texts: Transfering configuration to IEDs using IEC 61850

texts:
Sorry if this is a dumb question, but since I don't have much experience with IEC 61850 compliant devices, I am having trouble creating the "big picture" of how the whole system is being configured in practice.

Specifically, I don't understand how the devices which transmit data GOOSE or SV (without mentioning MMS in their datasheets) use the Substation Configuration Language (SCL) in practice, i.e. I cannot seem to find the exact part which mandates how the configuration is transferred to actual devices.

Can somebody clarify which part of the standard describes this? Are these files transmitted over FTP, or over custom vendor (proprietary) protocols, or does MMS provide a way to transmit SCL files in a standardized manner?


texts: Why delays cannot be synthesized in Verilog?

texts:
I have always read that delays declared in RTL code can never be synthesized. They are meant only for simulation purpose and modern synthesis tools will just ignore delays declarations in the code.

For example: x = #10 y; will be considered as x = y; by the synthesis tool.

What are the reasons delay declarations in any hardware description language (for example, VHDL, Verilog or Sytem-Verilog) cannot be synthesized?


texts:
Please help:

I am building a photogate. I was looking for help in building a circuit for the Raspberry Pi 2.

A little background:

I am still a highschool grade 12 student! and I have a basic understanding of circuits as we have not even started electronics and so that is why, I absolutely have no idea how phototransistors change current and so that is why, I have no idea what would the answer be. Also, I am semi sure of how multiple branches affect the current and voltage and resistance. Sorry! I am building this for my Physics IA. Going a little stronger. I will appreciate help or the circuit but if possible, I will appreciate any form of knowledge I can gain.

Design objectives:

What I am looking to build is a simple circuit which has one lead going to input of the GPIO board. One lead to ground and one lead to either 3.3V or 5.0V on the GPIO board, I have no idea how to select which voltage to use. The circuit would have a ir phototransistor that when dark would give an input in raspberry pi GPIO input of 2.0 volt-3.3 volt and 0.0v-1.0 volts when light. I can use any resistor. I want to build the most basic circuit that can give me these inputs when dark and when light.
Thanks A lot. Please ask for clarification if needed.

PS. this is a question to build a circuit whereas the other question is about input values from a pre-existing circuit.


texts:
I'm trying to implement a global timer, so that I can call time_us() anywhere in program and the function will return microseconds since program start. I've done this using TIMER2 (8-bit clock) and interrupt on overflow, and counting the overflows:

volatile uint64_t _time_overflow_cnt;

void time_reset(){
    TCCR2A=0; // no pin output,
    TCCR2B=(1<<CS21); // prescaler=8
    TIMSK2=1<<TOIE2; // interrupt on overflow (256 cycles)
    sei();
    TCNT2=0; // reset timer to 0
    _time_overflow_cnt=0;
}

ISR(TIMER2_OVF_vect){
    _time_overflow_cnt++;
}

uint64_t time_us(){
    return (_time_overflow_cnt*256 + TCNT2)/(F_CPU/8/1000000ULL);
}

However, this code has a race condition, which is in my case quite noticeable - if we rewrite this code into assembly, we see that the time_us is quite lengthy (64-bit calculations take some time) and if TCNT2 overflows during this time, the calculations is skewed by whole 256 cycles. I tried turning interrupts off before and turning them back on after calculation, but this does not help - it only secures the overflow counter, while the TCNT2 keeps increasing.
I also tried saving overflow counter, then saving TCNT2, checking if the former changed in between, and a few other 'solutions' similar to this one, but all off them had some TOCTOU (Time Of Check to Time Of Use) problems. Have you got a better idea for implementation?


texts:
I am trying to implement my own Bluetooth HID device (a kind of custom game controller), but am having trouble finding what I am looking for.

I have only come across two solutions which seem slightly expensive to me based on the task. The two solutions are the RN42-HID (click buy to see the HID version), and the Bluegiga WT12. Both seem expensive to me for my purposes. I am wondering how typical Bluetooth keyboards and peripherals which use the HID profile without installing anything do it. Are there other modules out there that I am unaware of?

Just to be clear, I do not want any software on my PC which translates, say, a serial Bluetooth connection's commands to HID commands. I strictly want the Bluetooth module to be recognized and operable as an HID device.


texts:
I've just searched for a suitable ultra low power design that is supposed to provide me 3V and only 10uA load from input 2...3V. It's quiescent must be reasonable low <10uA too.

One solution will be LTC3221 but it's quite expensive as all Linear circuits.

I have a MCU that have 32KHz crystalk in place, running all the time. One idea is to rectify that wave and use a low Iq LDO.

Any thoughts? Thank you.


texts: Electrical Load increase on Generator = More Fuel Consumption

texts: Why does more electrical current drawn from generator leads to more fuel consumption? I understand that it's due to conservation of energy, I just want to know what the phenomenon or reaction is called that leads to more power being transferred to the engine via the gears.


texts: Working with a sensor and a motor, can I use both or should I use a motor shield?

texts:
Update: I'm currently changing a few things with the project. I took some of you advice. I've changed from a stepper motor to a RC servo (controlled through PWM) and if I run into any problems and can't figure them out I'll ask.
Thanks for the help!

I'm working on a project with a friend and its our first time using an Arduino. We're using an Arduino to take data from a sensor (accelerometer) and then turn on the motor (6V, DC).

I've been doing some digging and it seems like the power out from the Arduino might not be enough for the motor and sensor at the same time. Maybe a delay of sorts could work (would this be possible?).

I'm contemplating using a motor shield. Will I still be able to control the accelerometer along with the motor?

I'm trying to use a single external source of power (max: 6 AA batteries; I'm trying to limit the amount of batteries since we're trying to keep it portable) so is there a way to use one source since the Arduino and motor shield need two different power supplies (from my understanding).


texts: How to get a PIC12F1822 running at 32MHz

texts:
I just can't get my PIC12F1822 to switch to 32MHz (8MHz + 4xPLL)
I am telling OSCCON to switch to 8MHz, but, according to the debugger, that value is never loaded into it! I also wait for the High Speed oscillator to be ready, but that bit is never set in OSCSTAT.

Here are the relevant snippets of my code.

__CONFIG _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOREN_OFF & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF
__CONFIG _CONFIG2, _WRT_OFF & _PLLEN_ON & _STVREN_OFF & _BORV_19 & _LVP_OFF

; > SNIP <

START
    BANKSEL OSCCON
    movlw 0b11110000
    movwf OSCCON

    BANKSEL OSCSTAT
WaitOsc
    btfss OSCSTAT, 4
    goto WaitOsc

; execution never reaches here

What am I doing wrong?


texts: Confused with the effect number of decimals at the output of transducer

texts:
There is an ultrasonic device which measures and outputs both wind speed and direction and has a very long manual. But to keep it short and summarize, the accuracy and the resolution for the wind direction is given in the following table:

As default, the device outputs the wind direction as for instance: 355.2 which is the direction with one decimal. Now the number of decimals can be user defined and be like 355.467 ect.

My questions are about comparing the logging of the output with one decimal versus with three decimals.

In terms of accuracy would increasing the number of decimals make any difference in the accuracy?
And in terms of resolution would increasing the number of decimals
make any difference in the resolution?
If neither, what parameter would improve doing so?


texts: LED only lighting up when my hand is hovering over it

texts:
I've got a pretty basic circuit, running an 10-segment LED bar graph through two TI HC595 shift registers. The very strange thing is that when I run the whole setup, and turn on a few of the LEDs, they only light up if I touch either the legs off the arduino that run it. Here's the circuit:

I'm assuming it has something to do with my hands' capacitance, but i don't understand what to do about it.


texts: Can a proximity sensor read through fabric?

texts:
I am trying to build an arduino project with the following requirements:

Proximity sensors detect human presence and its distance
The sensors are hidden behind fabric
Range has to be 1-3 meters or higher
It is for indoor use

After a bit of trial and errors, here are my initial conclusions:

Available light changes, and sensors being behind the fabric, photo sensors are out of the question
Even though they're not supposed to be very sensitive to soft material, Ultrasonic sensors such as the HC-SR04 don't fit. Their echo bounce right off the fabric
Pir Motion sensors don't read through fabric either

I am starting to wonder if this is even feasible. Is there such thing as a proximity sensor that reads through soft material?


texts:
I have to reverse engineer a PCB of a buck converter and figure out the component values. Given is that Vin = 15-20V and output is 5V @ 1.5A. The converter is LM2596, and datasheet I used is found here. http://www.ti.com/lit/ds/symlink/lm2596.pdf

I have constructed a schematic and read up on components that are on board as can be seen below

I tried breaking down the components and the reasons why they are present on the board. Current component values are not correct. First thing that confused me was R1 and R2, because it seems to me that fuse should be in series with everything that comes after the power supply, so in case of malfunction it pops and divides the power source from the rest of the circuit. Is there any reason why it is put in parallel? Do resistors create open circuit or a short when they burn, or can it be both?

Next question is regarding input stage of the chip: I gathered from the datasheet that there is one input capacitor, to smooth out current spikes from power source and protect the chip, however, what is the purpose of C2 and C3? I found online that it could be to filter out low/high frequency noise, but is it applicable if the source is DC?

Regarding output stage, I wanted to know if the potentiometer is in the feedback loop to adjust the phase compensation for output?

Also, and this is the last question, why are there 3 output capacitors? I understand that C5 would be smoothing capacitor to reduce ripple voltage, but what would C6 and C7 serve? Do these have something to do with noise from switching in the chip itself?

Any explanations or directions to useful materials would be appreciated!


texts: Headphone jack IR transmitter not working reliably

texts:
I'm working on a project to build a remote control app for some IR controlled toys like DeskPets, Robosapien, TOMY etc. including an IR transmitter that (hopefully) has a very high range.
I built an IR receiver that works with IrScrutinizer to capture the signals and export them to wave files.
I built 2 transmitters (one passive, one with a headphone amplifier powered over a USB port, later to be replaced with a LiPo battery). The LEDs are connected antiparallel to the left and the right channel. However these are not working reliably enough.
Both can send signals, however only if I play the recorded wave file using VLC media player and that only works a few times, leaving me wondering whether I broke the LEDs. A protoype app for Android successfully sent a signal once after countless attempts.
I have 2 theories:

I forgot to set up specific settings in order to correctly play back wave files. Maybe VLC does something right when playing back a wave file. Playing back the captured signal directly via IrScrutinizer also works. I downloaded a soundboard app for Windows and playing back the same wave files didn't work.

The wave files themselves are unreliable. While capturing the signals I noticed the timings are off (pauses are for example between 3395 microseconds and 3401 microseconds long). I didn't mess with the timings before exporting the wav files, but maybe if I fix the timings the signals could be read more reliably.

I hope you can help me fix this problem so I can continue with my project.


texts: Proteus 8 Simulation Errors. Loaded Netlist?

texts:
When I run the simulation, LEDs are not working. I don't understand the errors.
How can I fix it?

Errors:

Circuit:


texts: I'm not good at electronics, so can someone tell me what this component does?


texts:
I need to do a PCB layout where I have one digital signal that has relatively short rise/fall times crossing a slot in a GND plane. I know that this should not be done, because the signal return current should always flow directly under the PCB trace. But in this PCB desing, I have no other option.
So I thought it could be a good thing to place a capacitor (e.g. 1nF) across the GND plane slot. Then the signal return current can flow through that capacitor.
Does anyone have experience with such a kind of bridge capacitor across a GND slot? Is it possible to avoid radiation and/or reflection with this kind of setup? (I have to add that this PCB is extremely sensitive to EMI).
I know this is a very general question. I'm just seeking general advice from the cummunity.


texts: why do laptops have 10 or 20 volt batteries if most components only use logic level voltages

texts:
I've noticed that often laptop chargers and batteries are higher voltages than logic levels, 1 to 5 v. I am building a laptop and was originally using 3.7 v lipo battery. I am curious if I should put them in series to get a higher voltage and get an appropriate charging chip or just stay at 3.7 v.

What is the advantage to higher voltage batteries if it's regulated for logic level computing?


texts: IMU - How to calculate the orientation in a shaken environment

texts:
I'm trying to calculate the orientation on an IMU Sensor. Until now I'm doing it by calculating the Pitch angle and it's working fine:

float pitch = atan2(-obj.x, sqrt(obj.y*obj.y + obj.z*obj.z)) * 180/M_PI;.

My problem is when the sensor shakes heavily (even though it states on the same orientation), i.e. the Pitch changes drastically and it loses the correct orientation.

Is there a way to avoid this behaviour. What I thought to do, is to store the old pitch and compare it to the current pitch and if they differ +-20%* to each other then I ignore the orientation value. This obviously won't work if the sensor is shaken continuously.

Thank you in advance!

*20 is just a random number


texts: Induced voltage in the rotor of the induction motor

texts:
Given that the resultant mmf wave in the air gap of the three phase two pole induction motor is $$F(\theta , t) = \frac{3}{2}NI_m \cos(\omega t - \theta) \tag{1}$$
what's the value of the induced voltage in the phase coils? According to the Faraday's law of induction, we have $$\text{emf} = -N\frac{d\Phi}{dt}\tag{2}$$so we should calculate the flux linkage of the each phase coils and differentiate the result to obtain the induced voltage but I don't know how to find flux linkage. I've check various sources including Electric Machinery and Principles of Electric Machines and Power Electronics but they didn't help me to understand the solution. I'm mostly interested in the mathematical answer to this question rather than qualitative answer.
Edit: My problem main is as follows. According to the first equation, flux density should be of the form $$\vec{B} = B_{max}\cos(\omega t - \theta)\hat{r}$$so the flux linkage is $$\lambda = N\int_{-\pi/2}^{\pi/2}\int_{0}^{l}B_{max}\cos(\omega t - \theta)\hat{r}.rdzd\theta \hat{r} = NlrB_{max}\times2\cos(\omega t)$$the induced voltage should be $$\text{emf} = -\frac{d\lambda}{dt} = 2Nlr\omega B_{max}\sin(\omega t)$$
But it's given that $$e_a = k_w N_{ph} \frac{d\Phi_p}{dt} \cos(\omega_e t) - \omega_e k_w N_{ph} \Phi_p \sin(\omega_e t)$$
Apart from the scaling factors, why there should be $$\frac{d\Phi_p}{dt} \cos(\omega_e t)$$ term in the induced voltage? Also what changes has to made if the rotor also rotates? How the "slip" comes to the equations, in that case?


texts:
I'm working on an audio application where instead of storing audio data on an SD card (Waveshield on Arduino) I'm storing it on an SPI flash memory IC and rolling my own board with MCU, DAC, and amp.

I am using a Winbond W25Q80BVSSIG.

I'm pretty familiar with programming AVR using the AVRISP mkII or the USBTiny, is writing data to flash done with the same programmer? I haven't been able to find anything when looking for SPI flash memory programmers specifically.

This question is a follow up to this one.


texts: How to specify 100 ohm impedance on a pcb gerber

texts:
I've been using Altium for several years when I've needed to designed boards. However it's all been for simple analog designs and never anything too technical. I'm now trying to take a jump into a board requiring 100Base-TX ethernet.
I'm using a Microchip ENCX24J600 and it seems I need to use run 100 ohm impedance Differential Pairs for the TPOUT+/- and TPIN+/-.
I found a pretty good example video that has explained how to set up Altium here I thought I'd just need to call the manufacture and get the numbers as explained around 4:00 in the video. However I called the PCB shop and they said all I needed to do was provide a sample trace on the side and they'd make it work.
I'm sure this would work but I was wondering if there was a nice standard way that one should specify 100 ohm or 50 ohm for traces (as this seems complete different from in the tutorial I found).
Perhaps I'm making a mountain out of a molehill but I'd rather get things figure out once and then be consistent rather then get a few bad habbits that I'd have to relearn later on.


texts:
I need to simulate a power conversion system (using SIMetrix/SIMPLIS) in which solar energy is captured by a solar panel, which is then connected to an inverter for supplying current to the grid. Since I need to simulate this, I am struggling in finding a way to model the whole panel: it is clear to me that a single solar cell can be modeled through this circuit (keeping it as simple as possible)

simulate this circuit – Schematic created using CircuitLab

for which hold

\begin{eqnarray}
I_{out} = I_{PV} - I_D &=& I_{PV} - I_0\left(e^{\frac{V}{V_{th}}}-1\right)\\
I_{out}|_{V=0} = I_{SC} &=& I_{PV}\\
I_{out} = 0 &=& I_{PV} - I_0\left(e^{\frac{V_{OC}}{V_{th}}}-1\right)
\end{eqnarray}
where \$V_{th}\$ is the thermal voltage and the last two equations correspond to the short circuit and open circuit case, respectively, which for my case (the photovoltaic module is a BP MSX 110) are \$I_{SC}=3.6\:A\$ and \$V_{OC}=41.6\:V\$. If I try to model the whole panel using the aforementioned parameters I obviously am not able to compute \$I_0\$, since \$e^{41.6/0.026}\$ is a huge number; of course, if I just consider the fact that the module is made up of 72 cells connected in series I can model the single cell just fine (\$V_{OC} = 0.58\:V\$).

Then, my question is: is there a way (even different to the one I wrote about) to model one solar panel as a whole or have I got to actually connect 72 equivalent solar cells in series?


texts: Can you turn on a light bulb using only one of the two wires of the wall outlet?

texts:
Instead of trying crazy things I would rather ask. I am asking this for purposes of learning.

So I have learned that if the voltage is high you can get electrocuted by touching only one side of the wall outlet. That is because the potential difference is high enough for the electrons to start flowing.

Taking that into consideration, if I were to make this connection will the light bulb turn on?

Will this also happen with a higher voltage 120V DC battery?

If this were to also be true with the battery this would work by connecting only the positive side of the battery, correct? If you were to touch the negative side of the battery nothing would happen, correct?


texts: How to know if your SD card is SDHC/SDXC or SDSD in software?

texts:
When initializing an SD card, I reach the point where I need to use the ACMD41 command. This command takes 4 bytes as argument, of which bit 30 is HCS. Which is set for SDHC and SDXC. If the SD card is neither, it should be set to 0. However I am at a loss as to how I know if this bit should be set.

I can use CMD58, which should return CCS as bit 30, which would indicate whether the card is SDHC or SDXC, but there does not seem to be a guarantee that this returns a correct value unless the card has been initialized with the ACMD41 command.

How can I set the HCS bit correctly in the initializing ACMD41 command without having a way to figure out what it should be set as? Or am I reading the specs wrong.


texts: Can anyone help identify this part? It appears to be a DAA module but on some kind of carrier board. I've emailed Cermetek but received no response. Thanks.


texts: I am having problems analyzing this sketch of a continuous Fourier series as it can't find a single known function


texts:
I want to get into electronics and I am interested in creating oscillator circuits. In one experiment I wanted to use an Opamp for an oscillator and I am now stuck with the power requirements of it. I could use two batteries to get V+ and V- but I wondered, if it was possible to use an USB power adapter instead.
In order not to fry my one TL064CN chip with its 4 opamps, that needs VCC+ and VCC-, I want to ask what I have to take care of. I learned, that I could create a voltage devider with two resistors, where the connection between the resistors becomes the GND reference and the first resistor the positive rail and the second one the negative one. Would such a simple voltage divider using two reistors be enough?


texts: Is that possible to create a virtual ground,for electrical purposes?

texts:
It might sound crazy, but I have seen many houses that doesn't supplied with electrical Ground (earth), and today there are many devices exist that need electrical ground.
I know that some people using metal water pipes, as grounding electrodes but actually I am Interested for a possible way of making a circuit that visualize the electrical grounding
In terms of functionality and effects, including, noise reduction?


texts: Why is the data output of some ICs in two's complement form?

texts:
I've been looking into some ICs now. Some of them have the calculated result (data) in twos complement form, placed in register to be read by other IC. What is the logic behind converting the data to twos complement form before its read?

Examples are as

Analog to digital converter (Page 30 Output Data Format). LINK
Digital Accelerometer (Page 1 General Description). LINK

I have seen similar behavior in CRC calculation for IEEE 802.3. For example if we calculate the 32-bit CRC (using x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1 polynomial) the calculated CRC is bit reversed and complemented before transmission.

Well the question is why is it formatted in complement form? Can't it be read without the data being complemented?


texts:
I'm trying to make use of the bxCAN of STM32F103C8 on a bluepill but it doesn't work and I don't know what is the problem.I'm using the hal API
here is the main code in the while loop

while (1)
{
    char msg[50];
    CAN_TxHeaderTypeDef TxHeader;
    uint8_t data[5] = {'H','E','L','L','O'};
    uint32_t TxMailbox;
    TxHeader.DLC = 5;
    TxHeader.ExtId = 0x18181820;
    TxHeader.IDE = CAN_ID_EXT;
    TxHeader.RTR = CAN_RTR_DATA;
    if(HAL_CAN_AddTxMessage(&hcan, &TxHeader, data,TxMailbox) != HAL_OK){
        Error_Handler();
    }

    while(HAL_CAN_IsTxMessagePending(&hcan, TxMailbox));
    HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
    HAL_Delay(1000);
    HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
    HAL_Delay(1000);
}

The code breaks at the HAL_CAN_AddTxMessage.
this is my first time working with an STM32 so I've never had a working example and couldn't find any working examples online.
Please help I've posted many times :/


texts: Adding delay to single button on off circuit

texts:
I'm using this circuit to turn on and off.

When I press the button circuit instantly turns on or off. I want the circuit to switch after pressing the button for 2-3 seconds. I tried to change C1 and C2 values but nothing changed.
I would like to know how can I add this delay to the circuit.


texts:
Really basic question that I've struggled with for a while. In low-cost fans, a series of mechanical buttons select fan speed. I assume each button is connected to a specific resistor which limits the current/divides the voltage to the fan motor, depending on how they are arranged.

My question is, is it irrelevant to the overall power used by the appliance whether the fan is operating on low or high speed? My assumption is that the energy is simply wasted to heat the resistor on the low speed setting.


texts: Multi high input impedance chemical electrode buffer circuit

texts:
In What is the purpose of this op amp? you see my interested circuit.

Added:

The diagram above  shows a single pH measurement "channel".
 U1 sets a reference voltage of Vout_LM4140A/2, and U2 measures the voltage outut of the pH probe relative to the reference voltage.

I wish to add a second independent pH probe.
 I could add two new amplifiers say U1 as reference and U2B for measurement.

However, is there any reason why I should not add a U2B but share the existing reference source from U1 for both probes?

Original question:

I measure output of u2 in single ended mode. There is no problem with one electrode (for example pH).
But i need to measure different electrodes using same common reference in same time (in here reference is taken by u1). If i connect another electrode which have same characteristics with pH electrode and works with same reference to new lmp7721 (as u3) like u2, is it correct?


texts:
I am working on a project called LM317 power supply.

The schematic is from the internet, and contains the regulator, filter capacitors, rectifier, potentiometer and protection diodes.

I designed a layout and I made the PCB. The PCB contains large copper pours.

When I started to solder I realized that using the soldering station at about 350C, the copper pour took all the heat and the joint was not good.

So I started to find a solution to this problem.

I took my soldering gun and I started to solder the components and I covered the copper pour with solder, to prevent oxidation.

After I soldered using the soldering gun, I realized that the capacitors were hot.

What should I do to check if the capacitors are still good ?

Can the heat destroy the electrolytic and ceramic capacitors while soldering ?


texts:
This is the equation for which I have to make a state-space model.

$$m\ddot y(t)+b\dot y(t)+k_1y(t)+k_2y(t)^3=u(t)$$

For my A matrix I have

$$\begin{bmatrix}
0 & 1 \\
? & \frac{-b}{m}\\
\end{bmatrix}
$$
where

$$ \begin{align}
&x' = Ax + Bu\\
&x_1=y \\
&x_2=x_1'
\end{align}$$

Where I put the question mark, I have
$${(-k_1+k_2 \, x_1^2)\over m} $$

However, how can I fit the \$x_1^2\$?

Normally A matrix is only using numbers...


texts: How to size these resistors for the MOSFET gate or are they redundant for this case?

texts:
I want to control this solid state relay through a 0/5V digital output. The digital output should not draw more than 10mA so I will use this FET transistor. 12V DC power supply is used to switch the relay ON when the FET receives 5V to its gate. I have drawn the diagram as shown below:

Do I need R1 and/or R2 in this case? How can I verify that?
I was thinking R2 might help if the gate is floating but might be unnecessary.
I don't have much experience using discrete mosfets so I couldn't figure out if I need R1 or R2 at all.

edit:


texts:
I have a motor at home, it's a soviet era motor. It's connected to what seems to be a capacitor.

The setup pretty much look like the following one except the red box is much larger than the one on the picture and I can't see the markings. The one on the picture is 2uF 10% for 400v.

I was wondering if there was a particular reason why the capacitor is so big. If it's just that now capacitors for the same specs can be much smaller than the ones in the 70s.

Also I don't really understand the wiring of the motor. Mine is wired pretty much the same way except I have a switch that lets me change the rotation direction. I can't tell much for now as I'd have to dismount everything to access the readings to get a better idea. What I can tell is that this is a 127v AC motor. Here are the markings:

  127v 30hz 6w

To my understanding, the capacitor is used to somewhat limit the current to something around 127v. So tecnically, I could replace the beefy capacitor by one of same value that I gather from broken fluorescent/led lamps?

The pictures are taken from this article: How to connect a 127v motor to 220v (Russian)


texts: I am trying to use back-to-back MOSFETs/IGBTs to isolate my pulsed supply from my load. In theory, I will switch on the MOSFETs, and the pulsed supply will be attached directly to the load (but not on yet). Once my pulsed supply emits a single pulse through the MOSFETs, won't they turn off due to the sudden increase in Vgs? The pulse I am sending through is ~4 kV, so it is obviously MUCH more than my Vg voltage.


texts: How do microcontrollers achieve > 1 MIPS/MHz performance?

texts: Like this one, which does 1.49 DMIPS/MHz. Even with pipelining there's still only 1 execute stage per cycle isn't it?


texts:
I have two resistors which need to be replaced. I tried to determine the value, but it can't make sense of these black bands:

For reference the bands are:

brown - silver - green - brown - black
brown - silver - red - brown - black

Since a silver line can only be part of the multiplier, that means the black line on the right has to be the tolerance. Black can not be used for a tolerance from what I've read.

Is this black line a tolerance value or something else?


texts: Power Supply Circuit ±9V from a 6V centre tap transformer

texts:
At work, there's a power supply which is used on one of our products. The guy who originally made the board has since left and none of the senior electronics guys could give me a good answer.

Here's a schematic of the PSU

There's the transformer (Myrra 45055) a bridge rectifier (KBP305G) and some 10000uF caps.

From my understanding, from the output of the transformer I've got 12V AC. With the centre tap being GND I would have expected my outputs to be +6V with respect to centre tap and -6V with respect to centre tap. What the actual circuit gives is ±9V (±0.2V), I'm unsure how I'm getting a total of 18V difference between + and - from 12V out the transformer.

I've never really dealt with transformers or AC before, is there a misunderstanding in my thinking? Or are the caps doing something more than just ripple smoothing?


texts:
The software called gprMax which simulates EM waves in varying environments. I am trying to enter steel has material but from the picture, it also requires the magnetic loss(ohm/meter). But I have been searching for this property on the internet and cannot find anything. Can someone please assist?

I am trying to simulate the behaviour of the EM radiation inside a steel container. A rfid tag is mounted on a plastic rfid mount and the tag is affixed to it. Various materials are then placed infront of the RFID tag such has steel, wood and plastic. I got all the parameters for plastic and wood. I just need the magnetic loss of steel. The receiver then picks up the E and H fields from which I calculated the power received from the tag at that point.

This is shown in the picture


texts: Pump Automatic Pressure Control Electronic Switch


texts: Usage of a transistor configured as diode

texts:
I faced lots of circuits that has transistors connected as diodes (gate connected to the drain). I know some of these circuits employ such transistor for safety reason but I couldn't figure out the reasons of others.

My question: Is there any reason behind connecting the transistors as diodes other than the one I mentioned? Some of my colleagues suggest that they may be used to realize high resistance but I think connecting the transistor in such configuration (\$V_{g} = V_{d}\$) will force the transistor to work in saturation region, not in linear region. Am I right?


texts: AC divider circuit used to charge a capacitor

texts: The following circuit uses a capacitive divider network along with a diode rectifier to charge a capacitor. I assumed that once C2 is charged to its maximum( calculated to be around 14mV) the diode and C2 will behave as if it is independent of the divider. But it was seen that the voltage Vx was found to be clamped to negative voltage region. Why is this occuring?


texts: Can an amplifier deliver a higher power for a short burst as opposed to continuously using the same circuit

texts:
I am struggling to understand the fundamental power requirements for an amplifier.

If I want to deliver 56 V rms to a 7.5 Ohm load I can use P = V^2/R and find that I need 418 W rms. Requiring a current of 7.5 A rms.

But this is for transmission in a continuous mode. If, for example I only want the amplifier to transmit 10% of the time, for example, for only 100 mS in 1 S, sitting idle the rest of the time. Does my power requirement change?

And how is this change manifested?

Does the current requirement drop (meaning I need less output transistors in parallel)?


texts: Very high fanout net not being replicated by Vivado

texts:
I have a high fanout (~2300) write enable going into a RAM block. The RAM is distributed (hence the high fanout), and I am unable to use block RAM because of area limitations. The fanout_limit setting for synthesis is set to 500, but Vivado is failing to replicate this write enable accordingly.

One of my top failing timing paths is the path directly from this signal into the write enable of the RAM, and I think that reducing the fanout would alleviate a lot of the routing delay.

I get the following info message during the PhysOpt phase of Implementation:

  INFO: [Physopt 32-1022] Very high fanout net '.../d_qr_valid_in[0]' has -through timing constraint on its net segments or hierarchy pins. To preserve -through timing constraint its fanout number considered in optimization is changed from 2341 to 152 and it is not considered a very high fanout net anymore. Please consider modifying/removing the '-through' timing constraint on the net segment or hierarchy pin.

I do not understand the INFO message. I have not touched any timing constraints related to my design; the only timing constraints have been set by the vendor. This issue is internal to my design. What is actually happening here? How can I modify/remove the '-through' timing constraint as it suggests?


texts: How to obtain negative and positive voltage (±16V) for LM324N

texts:
I'm working with the LM324N op-amp. My project requires dual supply, ±16V. How can I produce negative and positive supply from a single supply source?

Some project have been using ICL7760 to obtain -5V. For my project, what IC type can I used to produce -16V?


texts:
I'm repairing a receiver and among other things I have to replace some broken wire wraps.

The existing wires are too short for reuse and I can't find any 22 AWG solid conductor wire on the market specifically for wire wrapping, only 24 AWG and up.

Can I use regular hook-up wire with good results and if so what specific kind of wire should I look for? I would appreciate if anyone can give me some advice on this.


texts:
I am reading the data sheet for the LEM current sensor LAX 100-NP. I find the PCB design a bit confusing when it comes to high speed or low speed design. If you look page 11, left column, high speed design, do you know where the primary current is supposed to enter the sensor in order to have a positive secondary current? In the high speed design, it seems that the primary current enters the sensor in the terminals where the primary current would exit the sensor in the low speed design case. Any opinion? perhaps we can work this out.

Thanks a lot

Lello


texts: How do I prevent a capacitive touch from registering?

texts:
I'm looking for a thin cloth-like material or something that I can treat materials with that will prevent a capacitive touch from occurring.  Everything I've tried either is too thick, or still registers a touch through the cloth.

I'm not an EE, although I think I have a very basic understanding of how capacitive touch works.  Essentially, electrons line up and are looking for something capacitive to travel through.  Once that thing (like your finger) touches the screen, they travel through it.  The device then detects the absence of the electrons in that space, which registers as a "touch".  If I'm wrong, feel free to correct me.  I'm always up for a better understanding.

Thanks!


texts: In what kind of circuit does current flow?

texts:
In what kind of circuits do current flow? For a circuit to be "closed" does the end point have to return to the start point like in the first image?

If you have a straight line conductor between two components of opposite charge like in the second image, will there be current flowing between them?

If it's true, will current then flow from one pole of a battery to the opposite pole of another battery(like the third picture) and why/why not?


texts: What is the LCCDE equation of this block diagram?

texts: I can't find the LCCDE equation of this system. I try to reduce but thing will get complicated.


texts: Surprise resistors found in old voltage divider

texts:
I'm a grad student in physics that hasn't looked at circuits since early in my undergrad. I was recently handed a voltage divider that my group used to bias a micro-channel plate detector stack as I'll need to build a new one for a new system.
What I'm confused about is the purpose of some surprise resistors (R1 and R4 on the included schematic) as I don't understand why they would need to be included. Any insight would be much appreciated as the person who built this graduated 8 years ago.
As for the bit with the capacitors in the bottom right along with the output labeled 'Sig', that was to read the bias off of the rear micro-channel plate capacitively to provide timing information on a detector event.
R1=1Mohm
R2=4Mohm
R3=470kohm
R4=150kohm
All capacitors are 4.7uF
Vin is a DC voltage that was biased at -2.5kV.
A microchannel plate detector is a radiation detector with many small channels typically constructed out of a lead glass that function as an electron multiplier. When an incident ion/electron strikes the wall of a channel, it kicks up secondary electrons. Those electrons then hit the wall further down the channel leading to a multiplicative avalanche of electrons that produces a readable voltage pulse on the anode. The resistance across the plate/plates is in the 10^9 ohm range, so as far as I understand it, the resistance of the load between each node (Vfront> Vback>Vanode) is approximately that much.


texts:
I bought XBee shield from dfrobot to do communication with XBee module and Arduino. This is how the shield looks like:

The question is, what is the meaning of the state of Association LED blinking?


texts:
Does anyone knows what kinds of capacitors are they?
I searched everywhere, but I couldn't find anything.
Why there are these three "strings" on the top?
Why the capacitor value is not reported on the side as a "standard" capacitor?


texts: How is Gate Trigger Current determined in a "dimming" circuit?

texts:
EDIT: DIAC part numnber is DB3TG
I'm trying to understand how a dimming circuit works, specifically TRIAC control. The TRIAC (D1) in this circuit is a BT136S-6. Where does the Gate Trigger Current come into play? I understand that the combination of R1/R3/C2 control the time that C2 is charged up and therefore hits the threshold of the DIAC (D2). Is the TRIAC just consuming full power at trigger point? Is that bad news? Should the gate current be limited by a resistor?


texts:
A while back I think I may have plugged the wrong power adapter into my MIDI keyboard and it started to smoke and then never turned on again.

So... I popped it open and it looks like it's a burnt 1N5187 diode.

I come from the completely different world of stats and maths stack exchange so I'm not really qualified to speak on these things and I have little training in electrical engineering and hardware.

But I have taken a class in soldering and so I came here to learn from anyone willing to advise whether you would recommend for/against me getting a soldering iron to replace it if I bought the right part and isopropyl-ed the affected area with a q-tip (assuming I'm a beginner).

Also, I'd like to understand what role this diode plays in the circuit. Just by looking at it, does it seem like the burnt areas would inhibit the flow even if the diode was replaced.

Any commentary, links, or help from experts is greatly appreciated. Main goal here is to learn more about how these things work.

EDIT: Adding image of the the other side of the circuit board.


texts: Triac not getting switched by optoisolator

texts:
I made this dimmer circuit:

simulate this circuit – Schematic created using CircuitLab
And it does not work (no light). I have looked up other circuits that serve the same purpose and they seem to be different on a few points:

There's a capacitor C1 (can't really tell its purpose)
They use another TRIAC (BT136)
The resistance at the optocoupler is less than 1kOhm

Another thing I could think of is that I wired the TRIAC wrong: I connected the optoisolator to T1 and G of the BTA16 800B
EDIT:
Several suggestions have been given in the answers. I removed the red LED, changed R2 to 500Ohm and I rewired the TRIAC. I tested the circuit with a 3.3V battery. It work, can't tell which part was the crucial solution.


texts: Maximum Initial cutrent parameter of Lead-acid batteries

texts:
On lead-acid batteries, there is a parameter called "maximum initial current" which is generally written on it. I have added some pictures of it at the end of the question. My confusion is how to interpret it? Is it:

The battery can demand more but I should maintain constant current below that limit.

OR

The battery will never draw more than that current. So, just use a power supply (of course with appropiate voltage rating) which will be able to handle that maximum current.

I think it is number 1 but I need some expert opinion.

Edit: I have an SLA charger which is rated 1A for fast charging and 0.5A for slow charging. (there is a toggle switch for these two modes). Now suppose I have a battery with max current rating 0.33A. Should I use the battery with the charger?

If number 1 is ture then I think I sould not use it but if number 2 is true, then I should be able to use it.


texts: Insertion Loss & Return Loss - GSML2 Link

texts:
I have a GSML2 Link specification connecting Serializer and Deserializer via coax.

While performing the SI analysis, I had a few doubts.

In the deserializer datasheet, we have forward channel of 3Gbps/6Gbps and for reverse channel, we have 1.5Gbps/187Gbps.

The analysis is plotted as : Inserting/Return Loss Vs Frequency.

How should the graph look for the GSML2 Specification?
How to understand the return loss and insertion loss while performing the SI analysis?

If the return loss fails (falls below the GSML2 specification curve @ SI Analysis plot) at a frequency, say 150MHz, does this imply that, this loss, will disturb my reverse channel data (as my reverse channel will communicate at 187Gbps) ?

And If the return loss fails (falls below the GSML2 specification curve @ SI Analysis plot) at a frequency, say 400MHz (greater than 187Gbps), does this imply that, this loss, will NOT disturb my reverse channel data (as my reverse channel will communicate at 187Gbps) ?

If I am completely wrong, help to understand with respect to Serdes and Return/Insertion loss.

Thanks


texts:
Can two ATX SMPS be connected in series to get +10 and +24V DC (from 5V and 12DC output of each SMPS)

Needing lots of current at 24V with atleast 5A so cannot use -5V or -12V inside SMPS as negative voltage have less than 1A rating

I know transformer based PSU can be uses this way, but professor telling that SMPS cannot be connected in series the same way.

He not tell me reason as he says I will understand better next year when SMPS in course offering.

If he correct, then why not SMPS work like transformer based PSU?


texts:
Specifically, the plug and socket at each end.

This is a board-to-board cable from a 1989-era Toshiba laptop, which connects a dedicated modem port to the modem itself (not present in my laptop). The pinout is a very cut-down ISA bus with only a few address lines, and looks eminently suitable for hacking --- if I can find a plug which will go into the motherboard connector (I'd rather not destroy this one). But for that, I need to know what it is; the cable markings are no help. (I'm hoping to find an IDC variant.) What is it?


texts: Can't understand a given answer about a 1st Kirchhoff's law question

texts:
I am currently studying the textbook "Lectures about the fundamentals of Electrical Engineering" by Adalbert Prechtl and after finishing the theory about Kirchhoff's law, I tried to solve some basic exercises on them, but my answers seem to deviate a lot from the answers the book gives. The question is rather simple, I have to apply Kirchhoff's first law on the nodes A to D.

Concerning node A, after considering the direction of current based on the voltage sources' poles my initial answer was:
$$ I_6  +I_4-I_5=0$$
My path of thought was: Current from 1st Voltage source, goes through R1 then through R4 and then R5. Current from 2nd Voltage source goes through R4 and then R5, and current from third Voltage source goes Through R6 then R5.

The answer that the book states is:
$$ I_6  +I_4+I_5=0$$

I was really suprised from this answer and I am still thinking that I am missing something rather important about Kirchhoff's laws. Then I simulated the circuit in a simple circuit simulator where the flow of current was as my initial answer stated.
Any idea on why this is the given answer would really help.


texts:
I am slightly confused about the terminology of rotary incremental encoders. The encoder in question is a dual channel quadrature encoder. I have attached the datasheet here: Nidec RE30E-1000-213-1 encoder datasheet.
The reason I ask is I am trying to calculate RPM of a motor that is rotating this encoder.
What is the difference between pulses per revolution (PPR) and line counts?
This encoder is 1000 PPR for each channel, so that is 2000 PPR total. However I am counting both rising and falling edges of each channel pulse, so am I correct in saying this encoder is 4000 PPR? What is the line count of this encoder then?
Also I have turned the motor at approx 4000rpm and the output frequency of each channel is 66.6kHZ.


texts: How to make fast (low latency) capacitive touch buttons

texts:
I'm looking to create low latency capacitive touch buttons for a musical instrument. The response time (from physical touch to touch registered in microcontroller) needs to be around ~2ms or less.
From what I've read it seems like this is possible (and there have even been touchscreens developed with sub 1ms latency - see here!).
Given that I merely want to implement a single button, it seems like it should be achievable. However, I've been shopping around for ICs and everything I can find seems to have 10-16ms response time.
So given the lack of an appropriate IC, how could I create such a sensor myself? Is it merely a matter of doing very fast AC voltage measurements on the sensor pad? - In which case, what is the limiting factor here? Why are all the products on the market so slow?


texts: If an I2C device does not appear in i2cdetect does it mean the device is potentially broken?

texts:
I am trying to get an I2C OLED (128x64) display working on a BeagleBoneBlack.  Unfortunately, no matter what I2C port I try I cannot see the device when using the i2cdetect utility.  As you can see below, i2c-0 and i2c-2 are "scannable" using the utility, however no device shows up.  The OLED panels generally show up at either 0x3C or 0x3D (in this case 0x3C).  The OLED panel is controlled using the SSD1306 controller.  I am still learning about i2c, but from what I understand, a device should have a unique address that will show up using the i2cdetect utility.

Any tips on troubleshooting would be helpful.  The c++ code I have is quite involved, but I can post it if you think necessary.

The BeagleBone should have 2 I2C ports available according to my web searches.  I have tried all the scl and sda pairs listed on the P9 header.

Previously, when I used an I2C LED Panel, I got the output below and was able to write to various pixels in the matrix.  As you can see, in that case I had a device available at 0x70.

UPDATE:

I asked the author of the library and this is what he wrote:

It sounds like the SPI device you're using might not be enabled with a device tree overlay. Can you try running this command to show all the SPI devices?

ls /dev/spi*
Based on the device and port you should see a /dev/spidev1.0 device. If you don't see that device then you'll need to enable it with a device overlay. Check out the bottom of this page for a little more info on how to enable the SPI device: https://learn.adafruit.com/ssd1306-oled-displays-with-raspberry-pi-and-beaglebone-black/wiring

One other thing to be careful about, since it looks like you're using Ubuntu. Make sure the kernel version is 3.8.x and not a later one like 3.14.x. The later kernels don't support device tree overlays so they can't dynamically add SPI ports, etc. You can check the kernel version by runnning:

uname -r
If it's a later kernel (like 3.14) try installing the official Debian image from there as it's still using 3.8: http://beagleboard.org/latest-images

It seems that /dev/spi* does not exist, and that I am running a later version of ubuntu (3.14), both of which could be bad.  It's a bit beyond me why Ubuntu 3.14 would stop supporting device tree overlays, and why I can't access these pins.


texts: Reverse engineering a high side MOSFET driver SMD circuit board

texts:
I am trying to reverse engineer a high side MOSFET driver smd circuit and I have a few components. I am trying to gather data for it.
One is a diode with markings UJ 8B.
Then I have two transistors with markings !2F A and the other !1A backwards F. I'm pretty sure 2F is an NPN and 1A is a PNP.
Here is the circuit. I know the resistors and Q4 are correct. I'm just not sure about the other transistors. The circuit just doesn't seem right around Q2 and Q3. Any ideas if this is correct or if im missing something?
I tested the circuit on a simulator and it seems to work but running in a PWM and there is a gradual off slope but a steep on slope. Any ways to improve the off slope?


texts:
I have seen and worked with interfaces like SPI and I2C.

However, when I started to learn about DDR interface/communication protocol, I want to understand like how many lines, what are the important pins and how are the bits sent.

For ex, While learning about I2C and SPI interface, there are some websites that entirely talk about those two interfaces like each line and what it does and how are the bits sent and on.

But I was not able to find like this for DDR and PCIe interface. Can someone share if they know?

I researched that to understand DDR protocol we need to download the standard from JEDEC and for PCIe, it is PCI-SIG.

But it is very detailed and technical and tough for me to grasp while reading those PDFs.

Is there any other way to learn about those standards?


texts:
Looking for help with reading my multimeter.

I would think by moving from 20 to 200, the decimal place would just shift one place. Why when I switch do I get a reading of 20ma vs 10ma?


texts: Why do some PCBs have these circular rings? Are they plated through hole vias?

texts: Do they serve any mechanical purpose? Also, there are eight dots on these rings.


texts: How can I assign a 256-bit std_logic_vector input

texts:
I realized an AES-256 algorithm which encrypts a 128-bit std_logic_vector (plain_text) with a 256-bit std_logic_vector (master_key). I made a test-bench in order to verify the behavior of the encryption process, and now I would like to implement this algorithm on my Basys3 board (I use Vivado as IDE). My questions are:

How can I map the input vectors? Should I declare signals in my architecture, knowing that I do not have enough I/O ports?


texts: Using TRIAC driver optocouplers without TRIAC

texts:
According to datasheet of TRIAC driver optocouplers MOC3041 it can bear 400v 1A, is that means we can use it without triac if the load draws current lower than 1A? if NO why? i tested it for a small 5W LED lamp and works well but dosen't work for 30W CFL lamp.
Other question about this driver is:
I know what means Zero cross detection but what dose Zero cross detection INSIDE this optocouplers?


texts:
I'm new to this site so excuse me if my question is not normal or a bit silly. However I am having an odd situation where Vivado 2015.4 seems to be optimizing my code and removing parts of it which it deems is not useful.

Trying to keep things simple, I am reading an SPI port on an Artix-7 FPGA and filling 4 FIFOs after each other, i.e. when one is filled I read a memory location from the first FIFO and write it to the second FIFO, and so on. I created a flag 'data_available' which goes high when data is in the FIFO.

The odd thing is that whilst testing the FPGA by downloading the bitstream to verify that all write enables and full flags are working correctly; when the data_available flag is outputted, then the system works fine, when the data_available flag is not outputted then nothing appears, as if the whole code is removed due to the flag not being set as an output.

Can anyone identify why this is happening and how to solve it? Should this information not be available please excuse me since as I said I don't know the norm of this site. The code is a bit too long to post.

Thanks :)


texts: What is this kind of temperature sensor called (Analogue Devices TMP36)?

texts:
I am reading about this stuff, and I have found clear definitions of thermocouples and thermistors online, eg on Wikipedia. But then I also found something different, e.g. what they at AdaFruit just call an "analogue temperature sensor" (link). It is called TMP36, from Analogue Devices (link).

What is this category called? If I have a name for it I can find general advice and information on whether this is the way I want to go.

Do they work somewhat like thermistors or thermocouples or in an entirely different way?

I am a hobbyist, if possible please consider this in your answer by not making it more complex than necessary.


texts: Can a 4051 Multiplexer accept +/- 12v bipolar power

texts:
I'm looking to use a CD4051B multiplexer as a digitally-controlled switcher for audio signals.

The audio is coming from the HP / BP output of a voltage-controlled filter in a synth. The signal output is about 3v peak-to-peak. The mux select will be controlled by 5v TTL logic.

I only have supply voltages of 5v, 12v and -12v in my synth.

I'm finding the datasheets for the 4051 rather vague - has anyone had any success powering these chips with +/-12v bipolar power? (the -12v supply going to Vee)


texts:
I am trying to understand the function of this input stage of a filter I am using.

The input current source is a 2uA peak-to-peak with zero offset.

(This specific stage is followed by an active bandpass with a gain of 40 and an active low pass with a gain of 30.)

Quick summary:

My first question before simulating it in Multisim was "Where is the input resistor?" and hence "How much is the gain?". Although my question still remains, I figured that the output voltage could be derived by adding the voltage drop across R2, to the non-inverting reference voltage 1.65 V. Specifically, the current passing through the feedback network is 1.65/47k =35uA  (+- 1uA due to input current) and therefore Vout =1.65 + 35uA*36kΩ = 2.91 V.

However, I could not find any relationship between the input Vin(pp) of 359 nV (probe1) and Vout(pp) of 71.8 mV. In fact, Vout(pp) remains constant despite changes in R1,  but is linearly proportional to a change in R2  ( if R2'=2*R2, Vout,pp'= 2* Vout,pp). So I assume there is no R2/R1 type of relationship to calculate gain. Then where does the gain of (71.8 mV)/(359 nV)~ 200,000 come from?

Another thing that I did not like is that Vout(dc) is different than the reference voltage 1.65 V.  I know I just explained above how this dc output voltage V(dc) of probe2 is derived, but, up until now I thought the whole point of a reference voltage in the non-inverting pin is to perform level shifting so that the ac signal in the output will be centered around that reference voltage.

After this realization (that vout(dc) does not equal the reference voltage), I went on examining other possible level shifting circuits, like this for example ,

where I would think that Vout= Vref + (1+R1/R2)*Vin. However by doing the math (superposition), I get: Vout=(1+R1/R2)*Vin-(R1/R2)*Vref.

Questions:

Is there a formula for calculating the ac gain of this active low pass configuration in the first picture?
If not, is the ~200,000 times gain of the ac signal intentional? Or did the
the designer just aim for the low pass
functionality and remained satisfied with this huge gain that is somehow
provided?
Please help me demystify opamp level shifting once and for all. Is the formula derived above for the opamp of the second picture correct? Vout=(1+R1/R2)*Vin-(R1/R2)*Vref. If it is, then how is level shifting achieved for the non inverting configuration?

**for an inverting configuration it can be achieved as explained by Spehro Pefhany in this post.


texts:
how do i performs a division by 4 of the 16-bit unsigned value in registers r4:r5 Where r4 is the most significant  bit.

I understand that by division of 4 which means i have to shift the bit by 2. but how do i do it in assembly language? can i basically just LSL r4;LSLr5;? thank you for your help in explaining this.


texts: Is mbed OS suitable for hard real time systems

texts:
I have been developing embedded stm applications bare metal along with ST Hal for a few years and would still consider my self a beginner as the process of learning in a bare metal environment can be tedious. My aim is to be able to develop hard real time systems like flight controllers.
I have known about mbed for a while but have not tried it as my impression is that it is not suitable for hard real time systems because of the overhead that comes with it. It seems that mbed is for IOT devices only.

I would like to go with a more standardized development ecosystem with good community support like mbed. Does it make sense to switch over to mbed or to just keep on the track I am currently which is using freertos or QP with bare metal?

more info: mbed OS claims to have an rtos in it, however it is not clear if it is suitable for real hard time systems.


texts: How to use VBT-1 vibration sensor? Why the measurement unit is in mm/s?

texts:
I need to use this vibration sensor for my project. I'm confused because of the measurement units. Out value of the sensor is in current 0-20mA, which corresponds to 0-25 mm/sec. Why is it being measured in velocity terms?

Please find the link to the datasheet here.


texts: Is this cascaded RC filter transfer function explanation wrong?

texts:
At this page I stumbled upon the following section and highlighted the part in question:

How come the total cascaded RC filters' response be the multiplication of each RC filter's  transfer function? Shouldn't there be an ideal non-inverting buffer in between them to claim this?


texts:
I'm making a buck regulator using L4970A using circuit from this application note figure 60 , except for the inductor. I change i to 180 uH

I wanna make it to be a power adaptor for laptop with solar cell source (about 100 W, Voc 27 V, Isc 5A), and the regulator itself can hold current to 10 A max, said the datasheet

As you know, usually laptop needs current from about 1.5 A-4 A, depends on it's using battery or not and how the laptop works. I've succeeded to make my regulator give supply to the laptop, but the current is too small to make it becoming primary supply.

Does anyone know what's wrong with the design? What actually limits the current of buck regulator??

I test this circuit using Asus A43SJ

For Russel, this is my inductor

I don't know either the wire type or the core type exactly, but because it's not magnetic, I think it's iron powder. Outer diameter 2.3 cm and inner diameter 1.2 cm


texts: A basic question regarding three phase power

texts:
I have a very basic question about three phase power. We have a three phase power supply rates as 32A/415V. The line to line voltage has been measured to be 415 V (using a multimeter) and the line to neutral voltage is 240 V. Does the current rating of 32A refer to the maximum allowable line to neutral current if the load consists of three heating elements connected in wye configuration?

Thanks!
Abhishek


texts: Define the s-parameters of 2-port network

texts:
How to define the s-parameters of the 2-port network below?
I don't know where to start exactly but it is not symmetrical
$$S11 = \frac{V_1+}{V_1-}\ $$
$$S12 = \frac{V_1-}{V_2+}\ $$
$$S21 = \frac{V_2-}{V_1+}\ $$
$$S22 = \frac{V_2+}{V_2-}\ $$


texts: Would this Solid State Relay work to control my portable electric heater?

texts:
My project controls my electronic heater over the Internet. The last step of my project is hooking up the system (which is working) to the heater. I realized that the relays I have on hand are not up to the job.

The heater runs on 120 VAC and requires 1500 W. Based on my research, I found the SSR-25 solid state relay to be an appropriate choice.

More specifically, this is the exact one I am planning on purchasing: eBay SSR-25

I would like to know if I have chosen an appropriate relay for my task or if there is a better way, and if I need anything else to accompany it (i.e. a heatsink).


texts: Partial switching of multiple LEDs using shift registers

texts:
I'm working on a hobby project where I have 4 groups of 16 LEDs (with a \$V_f\$ of 2.0V). I'm already past the point of putting the LEDs in parallel, since the entire circuit is powered by an Arduino (which can supply a maximum of about 50mA I've read)

Here's my circuit diagram. I left out the other 6 output pins on the shift register; 4 pins will be connected like \$Q_a\$, the other four like \$Q_b\$.
The part within the dashed box is a simplification of another circuit)

simulate this circuit – Schematic created using CircuitLab

My strategy is to use a single shift register for each group, so I'll be chaining 4 of them. This requires a series of two LEDs on each output pin, which should work, since I use a \$V_{cc}\$ of 5V.
I have two control signals per group, and the intention is to use one signal to ground the OE terminal. I thought that if I'd connect the other signal to the base of some NPN transistors, I get the following result:

SW1 closed: LED1 and LED2 are lit
SW2 closed: all LEDs are lit, unless SW1 is open

It is acceptable (and from the real setup, impossible) that SW2 is closed and SW1 is open, ending up with LED3 and LED4 unlit.

For the timing of the shift register, I'm using a simple Arduino program to have a single HIGH bit traverse through all shift registers. When it comes out of the \$Q_{h'}\$ of the last register, a new HIGH bit will be "inserted".

From my (limited) knowledge, I calculated the current as follows:

\$V_{R1} = 5.0 - (2 * 2.0) = 1.0V\$

\$I_C = \frac{1.0}{82} = 12.19mA\$

From what I understand of BJT transistors, I apply a base current of

\$I_B = \frac{5.0}{51,000} = 0.098mA\$

The transistor I'll be using is a 2N3904, which has a \$h_{FE} = 100\$  according to the datasheet.
I chose the resistor value so that it would be around the inverse of the \$h_{FE}\$ of the transistor, to "eliminate" the current gain:

\$I_E = (h_{FE} + 1) * I_B = 101 * 0.098mA = 9.8mA\$

I'm still a bit confused with the concept of \$V_E\$, since it would be a lot higher than \$V_C\$. Do I need an additional resistor between the emitter and ground?

According to the circuit below, will my idea work, or am I missing something?
I also wondered if I could "counter" the current gain by increasing the value of \$R1\$ and reduce \$R2\$ by the same factor? (I picked the \$82\Omega\$ value to get a 10mA current, which provides just the brightness I want for the LEDs)


texts: Is it considered a hack to use an op-amp in place of a relay?

texts:
I have an application that would traditionally be solved by the means of a relay. I have a 12 VDC load that I would like to switch on and off via a 5V microcontroller pin. But, I'm already using some 6134 (rail-to-rail) op amp chips in my project, and I have a free one I could use, since the IC comes with 4 op amps per chip.

Would it be considered a hack if I used my remaining op amp as a comparator instead of adding an additional relay to my circuit? If I put 2.5 V into the inverting input and the microcontroller pin into the non-inverting input, could that replace the relay? The positive rail of the op amp is already my 12 V load, and the negative rail is ground.


texts: Is this broadband noise calculation correct?

texts:
I came across the following paragraph from this application note:

I didn't quite get where the formulas come from to calculate the amplified signal and the broadband noise.
Why is signal noise not 5nV×1000 but 10nV×1000 even though the signal is 5nV where the voltage gain is 1000?
What is the generic formula they use to calculate the broadband noise here? They use:

input_signal × sqrt(BW_amplifier) × voltage_gain

Is that formula correct? When I do the multiplication it is not 1.6mV.


texts: Wireless torpedo charger: Coil design and torpedo detection

texts:
I'm building an RC submarine with torpedoes and I thought a good way to power them would be with a capacitor. To keep everything water tight, I am hoping to use wireless charging. Here's a rough diagram of what I am planning along with relevant dimensions:

The blue is water and the green lines are the primary coil which are onboard the sub (they wrap completely around the torpedo tube). Here's the circuit diagram:

What I want it to do is charge the torpedo while the reed switch is closed with a magnet. When the magnet is removed, the motor should spin and cause the torpedo to launch. The h-bridge is powered by batteries and the switching will be handled with an Arduino board via the digital pins.

My question is how to determine the number of turns I need for the coil and if there's any problems with the circuit? I know I need a secondary to primary ratio of about 1.2 to account for voltage drop in the rectifier. The capacitor on the torpedo needs to be charged to around 5V. If it helps, the distance between the coils is at minimum 5mm. I plan to drive the coil at 100 khz because that seems to be the limit for the arduino.

Additionally, in order to save power, I was wondering if there is some way to detect when the torpedo is put into the tube using the charging circuit? Kind of like how wireless phone chargers can detect a phone placed on them?

Datasheets:

N-channel mosfet: Link to IRLB8748PbF MOSFET

P-channel mosfet: Link to IRF7404TRPBF MOSFET

NPN Transistor: Link to 2SC5706-E

Diodes: Link to BAT54HT1G Schottky diode

Supercapacitor: Link to MAL219691204E3 capacitor

Motor: Don't know the type but it was taken from a plug in phone fan


texts:
I am trying to repair a broken toy car (a Bee-bot to be exact).

Each of it's two motors controlled by H bridges. One of the motors runs correctly both forward and reverse. The other motor runs only forward.

I believe the schematic is as such (for one motor):

I do not know what Y6, Y5 and 1G is but I assume they are transistors.

Since it has two identical bridges (one for each motor), with one of them working, I can easily compare them.

The signals are confirmed to be accurate low or high, and the motor is running fine in both direction with powered by another source.

When input is applied to input 1 on the GOOD bridge (motor runs fine), I get these voltages:

MR+: 0.3V
MR-: 3.3V (this is a bit counter-intuitive to me - feels
like it should be the opposite? have I measured wrong somehow)?
Between Y5 (near MR-) and 1G: ~0.5V

When input is applied to input 1 on the BAD bridge (motor does not run), I get these voltages:

MR+: 3.3V
MR-: 3.3V
Between Y5 (near MR-) and 1G: ~3.2V

Testing the Y5 near MR- as diode with multimeter between MR- and 1G reads 0.06V in both directions - i.e. it looks bad. Testing the other three Y5's on same pins gives expected readings of ~0.6-07V in one direction, UL in other.

Questions:

Is it likely that the Y5 transistor is the single failed point, or should something else be checked as well before replacing it?
What can I replace it with? I'm not able to find any specs of "Y5". I assume it is a silicon (~0.6-0.7V drop) NPN transistor, with Base against 1G, Collector against M-, Emitter against Ground. Is this accurate? What else has to match on the replacement? The current component is an SMD but I would be happy to replace it with something larger for easier soldering... Could it be replaced, for example, with a C547B that I may have lying around? :)


texts:
I'm very new to the electronics stuff. I've spent most of my discovering things so far, however there is something that I'm stuck on.

I want to get a PIC18F4550 to begin with, and I'm wondering if I can use a PL2303HX USB to TTL UART module to connect the chip to the programmer (image here).

If yes, would I need to connect RXD to RX/DT and TXD to TX/CK pins?

Yes, I know PICKit exists. I'm trying to find a way around that.


texts: Is it safe to make a dual supply out of two wall adapters?

texts:
I am trying to design a guitar distortion pedal circuit and I need +9 / -9 V dual supply in my application. I have two 9 V adapters:

https://www.phihong.com/assets/pdf/PSM03A-XXX.pdf

Would it be a proper way to create a virtual ground and dual supply if I connect the outputs of these two wall adapters in the following way?

What are the drawbacks? Would ripple be out of space? Or would it explode in some circumstances because I haven't seen any application as such?


texts: Difference between four matrices of state space?

texts:
I already know that there are two common types of representations used for mathematical modelling. One is transfer function and the other is state space.

When dealing with state space representation, we see 4 different matrices A (system matrix), B (input matrix), C (Output matrix) and D (feedforward matrix)?

What is the difference between all four of these matrices, especially 'A' and 'D' matrix? As the other two 'B' and 'C' somehow indicate their function/application that they might store input and output.


texts: How to interface camera to an atmega328 with bluetooth?

texts:
I am a newbie in microcontrollers. I read on the net that a camera can be interfaced to an atmega328. Only issue is that the atmega328 has less memory for even a single VGA image. Can i interface a SD card to the atmega and then store all the image in the card? If so, what is the maximum size of SD card atmega 328 supports?

Also, i want to interface a bluetooth module and then send the images captured by the camera to my cell.Is it possible with atmega328. or should i use some other microcontroller?

If someone can help me with the model no. of a compatible camera module for atmega, it would be really helpful!


texts: How do I non-permanently connect stranded wire to small screw?

texts:
This seems rather trivial, but I can't seem to find much information on this after a bit of searching online. I'm working on a project right now that requires me attach a passive electrode to a wire, in order to carry a signal from that electrode. The sensor is mounted via a small screw that runs through its center (my guess is on the order of 1/16 of an inch diameter across the threading, but I can't recall exactly off the top of my head).

I started out simply by wrapping the wiring around the screw, and securing it with a nut. Except this process is incredibly unwieldy because the screw is so thin, and the way the sensor is mounted doesn't give me a lot of room to get my fingers in to wrap the wiring and screw the nut on. Though it's proved to be more than just inconvenient, because I have to install several dozens of these sensors and also replace them regularly.

Is there some sort of tool out there that makes this easier that I'm not aware of? Or some sort of small, electrically conductive eyelet I can attach to the screw and then attach to my wires? Thanks in advance for any help you can provide.


texts: What is more conductive, copper or doped silicon?

texts: At room temperature, which is more conductive: copper, N-type silicon, or P-type silicon? What are their respective conductivities?


texts: What's the equivalent resistance of this circuit?

texts:
I am a student in 10th grade and our teacher gave us this schematic to work with (Remade with circuit lab):

simulate this circuit – Schematic created using CircuitLab

He asked us to find the equivalent resistance of the circuit. Based on my calculations, 24 Ohms should be the right answer. Apparently my teacher disagreed and told us it was around 2.5 Ohms or so.

I don't know which answer is the correct one, but I am fairly convinced that mine is the most correct one. Since even if my calculations of the series-parallel resistors are wrong, the minimum resistance is going to be 20 Ohms (R1 + R7).


texts: Anyway to avoid the startup delay on square wave generator (e.g. 555 astable) circuit?

texts:
In the classic 555 astable circuit the external capacitor charges to 2/3 of the Vcc (through R1 and R2) and then is discharged to 1/3 of Vcc (through R2) and then it continues to oscillate between 1/3 and 2/3 of Vcc.

I would like to avoid the initial delay while the capacitor is being charged from 0 volts.  The duration of the very first square wave produced by the circuit is almost twice as long as the period of all the subsequent square waves and it is this extended period (for just the first square wave) that I'd like to eliminate.

The problem also occurs with square waves produced with op amps ICs (as opposed to 555s).

Somehow maintaining the capacitor at 1/3 Vcc before the circuit is powered up is not an option.  Immediately before the circuit is powered up, there will be zero volts across the cap.

I would like the circuit to behave as though the capacitor had a lower capacitance for just the first cycle, and thus charges from zero volts to 2/3 Vcc though the same R1 + R2 as fast as the capacitor normally charges from 1/3 Vcc to 2/3 Vcc in all the subsequent cycles.

Is there a standard method of accomplishing this?

UPDATE:

I could not get @transistor's solution to work, at least not in a simulator.  What I did instead was add a separate R-C kick starter circuit:

If you fiddle around with C3 and R4, you can get the voltage across C1 to 1/3 Vcc very quickly.  When you do this, the 555's first square wave is the same duration as all the subsequent square waves.

Overall, I'd have to agree with @Dave Tweed's comment that this is starting to defy the spirit of using a 555 for its simplicity.  Plus, it's sort of a clunky solution, not having a comparator to shut off Q1 when C1 reaches 1/3 of Vcc.


texts: How is a PWM signal converted to Sine using a transformer?

texts: How does a sine choke exactly function? In most high power inverter systems, the primary side of the output transformer is always driven by a PWM signal. The secondary output which is sent to a load should also come out to be PWM. How does a pure sine wave inverter exactly convert this PWM into a pure sine wave?


texts: Modulation scheme for simple signal generator

texts:
As part of a vintage radio restoration project, I decided to build a simple signal generator for alignment.

The idea was straightforward, a short distance AM transmitter with a variable carrier frequency in the MW band (at least 550kHz to 1.6MHz) modulated by a fixed low frequency audio tone (2kHz ).  In my naivety, I decided to build the oscillators first: a JFET based Hartley for the carrier and a gain stabilized Wien bridge for the audio tone.  So far, so good and both oscillators perform very well.

The JFET carrier oscillator is described here: What's the purpose of the diode at the JFET gate in this Hartley oscillator?

I thought the final step of modulating the audio tone would be simple.  Boy, was I wrong.  I have spent several days of trial and error with various (suitable) AM modulation schemes with very little to show.  The montage below shows some of the modulators I've come across and I seem to be stumbling on the same issue with most of them: the band-pass filter!  This makes sense, of course since most modulators are designed for transmission on a single carrier frequency.  However, my requirement is that I can adjust the carrier across the broadcast band.

So, my question is this: how exactly do you design a modulation scheme for signal generator where the carrier frequency is adjustable?

Other notes:

One option I came across after I'd built the oscillators was explained (here).  In this case the author varies the supply to the carrier oscillator itself which solves the problem of needing a second band pass filter as part of a separate modulator.  However, I experimented with my JFET based Hartley and found that doing this led to a considerable amount of distortion (probably because the tuned circuit is at the JFET emitter).

I discovered that a major problem with many (all?) of these schemes is that even if you manage to get a half-decent AM output, when you adjust the carrier frequency you get large amplitude changes to the modulated output.  It's almost like you'll need some kind of AGC control in place, even if you did manage to alter the band-pass filter in line with the carrier adjustment.

I considered using the second (smaller capacitance) section of my air variable tuning capacitor to form the band-pass that would change alongside the carrier frequency section.  The result was a mess.  It was too difficult to pick a suitable inductance to track the changing carrier. So, a good idea that proved difficult to achieve in practice.


texts: I need to use the cs4270 for audio codec and I find that there are three bits to set the ratio select in Mode control part. I do not know how to set these three bits and what is the MCLK use for?


texts: I need to transmit data (less than 5Mbps) point-to-point over 100 ft. I prefer not using Ethernet due to the complexity. I can use low-scale FPGAs or similar chips if needed for functions like error correction control. I'm considering UART over RS-485/422, but I'm not sure if it can provide such performance. Do you have suggestions on not-too-complex solutions? Thank you.


texts:
I'm trying to reverse engineer the SPI communications between two chips. But, it's not clear who's master and who's slave.

I've found the chip select. Without lifting any pins or cutting traces is there a way to detect which end is asserting it?

The chips are:
CC1110 (SoC radio) and CY7C63803 (USB MCU). The chip select comes off of the SSEL (slave select) line on the CY7C63803 and into a GPIO pin on the CC1110.

The CY7C63803 is an SOIC, so I could lift a leg, but I don't want to break it.


texts: I notice that the mechanical life of some trimpot potentiometers specified in unit "cycles". But what "cycle" exactly mean?


texts: Why don't PC power supplies require heavy transformers?

texts:
When I take a look into most PC power supplyie (also some high power ones=800W) I don't really see transformers which seem big enough to handle the required power.
Looking around the internet, a transformer (e.g. 230V to 24V) with 100W of power is about the size and weight of these ATX power supplies with lots of times higher power.

I am trying to design my own simple mains power supply but don't understand how commercial power supplies get away with such small transformers while I seem to need a really big one(if I trust online ratings)

I suppose these ATX power supplies use PWM/are switching power supplies and not linear ones.

Can someone explain to me why they only need some very small transformers?


texts: Use 1.5 V Lithium batteries instead of AA alkaline?

texts:
My PowerShot A720 IS digital camera (from 2008) permits AA-size 1.2 V NiMH or regular disposable AA alkaline batteries. Can I use AA-size 1.5 V Lithium batteries?

The manual (pdf) warns against nickel-cadmium, but doesn't mention Lithium:

  This camera uses AA-size alkaline batteries or Canon AA-size NiMH batteries. While it is possible to use a size nickel-cadmium batteries, performance is unreliable and their use is not recommended.

Thoughts?

EDIT: Here are the proposed Lithium batteries.


texts:
I am looking to add overvoltage protection to a circuit of mine.

A standard way of doing this is with a crowbar circuit with a fuse to blow when tripped, thus disconnecting the circuit. However, I don't want to have to deal with replacing blown fuses. This leads to looking at resettable polyfuses.

However, I'm concerned about the condition where the overvoltage is maintained for a period of time - this would lead to the intended effect immediately, followed by a period of no current through the polyfuse, allowing it to cool, at which point we eventually get to a point where enough current flows to raise the voltage past my tripping point and the process repeats until the overvoltage is removed - this seems like unnecessary stress on the components.

Is there a better way of managing this situation? I've not really used polyfuses before - how long do they take to "reset"? The datasheet of the one I'm looking at doesn't mention this at all, but perhaps the period is long enough that it wouldn't really matter.

Simplified circuit for reference:


texts: Norton equivalent with a single voltage source

texts:
I'm trying to find the Norton equivalent with respect to the load resistor RL for the DC circuit below.

Each of the resistors have an equal resistance R. Removing the load resistor, I am having a lot of trouble figuring out which resistors are in series and parallel with respect to the load. It is very confusing with all of the different connections. Does anyone have any tips to simplify this circuit?


texts: How to pick/calculate component values for a tuned amplifier centered on 13.56Mhz?

texts:
Background

As a fun / learning project I wanted to build a circuit which can tell me if a given RFID reader on a wall is 125Khz or 13.56Mhz ( by lighting LEDs).
My approach is to build two filters which lead to diode detectors - one filter + detector for 125khz, and one for 13.56Mhz.

I was hoping to use a length of wire or an unmeasured coil of wire as the input (pickup).

Problem

I can't figure out how to calculate values for the tuned circuit - I havent found any online calculator or sensible derivation (I don't understand the math/electronics enough to do it from first principles, I know Ohms law + basic AC theory + putting numbers into formulas).

Complication: I cant give an exact value of the 'drive' (input impedance?) of the input coil, nor can I work out the impedance of the diode envelope detector on the amps output. Can we just guess these?

The whole circuit so far, including the 125Khz section

Why cant HF be as easy as 125Khz? Cheap op-amps work at 125Khz.

The tuned amplifier schematic so far


texts: Measuring the step length during walking

texts:
I would like to measure the step length during the walk and I am searching some ideas
to solve this problem.

I am not really an expert on sensors so I am trying to collect some information in order
to understand how to build a system for this purpose. Normally I use arduino with
accelerometers and pressure sensors embedded into shoes.

I was thinking that maybe a possible solution consists in finding the distance between
the two feet at every moment, and reading the distance values when each foot hits the
ground (such event can be detected by using pressure sensors).

I don't know if some sensors able to track small distances exist. In case can you
please give me a link where I can have some information?

Do you have any suggestion or hints to solve this problem?


texts: Junction between curved and straight edge in KiCAD

texts:
I have a round PCB with a tab that extends outwards for a connector. I am unable to get the outside lines to properly resolve and connect together at the ends.

Here is an image of the complete board and a zoom on the problem area.

How can I properly draw the outline so that the company will accept the file?


texts:
I did many research but couldn't find out what the problem it is. Actually my code as below. I am trying to implement a code in  C with XC8 compiler.

To enable a sentence on the LCD of the board while RB6 button is pressed. I enable INCTONbits.GIE = 1 and INTCONbits.RBIE = 1 and INTCONbits.RBIF = 0.

Inside of interrupt, the displaySentence() function is entered to infinity loop to see result. I checked all answers related with interrupt in here but didn't help my problem. What can be problem for RB7-4 interrupt, I am working on PIC18f8722.

void displaySentence();

void initialize();

void interrupt  RBINT_ISR(void){

    INTCONbits.GIE = 0;

 __delay_ms(10);

    while(1){
        displaySentence();
    }
    INTCONbits.RBIF = 0;
    INTCONbits.RBIE = 1;
    INTCONbits.GIE = 1;
}

void main(void)
{
    __delay_ms(15);
    __delay_ms(15);
    __delay_ms(15);
    __delay_ms(15);

    InitLCD();          // Initialize LCD in 4bit mode
    ClearLCDScreen();  // Clear LCD screen

    initialize();

    while(1);
}

void initialize(){

    TRISB = 0x40;
    PORTB = 0x00;

    // | GIE/GIEH | PEIE/GIEL | TMR0IE  | INT0IE | RBIE | TMR0IF | INT0IF | RBIF
    // |   1      |    0      |  0      |  0     |   1  |   0    |    0   |  0
    INTCONbits.RBIF = 0;
    INTCONbits.RBIE = 1;
    INTCONbits.GIE = 1;
}

void displaySentence(){

    WriteCommandToLCD(0x80);
    WriteStringToLCD("Interrupt");
    WriteCommandToLCD(0xC0);
    WriteStringToLCD("is working");
}


texts:
I am working on an application using ATmega328p atmel microcontroller. I started with the 28 PDIP version, but now I want to use the 32 TQFP, which I noticed has 2 extra inputs after compiling my Altium project.

These inputs are ADC7:6 which "serve as analog inputs to the A/D converter. These pins are powered from the analog supply and serve as 10-bit ADC channels," according to the datasheet.

I have read online that some people have got unknown results when they use the ADC and have floating inputs. What I read they've done is activate pull-down resistors, but I do not see how to configure them (since they do not belong to an I/O port). Also, my application does not even use the A/D converter at all.

What are the best practices? Should I connect an external pull-down resistor? Ignore Altium error?


texts: How to center a large symbol on the origin in KiCad

texts:
In Symbol Editor I drew a quite large symbol for an MCU.
I want to center it (I mean the rectangle that define its symbol) on the origin point.
I cannot find a way to do this precisely.
I'm using KiCad 5.1.6.


texts: Isolated UART communication: Which side should send the supply for the isolator?

texts:
I am in a situation to establish an isolated UART communication between two separate PCBs. The first PCB regulates and sends the required isolated power of the second one. The UART communication will be referenced to this isolated supply of the second PCB. There is an isolator IC on the first PCB. I will be using Si8621 if it matters.

Now the question is, how do I send the supply voltages of the isolator IC?

Solution 1:
Since the isolated supply is generated on the first PCB, I can directly feed the IC from the first PCB. This way, I only need to send the RX and TX lines on the communication connector.
Pros: A 2-pin connector will suffice.
Cons: Isolated voltage traces will dangerously travel across the PCB.

Solution 2:
I use a 4-pin connector and transfer the required power to the isolator.
Pros: Is there benefit in doing this?
Cons: I use a larger connector. I create a loop back of the isolated supply.

I am confused and I can't choose between these two solutions. Is there any rule of thumb for a situation like this? Please give me some suggestions.


texts:
I'm experimenting with UHF RFID. I have a setup that's working but my read range is only 1 - 2 feet. This is the equipment I'm using, it's all quite cheap, I don't mind spending more to increase the read range but I'm not sure which components would be most important to upgrade.

Antenna: LinkSprite UHF RFID Reader Antenna (902-928MHz, 8dBi RHC Pol)

Reader: Cottonwood: Long Range UHF RFID reader UART

Tag: Key Tag UHF RFID tag , EPC Gen2 (900MHz) (the little yellow ones on the cutedigi website)

I could upgrade to an antenna with 9dB gain, or even to a linear polarized 10dB antenna, I can't control the angle of the tags though so I'm thinking circular polarization may give me better performance. I don't know if an extra dB will make much difference though.

Alternatively, maybe I'm better to pursue higher-sensitivity, larger tags or a higher output reader.

I'd really appreciate any suggestions on this. Thanks.


texts: PIC programming - Get value of multiple buttons to a port

texts:
I'm learning PIC (pic18f4550) and pretty new to microcontroller programming. I'm trying get value of three button on PORTA and send it to a 8x8 led matrix as X coordinates through a 74LS595. The problem is that the value go to the led matrix doesnt change when i pressed the buttons to create different value. I'm simulating on Proteus so I guess I don't need debounce function. Here's my code and schematic:

#include<p18f4550.h>

#define SCK LATBbits.LATB0
#define DATA PORTBbits.RB1
#define SCL PORTBbits.RB2

void Data_in(unsigned char k){
    DATA=k;
    SCK=0;
    SCK=1;
}

void LatchData(){
    SCL=0;
    SCL=1;
}

void Send1byte(unsigned char data)
{
    unsigned char i,temp;
    for(i=0;i<8;i++)
    {
        temp = data & (1<<i);
        if(temp)
        {
            DATA = 1;
        }
        else
        {
            DATA = 0;
        }

        SCK = 0;
        SCK = 1;
    }

SCL = 0;
SCL = 1;
}

unsigned char getMatrixX(unsigned char in_X)
{

    switch(in_X)
    {
        case 0:      // the value stuck here
        return 0b01111111;
    case 1:
        return 0b10111111;
    case 2:
        return 0b11011111;
    case 3:
        return 0b11101111;
    case 4:
        return 0b11110111;
    case 5:
        return 0b11111011;
    case 6:
        return 0b11111101;
    case 7:
        return 0b11111110;
    default:
        return 0b11111111;
    }
}

void main()
{

    TRISA = 1;
    TRISC = 1;

    TRISB = 0;
    TRISD = 0;

    PORTD = 0x80;

    while(1){
        Send1byte(getMatrixX(LATA));
    }
}

This is link to my schematic: my Schematic

Really appreciate any solutions and advices. Sorry for my bad english.


texts:
Imagine a 20mm dc motor with a simple plastic propeller controlled by a microcontroller via PWM.

Consider the following correlations:

PWM - RPM
RPM - thrust
PWM - thrust

Are they proportional?
If not, what kind of correlations have they? And what makes them not proportional?


texts:
I'm trying to design a de-bouncer circuit , which is widely used in digital design . The module that I'm trying to implement is as shown below :-

I've written the following Verilog Module :-
`timescale 1ns / 1ps

module debounce_ckt(
input button,
input clk,
output reg result
    );

/************************************* Internal Variables **********************************/
reg Q1;
reg Q2;
wire EN1 = 1'b1;
wire EN2 = 1'b1;
wire xor_out;
/****************************** Debounce ckt Implementation code ****************************************/

DFF FF1 (button,clk,EN1,Q1);
DFF FF2 (Q1,clk,EN2,Q2);

xor g1 (xor_out,Q1,Q2);

counter C1 (clk,xor_out,~Cout,Cout);
DFF FF3 (Q2,clk,Cout,result);

endmodule

/***************************************** N-bit counter *************************************/
 module counter (clk, SCLR,EN,Cout);
     input clk;
     input SCLR;   // Clear of counter //
     input EN ; // Active 'HIGH' Enable //
     output reg [N-1:0] Cout; // Counter Output //

         // Time period of debounce ckt = T = (2^N + 2)/ f //
        // 'f' is the input clock frequency //
        // 'N' is the mod value of counter //

parameter N = 16;

            always@(posedge clk)
                    if(SCLR)    Cout <= 0;
                        else if (EN)
                            begin
                                    if (Cout == N-1)
                                            Cout <= 0;
                                    else
                                            Cout <= Cout + 1;
                            end

endmodule

/************************************* D Flip Flop Module (with Enable)**************************/

module DFF(input D,input clk,input EN ,output reg Q);

            always @(posedge clk or EN)
                    begin
                        if(EN)
                                begin
                                   Q <= D;
                                end
                    end
endmodule

Testbench is as follows :-
`timescale 1ns / 1ps

module tb;

    // Inputs
    reg button;
    reg clk;

    // Outputs
    wire result;

    // Instantiate the Unit Under Test (UUT)
    debounce_ckt uut (
        .button(button),
        .clk(clk),
        .result(result)
    );

   initial begin
      clk = 1'b0;
    end

always #5 clk = ~ clk;

initial begin

        #12 button = 0;#10 button = 0 ; #10 button = 1 ; #10 button = 0 ;
        #12 button = 1;#10 button = 1 ; #10 button = 0 ; #10 button = 1 ;
        #12 button = 1;#10 button = 0 ; #10 button = 0 ; #10 button = 1 ;
        #12 button = 0;#10 button = 1 ; #10 button = 1 ; #10 button = 0 ;
        #10 $finish;
    end

endmodule

The output 'result' is going to 'X' don't care state, when I'm trying to simulate the files.

Can anyone point out where the issue lies and what corrections are to be made. I'm not expecting a whole working code in the answer. I'd just want to know the error in my code which is causing this.


texts: Schematics for CJMCU-30 SGP30 sensor board

texts:
Does anyone have a schematic or detailed specification for the CJMCU-30 SGP30  Gas Sensor (TVOC/eCO2, triangle format) board?

I simply cannot find any for it, not even the information about interface voltage levels (is it 1.8V/3.3V/5V I2C?)


texts:
I am writing firmware for an ARM platform in which I want to have the main bootloader relocatable in memory rather than always loaded at a fixed address during boot. This means that I need a relocatable format stored in Flash, like ELF.

If ELF is used then I need an ELF loader stored in the ROM code that first gets execution after reset. While this is okay, I also need that same relocation code in the bootloader .. so I will have a lot of code duplication and loss of Flash space if. My intent for the ROM is to just load the bootloader from Flash, so it really is going to be very simple.

I toyed around with creating simple ROM stub that jumped into the text section of the stored ELF image (linked at the address it is stored at in Flash). While this sort of works, I think it might be overkill for my intent.

tl;dr: All I want/need is a relocatable format to store my binary in Flash. Are there other options that are perhaps simpler than ELF that retain relocation tables?


texts: Why I=(V(in)-V(out))/R in zener resistor circuit

texts:
I am a hobbyist electronics student who try to study "The art of electronics" book. I am having trouble understanding below passage from the book?

I am having trouble following what is going on with I = (Vin-Vout) / R part? How do we get that result?


texts: USB differential signal from single pin?

texts:
I'd like to make a device similar to the "Digispark", but what really bugs me about those (and most, if not all, V-USB designs, at least all I could find online), is the "waste" of a GPIO pin which is just the negative of another pin for the differential pair. so I wondered if there's an easy (and cheap+small, so low chip count) way to do the differential pair to single ended full duplex conversion?

methods I know of:

using an opamp to convert differential pair to single ended
using a NOT gate to convert single ended to differential pair

the problem is I obviously couldn't just put those two in parallel, or I'd produce a feedback loop.

Is this even possible without having a dedicated IC that understands USB or another "wasted" pin to indicate the direction? the circuit would have to distinguish between a driven output and a high-impedance input pin in real time essentially, and I have no idea if or how that could be achieved.


texts: What is wrong with this complex circuit analysis?

texts:
I tried mesh analysis of this simple circuit but it is wrong, i can't figure out why though.
I simply applied KVL using the two mesh currents.

EDIT:
the phasor Ig is known so i make the obtained linear system in a system with Vx1 and I2 as unknowns.
Plugging in the data from the problem:

R1 = 2;

C1 = 0.333;

L1 = 2;

Ig1 = −2;

C2 = 1;

R2 = 0.5;

ω =1;

I solve the system. The correct solution is Vx = -3-6j though.