texts: I'm working on an AVR computer, everything works fine, except when I tap any ground point with my finger (there are a lot of them exposed), the MCU (an ATMEGA328) hangs for a brief second. I have a feeling its the crystal, since I didn't put any capacitors on it. Also, when I tap the ground with an inductor on my finger, the MCU hangs for less time, then goes into turbo-charged speed. The only thing filtering the supply is 2 680uf capacitors on the main supply, then a 1uf capacitor for the MCU. And one more thing, the MCU will only run for several seconds, then freeze if the battery is almost dead, but everything else still runs perfectly. Can anybody help me design a better power filter for my next design?


texts:
I'm trying to use parallax ping ultrasonic sensor to measure distance but I'm having some problems. Here is the code that I'm uploading to my arduiono (duemilanove) that is kinda similar to the one in the example:

// this constant won't change.  It's the pin number
// of the sensor's output:
const int pingPin = 7;

void setup() {
  // initialize serial communication:
  Serial.begin(9600);
}

void loop()
{
  // establish variables for duration of the ping,
  // and the distance result in inches and centimeters:
  long duration, inches, cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);

  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);

  // convert the time into a distance
  inches = microsecondsToInches(duration);
  cm = microsecondsToCentimeters(duration);

  Serial.print(duration);
  Serial.print(" ms ");
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();

  delay(1000);
}

long microsecondsToInches(long microseconds)
{
  // According to Parallax's datasheet for the PING))), there are
  // 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
  // second).  This gives the distance travelled by the ping, outbound
  // and return, so we divide by 2 to get the distance of the obstacle.
  // See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
  return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds)
{
  // The speed of sound is 340 m/s or 29 microseconds per centimeter.
  // The ping travels out and back, so to find the distance of the
  // object we take half of the distance travelled.
  return microseconds / 29 / 2;
}

The problem is that the serial keeps returning

21491 ms 145in, 370cm

regardless of object infront of the sensor or no object at all. I've tried modifying the delayMicroseconds in the code and it still comes out the same. I've tried different pins as well. So I'm guessing its not a software problem but maybe hardware? I also read the parallax documentation and it doesn't specify if ambient sounds might effect it or not or if there is some sort of initial calibration that needs to be done? I've read the arduino documentation and double and triple checked everything but I can't seem to find what might be causing this. The wires are connected up correctly and everything.

Anyway, does anyone have any suggestions on what I might be doing wrong here? Thanks for any help


texts: Power Supply for Arduino on breadboard (ATMEGA328PU) from a car battery

texts:
I wanna power  my Arduino on breadboard (ATMega328PU) from a 12V car battery.

simulate this circuit – Schematic created using CircuitLab

Is this safe ?
What should I add more to make it a safer design?

The battery is attached to a generator for starting


texts: Which pins of ATSAMD51 are used for I2C in Adafruit Grand Central?

texts:
I am trying to recycle my old Adafruit Grand Central board to use with Atmel Studio.I Adafruit website , I2C pins ( SDA , SCL ) are marked as PB20 and PB21 to be used as SERCOM-3 but in ADSAMD51 datasheet those pins are not available for I2C.  I double checked with Atmel Start and it is not letting me pick those two pins for that purpose.  I am guessing Adafruit is using a hardware or software connection between PB20-21 and the available ones but can't find which pins. Any ideas ?

https://learn.adafruit.com/adafruit-grand-central/downloads


texts: Why is Leakage Current Important when a MOSFET switch is "ON?"

texts:
Referencing ADG5206. ADI has specs for Drainage Current at the Source and Drain when the switch is OFF. They also have channel leakage for Source and Drain when the switch is ON.

Why is it important to have specifications for leakage current when the switch is ON? Where does this leakage go? Does it simply get consumed within the MOSFET?

Also, I understand why it would be important to have leakage specs when the switch is OFF; however, how much of a difference does it make when the values are so minimal?

I am not designing anything as of yet, simply doing some research. I have found a few App Notes and am still not fully understanding. Thank you in advance for the help.


texts: Need a buck circuit to go from 48V down to 12V-9V less than 30mA (or half the supply input for a regulator)

texts:
I need a circuit to go from 48V down to 12V-9V less than 30mA, it doesn't need to be a buck converter. I don't want to use transformers as simplicity is good (and adding components to the library is bad) and I probably already have inductors that I could use on my shelf. Most of the stuff out there in IC's only goes up to 36V on bucks or regulators.

How do I make a circuit to do as I described?

Points for being more than 60% efficient as I don't want to burn up 60% of my power on regulation.


texts: How to determine sign across current source?

texts: I'm confused about how to determine sign orientation for current sources in circuits. From what I understood initially, it's negative to positive for both independent and dependent current sources. However, I've found a few examples where it's the opposite. Could someone clear this up for me? Here's the example where it's defined as positive to negative across a dependent current source:


texts: Change output voltage of a charger using the shunt resistor?

texts:
I have bought a 58v charger from asia and I selected the SLA one by mistake instead of Li-ion. It came with a 59.3v output when i want it to be more in the 58.3 range. My battery doesnt detect the 59.3 volts, I think it's to high, the BMS detects over-voltage.

1/ Is an SLA charger unuseable with 18650 14s8p battery, because a li-ion charger has an adaptive output ranging from 52-58?

2/ Can i change the 80N70 FET shunt's controlling resistor (it's 750 kiloOhm) on the circuit board to make the charger put out 58.5v instead of 59.3?

Resistor r29 goes to 2 of the 80NF70 FET pins, the middle FET pin also is the ground output of the battery. Can i change the resistor from 750k? Can i use a pot? How do i know the value to get 58.3V?


texts:
We are using a MAX517 DAC-device as slave and an ATmega8535 controller as master. Communication errors can be readily detected by comparing (TWSR & 0xF8) with 0x08 for Start, 0x18 for address transmission, and 0x28 for data transmission, respectively.

But I'm wondering where those values come from. In the Atmel datasheet I find the usual symbols START (for 0x08), MT_SLA_ACK (for 0x18), and MT_DATA_ACK (for 0x28), but not the numerical values. Neither are the values mentioned in the MAX517 datasheet.


texts: Serial comms over 3m cable, shared with USB

texts:
I am designing a system that needs to do serial comms over a standard USB cable, as well as normal USB (but not at the same time). In other words, when plugged in to a PC it will appear as a USB device and when plugged in to an embedded system it will use a simpler serial comms protocol. The USB side is only full speed (12Mb/sec), and the serial comms only need to be 100Kb/sec, although 1Mb/sec would be nice.

The stand-alone device will use a microcontroller for comms. Both the device and the embedded system will be microcontroller based, most likely Atmel XMEGA. One option would be to fit a device with USB OTG/host support, but I want to avoid this complexity, cost and limited choice of microcontrollers.

The XMEGA micros have UART and SPI peripherals on the same pins as USB D+/D-. I could route I2C from two other pins over to them as well, and I don't think it would harm signal quality. Since the USB cable only has two lines if I used SPI it would be unidirectional, which I could cope with. Bi-directional I2C or 3.3V RS232 would be nice though.

Has anyone tried anything like this? I am a little concerned about the capacitance of a 3m USB cable causing problems. None of these serial protocols are differential, but should cope with poor signal edges. You can get line drivers for I2C/SPI/TTL-RS232 but the ones I have looked at seem like they would interfere with USB when not in use. Thinking about it, I2C without a line driver could be problematic due to the need for pull-up resistors.

After doing some research I am leaning towards 3.3V RS232. I could use SPI but synchronous protocols may have issues with a 3m cable at high speeds. If the receiver generates the clock there will be some delay before the sender sees it and the response arrives. If the sender generates the clock there will be no problem with delay (since data will be delayed by the same amount), but it somewhat complicates two-way communications. The other disadvantage of SPI is lack of start/stop bits, but usually isn't a problem because you can use an enable line to start communication at a known point, but I don't have enough lines for one.

Then again, being clocked may be worth the extra effort on the protocol side in order as it should be more robust with signal degradation. Terminating resistors should help deal with reflections.

In any case, reasonably high speed should be possible. The Sony Playstation uses SPI at 3.3v with a 500KHz clock, and works fine with long leads. The N64 uses a single aysnc data line (no clock) at around 333KHz, again over long leads.


texts:
I have a project which is proving to be more challenging due to my limited knowledge of electronics.

I am installing a homemade central vacuum system. It uses 12 V signal from the outlets to operate a 230 V vacuum cleaner.
Plug the hose in, make the circuit, start the vacuum.
Unplug the hose, the motor stops.

I have a solid state relay which switches it perfectly.

I wondered if there was a way to keep the vacuum running for 20-30 secs after the outlet has been unplugged, to clear any debris in the pipework?

I was thinking of possibly using a capacitor on the 12v circuit but have no idea how to calculate the size I would need!


texts: How does the brightness of an LED depend on the average voltage?

texts:
I have a circuit where a LED is connected in series through a resistor to a PWM output signal.
The pulse width modulation (PWM) signal has two states (ON and OFF) where ON is 5V and OFF is 0V. The LED brightness can be controlled using this ON-OFF PWM modulation.
The output across the LED is constant while in the ON state. The duty cycle of a PWM signal determines how long the ON the state is ON.
How come the brightness varies when the voltage across the LED is the same?
Why does brightness seem to depend on the average voltage and not on the voltage across the LED at that instance?


texts: Transfering my arduino/TI-MSP430 Launchpad/Energia skills to real world projects and C

texts:
I'm learning electronics/microcontroller programming through TI-MSP430 Launchpad(Energia) and Arduino.

Both are based on wiring framework, and very good place to start for a beginner like me.

Now as I'm forwarding in my learning, I'm thinking to explore more and want to do a real world project. My project can be easily done on both above mentioned platforms, but I want to use STM8S-Discovery(Dev board or STM8S series MCU) for this but there is no wiring framework for STM8S as far as I know and I don't want to use if there is any.

What other skills/information I need to migrate from these wiring framework based platform to real world microcontroller projects?


texts: What differentiates Laptops from PCs in terms of power consumption?

texts:
Today I as a Computer Scientist stumbled about some strange facts.
Recently, I bought a new Macbook Model 16" inch. Today I tried to stress test it because I wondered if the 96 Watt charging cable could even keep up with this processor and GPU power consumption.

Running Cinebench showed, that running the program without charging cable, would completely overstress the battery. Running with the 96 Watt charging cable, however, the Macbook did not lose any more energy,

Therefore the whole computer must have run below or at exactly 96 Watt.

CPU: 2,6 GHz 6-Core Intel Core i7 (Turbo boost to 4,5 GHz)

GPU: AMD Radeon Pro 5300M 4 GB and Intel UHD Graphics 630 1536 MB

(And with the same charging cable, you can even power stronger Macbooks)

In comparison, I know that some Gaming PCs including mine can take up more than 500 Watts of Power. But they are not that much better in terms of performance. (they are better, but not proportionally to the power consumptions)

So, how exactly do manufacturers like Apple ensure low power consumption, while offering good computing ability? (Price does not matter)

Thank you!


texts:
I am trying to understand the Mixer operation for frequency up/down conversion. We just multiply our RF/IF signal with Local Oscillator (square wave) to do this job. Fine. BUT, if I start looking closely on operation things are getting confusing for me!

Say below is frequency domain presentation of the signal I am trying to upconvert.

Now the frequency domain presentation of periodic square wave is like following:

Now If I multiply these two signals time domain, which is same as convolution in frequency domain, the result would look like following:

And here is my question. Say, my intention is to move the signal to $$\omega_p$$ frequency. But clearly the result would contain higher harmonics of the above frequency. The Mixer datasheet from Analog devices does not talk about filtering the resultant signal post mixing. Basically the output of Mixer MUST go through signal processing to cut out the harmonics and retain the specific frequency region of interest. Or the Mixer by itself cuts out the higher frequency?? Something is amiss in my understanding, because so far I thought that I can use the Mixer output straight way without filtering, but the way I see, it needs filtering to cut out harmonics.

Also in Mixer stage, can I use clock signals instead of square wave as inputs? I believe if I feed Sine wave as the input in LO port, I can get rid of this higher harmonics issue altogether. Is it possible to inject sine wave at the LO port. The datasheet is not explicit on this.

Thanks for your guidance.


texts: How is a diode damaged by exceeding its Vrrm (maximum peak repetitive reverse voltage)? At this point it conducts more current than usual, so is it the current flow that damages it? Why would that be any different from being forward biased when it conducts almost unlimited current? Or is there some other factor?


texts: 3v3 power for a PCB that takes a 2/3A battery

texts:
I have a broken one of these: https://fccid.io/J69303MICA/Test-Report/Test-Report-1573814.pdf
I have a 5 pin UART and male to male & female to female jumper wires.
There is a header space on the PCB with 14 holes. I believe the squarish one in the corner is where to connect the 3v3 wire or would it be the outermost pin on JP1? I don't want to damage something else on it ignorantly. Thanks for your time. If my title or question isn't clear, please feel free to correct it.


texts: Using smaller tantalum capacitors in parallel vs a single large aluminum cap for decoupling

texts:
I'm designing a circuit that will connect to a series of WS2812b LEDs.  The recommendation is to use a 1000μF aluminum cap as a decoupler between +5V and GND just in front of the first LED to prevent surge damage when powered on.  I have a perfboard circuit setup that way and it works fine.  I'm looking to shrink the whole thing down onto an SMD PCB and wondered if I could use 2-3 smaller tantalum caps in parallel instead.

Basically, are these equivalent circuits?


texts: difference between sensitivity list and wait vhdl

texts:
I have sample 2bit multiplexer implemented with processes with one little different, first one has sensitivity list and second one implemented with wait.
I want to know what is difference between this two code and which one of them is more accurate?

 ARCHITECTURE Behavior OF mux2to1 IS
BEGIN
PROCESS ( a, b, s )
BEGIN
if s = '0' then
w<=a after 1.4 ns;
else
w<=b after 1.5 ns;
end if ;
END PROCESS ;
END Behavior ;

and the second code:

  ARCHITECTURE Behavior OF mux2to1 IS
    BEGIN
    PROCESS
    BEGIN
    wait on  a, b, s;
     if s = '0' then
    w<=a after 1.4 ns;
    else
    w<=b after 1.5 ns;
    end if ;
    END PROCESS ;
    END Behavior ;


texts:
I have been studying transistor throughly this semester and I have always doubted this circuit schematic.
First of all is this schematic correct? What about current directions are they conventional? I can't understand why collector current is heading to the transistor isn't it supposed to be output current and why they are written in small letters when the are effected by the DC sources VEE and VCC

Sorry I'm very confused!

Schematic is within the fullpage below

Addition:

Exam question:

Detailed answers : Explanation


texts:
I'm looking for an explanation about what type of relation have antenna gain with it's efficiency.

For example I want to use a ceramic antenna that is a dipole antenna.
It has:

Average Gain of -0.5 dBi typ. (XZ-V)
Return Loss 9.5 dB min.
Input Power 3W

and not more details.

Antenna Gain worth something in antenna efficiency? That mean that I have 0.5dB gain in one direction and -0.5dB in another. But if I want an omnidirectional antenna, should I choose 0dB gain?


texts: Monitoring serial communications between two PCBs?

texts:
Someone was asking me if it would be possible to monitor the serial communication between two PCBs and output something that is readable. The PCBs are part of an automatic door system - I'm not sure of the baud rate, protocol, or anything right now.

Do you think it would be possible to use an Arduino or something similar to do this? Would it be able to output readable text? Can logic analysers do this? At this point I'm not sure whether it would be I2C, SPI, or just have RX/TX lines, but I'm sure that could be figured out.

Since it would just be listening to a bunch of 1's and 0's without the opportunity to transmit back, I'm concerned it would just end up incorrectly interpreting a bunch of 1's and 0's, resulting in useless data. What do you think?

I am just trying to gauge the difficulty of such a thing, and the best way to go about it.

Thanks!


texts:
I want to convert 220 V ac to 5 V ac, and then fed that scaled ac to A/D converter.I don't want to use transformers.
How good it is to use OPAMP as inverting amplifier or voltage divider.?
I simulated the circuit in LTSpice by using LT1006 ,apparently there is no problem.
I also used Voltage divider and buffer combination,that also worked good in simulation.
Kindly suggest me the best and small circuit that has little problem associated with it.


texts: Add 3.5mm Jack to Raspberry Pi for TTL Signal with 5V

texts:
I am a 100% software guy, so i wanted to confirm that my little project is gonna work before i fry everything.

I am trying to create a controller for my (quiet old) Onkyo reciever. I am trying to do this by using a proprietary 3.5mm mono jack they have on their devices.

The protocol is quite easy.(If you want to have a look a it) I just have to connect a 3.5mm Jack to a gpio pin to signal high and low, the problem is that 5V are required and to my understanding the gpio pins only provide 3.3V.

So my idea was to wire the 3.3V GPIO with the base of a transistor and then use the 5V powersupply.

Now I have a few points i am unsure about:

Do i really need a npn transistor or a different one?
What do i have to consider while buying a transistor?
Did i forget something important?

Thx a lot for helping me out.

EDIT: Thanks to Steve G's response I was able to solve this and do some reading up, if anyone else wants to read up the keyword that got me started was "level shifting", an easy concept once you know what you are searching for exactly.


texts: Which layer contains the board outline in PADS Layout?

texts:
TL:DR If I create or import a board outline on PADS Layout, in which layer(s) is it drawn? Can I make it visible/invisible?

On Mentor Graphics PADS, I'm trying to import a board outline from a .dxf file. I see this can be done in 2 ways: by navigating to File/Import... or by clicking the Import DXF in the Drawing menu.

In the Import... window, where I can select which layers to use with the imported drawing, I noticed that I can only get the shape to display if I select the <All layers> entry, no matter what other layers I select. If I use the Import DXF button, the only option is the Top layer, which produces the same result.

Now I get the yellow outline displayed on screen, and if i right-click on the working area and choose Select board outline, I can highlight the shape I've just imported. But:

What layer is this?
How can I enable and disable it?
What if I want to also import other drawings such as fiducials and position references?


texts: Class D Amplifier Design: Simulation(/Practical Design?) Issues

texts:
For a college project my project group needs to make a speaker amplifier. We need to use a +-15V PSU for the whole system and the amp must at least provide 15W to an 8 Ohm speaker. One of the components for this speaker amplifier is the power amplifier, which needs an input impedance of at least 50kOhm.

So we decided to go for a class D amplifier design because of the good efficiency. However this type of design is pretty complex, which I figured out after my simulation didn't went according to plan. This is the design I came up:

The first part of the design is to ensure the input impedance is according to spec and to separate the positive waves from the negative waves. This is done with a voltage follower which has been connected to either a positive or negative 15V and to ground. Since this is done, it should clip at 0V and thus eliminate the positive or negative voltage. This is then fed into a comparator to make the positive or negative PWM sine wave which can be used to drive the MOSFETS. The MOSFETS have a cap connected to the voltage terminals to reduce voltage drops. This is then filtered to get the voltage and current amplified square wave back.

For the input two +-10V (Amplitude) sources where used, one a sine wave (1kHz) and the other a triangle wave (25kHz). Our goal is however to use +-15V sources by using a non-inverting amplifier to amplify the signal coming from the preamp.

However, the simulation shows something I didn't expect:
@SIN+:

@TRI+:

This shows clipping at the positive edge and I'm not sure why the amp does this.

However, the simulation goes weirder:
@SIN-:

@TRI-:

Not sure why this is happening, but I think TINA-TI SPICE is bugged af. So if anyone knows a good (free) alternative, I would love to hear about it.

Edit1:

So, I came up with a new plan:

In the old version I noticed that the TL072 are JFET opamps and this caused the clipping at the high voltage potential. Also, the MOSFETS were not oriented correctly.

I realised that I could also make a square wave when the sinus wave is high and then enable the triangle wave with an and gate. This idea works pretty good on the positive rail (red line), but I think I made a small mistake in the negative rail (green line)and I can't pinpoint it:

I do see that the green line should be flipped from 0 to 15V (and the triangle wave should also be gone from 0 to 500m), but I'm not sure where I made a mistake.


texts: DIY PCB Manufacture: Photoresist or Toner Transfer?

texts:
So here's what happening: I have my board layout ready to go on eagle, and am looking for a good way to produce this board at home, of a quantity of about 2 or 3, so not large scale at all. All the components are through-hole and the layout is single sided. For those curious the layout looks like this (the lines are from the a bad render as I just took a screenshot of it from paint):

Looking at DIY PCB manufacture all round the world wide web I have arrived at two most effective methods (from what I know): 1. Using a pre-made photoresist board to etch traces and 2. directly transferring ink from photo paper on to the copper (both using Ferric Chloride to route traces).

Since I have zero experience with this could someone please share some knowledge as to: for my application (low scale DIY PCB manufacture), which method would be the better choice and proved to be the most effective?

And for those with some experience in making your own PCB's at home, any advice or tips to share about this with a completely inexperienced guy like me? Any layout re-design required?

Really appreciate it.


texts: Finding the resonant frequency of a RLC circuit with a tweeter

texts:
I am asked to find the resonant frequency for the two following circuits:

They represent the tweeter and the woofer of a speaker. For the first circuit, I did the following,

But now I'm not sure how to proceed to calculate the resonant frequency. Could anyone give me a hint? I suppose that the second circuit requires a similar procedure to find the solution.


texts: Why does MSP430 have 2 capture signals for each capture/compare channel? Pin assignments recommendations?

texts:
Let's take MSP430G2553 as an example. If you look at the pinout in datasheet, you'll see:

P2.1/TA1.1
P2.2/TA1.1

One could think that those TA signals identical and multiplexed twice as a courtesy to folks doing PCB routing, but looking up pins in "Terminal Functions" table, it becomes clear that they are different:

P2.1/TA1.1: GPIO; Timer1_A, capture: CCI1A input, compare: Out1 output
P2.2/TA1.1: GPIO; Timer1_A, capture: CCI1B input, compare: Out1 output

So, when that capture/compare channel is used in compare mode, they are indeed identical. But for capture mode, they represent 2 different signals to start a capture, which one to use is selected in the control register. So the question is: Why so magic? Can someone decipher a usecase TI engineers had in mind while designing it? Don't get me wrong, it's cool to have twice more capture inputs, but if they're so nice, why don't put twice more real independent C/C channels?

Following up with the questions, suppose I have 6 P2 pins which have such C/C altfuncs (i.e. 3 channels, and 2 capture signals for each channel), and I need to use 3 of them for GPIO - what would be more flexible (future-proof, extensible) arrangement of pins? My obvious guess is that I should leave 3 independent C/C channels, and use "extra capture signal" pins for GPIO, but again, maybe I'm missing something?


texts: Automotive load dump protection with TVS diodes

texts:
In this marketing material by Littlefuse they explain how to use e.g. their TPSMA6L TVS diode for automotive load dump protection: TVS Diodes can provide secondary transient
voltage protection

Question 1: What makes e.g. the TPSMA6L20A more suitable to this application than any standard SMBJ20A? I cannot find any appreciable differences in the datasheets.

Question 2: More generally, is a TPSMA6L20A / SMBJ20A sufficient for protecting automotive circuits? Littlefuse speaks of TVS as "secondary protection", but they show no primary protection in their example circuits. What do they regard as the "primary protection", the Zener diodes in the alternator?


texts: Select one of two register spaces in VHDL

texts:
I want to create a system consisting of two register spaces (A and B, see the figure below). The purpose is to allow for instant configuration switching. When S=0, the registers in A will be select for writing (new configuration), and the registers in B will be selected for reading (running configuration). When S=1, opposite is true.

            +
            |
            |
    +-------v--------+ not(S)
    |  WRITE SELECT  <---+
    +----------------+
       |0        |1
       |         |
     +-v-+     +-v-+
     |   |     |   |
     | A |     | B |
     |   |     |   |
     +-+-+     +-+-+
       |         |
       |         |
    +--v---------v---+ S
    |  READ  SELECT  <---+
    +-------+--------+
            |
            |OUT
            v

My question is about how to code the read select in VHDL. Assuming only one configuration register:

signal S : integer range 0 to 1;
type slv_ary_t is array (integer range <>) of standard_logic_vector(31 downto 0);
signal reg_space : slv_ary_t(1 downto 0)
signal OUT : standard_logic_vector(31 downto 0);

begin
-- What is the difference between this:
OUT <= reg_space(S);
-- and this
OUT <= reg_space(0) when S=0 else reg_space(1);

My understanding right now is that this will result in the same hardware after synthesis. Is that correct?


texts: LT1019 voltage reference output 5V to 3.3V

texts: I have LT1019ACN8-5 IC output is 5V. I am using this IC to get Vref 3.3 for the ADS8320. is it ok if i use a voltage divider to the output pin to regulate 5v to 3.3v. Is it acceptable ?


texts: I know how to control where the servo will rotate: if I send 1 ms duty signal in a PWM interval it will rotate clockwise and if I send 2ms duty signal it will rotate counter-clockwise but how can I control the speed? I have searched and find that it is done with “delay()” method for ardunio but I use FPGA, so what is the logic behind it?


texts:
Is there a way to keep a stepper motor pushing without a given rpm?
I have a large stepper motor that I want to assist another motor with as much torque as it can. The other motor is a small 9hp single cylinder four-stroke engine, the stepper would be connected to the crankshaft of the small engine. The assistance would be triggered by user input to a stepper driver I'm going to create. The stepper would be driven with as much power as I can supply it. Its not a situation of "how much power do i need" as "how much power can I get with what I have" The numbers I've been given put the stepper anywhere between 4 and 8 hp. Its actually only 12steps per rotation.
My idea is that each time the motor reaches the powered step it would automatically activate the next step thereby keeping a constant torque. The issue I have with my own idea is that I wont know Which step is next. Is there some signal the micro controller can sense on the coils to indicate which step the shaft is at? Would a shaft position sensor be able to handle the nearly 4000 rpm?


texts: Switching on and off a LED light if a AC is passing through a wire or not

texts:
This is the basic setup of what I'm going to do. Have a wire plugged into the mains that is then connected to a ON/OFF flip switch then goes on to the rest of my project. Want I want to do is to add an internal DC circuit supplied by a 9V battery that when detects that the switch is closed i.e. their is mains power going through the wire, a green LED will light and when there is no power, there's a red LED.

What should I do to achieve this? (I was thinking of using some sort of transistor) A circuit diagram would be great as well.

Thanks,


texts: what tool to use for smd mark code to part number

texts: Is there anyway to find a chip part # based only on the mark codes.it says 633 then below it says MV.from the circuit it seems to be a cap at 2.2uF. any help is appreciated thanks.


texts: Nexys 4 DDR doesn't load bitstream from microSD card?

texts:
Following the lower half of page 6 of this PDF, I formatted a 2 GB microSD card to FAT32 filesystem using mkfs.fat on Ubuntu and copied main.bit from one of my projects. Then I inserted the microSD card onto my Nexys 4 DDR board, made sure the two jumpers are in the correct place (JP2 connected to SD and JP1 connected to USB/SD). Then I power-reset the board and saw the "BUSY" LED slowly pulsing, indicating that the board is waiting for a valid media to be inserted, according to the PDF.

Things I've tried:

Note first: I have tried 2 sets of all hardware involved here, including the Nexys 4 DDR board (and the jumpers on it), the microSD card, the USB flash drive (mentioned below) and the USB cable.
Formatted the microSD card in Windows 10 instead of Ubuntu
Verified that the bitstream file is working correctly by downloading to the board via the PROG/UART micro USB port using Vivado 2018.2 software
Regenerated the bitstream using Vivado
Pulled another bitstream file from another project
Renamed the bitstream file (keeping the .bit extension)
Replaced microSD card with a 4 GB USB drive inserted into the USB Host port on the board (and changed JP2 to USB)
Powered the board via a 5V phone charger

Here's what the board looks like (click to enlarge):

The microSD card is inserted in the slot on the other side so not visible in the image, as indicated by the arrow on the left. The two squares are JP2 (left) and JP1 (right), as I have correctly (I suppose) configured.

What could be a possible cause of this? How can I tell the board to load bitstream from the microSD card?


texts:
I was working on a program with an LED 5 X 7 dot matrix for my Arduino pro micro. There was a program that worked on the dot matrix and I was just making it simpler using arrays and such.

I just finished the setup and added one command in the loop just to turn on one led for testing. So I uploaded the code and I got a error stating "Serial port on COM 5 not found" even though just before I uploaded a different code.

So I did the usual... restarted Arduino, and I still got the same error.

Then I realized windows 8 was giving a bubble at the bottom right side of the screen saying "USB device not Recognized" so I figured maybe the drivers got messed up. I went to the device manager and saw unknown device (figuring that was Arduino) so I tried to update drivers with the copy of the pro micro drivers I already had. It said that the drivers were up to date. Just to make sure I uninstalled the drivers completely and downloaded a fresh copy from the Arduino website. Still it didn't work.

By this point I thought that my computer was having issues, so I tried it on my friends windows 7 computer, it still didn't work. Me and my friend figured we should move on. So my friend, who has been programming his  pro micro on his own laptop with a different cable, uploaded my led dot matrix program to his pro micro when it wasn't attached to anything (it wasn't on a breadboard, so it wasn't an issue with wiring on the breadboard) and the SAME thing started happening to his Arduino pro micro.

I have NO idea what the problem is, maybe, somehow, it is some weird issue with the code... Here is the code that I uploaded:

//rows
const int dotr1 = 5;
const int dotr2 = 4;
const int dotr3 = 6;
const int dotr4 = 7;
const int dotr5 = 15;
const int dotr6 = 3;
const int dotr7 = 2;
//columns
const int dotc1 = 9;
const int dotc2 = 8;
const int dotc3 = 10;
const int dotc4 = 16;
const int dotc5 = 14;
//extra
const int dt = 1;//for scrolls
const int timeDelay2 = 20000;//micsec//for weave
const int repetitions = 2;//scrolls
const int repetitions2 = 20;//weaves
const int scrollRate = 1;//timedelay2*scroll= duration of weave

int currentStep = 0;
const int frame1r[] = {4,0};
const int frame1c[] = {3,0};
const int frame2r[] = {3,3,3,4,4,5,5,5,0};
const int frame2c[] = {2,3,4,2,4,4,3,4,0};
const int frame3r[] = {2,2,2,3,3,4,4,5,5,6,6,6,0};
const int frame3c[] = {2,3,4,1,5,1,5,1,5,2,3,4,0};
const int frame4r[] = {1,1,1,2,2,6,6,7,7,7,0};
const int frame4c[] = {2,3,4,1,5,1,5,2,3,4,0};

const int high = LOW;
const int low = HIGH;
void setup()
{
  for(int i = 2; i < 11; i++)
  {
    pinMode(i, OUTPUT);
  }
   pinMode(15, OUTPUT);
   pinMode(14, OUTPUT);
   pinMode(16, OUTPUT);
   //for rows
   digitalWrite(dotr1,high);
   digitalWrite(dotr2,high);
   digitalWrite(dotr3,high);
   digitalWrite(dotr4,high);
   digitalWrite(dotr5,high);
   digitalWrite(dotr6,high);
   digitalWrite(dotr7,high);
   //for columns
   digitalWrite(dotc1,low);
   digitalWrite(dotc2,low);
   digitalWrite(dotc3,low);
   digitalWrite(dotc4,low);
   digitalWrite(dotc5,low);
}

void loop(){
for(int i = 0; i < scrollRate; i++){
  digitalWrite(frame1r[currentStep], low);
  digitalWrite(frame1c[currentStep], high);
  delay(dt);

}
}

If someone has had this issue or knows a possible way to fix it please help.


texts:
simulate this circuit – Schematic created using CircuitLab

The output is always outputting 5V, and I have no idea why. I have checked the inputs to the comp, I even switch them around its never hits 0 volts. Yes I am double checking that input from the OPA350 is greater than the Vrf.


texts: Altium designer direct connect on high power components

texts:
I'm designing a board which I'll solder it by hand.

In order to do soldering much easier I believe that many components need to be connected through relief connect to their adjacent polygon pour.

But, some components are connected to high power circuits, like dc to dc step-down regulator, output capacitor, input capacitor, high side switches, low side switches, etc.

And I think those component it's better to be connected with direct connect.

The question is: I'm trying to find a smarter way to distinguish the connection of the parts instead of putting one by one in the rule builder.


texts: Altium - How to lock information window on the top left?

texts: I somehow accidently unlocked the display on the top left in the PCB routing view (which shows the active layer, snap grid etc.) and now it follows the y-axis of my cursor, is it possible to fix it to the top left again?


texts:
I’m seeking to find/design a battery that can power a 230 kW electric motor at 680V for atleast 10 seconds. I don’t know much about battery mechanics besides simple circuit equations, so I’m seeking general advice on how to go about finding/designing a battery for my use case, and how to calculate figures such as weight, cell configuration, best battery composition etc.

This is the motor I’m looking to run: http://emrax.com/products/emrax-268/

Thanks!


texts: Audio: Camera activated external microphone

texts: I want to build a relay circuit that turns on an external microphone (powered by an internal 9V battery) when a connected camera is turned on (a camera offering only 1V plugin power through a 3.5 mm jack: Panasonic GH4). Hence, the circuit (that can be easily powered by the 9V mic battery if needs be) has to "wake up" the mic when it detects the 1V —sorry if this sounds vague, but I'm no engineer: a friend promised to build it for me if I provide him with the schematics.


texts:
simulate this circuit – Schematic created using CircuitLab

In one of our electronic circuit tests, this question was asked: What is the output voltage of  given circuit?

This circuit looks like a common emitter amplifier circuit to me, but when I tried to calculate the output, I am getting 0.047 V.

My questions are:

Why is this circuit not amplifying, is it required to add capacitors?
How to select suitable resistor values of Rb, Rc and Re in any transistor based circuits?

I know some of the formulas but I don't know how to implement:

$$I_b = V_{in} - \frac{V_{be}}{R_b}$$
$$V_{be} = 0.7 \mathrm{\;assumed}$$
$$I_b = 0.372\mathrm{\,mA}$$
$$I_c = \beta I_b$$

Considered β = 100, so:

$$I_c = 0.037\mathrm{\,A}$$
$$\mathrm{Gain} = \frac{V_{out}}{V_{in}}$$


texts: What connector is this? I haven't a clue, looks standard though

texts:
https://imgur.com/a/D4sBi3D

I need to get an adapter to connect the plug from the green board, to the plug on the brown board. However, I have no idea what the green board's connector is called, so I can't find the appropriate adapter. Can you lend a hand?

The green board contains tone generators for an electric piano, the signal is then passed though this connector to the brown board, which is the amp. Pins are spaced 2 mm apart


texts: Why does it take 2 clock cycles to move to the RESET state in my state machine?

texts:
I'm writing a finite sequence encoder in Verilog. Basically, an output Z will be activated if the input W is on for at least four clock cycles, or if its off for at least 4 clock cycles. See the following timing diagram

Also, to get some more context, take a look at the state diagram for the sequence encoder.

I've implemented a simple behavioral design and it works, but for some reason, it takes two clock cycles for the state to change when I'm trying to go to the RESET state. For example, when I'm in state C and put on the Reset, I have to press the Clock button twice for it to finally move into reset mode. Take a look at my code. Do you have any idea what is wrong?

module Part2(

    input Reset_L,
    input W,
    input Clock_L,
    output reg [8:0] Y, //group of 9 flip flops
    output Z

);

wire CLK;

assign CLK = ~Clock_L;

reg [3:0] SCURRENT= A; //initializing to RESET state

reg [3:0] SNEXT;

parameter A = 4'b0000;
parameter B = 4'b0001;
parameter C = 4'b0010;
parameter D = 4'b0011;
parameter E = 4'b0100;
parameter F = 4'b0101;
parameter G = 4'b0110;
parameter H = 4'b0111;
parameter I = 4'b1000;

always @(W or SCURRENT) //next state logic
begin

        case (SCURRENT)
            A: if (W==0) SNEXT <= B;
                else if (W==1) SNEXT <= F;

            B: if (W==0) SNEXT <= C;
                else if (W==1) SNEXT <= F;

            C: if (W==0) SNEXT <= D;
                else if (W==1) SNEXT <= F;

            D: if (W==0) SNEXT <= E;
                else if (W==1) SNEXT <= F;

            E: if (W==0) SNEXT <= E;
                else if (W==1) SNEXT <= F;

            F: if (W==1) SNEXT <= G;
                else if (W==0) SNEXT <= B;

            G: if (W==1) SNEXT <= H;
                else if (W==0) SNEXT <= B;

            H: if (W==1) SNEXT <= I;
                else if (W==0) SNEXT <= B;

            I: if (W==1) SNEXT <= I;
                else if (W==0) SNEXT <= B;

            default: SNEXT <= 4'bxxxx;

        endcase
end

always @(posedge CLK)
begin
    if (Reset_L==0) SCURRENT <= A;
    else SCURRENT <= SNEXT;

    case (SCURRENT)
        A: Y<=9'b000000001;
        B: Y<=9'b000000010;
        C: Y<=9'b000000100;
        D: Y<=9'b000001000;
        E: Y<=9'b000010000;
        F: Y<=9'b000100000;
        G: Y<=9'b001000000;
        H: Y<=9'b010000000;
        I: Y<=9'b100000000;
        default: Y<= 9'b111111111;
    endcase
end

assign Z = Y[4] | Y[8];

endmodule


texts: What is the name of this AC power connector?

texts:
What is the name of the connector in the picture?
I am not a native English speaker, and I'm having problem searching for this on Banggood.


texts: How to find the complex power for a current source?

texts:
The relevant circuit is shown below,

We should first find the complex power delivered by the independent source. I derived it but my answer was different than the answer given. So, I am wondering where I went wrong. My work is,

First thing we have to do is find \$V_x\$. We can see that the current through the inductor is \$\dfrac{V_x}{j}\$ so the current through the capacitor is then \$5cis(30)-\frac{V_x}{j}\$. Thus, the current in the 2 ohm resistor by KCL is \$5cis(30)-\frac{V_x}{j} +2V_x\$. Then doing KVL around the whole loop we get,

\$-V_x-j(5cis(30)-\frac{V_x}{j})+2(5cis(30)-\frac{V_x}{j} +2V_x)=0\$

Solving the equation for \$V_x\$,
$$V_x= \frac{5cis(120)-10cis(30)}{3+3j}$$
$$ S=V_xI^{*}$$
And to find the complex power we need only multiply by the conjugate of the current which is \$5cis(-30)\$ to get a final answer, \$-4.2 +12.5j\$ which is different than the given answer. Is my work wrong? I would appreciate it if someone can point out the mistake and/or offer a correction.


texts: Designing a power supply that drives an LED array supply

texts:
I want to drive an LED array from mains power. The wall switch has a dimmer on it, I'd like the intensity of the LEDs to reflect the relative position of the dimmer, so as I dim the switch, the intensity of the LED array drops.

Because I already have an 8V 12W Halogen bulb system in place, I want to replace it with as few parts as possible to convert it to LED.

I'd like to do this as simple as possible. I know there are more sophisticated circuits that could utilize MCU or other clock driven PWM, but I am wondering if there is a more simple solution I am overlooking.

My current plan was to use a step down transformer / rectifier circuit. I would calculate the maximum DC voltage available when the dimmer was turned all the way off, apply the correct resistors to limit the maximum current in this "max voltage" scenario, and then use a simple constant voltage regulator circuit to control the intensity of the LEDs as I dimmed the circuit.

Would this work? Do I want to keep a constant voltage and have the current variable as I dim the switch? Is there a cheaper/better/easier way to do this than my current plan?


texts: Name for soldering a PCB orthogonally into another? Vertical castellation?

texts:
(image stolen from OK to connect boards perpendicularly like this?)

Is there a name for the production method where say a base board (horizontal) has a slot milled into it with the solder mask open around it, most often the soldermask is split into several sections to give several electrical nets, and another PCB with an mechanically suiable edge connector inserted orthogonally (vertical) and soldered in place?

Heck, I even put a board like this into mass production for a previous company, but I can't find a name for it and hence no pictures on google to show what I mean.

Is there a name for this? It's similar to stacking a module on top of a base PCB in castellation mountng, but vertical castellation didn't give any good results. Think PCI without the PCI connector and permanent installation.

EDIT: Suggestions form colleagues:

tongue and groove
mortise and tenon


texts:
I am trying to establish I2C communication between STM32F030K6T6 mikrokontroller and HH10D humidity sensor. The problem is, that after I call I2C_TransferHandling() the I2C_ISR_TXIS flag won't be set, and the program stucks in the loop waiting for it.

Here is my code, I made it based on the example code in the std periph library.

void initI2C()
{
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_1);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_1);

    GPIO_InitTypeDef  GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    I2C_InitTypeDef  I2C_InitStructure;
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2C_InitStructure.I2C_AnalogFilter = I2C_AnalogFilter_Enable;
    I2C_InitStructure.I2C_DigitalFilter = 0x00;
    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
    I2C_InitStructure.I2C_OwnAddress1 = 0x00;
    I2C_InitStructure.I2C_Timing = 0x00201D2B;

    I2C_Init(I2C1, &I2C_InitStructure);

    I2C_Cmd(I2C1, ENABLE);
}

uint8_t I2C_Read(uint8_t address, uint8_t reg){

    uint8_t ReadByte;

    I2C_TransferHandling(I2C1,address, 1, I2C_SoftEnd_Mode, I2C_Generate_Start_Write);
    while(I2C_GetFlagStatus(I2C1, I2C_ISR_TXIS) == RESET); //the program stucks here

    I2C_SendData(I2C1, (uint8_t)reg);
    while(I2C_GetFlagStatus(I2C1, I2C_ISR_TC) == RESET);

    I2C_TransferHandling(I2C1,address, 1, I2C_AutoEnd_Mode,I2C_Generate_Start_Read);

    ReadByte = I2C_ReceiveData(I2C1);
    while(I2C_GetFlagStatus(I2C1, I2C_ISR_RXNE) == RESET);

    while(I2C_GetFlagStatus(I2C1, I2C_FLAG_STOPF));
    I2C_ClearFlag(I2C2, I2C_ICR_STOPCF);

    return ReadByte;
}

And the calling of the read function:

    uint16_t readSensitivity()
    {
//The sensor address is 0x01, the register adresses are 0x0A and 0x0B
        return (I2C_Read(0x01, 0x0A) << 8) + I2C_Read(0x01, 0x0B);
    }

The relevant part of my schematic is following:

What can be the problem?


texts: I have designed many two layer PCBs using Altium Designer. Customer has asked me to design a 4 layer board. I have searched the internet but I can't find any appropriate guide for switching from a 2 layer to a multi-layer board. Are there any recommendations, guides, or tutorials that I could use?


texts: When and how to separate Control and Datapaths for hardware designs?

texts: Must we always separate control and datapath during hardware programming? Are there any advantages? If yes then what is the basic methodology followed for this strategy? I am trying to interface an SDHC card with FPGA and am confused in implementing the protocol using separate data and control paths.


texts: I'm designing a linear actuator for a particular application, and the electric motor I'll be using will be a 1/8 HP three-phase motor. I need to decrease rotation of the motor, and my first idea was to design a reduction drive. But I know that this can also be done with a Variable Frequency Drive (VFD). I don't know how VFDs work and neither how to install and use them, but for this particular project, what do you think would be the best option? Would a VFD be cheaper than a reduction drive? And how VFD affects torque?


texts: Reducing voltage for analog input, or how to reduce number of wires needed?

texts:
TL;DR: I need to reduce the number of wires my setup is using. What would be the best way? A Voltage Divider?

Background:
I'm working on a project to design gloves that produce a lightshow effect for a Scarlet Witch costume. Each glove contains 3 flex sensors, values read and used analog via analogRead, and 2 RGB LED strips that will flash different colors. Each strip has 2 LED's on it, in series. I am not using the green channel on it, so I have 2 strips each with essentially 2 red LED's in series and 2 blue LED's in series. It's actually from an adafruit RGB led strip: https://learn.adafruit.com/rgb-led-strips/ where I desoldered the last LED in the series of 3 and jumped the connections so it only used two. I didn't need the 3rd LED, and it reduced the power needed from 12v down to where it can use a 9v battery.

So as I'm calculating, each glove will need 9 wires going to it. One is +3.3v or +5v as it will be running off an Arduino Pro Mini, I have both 3.3v and 5v available.

1: +3.3v or 5v
2: Bend sensor 1
3: Bend sensor 2
4: Bend sensor 3
5: +9v for LEDs
6: PWM for Red on Strip 1
7: PWM for Blue on Strip 1
8: PWM for Red on Strip 2
9: PWM for Blue on Strip 2

simulate this circuit – Schematic created using CircuitLab

My problem:
Every set of wires I have access to without heat shrinking stuff is 2, 4, or 8 wires. All of the connectors I have that will allow the gloves to be easily detached are 8 wire pins as well.

My problem is I'm trying to remove one of the 9 wires. One way to do that would run the flex sensors with 9v, and reduce the voltage back at the arduino. Would a resistor based voltage divider work? It would only be powered while the gloves are on, which will be at worst a 10% duty cycle (show them off for 30 seconds, walk around for a few minutes, etc). But would that work where I need to read a variable value? (The more the fingers flex, the light brightness and and pulse speed changes).

Is there a better way to do it? Everything I've ever read about voltage dividers with resistors is "just don't do it".

Or given what I mentioned above about the circuit, can anyone think of an ingenious way to consolidate one of the wires? The gloves are tight, fingerless leather gloves. There is VERY LITTLE room in them, otherwise I'd put the arduino in the gloves themselves, but the MOSFET's (or even transistors if I went that way) take up entirely too much room. Hence the 'power pack'.

Worst case I can take the flex sensor off the wrist (that turns the gloves on when your wrist is pulled back/up, like how spider-man bends his wrist when shooting webs) and turn the gloves on/off with a finger movement, but I'd rather not have to both program that, as well as having the gloves turn on accidentally if a finger twitches :)


texts:
I'm a novice hobbyist building a trivial circuit where an ATTiny 85 controls an RGB LED.  In addition to the three PWM outputs, I have 2 inputs.

The first input is a potentiometer I'm using to set the maximum brightness of the LED.  The second is a voltage divider where one of the resistors is a light-dependent resistor.

I'm running out of pins on the 8 pin IC so I have to use the SCK pin as an input.  If I put the potentiometer on the SCK pin, the ICSP no longer works; however, if I put the output of the LDR voltage divider on the SCK pin, ICSP works fine.

How can I determine what's going on here so that I can make deliberate choices about pin use?  Also, is there a common way to isolate the ICSP activity and during updates isolate the IC from the rest of the circuit?


texts: For an avionics application I need to make a keypanel which has NVG compatible LED lights behind its keys. I am trying to understand how does the NVG compatibility (Night vision Goggles) relates to the LED light? If I put a high-glow green color LED behind a keyboard button will it be enough for making it NVG compatible? Or do I need to apply any specific filter on top of the LED and that filter will make a normal LED into a NVG compatible LED light?


texts: Can different power socket in one house charge at different speeds

texts:
We all have power socket at our homes. Now I observed something:
When I connect my phone for charging at socket it charges up at a faster rate than other socket obviously with the same cable and adaptor
How is this is possible since all the connections have a common connection to main circuit in the house?
This is the typical circuit . I think the purpose of switch is only to supply power and that will be available at equation rate but is it somehow possible that the circuit had some problem which gave me this observation?
charges fast and less used
 charges slow and frequently used


texts: Whats the best way to control voltage AC from 0 - 18VAC with a Arduino

texts:
What would be a good method of controlling low AC voltage with an Arduino
I have an old motor (Lionel Postwar Train Motor from 1956 example) that runs on AC between 5vac and 18vac with a max of 8amp
I need to be able to manipulate the voltage with the Arduino so I can gradually increase or decrease it. Preferably as a percentage (0% = 0vac > 100% = 18vac) or decimals
So just to clarify. The power coming to the Arduino is already transformed at a constant 18vac.
I just need to safely control the voltage
Thanks


texts: Fast rising voltage on lead acid battery while charging

texts: I have a couple of 12V sealed lead-acid batteries, which I have to charge. But when I hook one of them on the charger at 12V/1A (the battery is 10Ah) the voltage from 12.6 drastically increases up to 14V in 5-10 seconds. I tried hooking it up at 0.4A charge current. But it's no use, the battery just raises its voltage to the max. The battery is surely not ok, but what is the case here?


texts: How does a grid-tie solar power inverter know when the mains power has failed?

texts:
Solar power inverters that send excess solar power back to the grid are (usually) required to shut down if the grid power fails. (This is to protect people working on the power lines.)
The inverter only has two wires connecting it to the switchboard. (Active and Neutral). How does the inverter know if the grid power has failed if it is using those wires to output power?
I suspect that every few seconds the inverter stops outputting power for one cycle and senses the grid voltage.
If that is the case, then why doesn't the back EMF from inductive loads (air-conditioners etc) fill in the missing grid-power for that cycle and make it seem like the grid is still active?
Also, how does it work when everyone in the street has inverters and the grid fails? Wouldn't the inverters just sense that there is still grid power (from the other inverters) and all of them continue operating?


texts: What is the best way to parallel two shunt resistors using a switch?

texts:
What kind of switch in place of SW1 will have minimum amount of error in current readings?
Max current is 10 A and we should be able to control the switch digitally.

simulate this circuit – Schematic created using CircuitLab


texts: Can someone help me figure out instinctively whats going on here?

texts: V4 is intentionally left disconnected. I understand that this is an open circuit and current cannot flow. What I'm trying to understand is why does Vout = 5V and not 8.2 V. What key assumption am I missing here?


texts: Problem with ATmega328P when used with DRV8302 gate driver

texts: I am developing a motor controller for a 48V BLDC motor. For this, I am using the ATmega328P microcontroller in combination with the DRV8302 gate driver from Texas Instruments. It uses a simple control algorithm, wherein it gets an input from the throttle and outputs a PWM signal with a duty cycle proportional to the throttle to the input pins of the gate driver, which in turn outputs a signal to turn on the MOSFETs corresponding to the phase that is to be energized. While testing this circuit on a breadboard, I found that the PWM outputs of the microcontroller work well independently, but on giving +5V to the EN_GATE pin of the gate driver, the microcontroller shuts down and ceases to give the PWM output. A schematic of my circuit is given below. Why is this happening and what is a resolution?


texts: Validation of power supply decoupling and oscillator connections in a PCB

texts:
I've been learning PCB designing lately to design a small controller board.The board has a micro-controller and its supporting components laid out as shown :

.

After having gone through some nice threads
here, about oscillator placement and here, about the importance of decoupling capacitors,their placement in the board and other critical considerations,I've come up with my own design which is a four-layer board.Can someone validate the same and suggest improvements (if,any) to the design? Thanks in advance.


texts: I'm currently learning about resonant frequency and harmonics under ac theory in tafe, and I've read a few things about resonant frequency in parallel, and it seems as if impedance at resonant frequency is at maximum, but when calculating impedance with Pythagoras theorem, we say that Xl and Xc cancel each other out. Therefore impedance is equal to resistance, or at minimum. I understand that there is current flow from the inductor to capacitor, but I'm having trouble because it seems like the two cancel each other out, can anyone help me understand a bit more of a what's going on? Thanks


texts: Power connectors: 2.1mm and 2.5mm, 1.35 and 1.7mm

texts:
I refer to DC power connectors used for a wide variety of common consumer devices.

I notice that I have to specify between 2.1mm and 2.5mm when I want to purchase these online. Are the two interchangeable or is the tolerance so precise that 0.4mm makes a difference?

Separately, I have an existing 5V adapter with the smaller connector. I can't tell whether it is 1.35mm or 1.7mm. I am trying to purchase an adapter to convert it to 2.1mm/2.5mm. Same question: does it matter whether it's 1.35mm or 1.7mm, or is there a good way to find out what my connector is?


texts:
I am planing my first MCU board and this MCU has several pins that need VCC (3.3V). My friend suggested that I put capacitors 0.1uF near every VCC pin to remove disturbances. But if these pins are close together it looks like this:

To me this looks like one big 0.4uF capacitor right? So should I only put one 0.1uF capacitor instead of 4 here? I mean: "Can I use one capacitor for multiple VCC pins if these are close together or is this not a common praxis?"


texts:
I'm redesigning a board that has a lot of peripherals attached to a SOC. These all use different voltages. Board is powered with 12V,1A

Most peripherals are connected like this:

RJ45 <-> GigE phy <-> zynq chip

1) These components all support 3.3V operation. Can I use 1 12V to 3.3V regulator? (If I calculate the current and power needed)

2)If I can, how would I go about doing that?

*Hoping this is easier to understand


texts:
I need a simple single supply amplifier that draws a lot of current when signal is applied. Without going into why, let's just say this is supposed to be part of a compressor. Distortion performance is not important. What is important is that it has a high ratio of current drawn in relation to the signal. So if the signal is low, the current drawn is low. If the signal is high, the current drawn is 100X as much.

So I have modeled and breadboarded the following circuit:

[Note: Right click and select "Open Image in New Tab" for larger version]

This circuit works fine (with a 100pF cap across the PI outputs) but it doesn't draw nearly enough current. The transformer is a standard Radio Shack style output transformer (actually an Eagle LT700) with a 1K2 primary and 3R4 secondary.

Ultimately the problem is that I cannot pull more than 2mA through the power transistors. Can someone explain why?

My first guess is that the impedance relation between the phase inverter and power section stinks. But it's not crystal clear how to resolve that.

Ultimately I would like a current gain of 100:1. If I could make a 1W power amp out of this circuit, that would be ideal.

Any ideas?


texts: Is there a way to reset an arduino to factory settings?

texts:
I tried to make custom library for my Leonardo to work as a native gamepad, but as it turns out, it isn't as easy as it looks. After i got some code of core arduino and imported it, everything uploaded fine but then Windows stopped recognizing Arduino itself (It is now listed as a Composite USB Device).

Now is there any way to wipe arduino back to its factory settings without need of an external programmer or without need for rewriting arduino drivers? Thanks in advance.


texts: How do you find out if a MUX is bidirectional

texts: I've used this MC74VHC157 in a project thinking this would be bidirectional but I'm not sure. How do you find out if any MUX is bidirectional?


texts: I want to draw 20 amps from my home power outlet is there any way to do that safely?

texts:
I'm wanting connect up a bunch of Raspberry Pis (micro computers) to one power outlet in my home. At about .5 amps per computer * 40 computer means I will need to draw 20 amps.

Now, I know that I'm only supposed to draw a max of 12-15amps from my standard 120volt North American outlet, but I'm wondering if there is any way to amplify the amperage and then use it to power all the computers, or alternatively, whether there is another way to somehow achieve this that I'm unaware of.

If there is no possible way to do this, what other method for drawing 20amps of power would you suggest?

EDIT: Computers run at 5V DC, I'm using a 5V, 20amp power adapter which I plug into the wall to get that but I don't want to draw the full 20amps because the wall socket can't handle it.


texts: What are the pins on this jack connector?

texts:
I've bought a PJ-3053 audio jack connector. I purchased it under the impression that it would have a microphone connection, but when I put in a TRRS jack, take a multimeter and measure connections, none of the pins gives a beep with the shield from the jack I plug in. It does have 6 pins, and comes with the following schematic: .

Pin 7 is the ground it seems, pin 5 is left, 6 is right and the other 3 are unknown to me. I know there are jacks with detection in them, but for that just pin 2 and 3 would be enough, right?


texts:
I have been doing hardware design for years but never really cared which process was used for the silkscreen. Now I have a manufacturer asking for a blanket approval to use acrylic silkscreen on all the PCBs they make for me.

On its face I don't see a problem but like everything in hardware, there can by many hidden trade-offs and differences...

What are the advantages of acrylic silkscreen?

What are the advantages of epoxy silkscreen?

When would you pick one over the other?


texts: Where do I perform circuit simulation and testing of the circuit schematic before actual implementation?

texts:
I am new in circuit simulation.In the given circuit obtained from TI'S WEBENCH, DC to DC buck conversion (110V to 5V) using flyback opto-coupler feedback topology is used. I want to perform circuit simulation and testing of the circuit schematic before actual implementation.

But which is best free software available on internet where I can do circuit simulation testing with Texas instruments UCC28C40 IC (PWM  controller) included in its component list?


texts: Replacement for uknown broken transistor - bipolar or MOSFET?

texts:
I try to repair the receiver board of Syma X8 series quadcopter. One of four DC motors is not drived properly, i. e. does not turn on after the signal from transmitters (the other motors do). The motor works if it's connected to other outputs.

Using an oscilloscope I found out that all big 4 MOSFET at right part of the board are OK but one of four SMD transistors marked Y1 (circled in green) connected to the gate of one MOSFET is dead.

I have no previous experience with SMD parts but I found that the Y1 marking is usually used for Zener diodes or transistors. I think this could be the latter, because I see square signal at the "input" pin 1 (base/gate) of other 3 transistors that is amplified at the "output" pin 2 of the other three.

Using the diode test at the multimeter I measure 797 mV drop from pin 3 to 1 and 795 mV from 1 to 2. So I think this could be NPN or MOSFET.

I tried a NPN like BC547 but it heated up after the start in a few seconds and the motor still not working. If I tried a PNP like BC556, it did not heated but still not turning on.

How can I find the right replacement for the broken transistor?
What should I measure to find out the correct type?


texts: Problems with analyzing a simple, non linear circuit

texts:
I have some problems with analyzing this pretty simple circuit (or more precisely with understanding the solution):

The task is to find the characteristic curve for $$|U_E| \le 5V$$

My first thought was that when the input voltage is below the threshold of the diode, the output voltage is only dependent of R1 and R2 as the diode doesn't conduct. When we are above threshold we have something like R1 + (R2 || R3) - U_D.

The first step would be to find the breakpoint between diode is conducting and not conducting.
Well.. The solution says that for the first case (diode not conducting):
$$ U_{R2} = U_S = R_{E,S}\frac{R_2}{R_1 + R_2} $$
$$ U_{E,S}=U_S\frac{R_1 + R_2}{R_2} = 2,1V $$

The explanation for this equation is that at the break point, the diode current was zero and following from this the voltage at R2 equals UD = 0.7V.
And here's the problem. When the diode is not conducting, why R2 is dependent of the threshold voltage of it? I'd expect that the voltage at this point was only dependent of R1 and R2.

For the output voltage the solution confirms my thought:
$$ U_A = U_E\frac{R_2}{R_1 + R_2} = \frac{U_E}{3} $$


texts:
I'd like to understand how a frequency meter treats a sine wave, i think i got it, but still I'd like some confirmation.

So i was taught with square signals where the meter counts the impulses in a determined gate time, my question is does the meter "see" the sine wave like a square wave? meaning does it see the positive part as the impulse and the negative part as the "zero"?

Does it actually transform the waves into square waves every time?


texts:
The following transistor circuit appears in the schematic for the Apple II disk controller card.

I don't understand the purpose of this subcircuit.  I think it must have something to do with increasing the current into the VCC input of the IC at the bottom of the figure, but I'm not sure. Also, why are the two transistors and resistors connected the way they are?  Why are 2 transistors used instead of just one?


texts: Can anyone explain what is in the tech.lef and  tech lib files? Which stage of PNR (Place and Route) are they used for? Are these things provided by the foundry or the EDA vendor?


texts: Resistor selection based on power rating

texts:
For example, I have a cicuit of single resistor R = 2k, apply with Vdc = 18V.
The Power of the resistor is about 162mW.
Should I pick a resistor with higher Power rating (Eg 0.25W 0.5W) or lower power rating (Eg 0.1W).


texts:
I've seen YouTube videos of supercapacitors replacing car batteries.   Is this practical?   And if so, why haven't they been offered in the automotive market place?

https://www.youtube.com/watch?v=GPJao1xLe7w

the type supercapacitor he is using has the following data sheet:

http://www.nooelec.com/files/2600f.pdf

Note that it contains 8,125 Joules of Stored Energy.

Then if you go to http://www.rapidtables.com/calc/electric/Joule_to_Watt_Calculator.htm
and enter 8125 in the box and let's say 5 seconds of starting (it shd start up in 1 second in actuality).   You then get 1,625 Watts.   Remember 1 HP = 750 Watts , so you have just over 2 HP of starting power.  Remember he's using six of them.
6 x 8125= 48,750 J. @ 16.2V.
 (for a 2 sec. start it's over 24,000 Watts(32 HP) of instant power)
Easily enough to start your car.
Without a battery too.

A good car battery would have 700 CCA.  @ 14V  = 9800 Watts(13 HP).   Quite a difference.  (The average starter is 1.9 to 2 HP)

Here, as time goes by,  I will post more videos to bolster my claim:

https://www.youtube.com/watch?v=EoWMF3VkI6U

http://www.extremetech.com/computing/183839-new-supercapacitor-technology-could-store-conduct-power-on-the-same-copper-wires

http://scitechdaily.com/graphene-based-supercapacitors-may-significantly-boost-power-electric-vehicles/

http://phys.org/news/2015-09-micro-supercapacitor-unmatched-energy-storage.html

https://www.tecategroup.com/ultracapacitors-supercapacitors/industry_news.php

http://www.skeletontech.com/news/skeleton-technologies-launches-markets-highest-energy-density-ultracapacitor/

https://www.youtube.com/watch?v=ZgozrScGN8U

Bottom line is,  if you have enough Farads, you have energy density.

And this really settles the matter once and for all...

https://www.youtube.com/watch?v=JAT_8H23iGI


texts: Danger of Saturation of Primary Coil in a Flyback

texts:
I was reading a book, "switching power supply design - Abraham Pressman", specifically the section about flyback converters. One part I'm not quite sure I understand is where he says that the saturation of the primary coil could destroy the driving transistor.

simulate this circuit – Schematic created using CircuitLab

I went back to school on how inductors work and I think what will happen is this.  At time zero when the transistor turns on, current will begin to flow slowly and the magnetic field will build up in the inductor.  Current flow will increase as time goes on and this will increase the size of the magnetic field.  At some point the core material will become saturated, meaning that even though you pump more current into it the magnetic field does not increase very much.

It was this build up of the magnetic field that was protecting the FET in the first place, but now that it's saturated its inductance will begin to drop.  So effectively the impedance of the coil is dropping and more and more current now wants to flow through the transistor.   Eventually that current times the RDS on of the FET will exceed the power rating of the package and the FET will melt down.

Am I understanding this correctly?


texts: Why do they make traces to LTZ1000 in spiral shape?

texts: I was browsing Google images of LTZ1000 voltage reference IC. I saw that in some of the PCBs, the traces that go to LTZ1000 are in spiral shape and cut out gaps are left between them. What is the reason behind this?


texts:
I have the following waveform from a Radar thats IVQ-3005
https://www.innosent.de/fileadmin/media/dokumente/datasheets/180222_Datenblatt_IVQ-3005.pdf

That Radar is using the PLL ADF4158
http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4158.pdf

I'm using a sawtooth as modulating carrier signal, what is in the following picture is a detected wall.

Why the waves are not real sin waves ?

Is that a problem of the gain of the IF signals that is controlled by a digital potentiometer ?

Or is it a problem of the generation of the sawtooth signal ?

Note that the signals are I1, Q1, I2, Q2


texts:
Please correct me where wrong and I would really appreciate intuitive explanation for the following fundamental questions. These may appear trivial but as I am not from Electrical background, these concepts are quite baffling for me.

It is preferred to have a low BER. Does the theoretical BER serves as the lower or the upper bound? If the simulated / emperical bit error rate for an uncoded AWGN channel, no pulse-shaping and no spreading techniques, after blind equalization is lower than the theoretical BER - what can be inferred? Basically, I am comparing equalization algorithm in literature and have encountered several variants of Constant Modulus Algorithm. Each paper claims to perform better than the other eventhough the improvement is negligible when compared to the complex modification done to the algorithm. So, this Question stems from the doubt that is when can we say that the equalizer performance is good? When the BER reaches the analytical BER or if it is even lower than the analytical BER?

What should be the ideal trend of BER at low and high signal-to-noise ratio (SNR)? I have found that the performance of equalizers is good at low SNR and worsens for higher SNR. In general, we seek to develop techniques that can do channel estimation or system identification at low SNR. But, in doing so that technique must also perform good at high SNR because the effect of measurement noise is negligible. What is the tradeoff?

Thank you, and please let me know if any modifications/ improvements need to be made to make my Question clear, if otherwise.


texts:
I would like to reuse a PCB layout of a design to make an Arduino shield. I want to reuse Arduino Uno R3 board to make an Arduino shield package in my library by deleting every components in the original design (leaving the stack headers intact for the shield).

I tried block copy to bring the block in board to the package window (in create new package) but it did seem to work. It did not allow copying of pads from layout to package window.

I would not want to draw everything from scratch and even pad placement in this case.


texts:
The noise margin is the difference between the min input HIGH and min output HIGH.
What is the significance of it?
Lets say the input HIGH voltage is currently 2.8V, a noise spike of -0.5V would still be a logic HIGH?


texts:
I have this exercise:

I can do point 1 without any problems, but for example in point 2 I do not know what I should do with source V2 if the transfer function has to be computed only based on V1. Is it ok to end up with negative poles? Same problem with point 3: I know what should be done, but I have no idea how to set V1 if I am interested in Vo/V2. The not-very-reliable results at the bottom do not help either.


texts:
I'm relatively new to electronics and I'm trying to understand how to use transistors, but I seem to be misunderstanding something.

I'm trying to implement a transistor switch as described in Electronic Formulas, Symbols & Circuits on p 118. The diagram above is based on my understanding of how the circuit should look if I want the LED on when the switch is high.

Based on my understanding of the first diagram, and the diagram shown in the book, I think this second schematic should turn the LED on when the switch is low.  But I also see a basic LED driver with the battery, resistor and led, which seems odd to me.  When I actually wire this up on a breadboard, I see that the LED is on for either position of the switch, and that it's actually brighter when I turn the switch on high.

Do these schematics actually function as I believe they should thus I am failing to implement it correctly, or am I misunderstanding something fundamental?

EDIT
The resistors should read 1K in the diagrams, not 100.


texts: What is the initial condition of the current in the capacitor

texts:
I have a problem solving this circuit using differential equations

For t>0 we have

$$\frac{V_c}{2}+i=4$$
$$\frac{1}{2\times 2}\int_{t_0}^{t}i({\tau})\,d\tau+i(t)=4$$
$$\frac{di(t)}{dt}+\frac{1}{4}i(t)=0$$
Solving the differential equation gives me
$$i(t)=I_0 e^{-0.25t}$$
where \$I_0=i(0)\$ is.
The problem is \$I_0\$ gives me 0. I know if I solve for \$v_c\$ then I can get \$i(t)\$ deriving and finally I get $$I_0=-6\,\mbox{A}$$
How I know this is true?


texts: Transistor switching instead of acting linearly

texts:
I am using a Darlington Transistor (MFG6388GOS) as the controlling element for a Current Controller. The controller has an oscillation which I have narrowed down to the transistor switching.

I want the transistor to operate as a linear DC current amplifier but it just oscillates on-off, controlling the current with the duty cycle. The transistor has very high DC gain which may be part of the problem.

Is there a circuit configuration that will force the transistor to operate linearly?

If the high DC gain is the problem how would I figure out the correct amount of gain?

Yellow is the control signal to the transistor Base

Blue is Vce. ( low means transistor is sinking current, charging the inductor)

The ramping up-down on the control signal is due to the inductor charge-discharge time.

Any help is appreciated


texts: how to prevent short circuit between thermal pad and vias on it as it is recommended that exposed pad should not connect to GND

texts:
All my QFN footprints are made with the Altium internal "Tools -> IPC Compliant Footprint Wizard". I get nice footprints with vias in the thermal pad.

When I try to place one of those footprints to the PCB, I get an short circuit violation between the via and the pad

but it shows the error as mentioned below

It is recommended in datasheet that exposed pad should not be connected to GND

let me know if allowing the short circuit in design rules is ok or is there any other way to solve it.


texts: How to calculate Pi filter for RF with PCB antenna - Nordic nRF52832

texts:
I have finished the layout of a bluetooth beacon based on SoC nRF52832 of Nordic, there is a Pi filter between the IC pin and the antenna that use the AN043 drawing of Texas.
AN043: https://www.ti.com/lit/an/swra117d/swra117d.pdf
How can I calculate/estimate the inputs for this online tool? Like Source Resistance, Source Reactance, Load Resistance, Load Reactance, Q Factor, the frequency I know is 2.4GHz.
https://www.eeweb.com/tools/pi-match
Is there informations that I should get with the manufacturer of the chip? (nRF52832)
I want estimate intial values for inductor L2, and capacitors C16 and C17. The 0.8pF cap. and 3.9nH inductor is required according to their application document.
I am asking this because I am not familiar with RF circuit calculations.
Regards.


texts: Correct implementation to run servo motor on Spartan 3E board

texts:
I want to use a servo motor with a SPartan 3E board. Below is the code I have developed, however, it doesn't seem to run as expected. My servo motor operates between the region stated in the code and the clock for the board runs a 50Mhz.
/*
  Takes an 8-bit position as an input
  Output a single pwm signal with period of ~20ms
  Pulse width = 1ms -> 2ms full scale. 1.5ms is center position
*/
module servo_controller (
  input clk,
  input rst,
  input [7:0] position,
  output servo
  );

  reg pwm_q, pwm_d;
  reg [19:0] ctr_q, ctr_d;
  assign servo = pwm_q;

  //position (0-255) maps to 50,000-100,000 (which corresponds to 1ms-2ms @ 50MHz)
  //this is approximately (position+165)<<8
  //The servo output is set by comparing the position input with the value of the counter (ctr_q)
  always @(*) begin
    ctr_d = ctr_q + 1'b1;
    if (position + 9'd165 > ctr_q[19:8]) begin
      pwm_d = 1'b1;
    end else begin
      pwm_d = 1'b0;
    end
  end

  always @(posedge clk) begin
    if (rst) begin
      ctr_q <= 1'b0;
    end else begin
      ctr_q <= ctr_d;
    end
    pwm_q <= pwm_d;
  end
endmodule

module tester;
reg [0:0] clk;
reg [0:0] rst;
reg [7:0] pos;
output servo;

servo_controller controller(.clk(clk), .rst(rst), .position(pos), .servo(servo));

  initial begin
  rst = 1'b0;
  clk = 1'b1;
  pos = 8'd100;

  always@(*) begin
  clk = ~clk;
  end

  end

endmodule
````


texts: Can a dependent current or voltage source make a circuit unstable?

texts:
Consider a circuit consisting of a variety of linear and/or non-linear elements and independent voltage and/or current sources. Now imagine a dependent current or voltage source is added to an arbitrary part of the circuit, and assume that the voltage or current the source depends on is non-zero. The dependent source would generate a non-zero current or voltage which would affect the rest of the circuit.

It's easy to imagine that the dependent source would affect the current or voltage it depends on, which in turn would change the magnitude of the dependent source, which in turn would affect the current or voltage it depends on again, essentially creating an infinite loop of the dependent source and the voltage/current it depends on increasing each other until both reach infinity.

An analogy might help. A man tells his friend that for everything dollar he has, he will give him another. (Analogous to the dependent source "agreeing" to "contribute" an amount that is a function of what another part of the circuit "has"). His friend starts off with $10, so the man pays him $10. His friend now has $20, so the man now pays him another $20. The man now has $40; this continues on until the man is paying his friend an infinite amount of money.


texts: Should I consider using RS-485 for my next project

texts:
I am planning on an automation project that will be using several different sensors including but not limited to: Temperature, Barometric Pressure, Air flow, Humidity, etc.

As I was talking with someone they mentioned that I should look into RS-485 as a means to connecting my sensors to my controller. Then ultimately to the PC.

After a quick search I gathered some information about RS-485 but now I am wondering if it's over kill or if it's even used now a days?

Couldn't I just use a microcontroller that has enough inputs and interface with the PC using USB?

Thoughts?

EDIT: Ok if distance to controller and environment (in my case an industrial application) then RS485 might be useful. Are there other bus alternatives that might be more useful?


texts:
I've got the following Situation.

An AT90CAN128 connected to a LCD,multiple Buttons, Sensors,LED's and engines.
Shown on the LCD are the Sensor Values and a Menu you can go through with a rotary encoder.
Menu just has some strings which are located in flash memory.

The malfunctions can be anything from using a button leading to restart, random restarts or 1 or more characters in the menu are exchanged with other characters. For example it should be shown "Level" but instead it shows "&evel".

It is on all controllers, 10 at the moment, but the malfunctions are varying depending on which controller and they are also varying on how much Program Memory is used.

The AT90CAN128 is running at 16MHz with 3.3V and Brounout Detection enabled at 2.7V. But it is not the Brownout leading to restarts.

What i need now are some hints on what could cause such an behaviour?


texts: Does anybody recognize this connector? This is Power terminal used on Solar Inverter. Rated for 150A/35V.


texts: If you replace the carrier signal in a phase modulated circuit with noise then presumably the noise will be modulated. What must be considered if we wish to detect this noise modulation? I’ve attempted to phase-modulate various types of noise in Matlab (pmmod), and in the FFT spectra I was expecting to see some sidebanding of the more discrete higher-amplitude components (in some frequency ranges) but none are visible. I assume it depends strongly on noise type.


texts:
Ok, so I am not new to electronics by any means, but I still can't grasp one key concept: AC voltage-current phase shift. I understand the math behind it, but I need someone to explain to me how it works at the fundamental level.

Let's take into consideration the circuit below.
The input sine voltage is 100V and we know that inductor causes voltage to lag 90 degree behind the current.

My first question is does the phase shift happen in the whole circuit, or only after/before the inductor?
My second question is if we would measure the voltage and current flowing through the resistor R1, and since they are not in phase, doesn't this violate the Ohms law (how can maximum current flow through the resistor when it doesn't experience maximum voltage)?

Thank you.

simulate this circuit – Schematic created using CircuitLab


texts:
Obviously the Torque and RPM of an electric motor are dependant upon how many turns of wire there are, is it possible to make the number of effective windings (semi)dynamic through the use of MOSFET taps in a layout similar to this? Is there any reason it wouldn't work?

Where the red circles are the the Drains of the MOSFETs, Sources are commoned together on the motor driver output and Gates are addressed by a controller to switch between.


texts:
Sierra Wireless and other manufacturer carry cellular cards in a variety of physical interfaces.

There are different digital interfaces to hardware like USB, UART, USB OTG, HSIC...

Additionally MiniPcie cards interface digitally with USB 2.0

Which do you think it's the best digital connection to the hardware? I doubt it's USB.

If you were designing a 3G router aiming for best performance. Which of these digital interfaces would you choose?


texts: How to determine the best diameter for a cable?

texts:
In my understanding having a cable that has a too large diameter can lead to power dissipation, having one that is too small can lead to the same result.

apparently the second case is much more popular in the "high frequency phenomena", the first case is probably caused by the material of the cable if i understood this correctly mainly because there will be an higher impedance.

i don't really get:

why this can happen? it's true what i have understood?
how i can calculate the correct diameter?
there are differences between AC and DC in this scenario?

I have X Volts and i have to provide a maximum of Y Watts, where i have to start to pick the best cable for the job?


texts:
I am currently building my own GPS disciplined oscillator. I have a OCXO which is used as clock source for a microcontroller and one of its counters, and the 1PPS signal from the GPS module is connected to one of the capture inputs of the same counter.

Currently, I have following control algorithm:
On the rising edge of the PPS signal, the counter's value is latched and compared to the previous value. If the difference is something else than 10000000, then the EFC voltage of the OCXO is increased or decreased accordingly. I have my GPSDO now running for several days, and it appears to be rock stable compared to a commercial GPSDO from Trimble, but it has the problem that it takes at least one full day until it properly locks. So I try to find a control algorithm which locks faster.

I was thinking whether I could implement something like a PLL in software.

E.g. each time the rising edge of the 1PPS signal occurs, I could calculate the value the timer should have the next time when the rising edge occurs and so on. By subtracting the actual timer value from the desired one, I get something like a phase error which I then could use to steer the OCXO. I would expect that this should lock faster than my current approach, and it should be more accurate because the integration time is basically infinite - even the smallest error will, at some point, lead to a phase difference greater than 1 count.

A further problem I have with both approaches is: how do I determine when the GPSDO is actually locked?

Are there other, probably better approaches for the control of an OCXO by a 1PPS pulse?


texts: Determining I2C Address without Datasheet

texts:
When setting up I2C communications, I know that it is certainly ideal to have the devices' datasheet(s), and find the I2C address of the device(s) that way.  However, in some reverse-engineering applications, you don't have a datasheet available.  (Or, you may just not be able to find it...)

Without the datasheet, how do you determine the default I2C address of a device?  Also, what tool(s)/equipment do you need?  (e.g. is a microcontroller with I2C support enough, or do you need an oscilloscope?)


texts:
I am currently trying to get my Bus Blaster v4.1a to work. I want to use openocd to communicate with a device over JTAG. The device that I want to communicate with is a Qualcomm_qca4531.

First of all let me show you the command that I enter in the terminal just in case that I am already doing something wrong here:

~/openocd/tcl$ sudo openocd -f interface/ftdi/dp_busblaster.cfg -f target/qualcomm_qca4531.cfg

The 2 config files that I am using were already provided by openocd and can be found here:
https://github.com/analogdevicesinc/openocd/blob/master/tcl/interface/ftdi/dp_busblaster.cfg
https://github.com/ntfreak/openocd/blob/master/tcl/target/qualcomm_qca4531.cfg

The error that I am receiving from OpenOCD right after entering the command is the following.

Open On-Chip Debugger 0.10.0+dev-00936-g0a13ca1a (2019-10-10-09:36)
Licensed under GNU GPL v2
For bug reports, read
    http://openocd.org/doc/doxygen/bugs.html
Info : If you need SWD support, flash KT-Link buffer from https://github.com/bharrisau/busblaster
and use dp_busblaster_kt-link.cfg instead
adapter speed: 2000 kHz

Info : auto-selecting first available session transport "jtag". To override use 'transport select <transport>'.
qca4531_ddr2_550_550_init
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : clock speed 2000 kHz
Error: JTAG scan chain interrogation failed: all zeroes
Error: Check JTAG interface, timings, target power, etc.
Error: Trying to use configured scan chain anyway...
Error: qca4531.cpu: IR capture error; saw 0x00 not 0x01
Warn : Bypassing JTAG setup events due to errors
Info : Listening on port 3333 for gdb connections

I already checked a few things:
I checked if any of the JTAG Pins is shortened to gnd or vcc. They aren't.
I also tried to use urJTAG to communicate with the device, it doesn't work either but I receive a different error: TDO seems to be stucked at 1.
I also checked if I connected the right pins. I have 6 pins that I have to connect. VCC, GND, TMS, TCK, TDI and TDO. There are only these 4 JTAG pins on the board but after a little research I found out that I only need these 4 pins, TRST and other JTAG pins are optional so I think there should be everything fine with the connection.
I can also confirm that the Bus Blaster supports the same voltage levels as my target device. (3.3V)

Can you think of any other reason why I get the error mentioned above?
Is it possible that JTAG is deactivated on the target device? I tried to find out what openocd output looks like when JTAG is deactivated but I can't find anything helpfull.

Thanks to everyone in advance.


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According to datasheet of LCD TFT ( https://www.gms-ds.com/fileadmin/produkte/pdf/DLC0700BIG-1.pdf ) page 11 there is power sequence necessary for proper initialization of LCD.
On the other hand at page 7 "Absolute maximum ratings" voltage (exclude AVDD) have large range from nearly zero voltage.
This means that we can avoid necessity of power suquence (f.e. if VGL will start before AVDD becouse VGL can have 0V according to absolute ratings values)?
Thanks for any answers.


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I'm currently using a LM5109B to attempt to drive a high-side N channel mosfet in a particular setup. I want to drive it independently of the low-side driver. I'm aware that the provided IC is used for H-bridge configuration. As expected, when there is no load and HI is pulled low, the HS is floating and the gate is driving. When I put a load with HI low, the gate doesn't drive. Is there any solution to ensure that HS isn't floating in this particular situation? Is there any High-side gate driver that can be used for this particular application?
Thanks


texts: 50 Ohm impedance RF transmission line PCB design

texts:
I am designing a PCB for a Bluetooth 5 device using Qualcomm chip and a Murata BP filter. The RF circuit is composed of:

an SMT antenna that has a 50 Ohm unbalanced feed point impedance,
a Murata 2.45GHz Bandpass filter that has a characteristic nominal impedance of 50 Ohm
a BT IC which has a 50 Ohm port impedance for BT_RF.

Below is the design guidelines from the SMT antenna datasheet:

ANTENNA>>---(1 w/ P1&P2)--->>BP Filt>>---(2 w/ Pi-LC)--->>BT_RF

With all these components having a 50 Ohm impedance, how should I design the PCB traces (1) and (2) and their matching networks? Should (1) and (2) individually have a 50 Ohm impedance or should the whole transmission line from SMT antenna feed point to BT_RF have a 50 Ohm impedance?


texts: When a voltage pulse is sent through an open transmission line, what happens to the voltage at the end of the line when the pulse is reflected?

texts: From what I understand, the voltage doubles since the reflected and incident pulses add up. But then why don't all open terminations have double the source voltage since we can consider the voltage there to be a pulse of infinite duration?


texts: I've been designing boards for Silicon Photomultipliers for about a year and half now. You can see the various questions I've posted about my circuits. Based on the replies, it is extremely evident that I need a strong foundation on PCB design, especially for high-speed circuits. I was wondering what are some good resources that would be helpful in learning about good PCB design in general.


texts:
Seen hot-air-gunning, super-gluing, epoxy-gluing, plastic-taping, other-taping, --. Super-gluing joints did not look good as you need acetone to remove it!

is epoxy gluing better substitute for soldering?
when to use such substitutes?
are they really substitutes or just bad habit?


texts:
I just recently found this tutorial (and various other places mentioning a similar technique) when trying to evaluate how one of my circuits behaves when using real world components with real world tolerances.

However normally I design it with ideal values, play around with .step directive etc. so to just do that evaluation I would have to change all the value statements to use the mentioned functions, and when I am not happy, change them back and to play with values again and so on. This seems like an awful lot amount of work. I could probably write a script that does it on the .asc files for me, but I was wondering if there really is no other way.

For most components you have a "Tolerance[%]" field, so I was wondering if this can be used in some global way? Just like some components seem to react on the .step temp variable. Unfortunately in the documentation I find the temp mentioned, but not the tolerance (which results in SpiceLine tol=xxx in the .asc file, if that helps anyone).

So, is there an easy way to have LTSpice (randomly) vary component tolerances over multiple runs, without having to put formulas at each and every one? (I am mostly interested in resistors and capacitors today, if that helps to find a 90% solution)


texts:
I'm only a hobbyist, so there is probably an obvious/better solution that i am simply unaware of.

Project description: I'm trying to build a quiet linear power supply to power a mini DSP that can be turned on by the remote trigger output of my stereo receiver. My goal is to keep it all solid state, and as low noise as possible.

This is what I have so far...
I've purchased a SolaHD SLS-12-017T linear power supply module. I had intended on switching the 12V out with a Fairchild FCP650N80Z N-channel MOSFET. I had intended on isolating the 12V source circuit from the trigger signal from the amp with an optocoupler.

So here is where I get stuck: I had assumed the trigger from the amp would go to 0V when turned off. But it doesn't, it reads 3.3 V in the off position and 14.4 V in the on position.

Any suggestions on how to make this work would be greatly appreciated.


texts:
I am using a ua741 op-amp. My question is, how can I use a potentiometer to null the output offset voltage?

I believe if I'm correct, that output offset voltage means the output voltage provided by the op-amp even though no input voltage is connected. But I don't get how you can use a resistor to null the offset voltage.


texts: Increase of component's height due to soldering

texts:
What is the increase of a two-terminal component's height after it has been soldered to a PCB in comparison to its height in an unsoldered state? Any rules of thumb?

I am interested in both reflow and hand soldering.

To understand what the question is look at the picture below:

picture source

There is some extra height added to the component's height relative to the PCB's surface due to solder under the component.

My current understanding is that during reflow soldering nearly all solder fillet is extruded from beneath the component (to the so-called areas of toe, heel and sides), video link. However, there are several hundreds (or maybe tens) microns of solder left beneath the component. If hand soldered, the increase could be greater than if reflow soldered, I guess (due to a greater amount of solder left under the component).

I am going to put several bypass capacitors beneath a chip socket (there are several areas where components lower than 0.5 mm or 1.1 mm are allowed). Thus, I need to be precise.


texts: Why can I see remote control radiation on my phone but not with my eyes?

texts:
I made this little video. You can see a white flickering light coming out of my remote control.
When I look at my remote control with my naked eyes, there is nothing to see when I press a button of the remote control. Why can I see the radiation (infrared, I guess?) on my mobile phone?