texts: Problems sharing data on a common uSD between a camera and micro; - Switch (TS3A27518E)

texts:
Having a lot of difficulties sharing a uSD card between two devices (Atmel micro which uses the SPI, and the camera). We used to do this using relays and all worked fine but cards got faster and faster until now where we get a lot of failures.
We have therefore been evaluating using digital multiplexers. We initially tried the FSSD07 fairchild mux but had problems when the uSD was being switched down from 3.3v to 1.8v operation as the data and clock lines change voltage but not the supply rail. This messed up the high and low level thresholds.
Then we made up a pcb to try using the TI TS3A27518E mux. Things were definitely better but we are still having problems with bus speeds over 50MHz. All of the SD lines apart from VDD and VSS pass through this one Mux (6 channel). VDD is switched separately. Looking at the signals on the oscilloscope, the clock sometimes begins to look nasty at the higher speeds. Looks like I may be having  two issues:

There could be some stray capacitance causing rolling of the clock signal edges which at the higher speed is delaying the rise and fall times enough that the clock is changing state before reaching the correct logic levels (this presents itself on the oscilloscope as a smaller amplitude clock with a DC offset). The PCB is about 80mm x 24mm, 4 layer (top, gnd, pwr, bottom) and tracks are 0.5mm where possible, else 0.3mm thick. PCB track resistances are less than 80 milli-ohm so that shouldn't be a problem.The mux resistance is 300 milli-ohm and given that I at times see a time constant of 10nS, that would equate to about 5nF stray capacitance. Capacitance of the switch is supposed to be about 21pF. I would have thought 5nF is way too big for stray capacitance.

Secondly, sometimes the clock looks like it is getting some reflection interference (admittedly I didn't specifically impedance match my PCB tracks).

Not really too sure if I am approaching this all the right way as I don't know a lot about the SD requirements. At first I thought the DC offset on the CLK was causing all the issues but then there are times where I see a DC offset and yet the camera writes to the card without any issues.
We would like this to work with a variety of cameras that can handle the higher speeds. We find that Nikon cameras have the most errors while Canon and Fuji cameras seem to be a lot better. We really need to be confident that we will have zero interface errors. Any thoughts on what I can try to get the SD working at 100MHz CLK speeds?

Limited to how many pics I can insert so here is a screenshot showing the PCB layers and the important half of the schematic.

This second pic shows in the top LHS the point where SD comms fails (when it switches to the higher speed). Below that are pics of the PCB where I bypassed the switch with 10 ohm resistors and then also with wire links. On the RHS is the CLK signal (Ch 3) when connected to the Nikon D5300 (comms failed). Ch 1 is the same CLK at the input (connected to J5). From that it makes me think that the camera is sinking the clock signal at the uSD CLK voltage is bigger in magnitude than the J5 side.

The problem is exacerbated when we use a SD card extender between the camera and my PCB. We could work around this by having the board in the camera and then running a cable between out micro and this board but that makes things a bit messier.

If I can't sort out a hardware solution, is it possible to write from the micro to the SD cards to force them to operate at a slower speed when the uSD connects to the camera??

Looking forward to seeing what wealth of info I might get back:)

Many thanks!

Paul


texts: Do I need to fully drain lead acid battery before charging them?

texts:
This is a follow up question based on this.

I have an ebike which uses lead acid battery, my question is do I need to fully drain it before charging it again?

How about when the battery is newly bought, any changes in charging it?


texts: Which USB 2.0 chip to interface PC with FPGA?

texts:
I'm planning to build a software defined radio.
I'm looking for some chip to get out data from FPGA, and sending it inside. I need to use parallel interface. I read about an FT4232, but these don't have really fast parallel modes. Or maybe I should approach it differently?
I need also to configure the FPGA using that interface, so I have to bitbang Spartan-6 pins.
Do you think I will be able to use CCLK and DIN pins after configuration in FPGA normal operation?

Can you advise me some chip to use?


texts: Can HEDS-5500 rotary encoder work with semicircular shaft?

texts: Does anybody know if HEDS-5500 rotary encoder can be used with a stepper motor semicircular shaft (with the shape like in this picture)?


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

void init(){
    // LED output.
    DDRB |= 1<<4;
    // Turn on ADC on third pin, continuous mode, prescaler 128.
    ADMUX |= (1<<MUX0) | (1<<MUX1);
    ADCSRA |= (1<<ADEN) | (1<<ADSC) | (1<<ADATE) | (1<<ADPS2) | (1<<ADPS1) | (1<<ADPS0);
}

int main(){
    init();

    uint16_t adc = 0;
    while(1){
        adc = (ADCH << 8) | ADCL;
        // adc = (adc + 1) & 1023;
        // _delay_ms(1);

        if(adc > 512){
            PORTB |= 1<<4;
        }
        else{
            // PORTB = 0;
            PORTB &= ~(1<<4);
        }
    }
}

This is the code I have running on my ATtiny13A. There is an LED connected to pin B4, and potentiometer to B3. The code is supposed to turn on the LED if the analog value is greater than 512 (half of maximum 1024). It doesn't work though, and LED seems to be disabled all the time.

Normally I would assume there is something wrong in configuration of peripherals, but there are some very strange things happening. For example, if I change PORTB &= ~(1<<4); to PORTB = 0 (which in this case should do exactly the same thing), the code magically starts working just as expected. Another thing I tried is changing LED status using simple counter by uncommenting the two lines near _delay_ms - and again, LED starts blinking as expected.

The only time when this code does not work is when it's in exactly this form - so there must be something wrong with combination of ADC reading and output port bit writing.

Why does this happen?


texts: Frequency response and the effect of phase

texts:
Lets say I have a low-pass filter in a sound system.

I draw a magnitude and a phase diagram as a function of the frequency.

Disregarding the magnitude, how does just the phase affect the sound we hear?


texts: I have been designing a micro strip patch antenna with inset feed and I have a few HFSS simulation questions

texts:
Substrate dielectric: 3.5
Substrate height : 1.5mm
Frequency: 2.5GHz
I followed a particular video on YouTube to guide me, and used an online calculator for the width and length of patch, inset feed length and width. The following are the dimensions used:
length of patch: 31mm
width of patch: 40mm
gap in patch was about 3.4 wide
inset feed point: 12 mm
width of conductor was about 4.5mm [impedance at the edge was about 202.5 ohms and my conductor's is 50 ohm]
I ran an optimetrics sweep and the best gain I have been able to get is about 8.5dB. Is this practical? I feel i should be getting more. I have seen certain simulations for similar frequencies in HFSS and some get around 20dB. Am I doing something wrong? Image to my S11 is below


texts: How to make and simulate cyclic closed circuits in Quartus

texts:
I need to simulate this circuit.

But simulation returns that, prior and hold lines is in 'U' state when they must output something. Prior line must output number and hold line must switch into high logic state.

Even if I just simulate one single block like with hold_out and prior_out connected to hold_in and prior_in accordingly I still get this issue with uninitialized lines state.

I get same result, prior line switch to 'U' state, when it must return some number.

So, is there any solution to simulate circuits like this one?

P.S Schematic of arbitr component. priorCounter and compareNums written on VHDL.


texts: What happens to a 50 ohm line when its terminated at an impedance less than 50 ohms?

texts:
Let's say I have a quarter wave section of a 50 Ω coaxial cable, and I terminate it with something that has < 50 Ω impedance.

When I measure the input terminals on that coaxial cable, what should I expect to see for an impedance? Would it be 50 Ω at that point, or should I expect to see a value > 50 Ω because of the way its terminated?


texts:
I built the typical application in the datasheet but after powering up the circuit I got no output and the IC is getting hot with in seconds even it is only consuming 60 mA, I am running the circuit from lab power supply.

I have double checked every connection and I have changed the IC 3 times but nothing is happening

Here is my schematic: All ceramic caps

EDIT
Adding the PCB
Red Is top blue is bottom

I am not sure what is wrong exactly!


texts: I've downloaded XILINX ISE 12.1 but I am facing problems with Modelsim. I've download it as well but there's no set up file in the Modelsim folder. How I get this installed? Do I have to install something else first. Generally speaking if someone knows how to install Modelsim for 12.1 suite please let me know.


texts:
I hope someone is familiar with Catapult - available tags make it seem unlikely.

My issue is that I have two blocks (as seen in Quartus) being worked on independently, separate RTL.

Unfortunately, Catapults naming during compilation means that both of these have several 'identical' (-ly named) elements, so Quartus cannot compile.

If we were to change them all manually, any change to the C++ causing recompilation in CatC, would mean we'd have to manually change the RTL names all over again.

Is there some way to tell Catapult to prefix all mgc_in_wire and similar names by something user-defined, so that we can ensure they are different when we bring them together?


texts:
As a design exercise I'm trying to come up with a design for NBFM. I'd like to stick with digital domain as much as possible, since that's what I know best. I'm familiar with RF enough to know that I know nothing of it... I did design a 868 MHz telemetry transmitter board using a Micrel RF chip almost ten years ago, and it worked without problems and to the best of my knowledge is still in production with the company I worked for at the time. But that was only following Micrel's app note...
So my idea is to use a DDS chip such as AD9832 to generate narrow band FM signal centered around 10.7 MHz. Deviation should be around 10 kHz, enough for human voice. I would then use a digitally controlled PLL along with a mixer to up the frequency to my target which is around 450 MHz. Is the AD9832 a suitable choice for this? From reading the datasheet it contains a 25 MSPS 10-bit DAC and can accept serial data up to 20 MHz. Therefore I think it should be able to do the 10.7 MHz signal.
Am I on the rigth track with this? Any pointers for a possible receiver end IC?


texts: Off grid solar PV system for developing countries

texts:
I am designing an off grid system for developing countries for charging cellular phone, tablets pad and notebook computers. Design aim is to use low cost, simple, mature (slightly older) and mass-manufactured technologies. Your idea and contribution are mostly welcome.

I plan to use ready made modules from ebay, etc.
Is mono crystal solar panel better for this task? What point to take care on choosing PV panel and controller? 100W panel seem mainstream size.
For notebook charging, I plan to use off the shell, 12V boost to 19 V, simple boost converter, 6 to 8A. Many excellent information in this post.  Why do many laptops run on 19 volts?
To what extend is 19V 'standardized'? Some posts mentioned some
brands use special '3 wires' charger that communicate between
notebook PC and charger, so that non brand charger will not work.

To what extend is the power connector size standardized? Do I need
to get those multiple size adapter kit?
https://en.wikipedia.org/wiki/DC_connector
For charging of 'slightly older' phone (USB 2, 5V, 0.5A), I plan to use an off the shelf 12 to 5V USB simple buck converter module.
How about those latest phone and notebook that use USB 3.1, USB C,
Quick Charge, Power Delivery mode, that are higher current, voltage
or both? Are they backward compatible? What will they do when
connected to a simple (no intelligent communication) buck converter
supplying 5V?

For use in developing countries, there is no need to chase the
cutting edge. However, if it is low cost and easy to do, what are
the prospect of something better than the basic "USB 2 at 5V 0.5A"?


texts: Identify the Maximum Voltage that can be applied across Zener, MOSFET and Transistor

texts:
In many Zener Diode datasheets, I have witnessed that in the Absolute Maximum Ratings section, they don't include the "Maximum Voltage" that can be applied to the Zener diode. If the applied voltage crosses the Zener breakdown voltage, then the voltage will start to conduct and will enter in the Reverse Breakdown Region.

The datasheet only include maximum power dissipation, Thermal, temperature and Maximum Forward voltage information.

I want to understand why the maximum voltage rating is not provided in the zener diode datasheet.

My questions:

How to find the maximum voltage that can be applied across zener? Should I reverse calculate the Maximum Zener Voltage from the Maximum Power Dissipation rating provided in the datasheet? If so, could you provide an example.
And in case of a transistor/MOSFET, the maximum voltage that can be applied across it, would be the Maximum Collector-Emitter / Drain-Source Voltage, right?

Please help to provide clarity

Edit :

Zener Datasheet = Zener

Transistor Datasheet = Transistor

MOSFET Datasheet = MOSFET


texts:
I have done this question on physics forum but for some reason my question didn't receive any attention there(maybe because physics site is for theoretical physicists mostly) and I have this question.
When there is current in a wire, a magnetic field is created around the wire. Will it affect the resistance of the wire at all or do we need an external magnetic field? And cN


texts: String manipulation of a http response using Arduino

texts:
I will like to separate into different vars some information from a HTTP response, at the moment I'm just printing to the serial port the raw data, using:

Serial.print((const char*) Ethernet::buffer + off);

And that prints:

HTTP/1.1 200 OK
Date: Wed, 21 Nov 2012 22:47:21 GMT
Server: Apache
Vary: Accept-Encoding
Connection: close
Content-Type: text/html

Temp = 28...

I wonder how can I extract the information I need for later analysis, like the HTTP response code (200), the date, and the value of Temp, how can I extract this values into variables?


texts:
Does anyone know how to import Sparameter (touchstone) files into ltSpice and how to use them?
I have downloaded s3p format file, but I don't know how to use it. I cant find any information in the Internet.

Thank you


texts: is it necessary add snubber network for a SSR made by mosfets?

texts:
I am designing a control circuit for AC/DC loads. To achieve this, I am using a SSR made by mosfets https://datasheet.lcsc.com/szlcsc/Vishay-Intertech-LH1546AEF_C142599.pdf

However this is not a thyristor based component, so it is not gate sensitive. I am assuming that snubber network is not necessary. is this assumption correct?


texts: Asynchronous SRAM routing crosstalk concerns

texts:
I'm routing a large BGA SRAM that is connected to a BGA FPGA, and there's about 40 signals altogether connecting the two. I'm using Henry Ott's recommended 8-layer stackup:

1 ________________Mounting Pads/Low Freq. Signals
  2 ________________Pwr.
  3 ________________Gnd.
  4 ________________High Freq. Signals (SRAM Layer 1)
  5 ________________High Freq. Signals (SRAM Layer 2)
  6 ________________Gnd.
  7 ________________Pwr.
  8 ________________Low Freq. Signals/Test Pads

I've fanned out the BGA such that all the SRAM pins are on layers 4 and 5. However, my routing results in a lot of parallel traces on adjacent layers, and I'm concerned about crosstalk:

(I'm in the process of length tuning. SRAM traces are different shades of blue, indicating address/data/control groups, not layers. Sorry for any confusion.)

Questions I have about SRAM routing:

Should I revise my stackup to seperate these layers with a ground, or should I just try to avoid traces that are directly adjacent for long distances? Should I try to get all signals onto one layer using vias, or is that even worse?
On a related note, when I'm calculating trace-impedence of signals on layers 4/5, is that calculated as a microstrip or an asymmetrical stripline? It's not open to the air, but it's also not sandwiched directly between two ground planes.
Finally, this is unrelated, but for asynchronous SRAM do I need to length-match all signals or are there groups like in DRAM? I'm under the impression that for a write, for example, address and input data would need to arrive together, hence everything is length-matched.

This is my first high-speed design like this, and any advice would be greatly appreciated.

EDIT: SRAM part number for reference is CY62187EV30LL-55BAXI


texts: Best battery for low power, long term application

texts:
Im designing a product which needs around 5 to 7v.
I need to power it from a rechargeable battery.

It spends most of the day in an off state, consuming about 0mA.
Sometimes is powered by the user, draws 40mA for 4 seconds and 200mA for 1 second, then it shuts down.

The peculiarity of the project is that it needs to run without any charging for 5 months a year. It will be subjected to ambient temperatures up to 50°C.

I've excluded, for one reason or another, pretty much every type of battery i know:

lithium based batteries are not happy to stay at full charge and almost full discharge for such long time
nichel based ones seems to have a big self discharge
lead acid batteries seems like the more suitable type, but it also seems that they are very heat sensitive. I understand that there are also some "deep cycle" ones, that would be more suitable for my application, but are pretty rare.

I don't have any weight or space constrain (well... As long as they are reasonable)

At this point I'm quite lost, i hope for your help. I'm not an expert on batteries, some of my considerations can be wrong.


texts:
I need to solder header connector dedicated
for SMT on my control PCB. My problem is that
I have only standard soldering iron and I don't
have a rework station. Please, can somebody tell
me whether it is possible to solder SMD by
soldering iron? If it is possible what is the
best practice how to do that? Thank you in advance.

The part I want to solder is:


texts:
I am trying to design current source of 20mA for LED 1550e(thorlabs).The circuit designed gives accurate result in proteus simulation that LED is giving a voltage drop of around 1.2V and drawing 20mA current. But in actual the current passing through LED is around 70-80mA. So what is the error i am making. Schematic of circuit is as folows

simulate this circuit – Schematic created using CircuitLab
Results of my simulation are shown in the picture


texts: Yagi gain reduction when using off frequency (2.3Ghz WiMax system using 2.4Ghz WiFi Yagi)

texts:
I have a new WiMax 2.3Ghz broadband service that has marginal reception. As the frequency 2.3Ghz used is close to WiFi I am thinking I can use a cheap WiFi yagi instead of a much rarer (and expensive) 2.3Ghz yagi to improve reception.

I'm aware that I won't get as much gain at 2.3Ghz versus 2.4Ghz as the antenna won't be perfectly tuned but I believe yagi antennas are somewhat tolerant to being used a little outside their tuned frequency.

Can anyone explain or point to more details on yagi performance outside its tuned frequency so I can work out if I should DIY a 2.3Ghz tuned one? I'm OK to lose 3dB of gain but not much more.

Thanks for the input.


texts:
LDO efficiency calculation output current do we need to consider load current value or LDO maximum current rating?
Ex: I have selected TI# LP38841-ADJ

Input voltage: 0.95V
LDO maximum output current: 800mA (datasheet value)
LDO quiescent current: 32 mA (datasheet value)
Designed output voltage: 0.85V
Maximum load current: 4 mA

When applying the above efficiency formula, is it necessary consider LDO maximum current (800mA) or maximum load current (4mA) for output current Io?


texts: Help reverse engineering RCWL-0516 microwave proximity detector module

texts:
I got a cheap RCWL-0516 microwave doppler radar proximity sensor module to evaluate. The RF part of this has surprisingly few components (what looks like a MMBR941M NPN and a hand full of passives)... but I think more important is the microwave magic PCB design. There is very little hard information available for this (eg even the operating frequency is left unstated.. I found mine at 3.181GHz!). My aim is to try to document the workings of this module as much as possible. I'm making my research available on GitHub (link below).

Unfortunately microwave is voodoo magic to me. I wonder can anyone with microwave design expertise have a quick look over my research to date and provide me with pointers for further research?

The GitHub repository is here:
https://github.com/jdesbonnet/RCWL-0516

There is also a datasheet for this module, unfortunately for the non-Chinese, it is in Chinese language.

Update (13 Jan 2017): the best explanation I've found so far is a patent which describes another module (a 5.8GHz module available from ICStation SKU 9552): https://patents.google.com/patent/EP3091605A1/en


texts:
While reading Linux User's Journal today, I stumbled across a little blurb about NuttX RTOS.  I checked out their website and was fairly impressed with it's feature set and it's ability to put it in an 8052! I find it interesting that it supports POSIX which is something I have helped worked on for one of my clients in-house RTOS.  This one seems a little more feature rich than the in-house RTOS.

Has anyone else heard of NuttX and has given it a try?  If so, how does it compare to other RTOS's such as FreeRTOS?


texts:
I have a H-bridge that is being supplied by 12V and using around 10A. I am turning it on/off with a microcontroller that has an output of 0V-5V. The switching frequency is "super low" so the gate charge of the MOSFET is not a problem. I am trying to "convert" this 5V logic to 12V logic (0V-12V), and thought of something like this:

simulate this circuit – Schematic created using CircuitLab

Is there any redundacy, any problem or anything missing from this design? I can see this work, but this will be in "somewhat of a commercial product", and would like it to be as robust as possible.


texts: STM32F1/F4: Risks of driving a LED from PC13

texts:
In the STM32F411xC/E advanced Arm®-based 32-bit MCUs reference manual on page 71/844, I can read:

  Due to the fact that the switch only sinks a limited amount of current (3 mA), the use of
  PC13 to PC15 GPIOs in output mode is restricted: the speed has to be limited to 2 MHz with a maximum load of 30 pF and these I/Os must not be used as a current source (e.g. to drive
  an LED).

You can read the same note in the STM32F103's reference manual.

What can go wrong or what is the risk if I connect a LED to PC13?

It seems "famous" prototyping boards like the Blue Pill and others I have found do have a LED connected to PC13. Is that wrong? Should I try not to use that pin in those boards or is it safe as long as the LED current is less than 3 mA?


texts: In case I upload a sketch to a teensy board via the Arduino IDE (teensyduino), should any of the TX/RX pins of the teensy be unoccupied?


texts:
This is a fairly general question with no specific example in mind as I was just thinking about the problem, but was unable to find any answers on the internet (probably because I am not asking the right questions).  I will however give a hypothetical example that may help to give clarity to my question.

Ok I am trying to understand how to combine 2 or more independent DC voltage sources, but will stick with 2 for now.  Say these sources were 2 solar panels which have different power and voltage characteristics, one 22Vmp at 180W and the other 30Vmp at 240W, it wouldn't be advisable to put these in parallel or series and for the purposes of the question lets say this is not an option.

What would be a good way to combine these 2 DC sources into a common DC source?


texts: On the ATTiny45 data sheets it states that PB5 can be used as a digital IO pin and I want to use it to trigger a pin change interrupt, my only issue is that it is also the reset pin and the moment I connect it to ground to try and trigger an interrupt it resets the ATTiny. Is it possible to use this pin for interrupts and if so how?


texts: SD card SPI initialization Check Pattern Fail

texts:
I'm trying to interface a Swissbit 512MB (S-450u Series) SD card (datasheet here) with an ARM microcontroller through the card's SPI interface. The datasheet for this card says it's fully compliant with SD Spec v3. When I send CMD0, I get the expected response. But when I send CMD8 with check pattern=0x1AA and CRC=0x87, I get the response 0x21F, even though the card is supposed to echo the check pattern.

This has been discussed here, but the accepted response doesn't make any sense, and doesn't work for me either. I haven't been able to find anything in the SD Card Simplified Spec to describe malformed check pattern responses. If I received the Illegal Command flag, I would know that this is a version 1 card, but I don't receive that flag, just the malformed check pattern. The card works just fine when I plug it into my PC and format as FAT. I've tried with a Samsung card and I get the same result.

I also have tried sending SCK pulses before each transmission, while CS is high, as suggested by many people.

What causes malformed check pattern responses in SD cards?

This is a screenshot of the dummy cycles for resetting the card.

This is a screenshot of CMD0 and response.

This is a screenshot of CMD8 and response.

EDIT: The SD card and the microcontroller were previously being powered from 2 different supplies. Now I've switched to powering them off of the same supply, and they draw about 30mA at 3V. This hasn't changed the SD card's response to CMD8. However, I have noticed that if I send CMD55 after CMD8, the SD card responds with the R1 response of 0x03 (idle bit and erase reset bit on). I'm not sure if this is a useful hint though, or just barking up the wrong tree.


texts:
This is a follow-up to a previous question, regarding the VO2223A opto-coupler/Phototriac. My understanding of the chip is that the IR LED triggers a phototriac, which in turn drives the gate of a power triac.  In which case... what's pin 5 for?  It's listed as a "triac gate", but there's no obvious reason that I can see for it (unless it's in a different configuration to the one that I'm assuming).

And if I don't need to use it, do I need to strap it to ground, to another input, or to leave it floating?  Unfortunately the specimen circuit diagrams in the datasheet (which are usually my first point of reference for pin assignments) aren't particularly helpful -- they don't include pin numbers, and appear to omit 5 entirely -- and I've never been able to find online any circuit example that uses the chip.


texts:
I followed a video (Click Here) to make the 0-9 Counter.
The counter does work but its a little bit buggy.

For the first 0 - 9 cycle it works fine but then it starts to follow this sequence:

Where is the bug being caused?

Schematic:

4 5 6 Are bugging then they fix and move on.
p.s Im Using a 9Volt Battery


texts: Are low ESR caps away from the LM317 liable to cause instability?

texts:
I'm building a standard LM317 supply for testing/general use:

Image source: ElecCircuit - Variable power supply using LM317
The datasheet states the output cap (C3) is not needed for stability, so I will omit it. I have also read low ESR caps for C3 can cause instability. So what happens if this supply is eventually connected to something with large and/or low ESR caps on its power input?
Won't those caps just act like C3 in the circuit and be liable to cause instability?
Will using a high ESR cap for C3, instead of omitting it, help prevent instability caused by whatever is connected to the supply?
If not, how is this dealt with?


texts: I'm really confused with the representation of PMOS device shown in the figure. Since conventional current direction in PMOS is from source to drain, shouldn't the current source be pointing upwards(from node Y to VDD)?


texts: net has only one pin in multi sheet design

texts: I am doing a schematic and following multi sheet hierarchical design. Connecting 2 sheet entries with a bus giving me an error of "net has only one pin". I have read many articles on this, but I want to understand what is wrong with this and even after connecting the net is connected at both the ends why the error shows up?


texts: Controlling a stepper motor with a motordriver and Arduino

texts:
I'm trying to controll a Nema 34 stepper with a motrordriver(EM-314) and Arduino Uno.

I have gotten the motor to rotate(slowly) by setting pin 5 on the Arduino to high. Pin 5 is connected to Preset 4 on the motordriver. I would like it to speed up, but im not sure how to do this.

Do any of you guys know how i can get it speed up?

Datasheet for the motordriver:
http://media.oem.se/Archive/FilesArchive/102826.pdf

Currently i'm using a powerslupply on 0-48V 10A.

Every answer is apprciated!

Edit:

Pin 7 on arduino is connected to STEP IN
Pin 6 is connected to DIR/STOP/RESET
And i'm using a potentiometer to controll the speed.

Here is the code im using in Arduino.

int sensorPin = A0;
int sensorValue = 0;

void setup() {
  //Serial.begin(9600);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  digitalWrite(6, LOW);
  digitalWrite(7, LOW);

  }

void loop() {

 sensorValue = analogRead(sensorPin);
 sensorValue = map(sensorValue, 0, 1023, 3600, 1);
 //Serial.print(sensorValue);
 //Serial.print("\n");
  if(sensorValue > 3000){
    digitalWrite(7, LOW);
   }
 if (sensorValue < 3000){
 digitalWrite(7, HIGH);
 delayMicroseconds (sensorValue);
 digitalWrite(7, LOW);
 delayMicroseconds(sensorValue);
 }
 }


texts: Driving a hobby stepper motor with an industrial PLC

texts: I am working with an industrial PLC, the Beckhoff BX9000, with 24 V digital outputs. I am looking to drive a hobby stepper motor with Polulu's 'A4988 Stepper Motor Driver Carrier', which accepts logic inputs with a max of 5.5 V. Will a simple voltage divider suffice to step down the 24 V clock signal to a 5 V clock signal to be input to the stepper driver? Or will issues occur?


texts: Power supply over-current protection mode: constant current

texts:
I am researching power supply over-current protection modes, and I have a question about constant current.

Wikipedia claims (https://en.wikipedia.org/wiki/Foldback_(power_supply_design)) that the current remains constant while the voltage goes to zero. Doesn't this violate Ohm's Law? R is not changing, I is not changing, but somehow the voltage can change willy nilly?

What gives?


texts: What is difference between Wait state & Bus idle machine cycle in Case of 8085 Microprocessor?

texts: I have Understood that Wait State provides extra time for slow devices by making ready signal low. Bus idle is a machine without performing any Read/Write Signal, I am able to figure out some differences but confused about their functionality as both provides some Delay only.


texts: Replacing capacitor from unworking TV with some other capatitors which has not the same value

texts:
I am repairing (trying to repair) my TV.

I found 1 capacitor 25V \$1500\mu\$F which i think is bad (it has some weird shape at top)
I don't have any capacitors with that value but I have some similar to that

25V \$470\mu\$F x3
35v \$1000\mu\$F

Can I replace the bad one with this 35V \$1000\mu\$F, or can I combine them (serial or parallel)?


texts:
Since I work with equipment where sensitivity to AC is an issue, I tend to build linear regulated power supplies for my projects.

What factors do I have to consider, to decide whether I need a line filter as well?


texts: Why are 11, 111, 1111, ... equivalent to -1 in two's complement?

texts: According to two's complement, the binary numbers 111 and 11111111 are equivalent to -1. Why or how are the binary numbers 11, 111, 1111, 1111 1111, etc. equivalent to -1 in two's complement? Can anyone explain?


texts: Designing Schmitt trigger oscillator using CMOS NAND gate

texts:
I am designing a Schmitt trigger oscillator based on a CMOS NAND gate. The block diagram along with schematics and its results are attached for your reference. I am using the CADENCE tool with 0.35um technology.
Question: it can be seen in the result, the charging time of the capacitor is large which affects the oscillating signal at the beginning. To reduce charging time I need to reduce the RC time constant but it affects my oscillating frequency. Once I reduce the RC time constant then I am limited to a certain oscillating frequency.
Oscillating frequency: f=1/2.2RC
How can I reduce the charging time of the cap (other than the RC time constant in my schematics) so that I get the least distortion at the initial stage of the oscillating signal?


texts: I am looking for tool to draw circuits on Mac OS X. I mostly need it so I can add it into presentations. So the requirements are that it looks preety.


texts: CDI ignition: Isn't the coil charged anyway?

texts:
I'm trying to understand how the CDI (capacitor discharge ignition) works and what are its advantages over inductor-based systems. The disadvantage of the inductor-based system is apparently that it takes a relatively long time to build up the current through the primary when the points are closed. Somehow the CDI avoids this problem using a capacitor.

My understanding of the CDI is pieced together from many (all quite undescriptive) sources, like this video:

https://www.youtube.com/watch?v=8DmjULMvNwI

It is shown that the capacitor is charged from the excitor coil, with the charging current flowing through the ignition coil to ground. So the current has to flow through a coil anyway to charge the capacitor, so isn't this already slowing the current build up time?

And I don't really understand how the discharging of the capacitor helps anyway, since doesn't the discharging current have to flow through the coil as well (the cap cannot simply discharge without equal current flowing to the negative, through the coil)?


texts: Class D Amp headphones grounding circuit

texts:
I am having a problem with some of the class d amps I've played with (PAM8302A), and it seems like this article here describes my problem:
https://www.edn.com/design/analog/4313726/Add-headphones-to-a-Class-D-amplifier
essentially the audio circuit turns off because of the headphone plug sharing a common ground or something. I am making a pi zero pwm to analog amplifier circuit and some suggestions would be appreciated.
Edit: How is this? 220uF cap highlighted


texts: Why is power factor such a meaningful quantity?

texts:
In my current electrical engineering course the concept of power factor has been a large topic, defined as the ratio of real power to apparent power. It is a measure of resistive power consumption in a circuit. Other kind of loss present in the circuit is the reactive or "parasitic" power.

In my material it is presented as a quantity that always should be maximized. But what I don't understand is why resistive power consumed is always a good measure of efficient use of power? There are lots of components where reactive power consumption is desirable, like transformers. If I connect a power source to a transformer, it would have mainly reactive losses and resistive power loss would actually be undesirable. But still, if we use power factor as a measure of circuit performance, it would be poor in this case as we would have mainly "parasitic" losses.

Not that I think of it, I can't really come up with many applications where purely resistive losses are good (in a resistive heater for one). So what do we really consider as consuming "real power" in this sense? What do we count as consuming "real" power and "parasitic"/reactive power when the circuit receiving power is more complicated than a simple example circuit consisting just a resistor, capacitor and an inductor?


texts: Is it safe to treat a system downstream of a reverse-biased diode as de-energized?

texts:
Suppose I have a 480 VAC line, feeding a rectifier and filter caps. Obviously this is not something to be trifled with while live.

Now, suppose there are blocking diodes coming off the DC bus, as shown.

simulate this circuit – Schematic created using CircuitLab

In theory, in a perfect world, no current can reach the non-energized side of those diodes. Does that mean that side of the diodes is safe to work on without de-energizing the entire system? If not, why not? Are there specific safety standards this would violate?

EDIT: If you're interested in the broader context of this question, I asked a related question about ethics at the engineering exchange.


texts: Trace Inductance when routing power nets for PCB

texts:
I have a situation where I have Analog and digital grounds.
In the picture below the white traces are AGND and the Green DGND.
The grounds split where the external supply contacts the board.
I am trying to reduce inductance in these traces so as to keep the analog and digital sections as clean (noise-wise) as possible.
What I have done is make every ground trace have its own separate trace so as to avoid any ground loops and everything connecting at its own STAR ground.
Is this a viable way of keeping the circuit clean noise-wise?


texts: Is it possible to add two independent power supplies together to achieve a steady 3.3V powers supply? One power supply will be running from a 9V battery and the other is a 12V source. They both don't have to necessarily run together i.e. the if the 9V battery is just connected, it should still supply 3.3V. I have a buck converter that can output a steady source of 3.3V (LM2576-3.3V) and can handle a wide range of voltages (up to 40V). Is there some kind of passive voltage adder circuit that I can use that has some power protection diodes?


texts: When looking for resistors, what is the `W` for?

texts:
I'm looking for a variety of resistors for my project. Since I'm so new to this, I don't have the slightest idea what I'm looking at.

Essentially, as I research ideas, I get recommendations that include "You'll need X resistors"

Since I'm looking for a variety pack so that I can have them at my disposal, I want to ensure I'm getting the right ones. I've found a pack of 1000 resistors that range from 1Ω to 10MΩ but all of them are 1/4W carbon film resistors (5% tolerance)

I know what resistance (Ω) I'm looking at, but not so much the rest of it. My "assumption" is that the "W" is "Wattage" but I'm not certain. Is there a general (rule of thumb) "W" rating that I should be looking for, and what exactly is that "W" representing?


texts: Nucleo-F767ZI won't start if powered through external 5V

texts:
I'm trying to power a Nucleo-F767ZI demoboard through external 5V(through E5V pin).
When it's powered by USB, the code runs as expected(some LEDs blink), but when i attach the external 5V, and i switch power source with a jumper, the code doesn't run until i plug a usb cable or i perform a reset.
I tryed to remove the solder bridge SB111 (to remove the connection between the STM32 nRST and the STLink) and to add the solder bridge to SB1(to bypass the USB power regulator), but the problem persists.
Sometimes the code starts immediately, sometimes it is necessary to perform a reset.


texts:
I'm a little confuse about this default assignment concept.
Normally, in order to avoid a latch, we should explicitly give a value to a signal in every case.
For example:

-- Assuming a is std_ulogic and b is std_ulogic_vector(3 downto 0)
process(a, b)
begin
    if a = '1' then
        b <= "1010";
    else
        b <= "0101";
    end if;
end process;

But why in the following process, an else statement is not necessary.

process(clock, reset)
begin
    if reset = '1' then
        b <= "0000";
    elsif rising_edge(clock) then
        b <= b_next;
-- Why don't we need an else statement here?
    end if;
end process;

Can anyone help me out? Thanks!


texts: Output impedance matching for SN74lvc1t45

texts: We are using SN74LVC1T45 IC for level translation and we are feeding translated voltage through BNC connectors (75 ohms) to other peripherals, during this we want to achieve impedance matching of 75 ohms.


texts: how to convert UART voltage from 5v to 3.3v?

texts:
I have PIC18F4455 connected to spark core wifi chip. I send data from PIC18F4455 to the spark core by using UART. The problem is the output data of pic18f4455 equals to 5v, and the spark core accepts only 3.3V. My question is there any way to convert this data to 3.3v ( softwar in the PIC18F4455 or hardware) ?

Ali


texts: Inverting boost converter by using MC33063A/MC34063A: Where does the IC get ground connection?

texts:
I want to design an inverting boost circuit by using MC33063A.
I want to generate -5.75V from a +5V supply.
My question is, how does the IC connect itself to the ground?
The 4th pin is the ground pin of the IC. But it is connected to the negative output voltage.
The input bypass capacitor is connected to the VCC pin of the IC, but the other terminal of the capacitor is not connected to the IC.
What is going on here. Can you please explain me how this IC works without being connected to the circuit ground.


texts: What power source and amplifier should I use for high reactive power purpose?

texts:
I searched the site but most I can find are questions on what reactive power is! I want to know how it affects my decision for the power supply.
I have to drive a coil (AC) with a high reactive power (1 kVAR) and little real power (20 W). I plan on using an amplifier and a separate power source otherwise designed for speakers.
I can't compensate the reactive power with capacitor banks, because of a varying frequency range (10-100Hz).
The amplifier should be able to handle 1kW, right?
But what about the power supply to the amplifier, does it to have to be 1kW, or can it be only 20+W?


texts:
I am using an LM324n quad-core op-amp. I have connected it between +24 V and GND. One of its op amps is used as a buffer. When I pass the buffer a negative voltage, I get it inverted at the output although I expected it to be zero. Is this weird response somehow logical or expected?

Unfortunately I had some issues with Windows lately and I have no other schematic but for this handwritten one. MOTOR VELOCITY input can become both positive and negative and that's where the issue is!


texts:
I'm trying to use a simple pi low pass filter using two capacitors and one inductor.

I've found the formula to calculate the value of the capacitance and of the inductance using the cut off frequency, but I would like to know where this formula comes from, I can't find any explanation on the internet.
These are the formulas :

L     =     Zo / (2pi x Fc) Henries

 C     =     1 / (Zo x 2pi x Fc) Farads

 Fc     =    1 / (2pi x square root ( L x C) Hz

For example with a RC low pass filter I just use the voltage divider formula and from that, using the impedances, I find the transfer function of the filter. Then from the transfer function I'm able to find the cutoff frequency. Could be done like this also for the pi LC l.p.f?
 Thank you


texts: Hints on how to attach resistors to SMD LEDs

texts:
I bought these type of LEDs for my car interior: https://www.amazon.com/gp/product/B01J0ZO0V0/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1).

LED Type: 31mm 5050 6-SMD.
Width: 15mm
Length: 31mm
Cross Reference: DE3175 DE3022 DE3175 3022 3021 3175 6428 6430 6461

It was suppose to be a plug and play but after a while I noticed a minute pulse of intensity and it is quite irritating.

I know a fix would be to mount a resistor but for SMDs I have no clue where to solder it. I had no luck on the web or my car forums.

May I get some advice on how to:
1- Methods to stop the slow gentle pulsation?
2- Where to attach resistors and or volt regulator to this SMD? (The two methods that I now know of to approach this problem)
3- Will this ruin my car's electrical system if I just put up with the SMD LEDs being fed with more power than they need?

I am a total greenhorn at this but I am willing to learn.
Thanks for your time!


texts: Choosing the right Relay for the mission

texts:
I am building new project, which I will power up the water tank heater from my smartphone.
I have few safety though I want to ask here to get your opinion..

I am going to use AVR to run a relay, that will be connected to the main AC line.
my heater takes about 11-12Amp on 240VAC.

Which relay should I use? SSR or mechanical? I looked into these 2:

SSR-25DA
Relay SPDT Sealed - 20A

I think the mechanical is better because I have physical disconnection, but I am afraid of "jumps" on the mechanical device (like de-bounce and such). what do you think will be better here?
Relay mount - if I am going to use the mechanical T9A relay, how do you think I should mount it? it has no mount, maybe I will try to use terminal block like this to connect the legs:


texts: PCB Ground and Power Plane Design Guidelines

texts:
I am converting a design from through hole components to SMT components.

The schematic is identical, except the maximum allowable current through an onboard relay will be halved from 20A to 10A.

It's a long time since I did a PCB layout and I want to do it right.  Everything is pretty straightforward but I am looking at the grounding and power planes, (on a shared physical plane), and not exactly sure what the rationale was for the shape and size of these planes

Are there any general design guidelines for placing power and ground planes?

e.g. Use thickest metal as feasible for ground plane (reduces resistance and provides improved thermal transfer)

I'm especially interested to know if there are any guidelines relating to current.

Interested to know if anyone knows why the previous design was using hatching? Could it be improved solder-ability or related to heat dissipation?

To put this in context, I worked in the test department of a large multinational years ago.  We had design rules that had to be adhered to, I am looking for a similar set of rules.


texts:
My need is to build (or purchase, if existent) a nanopulser, but not an ordinary one: it has to have some specific characteristics.
The premise is:

I have a device which acts as a variable capacitor as the
environmental conditions change; its working region is in the
microFarad's range (approx. 4uF...300uF)
this device has to resonate at different harmonics and, once found the best one (the user decide which one, by observing the device's behaviour in response to the environmental conditions) that resonant point has to be be maintained "fixed", accordingly to the harmonic chosen, following automatically the minimal variations in the device's capacitance - if there where any - so that the resonance takes always place (like a radio tuner, with a PLL or a similar method).

The nanopulser circuit:

has to produce DC sharp pulses in the amplitude range of +3V...+200V
(user selectable)
the single pulse should have a duration no longer than 100ns
the frequency has to be variable, in a range between 35KHz...100MHz
(user selectable)
the pulses will drive a MOSFET, or an IGBT, giving the opportunity to
output an amperage of 20A maximum (user selectable) to the LCR system
which comprises the device itself coupled with a fixed inductor
the frequency selected has to be maintained unchanged even if the
load varies in its capacitance, inductance or resistance, through
an autotuning system (PLL + VCO or similar method)

The device is a sort of oxygen/hydrogen separator (not HHO) which splits different kind of water mixtures (mainly dirty ones), plus it cleans itself, thanks to the different nanopulses issued: different polluttants mixed in the processed water require different frequencies to be separated and the device's plates require different frequencies for the periodically self-cleaning process.
A similar device can be watched here: https://www.pinterest.it/pin/542331980106296417/
The device is presently operative (in its prototype stage) and it works almost as expected but it is VERY HARD to me to achieve:

a stable resonant frequency in the regions over 200KHz (due to the
continuously capacitance changes when the different polluttants reach
the cell)
a so narrow nanopulses (I've achieved 800ns at minimum)
an adequate power output with such pulses (I'm unable to surpass 1A
total output)

My present circuit is this one: [![NanopulserCircuit][1]][1]
Why nanopulses?
After a series of researches and case studies, it has been established that working with resonance allows to achieve:

a power consumption reduction
a better separation of pollutants from the water
a more precise splitting in Oxygen/Hydrogen

The final goal of this research of mine is to create a filter for sanitation which extracts from dirty, black waters (sanitation, drainage, sewer) oxygen - to be released directly in open air - and hydrogen - to be further processed by a dedicated management system.
Question
Is there a circuit (or a series of different, matchable circuits) that perform the function of nanoimpulse generation - with autotune, which is the essential part needed - as per the specifications above?
Between the nanopulser and the LC circuit (my device) there should be a circuit able to "sense" the LC's variations. How can I automatically adjust the pulser's output accordingly with the resonant point desired?


texts:
This circuit shows a clock generator, where a capacitor is charged to a certain voltage for half a period (phi opening switches S1 and S2). The same voltage but with negative polarity will be shown to the comparator input V_IN in the second half (phi bar) and slowly charged up back to ground. The comparator will create a clock signal if V_0 = 0 (shorted to ground), where the output is high in the first half and low in the second half.

From what I understand, the D flip flop will change the output at the rising edge of the clock signal generated at the output of the comparator with frequency f. Now here is the problem: isn't the output of the D flip flop going to have half the frequency (f/2) of its input? Doesn't this create a loop in which the output signal frequency (frequency of phi) is divided by two at every cycle?


texts: multicycle datapath vs single cycle datapath

texts:
I have a fairly simple question but have not been able to find a good answer googling.

I understand how pipelining works by having 1 cycle per step, each instruction takes 5 cycles  and they start on the second step of the previous instruction to finish the whole load faster.

Now from what I have read multicycle also has multiple steps per instruction but each instruction starts after the previous instruction has finished. With the benefit being for instructions that arent 5 steps long they do not have to go the whole 5 steps. Im assuming that we have to use the time of the slowest step for the clock cycle to allow all steps to works.

Now if this is correct I have calculated a small program that i was give as a homework problem where single cycle datapath is faster than the multicycle datapath. Is this normal ? or is there something about multicycle datapath that I have wrong ?


texts:
I have a pressure sensor that has 200 mV offset. I wanted to remove this offset and double the result (to remove any present noise) so that be able to calibrate the sensor easier. So far I have used a simple op-amp based subtractor circuit. The problem is that if the difference between the two inputs is more than 300 mV, the circuit would work without flaw. If the inputs would be the same, there is an offset of 600 mV in output (While simulation with proteus fails to show this matter, haven't yet simulated the circuit with Cadance Orcade). How can I solve the issue?
Will using rail-to-rail opamp solve the problem? A simple schematic is attached.


texts: Error in Proteus simulation using ATmega16 with Arduino IDE

texts:
I am building a circuit in Proteus 7 Professional using an ATmega16 and 16x2 LCD display. I have code for the display. The code compiles with no error in the Arduino IDE, however in Proteus simulation the display not working. It gives me the following error messages:

  PC=0x0106[AVR MEMORY]Writing to memory location 0x08FE outside memory
  size 0x0460 PC=0x0000[AVR CPU]RET address = 0x0000 which repeats
  itself in SIMULATION LOG

What is the problem?


texts:
I want to do some BOM management in Eagle to make life more easy.

I want to create a multilevel BOM out of Eagle.(Multiple MPN's for the same part from different suppliers) Is this possible to manage in Eagle?
Or can I only link one MPN to each component in Eagle?

Thanks


texts: How much current does an LED in optocoupler draw?

texts: I am planning to actuate the relay (opto-isolated) using the GPIO pins of Nodemcu. NodeMcu's datasheet says that maximum current that can be drawn out of a GPIO pin is 12 mA. Any load more that may damage the device. Is it safe to use this relay -  https://www.amazon.in/gp/product/B00NR31V3W . How much current does its optocoupler LED draw?


texts: Why does the QUAD INPUT PAGE PROGRAM OPERATION command exist?

texts:
While reading the datasheet for the IS25LP512M series of Flash devices from ISSI I came across this weird command, 32h/38h called "QUAD INPUT PAGE PROGRAM OPERATION" (in section 8.11) with the following timing diagram:

This command seems very odd as it only uses the least significant bit of the data bus to transfer in the command and address, in contrast to all the other QSPI commands (as far as I can tell) like 02h, "Page Program Sequence In SPI Mode" which transfers the command and the address over all the data lines at the same time:

It seems like it would a pain to implement this command on the Flash device and on the Master side.

Googling "32h flash memory" and looking through the results it seems like there are a number of other chips that implement this command, GD5F4GQ4UAYIG, S25FL-S, W25M321AV ect... So I assume it is from some kind of standard. (though it looks like the JEDIC Common Flash Memory Interface standard does not cover commands).

Where did this command come from? Who uses it? Why does it exist?


texts:
I have read about a phone unlock boxes (JAF, Phoenix, etc).
What are they exactly? Some serial adapters? JTAG adapters?
What is their role and what makes them so expensive?


texts:
Is there a nominal dead time for rotary switches?  Obviously all switches are different, so this value will not be precise.  For making a reasonable situation, let us assume that a detent style switch is independent of the speed and/or vigor of the user.

As I understand it, a non-shorting rotary switch works by completely disconnecting from a pole before connecting to another.  Therefore, there must be a non-zero delay time when the throw is not connected to any pole.  Has anyone measured this?  Is there a good way to estimate it?  I had a Clever Solution(tm) to a problem which uses a NOR gate between switch poles to momentarily toggle something else.

Edit for clarity:  Assuming the delay time based on how fast someone operates the switch, which we will term vigor (v), goes really high.  What is our time delay?

$$
\lim_{v \to \infty} t_{delay}
$$

What I really need to know, is how this value compares to the logic delays in my circuit, but I am keeping the question generic to match with the purpose of Stack Exchange.

$$
\mathrm{Test~if:~~} t_{switch~delay} \gg t_{propagation~delay}
$$


texts:
I have made the driver for enc28j60 for LPC1788 and I'm trying to send UDP message to LPC via wifi enabled device (iOS, windows over wifi). But transmission fails. Wifi device sends the ARP request. LPC sends the response, but it doesn't arrive. I have checked the ARP cache on windows machine and it stayed empty. When I do the same with cable connected machine, it arrives correctly, ARP cache is populated. That concludes that ARP response is sent and it is correctly built.

I have tried ping as well and same thing, every device that comes via router failed to get ARP response, but devices that are connected by cable receives the ARP response.

But, same enc28 board is working fine with Arduino. Arduino implementation of driver and ethernet was not done by me.

That means that it is somehow related to the driver. I have either forgot to switch some option of enc28 chip or ...

I have looked at Arduino driver but I could not find any obvious error in my implementation.

Any idea what could be wrong?

UPDATE:

I now have Wifi router with tcpdump installed on it. I have run it and sniff the packets from Wifi to Arduino (everything is fine there. ARP request, ARP response and Ping echo/reply can be seen in trace). When i start Wifi to LPC i only see ARP requests. Although it says that few packets are received by the filter, but i cant see those packets in dump file. Is there any option on tcpdump to see raw data ?

What I can see when use tcpdump with "-i any" option, is my lost arp response. But it looks fine to me.

ARDUINO

ARP Request
0004 0001 0006 d89e 3f87 3ad5 0000 0806
0001 0800 0604 0001 d89e 3f87 3ad5 c0a8
0564 7069 692d 3031 c0a8 0508

ARP Response
0003 0001 0006 7069 692d 3031 0000 0806
0001 0800 0604 0002 7069 692d 3031 c0a8
0508 d89e 3f87 3ad5 c0a8 0564 0000 0000
0000 0000 0000 0000 0000 0000 0000

LPC

ARP Request
0001 0001 0006 d89e 3f87 3ad5 0000 0806
0001 0800 0604 0001 d89e 3f87 3ad5 c0a8
0564 0000 0000 0000 c0a8 0507

ARP Response
0003 0001 0006 891d dc9f da6e 0000 0806
0001 0800 0604 0002 891d dc9f da6e c0a8
0507 d89e 3f87 3ad5 c0a8 0564 0000 0000
0000 0000 0000 0000 0000 0000 0000

I dont see any differences in the response from LPC (which doesnt work) and one from Arduino (which works).

Could it be some kind of timing issue ?

LPC

11:39:05.194814 arp who-has 192.168.5.7 tell 192.168.5.113
11:39:05.194889 arp who-has 192.168.5.7 tell 192.168.5.113
11:39:05.195001 arp who-has 192.168.5.7 tell 192.168.5.113
11:39:05.194814 arp who-has 192.168.5.7 tell 192.168.5.113
11:39:05.195537 arp reply 192.168.5.7 is-at 89:1d:dc:9f:da:6e (oui Unknown)
11:39:06.194815 arp who-has 192.168.5.7 tell 192.168.5.113
...

Arduino

11:42:27.712993 arp who-has 192.168.5.8 tell 192.168.5.113
11:42:27.713068 arp who-has 192.168.5.8 tell 192.168.5.113
11:42:27.713180 arp who-has 192.168.5.8 tell 192.168.5.113
11:42:27.712993 arp who-has 192.168.5.8 tell 192.168.5.113
11:42:27.714049 arp reply 192.168.5.8 is-at 70:69:69:2d:30:31 (oui Unknown)
11:42:27.714141 arp reply 192.168.5.8 is-at 70:69:69:2d:30:31 (oui Unknown)
11:42:27.767303 IP 192.168.5.113 > 192.168.5.8: ICMP echo request, id 56841, seq 0, length 64
...


texts:
Why do these two resistor networks measure differently?

Aren't two 100k resistors in series supposed to be equivalent to a single 200k resistor?

These are being simulated with Circuit Wizard.


texts: Micro and Nano Memory, Calculate Reducing Bits?

texts:
I ran into a question:

in digital system with micro-programmed control circuit, total of 32 distinct pattern operation signal  is 450. if the micro-programmed memory contains 1K micro instruction, by using Nano memory, how many bits is reduced?

1) 22 Kbits

2) 23 Kbits

3) 450 Kbits

4) 450*32 Kbits

I read in my notes, that (1) is true, but i couldn't understand how we get this?

Micro instructions are stored in the micro memory (control memory). There is a chance that a group of micro instructions may occur several times in a micro program. As a result the more memory space isneeded.By making use of the nano memory we can have significant saving in the memory when a group of micro operations occur several times in a micro program. Please see for nano technique ref:

Edit:

Micro-memory The micro memory only concerns how we organize whats in the control memory. However when we have big instruction sets, we can do better than simply storing all the instructions. We can subdivide the control memory into "control memory" and "nano memory" (since nano is smaller than micro right ;) ) This is good as we don't waste a lot of valuable space (chip area) on microcode.

The concept of nano memory is derived from a combination of vertical and horizontal instructions, but also provides trade-offs between them.

The motorola M68k microcomputer is one the earlier and popular µComputers with this nano memory control design. Here it was shown that a significant saving of memory could be achieved when a group of micro instructions occur often in a microprogram.

Here it was shown that by structuring the memory properly, that a few bits could be used to address the instructions, without a significant cost to speed. The reduction was so that only the upper log_2(n) bits are required to specify the nano-address, when compared to the micro-address.


texts: Calculating total current consumed over time?

texts:
I'm currently building a battery testing rig which drains a battery and then charges it continuously and monitors/logs all associated data (voltage, run time, and instantaneous current discharged/charged).

I'd like to determine the current discharged over time, but not sure how to calculate that.

> For example: Say I at program time 00:00:01s the current consumed is
> 15mA, and then at program time 00:00:02s the current consumed is 20mA
> (so on and so forth).

Currently my program is just logging the instantaneous current every second. Beyond that I'm not sure what calculations are needed.


texts: Can I use a threaded rod on a wimshurst machine

texts:
On my Wimshurst machine which is built similar but not the same as http://steampunkworkshop.com/how-build-wimshurst-influence-machine-part-1, I'm using a threaded rod that comes out of the Leyden jar where my collecting comb and spark gap rod connects to.

I'm worried that a threaded rod will leak out too much voltage, which is why you have to put a ball over all points in the first place. I'm not sure if a threaded screw will act in the same way or if I should be fine. If I can use the screw rod listed below let me know!


texts:
In essense, whatI have are four 555s (2x556) One is a 0.5 s monostable,the other a 147 Hz tone generator. The other is a (30 s) monostable, and a 0.3 s astable.

If I run the 0.3 s astable on its own, (disconnect diodes) it runs fine. I have the reset tied to ground via a relay coil which disables the astable. Place VCC on the high side of relay, and it is enabled as planned.

The other part of the circuit was originally a 30 s timer, but it would cut off after about 1.5 s despite a 150 kΩ and 470 uF cap.

So I  changed the circuit a little so the threshold was grounded via 100 kΩ. Now when triggered, it should stay on indefinitely.

However, the problem arise trying to connect the two parts.

Again, my theory says that the high output of the monostable should power the relay and present a high to the reset pin.
That's when it chops off at 1.5 s. (Why it is 1.5 s when there are no timing components with that RC period is also a mystery; I have tried 4700 uF as a supply decouple, but it makes no difference.)

simulate this circuit – Schematic created using CircuitLab

The GND to relay top is a protection diode, and the other was suggested to stop the circuit "locking up".

The relay is a FRS-1 with a coil value of 320 Ω.

(Maybe the reset is being pulled low? But I thought the top of the coil should be at the voltage of the 556 output)

** I have shown two 555's in diagram as there is no 556 on Circuit Lab. But the 556 IS two 555 chips anyway !


texts: When do we use all pins in RS-232 cable?

texts:
I think the minimum for simplex communication are TX so we can transmit and the power supply pins +Vcc and GND. That is all we need. When do we need to use all 9 pins of RS-232? I think that the reciever can decipher when data has started coming in and if it knows the baud rate already, it also knows when the latch the incoming bits. Therefore, I don't see the purpose of all the remaining pins on the RS-232 cable besides TX, RX, +Vcc and GND. Do we still need them?

The problem is that I wish to connect a PC to a waveform generator through RS-232 cable. I have the software for this installed on the PC but no RS-232 cable. If I do make my own using RS-232 connectors (which is what I intend) with my own wires soldered to it, how do I know if I just need TX, RX, +Vcc and GND or if I need all the other pins as well?

Soldering all the pins is not such a hard thing to do anyway, but I am just curious.


texts: Can iIuse a push button switch to operate an actuator?

texts:
Please forgive me if my question is just silly. I'm really struggling to find answers.
I have bought what I believe to be a DPDT switch. It is however a push button switch. It is an 8 pole switch with 2 simply because the switch is lit. My issue is I need to use it to operate an actuator and I need the push button because it needs to be used behind a cabinet door, pushing the door to operate the switch.
Wired correctly (as I have been told,) I cannot get the poles to reverse  (the actuator to retract.)
The wiring configuration is simply using the centre terminal NO1 for the load (the actuator in this case) with power running to all 6 other terminals. Direct to the light and NC1 then bridged and polarity reversed from NC1 to the C1 terminals. I guess I'n showing my level of knowledge with my explanation. I was under the impression in purchasing the switch that upon pressing I could wire it to start the actuator, and upon depressing the switch the actuator would close. (Poles reverse) Hopefully someone can help.
Am I simply trying to use a switch that cannot be used here? Again, forgive me, learning and many tell me this switch works but as I try to explain.


texts: Bluetooth module to have microcontroller communicate with Android phone?

texts:
Found couple of fairly inexpensive Bluetooth modules based on CSR chipset that do Bluetooth 2.1 + EDR, and connect to uC over TTL, however the cheaper variety supports only "slave mode", which the more expensive (almost double the price) variety supports user selectable "slave" or "master" modes.

My use case is to transfer information (bi-directionally) between a uC performing data-logging and an Android phone. Preferably, a pairing should be done once, or very infrequently. Following that, a connection should be established automatically, everything Android phone and the uC+BT-module are in range. Once connected, I'd like an application on Android to pull the data from the uC, and send back few commands, s.a. clear the SD-card, place "read-time" and "reader-signature" in a access-log on the uC.

I've read somebit about Bluetooth, but probably not enough. My present challenge is to know for sure, if a "slave" module will serve my purpose, or I should go for one which can switch to "master" mode, as an option.

Also, wondering if the module should be able to support RFCOMM and SPP, or is it that RFCOMM alone would suffice?


texts:
I have 6 MG996 series servomotors. A single motor can be controlled by an Arduino board using a 5V power supply.

Some specifications

Running Current 500mA - 900mA @ 6V
Stall Current 2.5A @ 6V

Can anyone provide some suggestion as to how I could power all 6 servomotors at once?

I don't know if I should use that really large 6V battery you typically get from the stores, and from our experience a 9V battery is too much.


texts: White noise generator transistor voltage question

texts:
I have a very newbie question.

Here is a white noise generator schematic I'm using (from http://montalk.net/emwng.html)

It all works fine. What I want to understand is why this works at 9V (and down to 8V) but under 8V the whole thing just stops generating noise. I was wondering if it's possible to do the same circuit running at 5v for example.

Thank you.


texts: USB battery charger and GPIO power supply schematic for Raspberry Pi

texts:
I'm trying to design a circuit in Eagle to provide reliable + safe battery power to a Raspberry Pi via the GPIO pins.

The requirements are:

Accept power input via micro USB (separate from the Pi).
Intelligently charge a large Lithium-
Ion battery like this one.
Provide a regulated 5V output with up to 1A current draw.
Provide a fuse on the output to safeguard against accidental shorts on the Pi.
Continuously power the Pi without interruption when supply connected/disconnected.
Use small number of easily obtainable components (preferable via Adafruit or Sparkfun)
Simple to understand
Easy to solder (no microscopic SMDs, larger SMDs OK)

I know this is probably an easy design for many of you out there, and it's well beyond my knowledge, so hence me asking here. I also feel it would be really nice to have this circuit publicly available online.

A schematic with a list of part numbers will win the green tick plus my eternal gratitude :). I know there are many people looking for a pluggable solution like this for their circuit designs so an actual Eagle file gets extra points.

PS: to be clear - I am not looking for a prefabricated solution to purchase. Specifically looking for a schematic that can be added to a Eagle project.

PPS: the schematic for the PowerCell from Sparkfun might be a good place to start, however it has a max output of 600mA, may or may not provide UPS capability, doesn't have the fuse, and looks a bit complicated to solder.

PPPS: Power management IC's like the LTC3586 look promising but they seem to only come in microscopic packages.


texts: Mixing CAN nodes with and without transceivers on one bus?

texts:
I can see based on the answer to this question that it's possible to make a short/slow CAN bus without using transceivers and a differential bus. This brings up (at least for me) an interesting related question: is there a way to mix nodes on a single CAN bus, some of which have transceivers and some of which do not?

The use case I'm imagining is as follows: there are several MCUs on one PCB that are on the same CAN bus. They're close together, and the enclosure is well shielded using, say, an aluminum case. Let's assume that connecting them in the manner recommended in the above link works.

This bus then goes off-board, to several remote CAN nodes. Sending the single wire out of the enclosure is a terrible idea. But is there a generally accepted design that would allow you to connect these non-transceiver-ed nodes to a transceiver that then sends a fully differential pair off-board to the remote nodes?

As an alternate way of considering this question: is there a way to connect multiple CAN-enabled MCUs to a single transceiver?


texts: Converting 12 Volt Lipo to 5V with Buck Convertor

texts:
I'm trying to power a large bank of LEDs that require 5V at 5 amps. I plan to use a 12v hobby Lipo attached to a buck convertor to step that down. I also need to power a teensy microcontroller with the  same battery. This is the buck convertor I plan to use https://www.amazon.com/gp/product/B01NALDSJ0/ref=ox_sc_act_title_2?smid=AFHAE9RJVUMB&psc=1
My question is will I be able to power the teensy and the LEDs off the same buck convertor or will they interfere with or put too much load on the convertor?


texts: Does anyone know the history of the earth ground symbol

texts:
I Googled for hours, asked every EE professor in my college, then checked every electrical engineering book in my university's library (hours), and have found nothing about the history of the ground symbol. Please point me if you can.

Who coined it? What does the picture represent? I have many probable theories and almost no interest in theories.

Thank you


texts:
I am planning to do a current measurement with Arduino. The board I'm using is mega 2650, operating voltage is 5V (I/O pin limit is 3.3V). And the CT I'm using is exactly the same as this tutorial, the only difference is that the output of the CT is limited to 0-1Vac.

Now, I'm thinking if it is possible to directly connect the CT to the Arduino board? What would be the outcome if I connect a AC voltage source to it?

Moreover, if direct connection is not possible, then a simple bridge diode could turn AC to DC. But again, a ripple signal will be resulted and with a measuring current of 0-100A ac and output signal of 0-1Vac ( meaning 1A ac measured current only result in 0.01Vac). What would be the resulted accuracy? Best if could archive measuring accuracy to +-0.1Aac.


texts: Any dangers of splitting the output of a universal laptop charger?

texts:
I am looking at a 90W laptop charger and I would like to charger a laptop (65W) and a phone (15W) with it. The laptop charger has a 5.5mm / 2.5mm plug, one female to two male splitters are widely available, then I could use one of the male plugs with another plug converter for my laptop and with yet another to feed a Dell accessory which takes a barrel input and provides USB C power.

The question is, is this pile of plugs dangerous to the laptop or the charger?


texts:
I in my design I have boost converter (using PAM2423) which is powered by LiFePO4 (3.2V) cell. It works and gives accurate output but it is very inefficient. I checked voltage on the coil and I think strange pulses is the reason of it. All the other components cant cause so much loses (I use ceramic capacitors both on output and input, low Resistance coil and low voltage drop diode). Here is scope of voltage on the coil and circuit itself
Output Ripple
Do you have any ideas why it is happening?


texts: I'd like to set up an arduino to remotelet monitor temperature using a wired sensor.  Will wire length come in to play?  For example, if I have 2 sensors 1 with a 10 ft run the other with a 30 foot run, will that work with the same code and components? I guess the short question is how much to I have to worry about resistive losses?


texts:
I want to measure current going into and out of an op-amp. However, when I do .op command, I am not able to understand which current is being referred to here. Currents are named as -
Ix(u1:1), Ix(u1:2), Ix(u1:99), Ix(u1:50) and Ix(u1:28). Kindly tell about the naming conventions or how to change these names to something meaningful like we can do with voltages (labelling nodes).
Thank you.


texts: How do reactive currents cause power transfer?

texts:
I read in 'The Art of Electronics':

  Power factor is a serious matter in large-scale electrical power distribution, because reactive currents don't result in useful power being delivered to the load, but cost the power company plenty in terms of I2R heating in the resistance of generators, transformers, and wiring.

However, I have also read many times that only 'True Power' is dissipated.

How do reactive currents cause I2R heating?


texts: Basic Voltage divison question - is this correct

texts:
Just having some doubts. For the following circuit

No current to Vg


texts:
I have a prototype of a simple monostable multivibrator components like this:

-- Libraries -------------------------------------------------------------------

--! Main library
library ieee;
    --! std logic components
    use ieee.std_logic_1164.all;

-- Entity ----------------------------------------------------------------------

--! Monostable multivibrator input and output signals:
--! \image html images/multivib_mono.png
entity entity_multivibmono is
    generic
    (
        --! The \p q and \p nq pulse length is this value x \p clk frequency
        pulse_len   :       natural
    );

    port
    (
        --! Clock signal. Events occur on rising edge.
        clk         : in    std_logic;

        --! Non-inverting trigger input
        a           : in    std_logic;

        --! Inverting trigger input
        na          : in    std_logic;

        --! Active low logic reset input. When asserted, \p q = lo, \p nq = hi
        ncd         : in    std_logic;

        --! Non-inverting pulse output. the pulse level is hi
        q           : out   std_logic;

        --! Inverting pulse output. The pulse level is lo
        nq          : out   std_logic
    );

end entity_multivibmono;

-- Architecture ----------------------------------------------------------------

--! Monostable multivibrator implementation
architecture arch_multivibmono of entity_multivibmono is

    --! Enumeration tame for the finite state machine
    type state_t is (st_idle, st_pulse);

    --! A \p state_t instance
    signal st_current   :   state_t;

    --! Buffer signal for q output
    signal q_tmp        :   std_logic;

begin

    --! Multivibrator behavioral process
    process_multivibmono : process(clk, ncd, a, na)

        --! Counter variable
        variable cnt    :   natural range 0 to pulse_len := 0;

        begin
            if (ncd = '0') then
                q_tmp <= '0';
                cnt := 0;
                st_current <= st_idle;

            elsif (falling_edge(na) or rising_edge(a)) then
                if ((a = '0') and (na = '1')) then
                    q_tmp <= '1'; -- beginning of the pulse
                    st_current <= st_pulse;
                    cnt := 0;
                end if;

            elsif (rising_edge(clk)) then
                case st_current is
                    when st_pulse =>
                        if (cnt < pulse_len) then
                            cnt := cnt + 1;
                        else
                            q_tmp <= '0'; -- end of the pulse
                            cnt := 0;
                            st_current <= st_idle;
                        end if;
                    when others => -- unexpected case
                        q_tmp <= '0';
                        cnt := 0;
                        st_current <= st_idle;
                end case;
            end if;
    end process;

    q <= q_tmp;
    nq <= not q_tmp;

end arch_multivibmono;

Please notice how this code part:

q_tmp <= '0';
cnt := 0;
st_current <= st_idle;

Occurs 3 times in the code. Is there a way in VHDL to encapsulate this somehow easily? I would appreciate all help.


texts: Body interference in my analog multiplexer, maybe AC electromagnetism induction?

texts:
I just wired a CD74HC4067 analog/digital multiplexer to a matrix of leds. The multiplexer is wired to control the LEDs, and is connected to an arduino board, which is connected via USB to my macbook air. Then, I noted something odd: when I approximate my hand to the multiplexer, some leds light up, even if I'm not sending any signals to the multiplexer. I can only assume that my hand is interfering with the signal pins of the multiplexer, which are four. Then, I noticed that when I unplug the AC charger from the macbook, the interference disappears.

I've searched about this kind of interference, and it appears that what is happening is some kind of AC hum touch switch like the one described in this article. It appears that a near by AC current propagates through the room and makes me induce some electric current on things I touch. However, why is it that the interference only works when the macbook is plugged to the AC charger? First of all, the AC part of the charger is far away, the cable that is connected to the macbook is already DC. If the problem was about a near AC current, it'd happen no matter if the cable was connected to the macbook.

If I touch the macbook and approximate the hands to the multiplexer, the interference also disappears completely. I tried to take my macbook away from the multiplexer to see if the AC signal was being generated inside the macbook but the interference appeared to stay the same.


texts: Why does this optocoupler's datasheet recommend splitting a current limiting resistor in two?

texts:
And not only that, they also want to keep a ratio of R1/R2=1.5

The opto in question is ACPL-M21L by Broadcom

Here's a link to the datasheet:
https://docs.broadcom.com/docs/AV02-3462EN

Thanks.


texts: Why can't this circuit work for an inductive load?

texts:
I am using a similar circuit to speed control a 60 W AC fan using phase control. Unlike a TRIAC, supply to fan is given at the start of the cycle. I thought it would minimize the switching noise usually heard in TRIAC controls.

PWM is from 0 to 10 milliseconds. In low PWM, the MOSFET heats a lot with an inductive load, but not with a resistive load. A snubber using a 0.1 µF capacitor and 100 or 39 ohm resistors is connected across the MOSFET's source and ground pins.

What should I do?


texts:
As an assignment for the HDL course I'm taking, I've to design an FIR Filter. The module consists of two a small combinational circuit which can be used to reset the module, another combinational part which handles the convolutional multiplication and therefore, is considerably bigger and finally a bunch of registers all using the same clock pulse signal.

The odd thing is after synthesizing and implementing, the software reports that it can operate at a maximum clock rate of around 600MHz! Apparently, the latency of the combinational circuits in total is about 27 nanoseconds but the minimum clock period is 1.5 nanoseconds.

So to generalize the question, consider the following module:

If S is considerably larger than T should the minimum clock period be as large as S or does it depend on T? Or should it be larger than S+T?


texts:
I have attached a step up converter with 3.7V mobile battery and also attached a lithium Ion battery in parallel and for recharging both batteries I have attached a power bank circuit. I have attached step up converter to run a 12V light and through power bank circuit I can also charge my phone.

Is this type of thing that I made safe?


texts: Interfacing TinyAVR with bluetooth and passing message

texts:
I'm looking into interfacing the TinyAVR micro controller (not sure which one will work yet) with a Bluetooth module either the CC2540 or the nRF8001. I want to have the TinyAVR micro controller use the Bluetooth module to send out a small message like 0xf for example, which my computer would then read and display on screen.

My goal is to see if I can make kinda a hardware echo. Is it possible to interface these two units? If they can be interfaced what is required to get this to work?


texts: Is it safe for a CR2032 coin cell to be in an oven?

texts:
I'm designing a portable temperature logger that I would like to be able to measure temperature within my home oven. I plan on designing a mechanical enclosure to hopefully protect the design from 'frying'. Essentially I will be insulating it and I don't intend on keeping it in there any longer than it has to be.

I was looking at small coin cells to power my design (it's very important that this design be very flat, only a few mm's tall). I was looking at a couple CR2032 coin cells that assumed to be appropriate for my current draw and required capacity. However, I have noticed that they are only rated to 70C.

Now my oven will likely be getting up to 250C, so obviously it will be important to have good insulation because the battery will be outside of its rated temperature.

But I'm curious, is this safe? Assuming my design isn't exposed to an open flame, could the battery explode? I've been hearing a lot in the news of exploding batteries. I assume the battery would eventually stop working if it got too hot, but could the battery explode? Or would it likely just stop working? Again, I'm looking at a small CR2032 coin cell. I'm primarily curious in the case my insulation fails.


texts: charging 4 Li-Ion cell in parallel with a bench top power supply

texts:
I got a Li-Ion battery which has four INR18650MJ1 cells connected in parallel. Since I don't have a charger dedicated to custom batteries, I'm trying to use a bench top power supply.

I saw from internet that it is optimal to charge Li-ion cells in Constant Current mode first and then in Constant Voltage mode. Also one needs to switch the mode when the voltage reach at 4.1V or something.

But here I have a questions. What does the 4.1V mean? Is it the output voltage of power supply, or the voltage at the node between the + terminal of the battery and the + terminal of the power supply? With an output voltage of 4.2V from the power supply, I have 3.5V at the node. In order to maintain CC mode with a charging rate of 0.5C(1.6A), I think I should use 5V or a higher voltage until the actual terminal voltage of the battery goes close to 4.1V. Is it correct?


texts: What is the XTAL clock used for in an 8051 microntroller?

texts:
I'm trying to design an 8051 microcontroller circuit which uses timers/counters, and the circuit I'm using for inspiration uses a clock generated using the XTAL1 and XTAL2 pins of the IC, shown in the picture.

What I don't understand is why this clock is necessary for using the counter function of the IC, and where the output of the clock goes. I tried using a logic probe to test where the clock was outputted but couldn't figure it out.


texts:
In the book: Advanced DPA Theory and Practice: Towards the Security Limits of Secure Embedded Circuits 1, it is explained that the countermeasures against Side-channel Cryptanalysis could be ensured through 3 levels; Software Level, Hardware Level and the Logic Style Level.

The question is, why the Logic Style, which is defined in 2 as

  "the way how logic gate is constructed"

not considered as a part from the Hardware level?

I can't clearly spot the difference, is there some fundamentals that I might be confusing?


texts: Confusion regarding effect of dielectrics on energy stored in a capacitor

texts:
If inserting a dielectric has the effect of reducing the magnitude of the electric field in a capacitor (holding all other variables constant), then why is the energy stored in a capacitor directly proportional to the relative permittivity of the dielectric?  This seems contradictory to me. A higher relative permittivity leads to a more reduced electric field magnitude. It seems like a decreased electric field magnitude would mean reduced energy stored in the capacitor.  What am I missing here?

EDIT: Folks, let's assume that the cap is connected to a constant voltage source, so V cannot change.  Also, what I mean by hold all other variables constant is to hold V, plate area, and plate distance constant.

EDIT: After stumbling across (web.mit.edu/viz/EM/visualizations/coursenotes/modules/guide05.pdf), it appears that the answer to my specific scenario question can be found on page 5-22.  With a constant voltage source in play, Q has to change and the E field appears to remain constant across the cap since E=V/d.  So it's not always true that the E field strength decreases with dielectrics added, contrary to what certain sources imply (Wikipedia and parts of hyperphysics)- only under certain conditions is that the end result for a cap (i.e., if the voltage across the cap can change/is not held constant by a source).


texts: Field tests for veryfying stator core laminations loose in 3-phase, 3000 HP motor

texts: We have a 4000 V, 3-phase, 366 A, 3575 rpm, 3000 HP induction motor that is making a modulated buzzing noise. The vibration in the horizontal planes of both bearing housings has increase from 0.1 IPS-PK to 0.3 IPS-PK over a one year period. My electrician suspects there maybe loose stator laminations, are there any field tests that can be employed to verify?


texts: maximum achievable bandwidth for that opamp ft(max)/10

texts:
The figure below is from Analog-Digital Interface Integrated Circuits course here (page 4/25).

Could anybody explain why maximum achievable bandwidth for that opamp is ft(max)/10 instead of ft(max)?


texts: What are the Analog to TTL serial ICs called?

texts:
I have a sensor that measures an analog value and i want a ICs to convert it to TTL serial ,

because i want to send it afterwards via a bluetooth IC that takes TTL serial as input. I already  have a working prototype with a µController but i want something more compact and doesn't need to be programmed.
What are the keywords that i should use form my research?
thank you


texts: Diode connected transistor for voltage biasing

texts:
I am trying hard to demonstrate that the transistor M1 in figure works always in linear region. Transistor M2 is diode connected and consenquently (I am using the EKV model) it works always in saturation:

Vg2 = Vd2 > (Vg2-Vt)/n           Saturation condition

I know that voltage drop Vds2 is surely bigger than Vt but this doesn't allow me to state that the transistor M1 works always in linear region:

Vd1 < (Vg1-Vt)/n                       Linear region condition

I would really appreciate your help, thank you!


texts: Microcontroller reset on mains connection

texts:
I'm helping someone build a static VAR compensator. We figure it'll be evident that the power factor is being corrected if there's a display that shows AC voltage and current waveforms, so one can see as they come into phase. For getting the mains voltage waveform on a TFT display, I used this circuit:

Only difference is I'm using a cheap 240V-12V transformer in place of the adapter. Also I'm using an LM358 in place of the LMV321.

The 'brain' is an Arduino Mega powered through a USB port, for now. The problem is each time I plug the transformer primary into mains, the Arduino resets but after that the waveform is displayed as expected, though it has some weird dips at the crest and trough. If I disconnect or something affects the plug's contact with the mains socket, the Mega resets again. And the thing is, it not only resets but I actually hear my PC make the tone of a disconnected USB device. At some point, avrdude started acting up till I disconnected and reconnected the Mega.

Calculations and the TFT waveform show that the voltage at the analog input is within bounds. This seems like an issue of excessive current draw over USB but I'm not sure. I've also not gotten around to properly terminating the other op-amp in the LM358, if that's relevant to this issue. I would appreciate any suggestions as to the cause and a solution.


texts:
I recently purchased five LED strips online (these specifically: http://www.ebay.com/itm/331059064977) to hang up along the outline of my room.  Each strip is 5m (16.4 ft.) long, requires 12 V DC to power, and dissipates 0.08 W/LED.

Each strip dissipates 48 W, meaning that at the recommended 12 V DC, there would be a current of 4 A.

I planned on soldering the five of them together in series so that I could have one long chain of LEDs that will only require one power source.  However, I am slightly confused regarding what adapter I should purchase that  will power the chain.

Each strip seems to come with two cables attached to both sides (power and ground); I'm a little confused regarding this, because I know that LEDs should be forward biased, so why would both sides require power and ground?

Also, because I will have five strips, should I be passing 60 V DC through the entire thing if it's recommended to only pass 12 V DC for each strip?  I just want to make sure that I don't blow anything up accidentally by exceeding the maximum rated amperage (I probably wouldn't want to go over 4 A if possible).


texts: Switch operating at particular touch IC voltage

texts:
Is there any circuit to perform such task more efficiently?

I am trying to control a small motor (like a smartphone vibration motor) with specific outputs from the touch IC, so that it can be turned on and off at  particular outputs from it. That is, it can turn on at a particular current / voltage input and turn off at another.


texts: How to create a complex board outline for KiCad?

texts:
I would like to create a board border featuring more complex arcs, constrained shapes, etc. for use in KiCad (and compatible tools like Topor). The internal tools are much worse than what other programs offer.
So what would be the best way to import an externally created shape (for example from an SVG file) to the cuts layer in KiCad?


texts: is there any program which I can use to draw waveforms for digital encoding schemes such as biopolar-alternate mark inversion, manchester, b8zs and hdb3?


texts:
I was randomly browsing around some Introduction to circuits websites when I came along this:

The text that went with it is:

  Now let us consider what happens when using the output of a chip, such
  as the 74HC04, to operate an external device. For example, the circuit
  on the right drives an LED. When the gate is HIGH, then there is no
  path to GND for cathode of the LED L1. When the gate is LOW, then
  output pin 2 is connected to ground, and current flows. Since R3 only
  allows 15mA of current to pass, the gate is safe from being
  overloaded. Remember that most gates can handle 20mA of current. The
  same holds true for most microcontrollers.

Can someone explain how this works (I realize this is probably super newbish to most people)
I understand how logic gates work, that is an OR gate correct? My "assumption" is that since it's an OR gate....when the Input (or 1) is set to low (or zero) it allows current to pass through?....but if thats the case shouldn't it be like....facing the other way. I guess im confused at why the LED is on the output side with Vcc. I guess I just don't understand why the OR gate isn't facing the other way. Im probably being dumb lol


texts:
How to find a battery health/wear for rechargeable batteries? Especially for the most commonly used AA NiMH and proprietary Li-Ion or Li-Pol batteries?

How to find out a percentage of their original capacity?

If there is a need to measure a full discharge, how to do it quick and easy?


texts:
I am experimenting with MCUs, specifically AVR.
I am programming them with USBASP v2.
When the circuit is small it can be powered by the programmer itself; one of the PINs from the programmer to the MCU is a VCC that can provide a (tiny) current, which is definitely enough to power the MCU and a few LEDs.
As soon as I attach a servo motor to the circuit, the VCC from the programmer is not sufficient anymore. The solution is of course to use a separate power supply (batteries or 9V DC input and regulators) for either the servo alone or for the entire circuit, including the MCU. If for the entire circuit, I don't need the VCC from the programmer anymore and I can (and should) disconnect it.
This is what I would like to do:

When the power switch on the circuit is OFF, the circuit is, well, OFF, but if connected to the programmer I would like the MCU to still receive the VCC from the programmer so that it can be flashed.
When the power switch on the circuit is ON, the separate power supply is used to power everything, and the VCC from the programmer, if connected, is "ignored".

This would allow me to program the circuit irrespective of whether it's on or off, and it would also enable the circuit to function on its own when not connected to the programmer.
Questions

Is there something wrong with this idea?
How do I implement this? Clearly I cannot connect different VCCs together.


texts:
I'm still pretty new to electronics, and this is my first time on the EE StackExchange, so please bare with me :)

I'm currently working on designing a schematic for a quick prototyping board, in Eagle, for use with the Intel Edison. On the board there are a couple chips that require 5v to operate (an FE1.1s and a PCM2902E), and the Edison needs 3.3v to run.

In my schematic, I have a standard barrel jack and two screw terminal that I'm going to use to power the board. Now as I have a history of acidentally blowing stuff like LEDs, some chips, and speakers by acidenatlly applying to much voltage, or acidenatlly using a wall adapter set too high, I want to install some protection. (Especially since the Edsion don't have any type of voltage regulator, I don't want to fry a $50 board!)

The idea is that the user can input any voltage (5v and above, say up to 12v) through the screw terminals or the barrel jack, and the board will shift to voltage to the levels it needs.

Right now, using this tutorial I have a 5v voltage regulator in my schematic to shift the input down to the 5v I need to run the chips. Now I need another circut to shift it down to 3.3v so I can power the Edison

simulate this circuit – Schematic created using CircuitLab

Whats the best way to go about shifting the voltage down to 3.3v for the Edison? and is there a better way to shift the unknown input voltage (max of 12v) to 5v?


texts: I need to use pogo connectors/pads that will be routed to MSP430 microcontroller. These pogo pads will be routed in a way that allows for JTAG 4-wire programming to program the microcontroller. Is there a way/cable to connect from your PC (like USB) to JTAG that uses pogo connectors? I need to incorporate these three elements: POGO, JTAG, and USB.


texts:
I am trying to make a colorimeter using TCS3200 sensor and white LED light source.

After weeks of research and understanding on how different white light sources work and what are the algorithms involved in calibrating the sensor in CIE1931 space.

Now I am facing problem in getting a reference for getting a calibration curve.

For example, if I want to map R values, then I also need some reference for which I know R values.

I initially planned to use RAL cards to calibrate my sensor, but the RGB values are not shared on their official website and other websites provide sRGB values and not the actual RGB values.

I even thought of printing varying shade of Red on paper, but I believe there will be a lot of unknown factors in this (printer calibration, RGB space used by the software, etc).

So is there any standard source of known colour against which i can calibrate my sensor?

Edit:
My application is more to sense the change in shade rather than getting the actual color of the subject and that's the reason I was thinking if I can get away with calibrating it against some standard color swatch of known RGB values.


texts: can i replace a linear100k potentiometer with multi turn potentiometer 100k to get more resolution

texts: can i replace a linear 100k potentiometer with multi turn potentiometer 100k to get more resolution. The linear potentiometer 100k which i mentioned is used in pwm which i brought from ebay for controlling speed of a 12v 9a 500rpm dc motor but when i am using 100k linear pot i am not able to get proper resolution in speeds of dc motor eg:at 1,2,3,4....hz.so i wanted to replace linear pot with multi turn pot is it possible or not.Do i need to mention anything else