the power contours at Pin= -30dBm, Pin=9 dBm, and my small signal results along with the schematic. If anyone knows how to size the components for large signal with the load-pull set up in order to achieve the optimal output impedance.


texts:
For the longest time I chose to ignore the true definition of voltage because it did not make sense to me to think of voltage by its definition. Most of the time, it made more intuitive sense to think of voltage as pressure or as a force, but these substitutions only go so far, and I'm trying to wrestle with how voltage's true definition (from hyperphysics) - "the work which would have to be done, per unit charge, against the electric field to move the charge from A to B" - makes sense when trying to understand the behavior of circuits.
Also, from what I understand you can have voltage without current but not current without voltage.
So lets say:

we have a voltage 'V' applied cross some point 'A' to some point 'B' then to some point 'C'
no current flows from A -> B -> C.
'V' drops across A -> B, however the voltage at/"entering" 'B' is not 0, lets say its V - 1.

Now, say that 'B' has a input voltage tolerance of V - 2, so in this current state, 'B' is experiencing +1V more than it can accept.

My question is:
if voltage is the amount of work needed to move a charge from A -> B not the actual the amount of work being spent across A -> B but the work needed [if] we were to move a charge from A -> B
In this situation, if it takes V - 1 volts to move a charge from B -> C, but we are not moving any charge since there is no current, is the input 'B' still damaged?

If yes, why? voltage is not a force or pressure, from what it seems, its a hypothetical, its only if we are moving a charge and in this example we are not, so no physical, for lack of a better word, thing is being experienced at 'B'.


texts: Global and Individual Gain Setting on 16 Channel System - Analog Solution

texts:
I am working on a system with 16 analog channels. Each channel has an individual amplifier stage (for the sake of simplicity assume an inverting amplifier for each) that then feeds into an ADC.

How can I design this system to provide individual per channel gain trim and a global gain trim for all 16 channels? Trying to avoid a digital solution that requires programming.


texts: How to increase 400 V to 1600 V? Or oscillate the 400 V for a voltage multiplier?

texts:
I am using a flyback transformer to obtain 400 V DC from 120 V AC mains. I cannot find a transformer and switching controller available which give a higher output voltage, and do not want to deal with higher output voltages from this transformer either as it would require filter caps with larger voltage tolerances.

Therefore, I plan on using a voltage multiplier to quadruple this 400 V output. In order to do that, I need to oscillate this new input voltage to the voltage multiplier circuit (400 V) between 0 V and 400 V.

How can I go about making this oscillation circuit?

Frequency is not too important, 10 Hz to 100 kHz is in the range. Also, this 1.6 kV ouput will experience zero load under normal conditions, therefore a feedback control to stop the oscillation once the output is charged would be beneficial (as no switching power will be wasted).

I considered using a voltage divider, with an N MOSFET replacing the low side resistor, and driving the FET to oscillate the voltage, and it worked for lower voltages (12 V) but experienced some trouble when I tried the circuit with 400 V input.

I am considering a digital inverter type circuit driven by a 555 timer. Is this a good approach to follow? I have worked plenty with N FETs but am hesitant on how to drive the high side P FET given such a high voltage. I appreciate your suggestions.

This question should not be marked as a duplicate. The other question asks for different circuits to generate a high voltage. This question specifically focuses on how to create an AC voltage from a high DC voltage, sine, square, or otherwise.


texts: How to find the USART TTL levels of this board?

texts:
I have this Nucelo board with this manual and need to communicate with it with PC through its one of USART peripherals which are:
USART3_RX (CN10 pin18)  and USART3_TX (CN10 pin 25)
So it seems I need an FTDI interface between the PC and the board such as:
PC ---> FTDI interface ---> Nucelo
If that is correct, I am planning to use this FTDI interface for the purpose.
But from the datasheets I cannot figure out whether they are compatible. I have seen some interfaces which have switches to set TTL level to 3.3V or 5V. So in this case, how can we be sure of the compatibility between the Nucelo and the FTDI interface TTL levels?


texts:
This is the working circuit :

I have researched it quite a lot in the past few hours but still I don't understand what the error is about.

The Problem

But when I added a switch, it gives an error ( I am quite a noob with proteus and electricals ) :

Thanks :)

Sizu


texts: Small single phase induction motor - triac control for startup and run

texts:
To repair a control board for a small single phase induction motor (35W 0.38A) I created this schematic to help me understand how it operates. The motor was overheating and not starting/running "properly" according to the owner of the machine which is a bank note counter. The problem was triac T4 had blown, low resistance between MT1 and MT2. I replaced it with a different brand/type of triac, an ST BTA06-600B thinking all should be well but it wasnt. With that triac the motor would creep when it was supposed to be stationary- short jerky movements probably caused by T4 firing intermittently. When the motor is supposed to run (when feeding bank notes into the machine) it seems to run ok although I havent tested that thoroughly, concentrating more on the other issue. I am waiting for a BT137 triac to see if that will solve the problem, meanwhile I tried to decipher what is going on in the schematic. I believe the schematic is accurate - I took a good deal of time to check it against the hardware. I can figure out in general what the circuit is supposed to do but there are details that are puzzling me, and are what my questions are based on.
So my idea of how this is supposed to work is as follows - please forgive obviously wrong assumptions/explanations, I am not a died-in-the-wool analog or power engineer.
The induction motor requires a startup capacitor (C1) and T4 applies 230Vac via R100 to C1 as well as directly to the motor during startup, via pins 2 and 3 of the motor connector J3. This gives the required phase shifted voltage across the start winding of the motor. In run mode, T3 provides direct 230Vac to the motor via pin 2 of J3, bypassing C1. A microcontroller controls U1 and U3 via Q1 and Q2.
Thats the extent of my guesswork. During my research trying to get more insight I studied the driver and triac data sheets as well as other posts on EESE such as here and here.
I have the following specific questions:

Is my take on what is supposed to happen on the mark? If not please correct/elaborate.
What is the purpose of the two diodes D100 and D101? It appears that they are half-wave rectifying the motor voltage but only when T3 is on.
Why would sensitive gate triacs be used in this application? I would have thought that other types should work equally well given that the MOC3063's are driving the triac gates, yet when I replaced T4 with a different type it did not give a 100% fix. Perhaps U3 is suspect?
Do both T4 and T3 need to be on for the motor to run?
Why are U3 and U1 connected differently to the triacs, in a mirror image fashion? This application does not require the motor to vary speed or to reverse so I wouldnt think there is any phase control going on.

I do not have test gear other than a multimeter so unfortunately cant provide more detailed insight into waveforms, timings etc.
Hopefully someone can shed some light on my questions and give a better explanation of what is supposed to be going on.
Thank you.


texts: How do I use one output to block an input until that output turns off?

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I have a device with two inputs, each with an associated output.
I require a means of allowing only one input-output circuit to be active at a time. If a second input is activated while the other is already active the second input should have no effect until the first input is deactivated. ie

If both inputs are inactive and then input 1 becomes active then output 1 should become active.
However if input 2 becomes active while input 1 is active then output 2 should be blocked from becoming active until input 1 becomes inactive.
The opposite applies when inputs 1 and 2 are swapped in the above description.

"State diagram" - xx xx below indicates the states of In1.In2 Out1.Out2

00 00 to 10 00 results in 10 10
10 10 to 11 10 results in 11 10, and NOT 11 11
11 10 changing to 01 10 results in 01 01

equally

00 00 to 01 00 results in 01 01
01 01 to 11 01 results in 11 01, and NOT 11 11
11 01 changing to 10 10 results in 10 10

Basics of the circuit.

The system operates from +24 VDC.
Equipment to the right of the connector in the diagram is proprietary and sealed and can not be adapted.

Inputs are active low (grounded) and are at 24 VDC when idle.
Outputs are active low (grounded) and are floating when inactive - but could probably be taken to +24VDC when inactive if necessary.
Two LEDs (one per output) are illuminated by the system when their corresponding output is active, but this is probably independent of the action required from this interface.

24 VDC+ with 0VDC Ground reference. When switch A closes, 0VDC (GROUND) is supplied to the controller input for "A". Immediately "A" output turns on (becomes grounded) which illuminates the LED for that switch selection. I need to block the "B" input until "A" output turns off. The solution has to be implemented at the switches or wiring because the equipment is proprietary at the 6 pin connector and beyond. My idea is an interface board installed into the wiring between the switches/LEDs and the 6-pin board connector. I could use the N/C contact on a relay to open continuity on wire #3 when OUTPUT A (wire #4) is grounded, but I need the implemented circuit to have a minimal current draw. Ultimately, I need to block INPUT "A" when OUTPUT "B" is activated also.

This is essentially a direction interlock circuit. Once a direction is selected, the opposite direction may not be selected until the output for the initial direction has returned to an "OFF" state.

Thanks for any ideas.


texts: Is there any way to match Vth of 2 mosfets with different aspect ratio?

texts: For the floating mirror circuit to work properly, the threshold voltage of M1 and M2 must be the same. However, (W/L)1 ≠ (W/L)2. So I thought to get a first order matching I can match L1 and L2 (to match λ to get better mirroring accuracy) and to connect bulk to source (to remove the body effect). Is this the best I can achieve in matching or is there any other way to improve matching in Vth (and mirroring in general).


texts: This is a power circuit. I have no idea what it is trying to protect.


texts: What is the difference between debug mode and normal execution on dspic?

texts:
I have a dspic33fj128mc802 microcontroller. I am using mplabx and xc16 compiler. I have my internal oscillator set up to 80MHz.

I have managed to setup FreeRTOS on the device and everything compiles without errors.
I'm toggling an output pin with a 100Hz frequency. If I'm in debug mode and measure the pin with an oscilloscope I see a perfect square wave with the expected frequency of 50 Hz, High voltage is 3.313 V and low is 0V. This is in debug mode and this is what it should do.

If I let the application run on its own, without the debug, I have impulses coming at about 17 ms intervals. Each impulse lasts 3.82 microsecs with 3.313 Volts and then a very fast decrease to 0 Volts. I have absolutely no idea whats causing this. Has anybody encountered something similair before? Could this be the chip's fault or my program's fault or FreeRTOS' fault?


texts: Modest DC arc welder with Bipolar transistors

texts:
I am building a modest 50V/50A welder-variable switchmode power supply.
luckily I have some parts in my junk and salvaged parts, unluckily not all!
I intend to build this welder around a TL494, toroid cores and 4 bipolar bjts BUX23.
I've already mounted them on a heatsink and supported them with U1015 freewheling diode each.
But still I am not sure the design won't be on the verge and the brink of bjt blown as I have the feeling they are not robust enough.
My math and engineering estimation and calculation is modest too, so I need your help to help me decide whether to proceed with:

a bridge design where every single transistor is at stake (I've got only 2 pieces spare! ), or
pushpull paralleling each too bjts, or
single mode paralling the four of them so they are supported and robust.

PS. I've prepared a lot of fuses, breakers, and 220 low amp supply in case.
I have the feeling different topologies have pros and cons but how far can that (single mode) deviate from the power I need?
Thanks a lot for your patience and perserverence.

my schematic is very similar to the one here:

https://m.youtube.com/watch?v=isZ9tApXwc4


texts: Prerequisites for Power Integrity Analysis

texts:
I try to learn about the topic of Power Integrity Analysis of an PCB, i.e. analysing the Power Distribution network (PDN) of a PCB to locate the regions of biggest noise or DC voltage droop.

Independent of the concrete CAD package used, where and how can I learn about the device models used for such an analysis. There are e.g. IBIS models for many ICs that provide the information for signal integrity simulations - what would be the analogy for PI Analysis? Do manufacturers usually provide models for PI or do engineers create there own ones based on assumptions on current peak amplitudes and frequencies? I doubt that because I suppose that would be plain guessing most of the times since the device-internal behaviour is only known by the manufacturer.


texts: Developer/application board with a CAN/SD card

texts:
We have to develop a data logger. I should get some data over CAN (1 MBit/s), compress this data and save it to an SD card. To save time, we would prefer to use as much existing hardware and software as possible.

I looked into Arduino (CAN and microSD card with a shield, but I'm not sure if it has enough RAM or speed) and Gumstix (enough speed/RAM but no existing hardware and software for CAN and is expensive).

What should I do?


texts: Is the switching speed of MOSFET comparable to that of a Schottky diode?

texts:
Assuming identical voltage and current rating, which is having higher switching speed? MOSFET or Schottky diode?

In synchronous buck converter, we replace Schottky diode with MOSFET (low side) for reducing the conduction loss. I want to understand the impact on switching loss due to this.

I realise MOSFET gate-source terminals act like a capacitor which needs to be charged and discharged everytime switching occurs. Whereas Schottky diode is a majority carrier device which requires no recombination of minority carriers. So can I say Schottky diode would be faster? I'm not sure whether I'm comparing apples to oranges.


texts:
I'm using LMC6482 opamp with +/-15V rail voltages and having weird behavior. This means Vcc is +15V and Vee is -15V in my case.

Am I exceeding the specs? The jargon in the datasheet is not clear or should I say I'm not familiar with it.


texts: Description of H1, H2, S connections on a pulse igniter

texts:
I would like to replace a piezo igniter in a small project with something that can be electronically controlled (I have created some simple hairspray-powered foam rockets, and I would like to be able to sequence several of them from a computer).

It looks like pulse igniters, like this, are relatively inexpensive, but it's been hard to find any documentation or wiring diagrams for them and I'm unsure if I understand all the connections.

There are obvious inputs for power and for a switch, but on the high voltage side there are three wires, labelled HV1, HV2, and S.  HV1 and HV2 appear to come off either end of a coil, and S is a mystery.

The igniter looks something like this:

And the innards look actually like this:

HV1 to HV2 seems to generate the most effective spark, but I don't know if that's using the igniter correctly or slowly frying its innards. Can someone help explain these labels?


texts: 74161N counter isn't counting with clock input

texts:
I am trying to get a 74161N 4-bit counter to work. If I connect the clock input to a button to ground, pressing the button increments the counter. Unfortunately due to the physical connection in the button, it will sometimes send out extra pulses causing the counter to do multiple counts in fractions of a second. This leads to the counter counting unreliably. So to circumvent this I used an Arduino with a simple blink program to send clock input to the adder. To no prevail, something odd happened, the first bit kept blinking at half of the speed I set the Arduino to count to, (500ms -> 1000ms) and this confused me. Next I set up a simple astable 555 timer circuit and fed that into the clock input. Now a similar thing is happening as before but except to the 4th bit. I check to see if this was the IC by replacing it with an identical, but still no prevail. I've been stuck on this for days without answer. Here's the datasheet I used: http://www.jameco.com/Jameco/Products/ProdDS/49664.pdf
I hope someone can help be get the counter to work properly.

(Also if this is really simple and I'm being dumb I am very much a noob at electronics.)


texts: How was Vc(t) found in this source free RC circuit?

texts: Shuldn't \$v_c(t)\$ be the same as \$10^4\space i_s\$ after \$t=0\$?


texts: I am working on dielectric elastomer actuator which just like the variable capacitor. To charge this we need high voltage fro 5 to 10 kV. I charge this capacitor to  this voltage and want to measure leakage current of the capacitor. How can I measure the leakage current of this capacitor? Is there any electrical circuit that I have to build or there any instrument for that?


texts: Why does the Green LED stay lit and Red LED stay off in this 555 circuit

texts:
This extends my previous question involving same circuit, information replicated here for convenience and independence of this question.

The following circuit schematic:

Has been connected as shown here:

However, on connecting it to the power source (now a 12VDC lead-acid battery, with unloaded terminal voltage as bit over 13VDC, from a robotics kit), I see that only the green LED is glowing (permanently lit), and red LED is unlit. The expected behaviour is both flashing alternately (aka Railroad crossing lights). What all could be wrong here ?


texts: Water conductivity measurement AC, interfacing with arduino

texts:
I want to implementate this device, mentioned in the title.

The problem is how to correctly build the " read out device" that is clearly a wheatsone bridge?

But in AC, the problem is the signal conditioning for a frecuency between 1-20khz probably I suppose that I need to use an OP AMP stage and an AC to DC meter after it.

Nevertheless the whole thing needs to be very acurrate. Any advices?

The final goal is to interface with arduino.

Thanks!


texts: Is it safe to use hot glue in electronics?

texts:
I know question seems too basic to ask but I couldn't find any specific information anywhere .

I want to use hot glue gun to stick components and cables into cardboard to prevent them move or break but someone said hot glue is electrostatic and it'll cause problem.

So can I use it or should I switch to alternative ways ?

Circuits I'm talking about MOSFETs or IC circuits and hot glue will directly touch into pins.


texts: Export contents of block ram to a file in Xilinx FPGA

texts:
Assume I have a simple adder Verilog code which does

sum=a+b

This code is implemented on a Xilinx FPGA (Basys3).
At every posedge of clock, I change a and b. I get sum. I run this simulation for 10000 clock cycles. I want to dump this output at every posedge of clock to a file for postprocessing.

Basically, I want to do an equivalent of the following:

always @(posedge clock)

$fwrite(a,b,sum)

I can obviously not synthesise fwrite and there is no filesystem interface with the FPGA. So, I am storing a,b,sum to a block RAM at every posedge of clock.
Now, I want to read this content or export this block RAM content to a file. That is, all 10000 lines (from 10000 clock edges) need to be read from the block RAM to a file. I use Xilinx Vivado and a Basys3 FPGA. Request someone to shed some light on this.

I tried using ILA without the BRAM- but when I use the export option through ILA in Vivado, it just stores the a,b,sum at a single trigger point, and not all all clock edges.

Is there some other way I can read out the content of this BRAM to a file?


texts: Why is it that the real part of \$G(j\omega)\$ (where \$G(s)\$ is transfer function) is related to active power of the circuit?


texts:
I'm tring to choose a relay for my circuit which has a Filament LED bulb as load.

The bulb is 230VAC / 60W 6W.
The nominal current should be about 0.03A which is not an issue for a regular relay. The inrush current can go from 10 to 15 times that value, from what I understand. So it can go up to 3A0.4A.

So I just need a relay that can handle a max switch current of 3A 0.4A?

How can I control the inrush current before it goes to the relay? If I add another bulb to the circuit, I'll have to get another relay that can handle twice the current. And this is not a good idea in the long-term.

UPDATE 23/03

The bulb's power is 6W, not 60W as @Misunderstood pointed out.
I was able to probe the bulb in an osciloscope and the inrush current max was about 2A. The average value was about 1.5A. These values may not be much accurate because the probe used was for high current values and it has low sensitivity to low current values. The real inrush current is probably below these values but since it's not much and it doesn't require a special/expensive relay, I'm not too worried.
Conclusion: Since I'm not thinking of using more than 3 bulbs, I'll get a relay rated at >= 6A peak. I'll probably add a relay socket as suggested by @Harper and put everything inside a junction box. I'll add the full schematics (with the relay controller and the other switches) later, in a new post, so I can get some feedback.

UPDATE-EDIT:

I have used triacs, in the past, to control the brightness of a bulb but it wasn't a LED bulb. I was told triacs dont like LED bulbs and may not be suitable to be used as dimmers. What are my options here?

Thanks everyone for your help. Feel free to comment if my conclusion is wrong of if there's something I'm missing.

EDIT: Added schematic.

simulate this circuit – Schematic created using CircuitLab


texts:
How do I lower the clock frequency of a PIC18F2550 and recalculate the peripheral dividers?

I'm trying to make it run cooler. Currently, it runs at 12MIPs/48mhz (USB-CDC-ACM).


texts:
To simplify the outside design as much as possible (keeping it simple to use and less expensive) I would like to use just one small 2-pin connector both as output to drive an external led and as 5V input that would charge the internal battery via a tp4056 lion charger IC.

Right image:Using the connector as output to drive a led:
Left image:Using the same connector but now as 5V input:

I have some basic knowledge of electronics but not enough to determine how to separate the in and output from interfering with each other. Would this be possible? If yes, could anybody give me some help/hints with this?

Thx!!

#

The answer Theamk gave made me thinking...

would this work?:

+Batt = 3.7V

When Arduino port is high (3.3V) Q1 and Q2 open (Led on) and Q3 closes preventing feedback from +bat to the VCC pin of the charger IC. (R4 is a pullup for Q3)

When Arduin port is low current Q1 and Q2 are closed (so no feedback from Vbat to VCC) and Q3 is open allowing current to flow from pin 1 of the connector to VCC of the charger IC.

Only thing is when the arduino port is high and the connector is used for charging nothing happens (5V from connector is higher than +bat so no flow through D1 and Q3 is closed) untill the arduino port goes low.

The diodes prevent:
D1 prevents current from 5V charging to +bat
D2 prevents the solar panel from backfeeding Q3
D3 prevents backfeed to the solar panel

Could anybody confirm if it indeed works like this? Thx!!
(and if it should work which resistor values of R1, R2 and R4 and transitor types (SMD) I could/should use (LED is max 100 mA) )

THX!!


texts: Ok to use one of the two 12V batteries of a 24V system?

texts:
Coach bus with a 24V system of 2x12V 120Ah batteries for aux load. I need 12V for IT stuff. Is it ok to take it from a single battery or is it a bad idea? Right now I have a crappy 12V->24V converter that I would need to replace if this is a bad idea.

Update: Great answers. Sadly I could pick only one although all 3 are very useful. Thanks!!


texts: I want to make a custom lithium-ion 18650 standard cell charger as I will be charging 100s of them (recycling old laptop batteries). Base on my research, lithium-ion cells use constant-current, constant-voltage charging. I'm thinking of using 5v and PWM using an Audrino with a feed back loop to maintain the constant current and voltage. Will the PWM ripple cause any damage to the Lithium ion cells? Is there any major short coming to my thinking?


texts: Verilog Generic Multiplexer - synthesis warning and simulation compile error using Xilinx ISE 14.7 "Port must not be declared to be an array"

texts:
I am pretty new to Verilog. I wrote a description for a generic multiplexer in Verilog as follows:

module mux_generic
#(parameter BUS_WIDTH = 4,
  parameter SEL = 5 )
( input wire [BUS_WIDTH-1:0] data_in [(2**SEL)-1:0],
  input wire [SEL-1:0] ctrl_sel,
  output reg [BUS_WIDTH-1:0] data_out );

  always @ ( * )
  begin
    data_out = data_in[ctrl_sel];
  end
endmodule //mux_generic

And though it synthezies with Xilinx ISE 14.7 without error, I so see a warning at line #4:

  WARNING:HDLCompiler:1335 - "D:\verilog\mux_generic.v" Line 4: Port
  data_in must not be declared to be an array.

I also wrote a top level module, which instantiates the above module:

module mux_generic_top( input wire [1:0] data_in [31:0],
                        input wire [4:0] ctrl_sel,
                        output wire [1:0] data_out );

  mux_generic #(.BUS_WIDTH(2), .SEL(5)) mux_32to1_2b(.data_in(data_in),
                                                     .ctrl_sel(ctrl_sel),
                                                     .data_out(data_out));
endmodule // mux_generic_top

The synthesis tool now given an error:

  ERROR:HDLCompiler:251 - "D:\verilog\mux_generic_top.v" Line 5: Cannot
  access memory data_in directly

Also previous warning shown during synthesis of mux_generic i.e. HDLCompiler:1335 , is now shown as Error by Xilinx ISE simulator.

Has it something to do with Verilog language version support ? Can ports not be declared an array in Verilog as they can be done in SystemVerilog ? How to avoid these issues in Verilog while still being able to write generic designs ?


texts:
I'm a software guy who wants to get into the hardware side of things so I can enjoy the same creativity from software design in the physical world.

I've found plenty of posts here regarding how to get "up and running" in the electronics world, but I would like to know if there are any gotchas when embarking on this journey if your goal is to potentially have a device manufactured in the future. (probably robotics-centric solutions, boards that would control servos, sensors, etc).

I would like to make sure that wherever I aim my focus, I won't be "learning myself into a corner", so to speak.

I have read good things about the flexibility and easy to learn nature of Arduino devices, but have trouble finding anything about getting them manufactured. Are there manufacturers that can produce an arduino-based solution? What kind of production volume is available for something using Arduino?

What realms/devices of programmable electronics are best for having manufactured?

Any tips or info regarding learning and designing with manufacturing in mind? Any general tips for a newbie?


texts:
I have two issues about enclosing/casing electronics:

I have some leads connecting each other with a few resistors in between.  I have put the resistors and wire connections on a small piece of stripboard and want to enclose somehow just to look better.  I've considered shrinkwrap, boxes from maplins (which need filing out for leads to go in), fimo (to encase and bake) - but don't know the best solution that other people use - or is it always just bespoke?
I have a PCB with a number of jack connectors and want to enclose in a case - any recommendations for case companies that will make bespoke cases?  will they use the pcb design software to make cases?


texts: Level-shifting for negative-voltage logic

texts:
I'm trying to fix a 1970-vintage calculator - a Wang 360 (http://www.oldcalculatormuseum.com/wang360.html) - for a hobby project.

The power supply voltages are +11V and -11V. It looks like a logic "0" is 0V and a logic "1" is -11V. I'd like to shift these levels to normal TTL/CMOS so I can hook up my logic analyzer and get down to tracing the faults.

I've thought of several things, none of which are entirely satisfactory and I'm wondering if there's something better out there. I'll need to monitor as many as 16-lines so parts count per level shifter is an issue. Here's what I've thought of:

A simple transistor circuit. Pro: easy & cheap. Con: high parts count (probably 3-4 resistors per shifter).
An inverting op-amp with "gain" of ~3/11 to convert -11 to +3V. Pro: easy and relatively cheap. Con: moderate parts count (2-3 resistors per channel: Rin, Rfeedback, and an optional pull-down resistor).
An opto-isolator. Pro: low parts count (2 resistors for current limiting; one on input & the other on output). Con: too high current drain. Typical ones draw 20mA! "low current" ones draw 0.5mA - at 11V, that's ~equivalent to ~22K and the resistors in the circuits are often larger than that. There are very expensive ones that draw 10's of uA but they cost $5 each.
A "digital isolator" - Pro: low parts count. Con: expensive and require ~20mA input current.
a comparator. Here, I think I'd need one that can have separate power supplies for the input (+/-11V) and output (5V). There are some like this (LM361 & AD790) but they're very expensive (at least $5 each). As far as I know,  "regular" comparator would have to be run from -11V and either 0V or +11V so the output would swing from -11 to +11 and that's not good.

So, it's looking like the op-amp is the best choice. But am I missing something?

Any help/suggestions/thoughts would be appreciated.

Thanks


texts: What kind of issues might I face when moving from 400 kHz I2C to 1 MHz I2C?

texts:
I'm thinking of migrating from an I2C bus at 400 kHz to one running at nearly 1 MHz.

I am using 1.2k pull-ups at the moment and on the clock and data lines, I get a rise time of 383ns average when sending out pulses. Fall time is approaching the limits of a 100 MHz oscilloscope at ~15ns. Are there potential issues with this kind of rise time? What about noise and signal integrity? Clock jitter? etc. Would there be significant issues? I will probably stick with 400 kHz on my breadboard which works fine, but the final product may use 1 MHz I2C.


texts:
I am trying to get a simple IR sensor to work on my an attiny85. To do this I first wrote some code to setup the ADC and the perform an operation based on the outcome. Because the code didn't function as expected I decided to test if some code where I simply do one ADC conversion and then turn on an LED works.
This did however not work. The cause of this seems to be that the attiny stops executing code after the ADC conversion.
I am running the attiny at internal 8Mhz clock and the ADC is hooked up to ground through a 200 ohm resistor.

The following code does not turn on the pin at PB0:

#include <avr/io.h>
#include <util/delay.h>

int main(void) {

DDRB |= _BV(DDB0); //set PB0 to output

ADMUX = _BV(ADLAR) | _BV(MUX1); //set ADC 2, left adjust result
ADCSRA = _BV(ADPS1) | _BV(ADPS2); //prescaler 64
ADCSRA |= _BV(ADEN); //enable ADC

while(1) {

    ADCSRA |= _BV(ADSC); //start conversion
    while (ADCSRA & _BV(ADSC)); //wait for conversion to end
    uint8_t adc_result = ADCH; //adc results (should be 0)

    PORTB |= _BV(PORTB0); //set PB0 to high

}

return(0);
}

When I, however, put the "PORTB |= _BV(PORTB0);" line at the start of the loop, so before the ADC conversion, the line does execute and the LED at PB0 does turn on.

Also commenting out the line "ADCSRA |= _BV(ADSC);" makes the code run fine and makes PB0 go high. So I am pretty certain that the attiny somehow crashes when executing that line.

Disabling interrupts using "cli()" does not solve the problem either.


texts: We know by Faraday's law that emf induced in a closed coil is given by the negative rate of change of magnetic flux associated with the coil....but is the induced electric field set up in any coil due electromagnetic induction always non conservative....for example, the one setup due to self induction or due to mutual induction?


texts: what is the smd equivalent package of BD139 transistor?

texts: I am developing a basic switching circuit using a PIC microcontroller where the maximum drive current will be up to 2A in this case I was using BD139 but now due to my PCB has a Single-layer option I have to use SMD for it. so, please anyone suggest to me the best NPN SMD transistor for my current requirement.


texts: In i.e. a TO-220 package, why is mounting the (pin connected) tab to case safe?

texts:
All the time I hear that the tab on a TO-220 like package is electrically connected to the centre pin, for example "out" on voltage regulators.

Does mounting them to a heatsink (of which may come in contact with tracks on the PCB) or casing for heat distribution not matter? My worst case thoughts are more than one regulator mounted on the side of a casing, and 5V and 3V coming together (harmless, but something)


texts: Transient voltage suppression diode not doing its job

texts:
I have a circuit which works on 21V DC and draws 3A maximum current. I need to get it tested to IEC 61000-4-4 and 61000-4-5 standards which are surge immunity tests.

I use a UL certified switch mode power supply to power my unit. The supply actually emits surges which is more than 21V (approximately +/-150V).

So I put in a TVS diode SMLJ22CABCT-ND in my circuit to protect against surges. This diode has a response time of about 5 picoseconds. But the pulses which are given in the surge tests are 8/20 μs pulses of 2KV. which in turn makes the power supply to give out surges as shown in the image. As you can see in the image, the output varies for a few microseconds.

My question is why hasn't the TVS diode suppressed the high voltage. My circuit is damaged by this over voltage.

The schematic of the power circuit is given below.

There is not a lot of protection in the circuit. The 21V is taken for a different interface. I need to find a fix for this rather than designing a new circuit board.

The testing circuit for the IEC 61000-4-5 is standard.

1KV across Live and Neutral; 2KV across Live and Earth, Neutral & Earth (detailed description)


texts:
I'm trying to run a mini project about wind generator for charging electronic devices(smartphones, mp3 player, powerbank,  etc). Rough project description; I want to  have several usb ports and the supply is from wind generator.  Mostly electronic devices that    use 5V . So the questions are:

Type of suitable motor for wind generator(small in size because it's mini project)
Suitable current output
List of components that I need(please recommend)


texts: Will a LED strip be less bright when I drive my mosfets with 3.3V instead of 5V?

texts:
I was originally planning to drive my 12V RGB LED strips (5m + 1m) from an Arduino Uno. It's not an addressable strip so I'll use a mosfet per channel. Since I am now looking to connect it to my Domoticz, I want to drive it from a NodeMCU (ESP8266) which only has 3.3V on the GPIOs. Will this influence the brightness of my strip?

I've got some IRLZ44N N-channel mosfets laying around that should work with the 3.3V GPIOs (Vgs(th) = 2V, if I recall correctly.)

EDIT: forgot to mention that I'll be drawing about 2.5A per channel (i.e. 2.5A per MOSFET) for the complete 6 meters.


texts:
For my first project, I'm trying to make an LED light up when the voltage from a variable source reaches a certain point (13V in my exiting circuit).

To do this, I'm going to take the output from a 5V voltage regulator (L7805) and and run it to an LM360N comparitor, and then compare that voltage with the output of a voltage divider from my source voltage.

The problem I'm currently having is that I can't seem to figure out the pinout for my LM360N. It's a 14 pin DIP format and all the examples I see online are 8 pin SOIC. Can anyone offer some insight?


texts: Starting motor for 5 seconds after 30 minutes, turning it off and start in reverse direction after 30 minutes

texts:
I want to start a 9v DC motor in one direction for 5 seconds after 30 minutes delay, then turn it off and then after 30 minutes, restart it for 5 seconds in reverse direction and then stop it. The same process should continue in cycle.
I already have a 30 minutes timer circuit which can turn on the motor after 30minutes. I need this circuit for a Hatchery, the motor will be used to turn eggs on another side after each 30 minutes. What I want to ask is that can I make a circuit with these functions without using micro-controllers?

Please guide me so that I can proceed in the proper direction.


texts: Can i charge an LiFePo4 32650 cell using an 18650 li-ion charger

texts: i have this li-ion 18650 charger i found, pic attached below. I need to know if i can use this to charge a LiFePo4 32650 cell i bought here, the cell doesnt fit in due to the obvious differences in size, but apart from that could i use it to charge my lifepo4 cell by just hooking up the terminals, or would the battery be damaged in any way, any help would be highly useful. Thank you.


texts: General Electronics vs. Embedded programming oriented program

texts:
I've got a choice between two types of Electronic Engineering degrees, as the title says.

One goes the general route, basics of electricity, analog electronic, digital electronic, measuring stuff, some microprocessor basics, digital signals, operational amplifiers, PLCs, Combinational and Sequential Logic...

The other one (due to me being a web-developer with experience) would likely let me start at the middle of year two, with a lot of these basics skipped. I'd cover digital signal processing, data communications, microprocessor architecture (8-bit, 32-bit) and programming, operating systems (RTOS), programmable logic technology and embedded programming (maybe I left something out, but that's the bulk). There are some projects to be done and some mathematics.

I don't know what to choose, I'm mainly interested in embedded programming, but I'd hate to be an Electronic Engineer without a proper grounding in all the basics of Electronic. Wouldn't feel good when telling someone my title and field I'm in. I also wouldn't like my future choices to be too narrowed down because of such education. Embedded systems are only a subset of electronics, if I'm not mistaken.
On the other hand, are the basics of Electronics so important to be a good embedded systems programmer?


texts: How to continuously measure the RSSI of a Bluetooth signal on multiple PCs/devices?

texts:
Like WiFi, where one can scan and log the RSSI of a transmitted signal from a WiFi device on multiple PCs, do you know a way where one can log the RSSI of a Bluetooth signal on multiple devices/PCs/machines simultaneously?
The answer in 1 only suggests a method to print the instantaneous RSSI value for a Bluetooth signal on a single device when both the devices (i.e., the one transmitting the signal and the other measuring that signal) are paired.


texts: TLC5940 and ADXL335 circuit 'glitches' on perfboard. Need decoupling caps?

texts:
I created a circuit containing one TLC5940 and one ADXL335 breakout board. The ADXL board comes configured with 0.1 uF capacitors to set the bandwidth of each axis to 50Hz.

It is wired to an Arduino Mega 2560 like this. The ground is shared between both the TLC and the ADXL. 5V and 3.3V are hooked up to the Arduino.

On a breadboard, there is no problem. With the exact same circuit a perfboard, the ADXL values seem to fluctuate when the TLC is updated. Also, when fiddling with the 3.3V wire  to the ADXL (connecting/disconnecting), LEDs are turning on and off randomly.

I checked my soldering, and while not the best there is (it's my first perfboard) there aren't any shorts/mistakes as far as I can see.

Could it be because the power sources are 'dipping' when updating the LED's? If so, do I need decoupling capacitors to smoothen it out?


texts: System Identification - Mathematical expression for a signal

texts:
I am having problems to formulate the signal d[n] that is given in the image below. What I am not getting here is that the result imho should be a scalar but no matter what I do I always end up multiplying a vector, the filter F_2(z), with a scalar.

Given:

\begin{align*}
H(z) &= 3 + 2z^{-1} \\
F_1(z) = F_2(z) &= z^{-1} + 0.1z^{-2}
\end{align*}

The equation for d[n] should look something like this:

\begin{align*}
d[n] &= \mathbf{f_2}^T \cdot \big( \mathbf{h}^T \mathbf{w}[n] + \nu[n] \big)
\end{align*}

But as you can see, the result wouldn't be a scalar.

What am I missing here?

Hint: It appears that we might have to rearrange the filtes F1, F2 somehow. But I don't know how that can help me.


texts: how does this differential ddr receiver work?

texts:
I'm looking at this simple schematic trying to understand how a DDR SSTL receiver works (the one on the left).  I get that the input voltage will be compared to Vref and the output will be a corresponding one or zero.  I don't understand how the current flows, what the transistor configuration at the top is or what the symbol at the bottom is.

My second question is we usually specify a separate threshold for Vih and Vil such as 125mV above or below vref respectively.  However from the circuit below it looks like there is only one threshold either slightly above Vref or slightly below it.  So are those Vih, Vil thresholds just there as a guaranteed range and not really the number the output switches at?


texts:
I need to make a usb which is powered by an external 5v power supply, but still connect the device being powered to the raspberry pi.
To do this I've attached the 2 data pins directly to the raspberry pi, the positive pin to the external power supply, and the ground pin is split to the usb on the raspberry pi and the ground of my external power source. Is this a valid circuit?
Thanks
Edit: To clear things up, I have a female usb breakout, which my device will be plugged into instead of the raspberry pi's usb port. I have then connected the data lines of said female usb port to the port on raspberry pi, the positive is connected to an external power supply, and the ground is split between the external power and the ground on the usb of the pi.


texts: Low pass filter for differential signals

texts:
I'm building an adc and amplifier circuit for sensing a differential signal out of a pressure sensor. My plan is to use a circuit very similar to what is seen below:

The total differential output from the pressure sensor will likely be quite small (less than 1mV) so the amplifier will have 30x or 100x gain so I am worried about noise on the output. The frequencies I want to measure are very low (1-30Hz) so I can put in an appropriately designed RC circuit. However, since noise is an issue, I was considering using a Sallen-Key low pass filter on each of the outputs from the amplifier so I can get a sharper drop off.

Does it make any sense to do this? I'm worried that voltage offset errors from the sallen-key amplifiers would change the results of the ADC conversion of the differential signal.


texts: Armature and terminal voltages in DC machines

texts:
In the below page I am trying to grasp the way the terminal voltage and armature voltage are related to each other.

Below is my attempt to understand their relation:

Do you agree with my interpretation?
The source:
FE Reference Handbook 10.0.1
ISBN 978-1-947801-11-0


texts:
I'm trying to understand GPIO, and have read a bunch of different blog posts and I think I'm close to getting it, but still struggling with a few things.

I've seen a few reference to GPIO only being able to work with binary values, but other posts which say the value can be from 0-255. I'm assuming this is the difference between analog and digital GPIO. Is that correct? Is it possible that a single GPIO pin can act as both analog and digital?


texts: Suitability of standard-gain pyramidal horn for UWB signal

texts:
Objective
I'm interested in evaluating the suitability of a standard-gain pyramidal horn for an ultrawideband (UWB) signal. However, I've had difficulty finding reliable information about the phase response over frequency that would be needed to make this determination.
Background
UWB Definition
In this context, use the FCC's definition of UWB, the relevant parts of which are:

Operates in the 3.1 GHz to 10.6 GHz range
Bandwidth greater than 500 MHz

The application I have in mind will not need to work over every frequency in that band, just a subset of it that is approx 500-2000 MHz wide.
Considerations w/ Wideband Antennas
There are many types of "wideband" antennas that can easily meet the bandwidth requirement (log periodic, horn, etc.).  However, a good UWB antenna should also have these properties (according to [1]):

Linear phase over the signal bandwidth
Constant phase center over signal bandwidth

These conditions are necessary to prevent the UWB pulse from being distorted during transmission/reception.
This is relevant to point out because many "wideband" antennas violate these conditions. E.g. a log-periodic antenna has a phase center that changes with frequency (i.e. as the frequency changes the active region changes), and some wideband antennas may have a relatively flat gain response over frequency, but might not have a linear phase over the entire band of interest.
Question
Does a pyramidal horn antenna meet these requirements?
References
[1] Stutzman, Warren L., and Gary A. Thiele. Antenna theory and design. John Wiley & Sons, 2012.


texts: Suggestions to build high-power RGB LED matrix display

texts:
I'm building an 8x32 matrix display but it has to be high power so people can see it from 700 feet away.
I can't use ordinary RGB LEDs (pixels)so enter image description here I'm using 3 watt pixels. I'll scan the 8 rows with a 74138 decoder, using an Arduino Uno for now. If it's not fast enough, I'll upgrade.
For the row drive, I'm using TIP125 (TO-220) PNP transistors, fed from a 2N2222 to not blow up the Arduino. I'm using 12 volt power supply. So each row of 32 pixels is getting scanned through this arrangement (see attached schematic).
For the 32 columns, I was going to use TIP120, with logic coming from a DM13 16-bit constant-current driver with one transistor for each pixel as shown on the below PCB layout. This drawing is ratline connected so I can use autorouting feature of my PCB package. The 16-pin DIPs are resistor arrays for the transistors bases and the SIPs are connections back to the computer.
I'm assuming I need one transistor per pixel and not one transistor per column. So do I connect all the bases together in parallel for each column?
If I have one transistor per column, sinking up to 8 LEDs at a time, I'm afraid I may get brightness variations if one or two LEDs are on versus all 8 on. Or will the DM13 (located elsewhere) take care of this?
I have a test matrix and tried using UDN2981 and ULN2803 to perform the same function and it worked but the DM13 got very very hot. The DM13 is good for 70 mA per output. I don't think the UDN and ULN have enough oomph to light up the LEDs with 100 mA at 12 volts, which would give me the lux I want/need.


texts: Connecting a 18 gauge wire to a small housing

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I'm using a sensor that has a specific connector, which outputs signal with 18-gauge wires, such as these:

And I need to connect it to standard male header pins, where cables such as these would connect to (sorry, I don't know the name in english):

The sensor is going to be connected to a board in an UAV, so the connection needs to be firm, as the UAV would be flying around. I will also need to power the sensor from the board, so there would be:

A ground and a output wire from the sensor to the board

A ground and an +5V wire from the board to the sensor

The sensor wires are all 18-gauge, and the board housings are all smaller (same size as in the picture)
Here are some ideas I've had:

Make a separate adaptation board and use a phoenix-type connector.
This board would have a 3-pin female cable such as the picture above, and that would go into the board.
Use some sort of molex-type connector.
This would have no board, but I'm not too familiar with making these types of connections.
So I would like inputs on my ideas to make this interface, as well as your own ideas that would allow me to make a stable connection occupying as little space as possible.
Please let me know if I'm not clear on anything.
EDIT: Here's a schematic for clarity. I'm just looking for suggestions on how to do the ? part, in order for a secure and safe connection. I am also not sure if it's good practice to connect both grounds on the board or if I can just get away with one.


texts: How to quantify calendar aging of lithium ion battery?

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I am working on a machine learning project regarding battery lifetime prediction (predicting total cycles). Now I need to include something in my dataset that could account for calendar aging.
I have two test sets, one has not gone any calendar aging but other has gone calendar aging of one year.
Is there any way I could include a feature that could account for this or some empirical method I could use to account for calendar aging?


texts: Feedback sought on audio output circuit for Teensy 3.2

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I'm stepping up my Teensy carrier board game, and adding a header to output the DAC0/DAC1 signals. I haven't done analog anything for about 25 years, but here goes :-) This circuit goes on a carrier board for the Teensy that also interfaces with the rest of my system (robot.) I'd love some feedback from anyone who does audio/analog more regularly than me.

The header conveniently also pulls 5V and 12V from the board for powering a small amplifier.

The areas of consideration I have are:

1) Teensy DAC is 12 bit, and there's no anti-aliasing filter internally, so there will be some stair-stepping crunchiness. I need a bit of anti-aliasing filtering; it's more important to get somewhat smooth output up to 5 kHz than to get the highest sample rate entirely un-attenuated. That being said, this is for piping to two-inch speakers for robot speech and effect music, not for a Hi-Fi sound system, so an expensive (and big) brick wall filter isn't warranted. The 47 Ohm / 1 uF RC filter has a corner frequency of 3.4 kHz, which gives me about 18 dB attenuation at 20 kHz, which seems reasonable. I know that DC blocking is a high-pass filter, and I'm prepared to accept a high-pass filter with a corner frequency at 340 Hz from the 47 Ohm / 10 uF series pair. But how do these two filters interact?

2) The 5V rail is driven by a MuRata OKI-78SR05, which has some ripple at 400 kHz. Other than that, it's a great, reliable part. The 12V rail is driven by batteries or DC in, but also drives a number of motors, so there will be switching/EMI noise on that rail. In order to be nice to the amplifiers (who are cost-optimized, not quality-optimized,) I'm adding a bit of filtering on the power rails. I expect to draw 1A or less from either rail. Is this overkill, not enough, or about right? I'm using 6.3mm electrolytics for the 47 uF capacitors, and my main concern there is size -- anything significantly bigger would be a problem. The inductor is rated for 1.2A. An online calculator puts the Q of a 400 mOhm, 10 uH inductor, and 47 uF capacitor, at 1.15 and the corner frequency at 7.3 kHz, and a resonant frequency of 6.6 kHz. How should I think about this, if at all?

3) The amp will be right next to this board, so I don't worry about shielded connectors or balanced/differential signals or anything like that. But, isolating ground might be valuable in routing. So, what's the best ground pin on the Teensy to return the signals to? AGND or one of the GND pins, and if so, which? (I need to separate the signal ground and the power ground on the connector.)

4) How do surface mount X5R capacitors perform, audio-wise? Are they noisy? Do they pick up vibrations as microphones? Do I need to worry about mylar film capacitors and so forth? (Both 1 uF and 10 uF caps are X5R MLCC)

5) What else am I missing, or should think about? Any and all feedback happily accepted! (And thanks in advance)


texts:
I am trying to use a gate driver HCPL-3210 for an IGBT
but one of the big disadvantages that I can notice is that each chip needs its own power supply of 15 V. So as a total I would need 4 power supplies for 4 gate drivers (to implement a single phase inverter).

As an alternative way to implement it. I tried to connect all the chips in a certain way such that one power supply will be used. But after testing this way I got a very strange output signal.

Below pictures show the circuit diagram that I used & the result at the output.

I am
looking forward for your kind reply & help.


texts: Cellular module(4G/3G/GSM) interface to host processor or microcontroller through UART how the data rate is achieved?

texts:
The majority of cellular modules are interfaced to host microcontrollers or microprocessors using UART interface or some times USB interface (where internally it's UART).
But the data rate of UART is much less. How are we able to achieve cellular data rates with respect to UART data rates?


texts:
Is it possible to both change and apply conditional logic on a local signals?
I used internal signal to drive an output tried the below but got X1X1 for the output.
Does anyone have any ideas? Thanks!
For example,
--Architecture
signal internal: std_logic:='0';

process(clk) begin
if(internal='0') then
  internal <= '1';
elsif(internal='1') then
  internal <= '0'
end if;
end process;


texts:
The question Noisy data line clears up on wiring up multiple output pins of uC to Logic Analyzer got me to thinking that the best way to see if outside interference is causing problems for a circuit is to test it in a Faraday cage. Big companies will even go to the expense of testing in Anechoic test chambers.

Very few hobbyists could afford an anechoic chamber, but what about a faraday cage? Could an old microwave oven be used as a Faraday cage? It would be cheap, or free, have a nice glass window to look through as well as a nice tight mesh for all openings good up to the microwave (duh!) frequencies. The only issue I would think would be to make sure that the door seal was in good shape and that the door closed properly.

Has anyone done this or is there a better, cheaper solution for use at home?

PS: I'm not thinking of EMP hardening like this guy: http://www.unitedstatesaction.com/emp_and_faraday_cages.htm only routine testing.


texts: What are these double lines in Altium designer?

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I have a problem with Altium: I want to know what these lines are. They look like a net with 2 perpendicular lines, but I don't know what it is! It's very boring to design my circuit.

How do I disable it?


texts:
I work on a project where i need to combine sound that comes from audio jack input (let say from tablet) with a sound we create from an MCU with DAC. So it basically means I need to sum the sound of : right speaker + left speaker + DAC.

Please see examples of what we did so far (notice we didn't yet chose the resistors for the op-amp):

How do you recommend to do it?
Is op-amp is the right way?
Do I need an amplifier at the output before I connect the it to a speaker?
Can you advise on values for resistor/any other component/other solution?

I don't have much experiment in that area.


texts:
I'm working on a project. I'm going to use a 'pulsing' electromagnet, and want to know how much power it's draining.
Is it just a case of, if im using a 12 volt battery for example, then I'm using 12 volts? Or is there a way to hook it up to a volt meter or DMM?
Also, does the magnet get stronger simply by coiling the wire more times around the iron core? Or are there other variables?
Any help would be appreciated, and answers in simple English as I'm a novice.


texts: Can someone explain the battery management schematic for the following robot?

texts:
This seems like a good start to build my own battery management system. Can someone explain how exactly is this circuit working? See link for full size image.

Link to Full Size Image
Link to Robot Here


texts: How to modifiy DC2259A evaluation board to access Vref2 on LTC6811-1 IC? For the purpose of powering external thermistors

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I am using a DC2259A Evaluation Board, to monitor battery cell voltages and am hoping to drive external thermistor circuits for the purpose of measuring battery cell temperatures from Vref2 on the LTC6811-1 IC (the IC at the center of the DC2259A evaluation board).
Has anyone successfully modified the DC2259A Evaluation Board to access Vref2 on the LTC6811-1? Using this modification then to drive external thermistor circuits? If so what strategy would you suggest?
link to DC2259A manual:
https://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/DC2259AF.PDF
link to DC2259A schematic:
https://www.analog.com/media/en/technical-documentation/eval-board-schematic/DC2259A-2-SCH.PDF
link to LTC6811-1 datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/LTC6811-1-6811-2.pdf
thanks for any help


texts: Powering peripherals from a microcontroller (ATmega328P)

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I am wondering if it is possible or even safe to power peripherals like sensors or bluetooth modules from the ATmega328P by setting pins of the microcontroller (uC) to high given that the peripherals are within the current sourcing capabilities and voltage limits of the pins.

I'm asking this because it seems more convenient to enter power-down mode on the uC and control the high/low of the switches in software before and after this mode to turn on or off the peripherals. I'm probably missing something and I'd like some clarification on the above.


texts: Creating a LoRaWAN gateway with multiple nodes?

texts:
I'm working with a project to collect temperature data from about 50 cabins that are located close together. It therefore seems easiest to use 50 Lora nodes with temperature sensors and one gateway.

So I'm searching for a way to use multiple Lora nodes to create a sensor network. From what I've gathered it might be more cost and time effective to buy a readymade gateway such the Dragino. But I can't seem to find any good guides on how to create a small Lora node? I live in Europe and therefore want to use 433Hz frequency. I'm thinking something like a RFM96 and an Arduino nano should do the trick? Or is there easier solutions?

Since there is little documentation about this I hope others can find this useful as well.

Thanks in advance!


texts:
I'm trying to use an LCD (DEM16101) from a uC.
At some point I've connected it's power input to a 6V battery (above its 5.5 V max rating).

I can't initialize it properly so at this point I'm wondering - how can I tell if I've fried it?


texts:
How can I calculate ideal values of current for both short  and open circuits by using Ohm's law.
Further more usually said that it is not advisable to connect DC batteries of different voltages in parallel can you explain it for me in the light of Ohm's law?

edit:

A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. This results in an excessive electric current limited only by the Thévenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors. while an open electric circuit through which current cannot flow because the path is broken or interrupted by an opening.


texts: How do I get the voltage to stay at 5V when using air pumps?

texts:
I have a design where I am using 2 mini air motors pumps of (3 V each, rated current< 150mA each,) 2 release valves (5V each and 263mA each.)
The Arduino microcontroller sends 5V to the motors and the release valves.
As of right now, the voltage drops when the motor kicks and when the LCD kicks in.
We want to resolve that issue to have a steady 5V baseline.
I tried to remove the transistors and replace them with flyback diodes but it didn't work. I also tried keeping the transistors and adding flyback diodes to the pumps and the release valves, no result.
I tried designing a flyback converter but I have a tons of questions regarding the choice of the values.
Would that help?
How do I get the voltage to stay at 5V?


texts:
I bought a Raspberry Pi and I noticed some of the routings are not straight lines but instead they make a funny ondulatory shape (see picture at the right and bottom of the processor).

I'm not sure the reason of this shape. I have two guesses:

It makes this signals slightly delayed compared to others.
It makes the the route a certain exact length which would avoid resonance frequencies.

Are my guesses correct? Or this shapes are for something else?


texts: Capacitor as power buffer for battery change

texts:
I have a quite simple question and quite a simple circuit in mind.
I have an application, which is battery powered and uses a RTC clock for timekeeping.
I would like to preserve the time during battery change, which is to be expected less than 10mins.
The RTC consumes 5uA max. and keeps working until Voltage is as low as 1.3V.
According to the standard RC discharge formula, a capacitor of about 1mF would be enough.
Is this circuit for backing up the RTC too simple/ have I forgotten anything on there?
Thanks in advance

simulate this circuit – Schematic created using CircuitLab


texts: What's the purpose of the OpAmp in this circuit?

texts:
This circuit is from the datasheet of the famous voltage reference LTZ1000. Can anyone explain how the circuit works in detail? Particularly the OpAmp.

I find another similar circuit without Op-amp using in the book "Current Sources & Voltage References" by Linden T. Harrison.

I think there are something similar. My question now is what we can benefit from the op-amp ?


texts:
A am new to AVR programming. I have an Attiny85 and an LED hooked up to pin 5 on the chip (PB0). My goal is to get the LED to fade on, then turn off and repeat. When I give power to the chip the LED lights up very little. It is a very faint glow. It stays the same brightness for several seconds then lights up to its full brightness. Below is my code.

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

double dutyCycle = 0;

int main() {

    DDRB = (1 << PORTB0); // Set PB0 as output

    TCCR0A = (1 << COM0A1) | (1 << WGM00) | (1 << WGM01); // Clear OC0A on compare, WGMxx selscts fast mode
    TIMSK = (1 << TOIE0);

    OCR0A = (dutyCycle / 100.0) * 255.0;

    sei();

    TCCR0B = (1 << CS00); // Set prescalar and start timer

    while (1) {
        _delay_ms(100);
        dutyCycle = dutyCycle + 15;

        if (dutyCycle > 100) {
            dutyCycle = 0;
        }
    }

    return 0;
}

ISR(TIMER0_OVF_vect) {
    OCR0A = (dutyCycle / 100.0) * 255.0;
}

I tried changing the type of the dutyCycle variable to an uint8_t but the results were the same. I removed the '.0' from some and all of the math calculations but again the results were the same.


texts: System Generator: How to configure the CORDIC divider block. Understanding the block parameters

texts:
I have some dudes about the block parameters of the CORDIC DIVIDER.
I would like to someone explain me the parameter called "Latency for each processing element".
(See the parameters inside the red rectangle)

I don't understand the notation that is used, some zeros or ones between two brackets.

By the way, this question is realted with one I asked before:
System Generator: How to configure the CORDIC divider block?


texts: Relate Pyroelectric Passive Infrared Sensor analog output to the digital "motion detected" signal

texts:
I'm using a digital PIR sensors from the picture below.

it outputs a high (3.3V) on motion detection, low (0V) when no motion was detected. The analog sensor component of this motion sensor is the Pyroelectric Passive Infrared Sensor (RE200B) on the image below:

I measure in parallel the outputs from the RE200B pins and the digital output to try and figure out what does a "motion detected" means in terms of voltage on the RE200B. Below is the graph of the measurement:

My assumption was that the voltage on the RE200B would be more variable and with larger amplitudes. This turned out to be false. Other that that, I can't seem to understand how to correlate the two outputs. At first I thought I could relate the flickering of blue the signal the first "motion detection" showed by the red. But the second digital motion detection has no accompanying flickering.

I've tried looking at the datasheet but don't know how to read the expected behavior.

Any ideas on what the expected output of the RE200B would be?


texts: Calculation for the Boot Strap capacitor

texts:
For design of a synchronous buck converter (which would be used to charge the battery) which would be driven by Micro-controller's PWM output, i selected the IRLB8748 NMOS Power transistors (for both high and low side switches) which would be driven by the gate IC NCP5351. As its my first time, while going through the data sheet of the driver IC NCP5351 (page 7, Figure 3)  I found the concept of the BOOST capacitor. Searching more for it I found the purpose of its use and also the method to calculate its value.

So for the capacitor's value calculation purpose I followed this design document from Silabs and calculated the value of capacitor and the resistor which would be needed in my case.

But i have a few confusions, which i needed to clear:

(My application specifications are : Vin = 12V , Vout = 4.5 , DutyCycle(max) = 0.375 , Switching Freq = 62.5kHz).

1) In the Design document (at Page 4, 2.2 Design Example) the value of Ib (supply bias current) is needed for the calculation of Eq. 1. I found this value for my case to be 50uA, given in NCP5351's datasheet page 5 (given as VBST Quiescent Current, Operating). So is this the right value to be chosen for my case for Equation 1's calculation ?

2) For equation 2, the value of Maximum allowable Ripple was taken to be 5% of VDD. What significance does this value has ? I also did the calculations in my case using 5% for this value. I hope it works fine.

3) If we look at the NCP5351 's Data sheet (page 7, Figure 3), the connection of the resistor and the boot capacitor is not the same as it is in the Design document in Figure 1 and Figure 2. The resistor in the design document is placed in series with the Diode and the Capacitor, however in the NCP5351's datasheet page 7, the connection is a bit different. So can i calculate the values for my Resistor and the Bootstrap capacitor (which turned out to be 21.5 Ohms and 93.2nF respectively), and place them like they are in NCP5351's datasheet page 7 ?

4) In NCP5351's datasheet page 3, its written that In conjunction with a Schottky diode to VS, a 0.1 uF to
1.0 uF ceramic capacitor connected between BST and DRN develops supply voltage
for the high−side driver (TG).. However the value for the Resistor is not given. Does that mean that i will select the value of the resistor which i calculated by the above mentioned Design Document ? (As the value of the capacitor that i caluculated came out to be 93.2nF which is approx equal to 0.1uF).

5) Also the main question, does This design document that i followed, provides the right way to calculate the Bootstrap Capacitor and Resistor values which would be needed in my case ?

Your helpful comments and suggestions would be appreciated.

Thankyou!


texts:
I have been putting together a project for work in Vivado 2015.2 When I try and implement the design I get these errors. The project is pretty large that's why I haven't included it in the post. Is there a way to find this net error using the TCL command?

I can't find this MEM/Q[0] anywhere in the design.

  [Opt 31-37] Multi-driver net found in the design: MEM/Q[0].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[10].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[11].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[12].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[13].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[1].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[2].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[3].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[4].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[5].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[6].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[7].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[8].
  [Opt 31-37] Multi-driver net found in the design: MEM/Q[9].


texts: AC: Why differentiate between Ground and Neutral?

texts:
Current flows through a conductor connecting points at different potentials.

Leaving aside multi-phase details, common/conventional AC systems use a 3-wire setup:

Wire-1: a line/live/hot/phase wire presenting a point that oscillates between 2 potentials.
Wire-2: a neutral wire presenting a point of unknown/unspecified and varying potential, that nevertheless presents some fixed/specified potential difference to Wire-1 at least some of the time.
Wire-3: a ground/earth wire presenting a point at 0V potential difference to its immediate physical surroundings.

Wire-1 and Wire-2, in addition to some device that is to be powered, are used to construct a closed electrical circuit. Wire-3, leaving aside EMI/shielding concerns, is used to ensure that current will flow through it, rather than the device's user, if there ever occur any faults and the device's user comes in contact with Wire-1 or Wire-2.

Additionally to this however, Wire-2 and Wire-3 are at some point connected. This is done to ensure that Wire-2's potential remains close to that of Wire-3 .. which seems to be important for some reason.

Now the part I don't understand is why there needs to be a distinction between Wire-2 and Wire-3 at the power socket, if there is none a few meters further down the line.

I have tried to look this up, but all answers I could find so far seem incomplete. The answers depend on how the question is phrased:

If the question is phrased as "Why do we need Wire-3 in addition to Wire-2" the answer is because "Wire-2 may be at a substantial potential difference to its surroundings/user and thus endanger him/her if he/she ever comes in contact with it or Wire-1".
If the question is phrased as "Why do we need Wire-2 in addition to Wire-3" the answer is because "Wire-2 is needed to form a closed electrical circuit" or phrased somewhat differently "Wire-2 is needed to create a potential difference to Wire-1 and thus for current to flow" .. with the argument further being that when taking practical considerations into account Wire-3 can't provide a reliable/stable potential difference to Wire-1 like Wire-2 can.

This doesn't really answer why there's a need to differentiate between Wire-2/Wire-3 though, considering how

Wire-3 remains Wire-3 and maintains 0V potential difference to its surroundings/user, regardless of whatever else happens around it .. since that is what it's supposed to do, or phrased differently, since that is the reason for Wire-3 being useful in the first place .. right?

and

Wire-2 is connected to Wire-3

What am I missing here?

Why is it safe to touch Wire-3 but not Wire-2, or why can Wire-3 provide a level of protection that Wire-2 can't?
Why differentiate between Wire-2 and Wire-3 at the power socket but then connect them further down the line?


texts:
I'm reading the datasheet of MAX4310:
https://datasheets.maximintegrated.com/en/ds/MAX4310-MAX4315.pdf
and I'm not sure how to configure the supply rails. The video input signals are AC coupled, hence they span below the GND rail.
I don't want to put a common mode voltage because I have very small free space on the board. At page 11 I read:

Vcc: Positive power supply
Vee: Negative Power Supply. Ground for single-supply operation.

I wonder if I can generate a -3V rail with an LTC1983-3 (http://cds.linear.com/docs/en/datasheet/1983fc.pdf) and then power the MAX4310 using a +5V on Vcc and -3V on Vee.
It hasn't a ground pin, though... how it can sense "where" is the 0V rail?


texts: Which pins need to be free to flash NodeMCU via USB

texts:
It is not completely clear to me, which pins need to be free (disconnected from other components) in order to flash the NodeMCU via USB with a firmware.
Of course, this depends on the connected components. But let's assume reasonable worst case scenario. e.g. LED with a resistor, which pulls down GPIO0.
I was wondering, if RXD0-TXD0 pins (GPIO3 and GPIO1) also need to be disconnected?
e.g. I have ublox GPS Neo 6M module connected to (only) RX on NodeMCU and I can't upload when this is connected. I left TX not connected to get debug messages via USB.

Is it possible to flash via USB->UART1? Is the USB-UART chip capable of this? If not, then also GPIO3 and GPIO1 need to be "free".
The reasons are:

For beginners to understand, why and what to disconnect, when they have issues with uploading their sketch/firmware.
When device is in an enclosure, it might be difficult to disconnect components.
When device is soldered, it will be difficult to disconnect. In order to plan accordingly, one might introduce switches on certain pins to avoid such problems.

Basically, what pins may cause issues to upload firmware/sketch, when connected to certain components during the upload?

Module: Lolin v3, but it would be interesting to know for others too.


texts: Importance of Common-Emitter Input & Output h-parameters

texts:
Speaking for NPN Bipolar transistor:

In many practical examples parallel resistance of base-emitter junction (aka hie) and finite collector-emitter parallel resistance resistance (aka hoe) are usually neglected. Why? Because their values shouldn't significantly change input and output resistance of the transistor circuit.

In my opinion their values are actually very important - why? Because "hie" and "hoe" are usually small enough to cause drastic changes in input and output resistances of transistor circuit.

Differential resistance of base-emitter junction is defined as rbe = β/gm, where gm = Ic/Ut (where rbe is from few kΩ to few tens of kΩ for Ic values of few mA and β values 100 - 500). Example shown below:

It can be seen that parallel differential resistance of base-emitter junction has significant effect on input resistance small-signal calculus (e.g. voltage divider).

So why does it get neglected so many times if practical values of hie shows important meaning of it in calculus of input impedance?
Same thing for differential collector-emitter resistance which is defined as ro = Vce+Va/Ic, where Va has values from few tens of kΩ and on - which can also have significant effect on output resistances.


texts: Designing an adjustable count-down timer

texts:
I am trying to design a digital timer that receives a time, t, as input and after t seconds it triggers a buzzer. It is actually similar to a kitchen timer but we can adjust the time ourself.

A way to do this is using a "555 IC" but the time will be a function of the resistor and the capacitor we choose and we don't have control over the time after we build the circuit.

Can anyone please help me with this problem?


texts: What loading capacitor do I use for my crystal?

texts:
I am using this crystal (the 7.3728 MHz variant).

The datasheet specifies a 5pF to 55pF load capacitance; is this really so? I was under the impression that most quartz crystals had an optimal capacitance which was fairly critical for oscillation.

In my design, I have specified 18pF based on another crystal (of the same frequency and nearly the same specifications), which is not available at the moment. In that case, the datasheet clearly specified 18pF.

If it matters, I am using a dsPIC33FJ128GP804 microcontroller/DSP.


texts: Current flow through resistor in as current

texts: While I was working in an AC current lab, I used a very simple circuit. 1 resistor and a wave generator. The voltage was about 3V (RMS) and the resistance 1.173 kohm. According to Ohm's law i.e. V=IR I should have a current flow around 2.5 mA. But the multimeter showed me a quite different value, that is .2 mA. What is the problem, is there anything I missed?


texts:
We are working on a system that will need some predictive emergency stop. As a possible solution the RTOS was mentioned. Not sure if RTOS is a way to go, might just be that we do not have full understanding of the flow of it.

So there is a process running on PC that does some calculations and it needs lets say X seconds to fully finish while the machine continues working. What we want is the data that needs to be analyzed sent to RTOS and run quick check if that is possible at all and if not to stop the machine. Also some check to see if the process is running on PC at all, otherwise stop the machine.

Does that make sense, should that use RTOS?

Idea is to add RTOS, so that is a fully parallel OS running on same machine and it can communicate with other OS, to receive data or listen to running process? Or does OS need to send stuff through API to RTOS?

FreeRTOS is something that has been checked and we would go for if that is the solution.