texts:
I'm looking for barometer sensors for use in Arduino projects. One of the items I consider is the HP206C (at Reichelt, Germany). The vendor contradicts himself a little bit when he mentions 0.1 m and 0.01 m accuracy. Therefore I'm trying to look it up in the data sheet.
The original data sheet provided by Reichelt says:

Pressure Relative Accuracy +/- 0.6 mbar
Pressure Resolution of Output Data 0,01 mbar
Altimeter Resolution of Output Data 0,01 m

So, the datasheet contradicts itself, IMHO.
There's a newer data sheet by the Producer available as well. It says:

Pressure Relative Accuracy +/- 0.5 mbar
Pressure/Altitude Resolution in Pressure mode 0.01 mbar
Pressure/Altitude Resolution in Altimeter mode 0.1 m

That's ok so far.
The product is advertised with 0.1 m. Is that a realistic number? IMHO the output resolution is irrelevant, only the accuracy matters.
If my bank account has $1000.00, I can increase the output resolution to $1000.00000 but the values do not get better, right? The accuracy is still 1 cent, even if the output resolution is 1 millicent.
Is my understanding correct?
From the comments of @PlasmaHH, it seems I need to explain the application:

I need relative pressure measurement only, not absolute values. That's why I ignore other values in the data sheet.
I cannot wait "a few seconds" and take an average of the measured values. Reason is: I need to measure the height of a short flight, which lasts less than 2 seconds.


texts: Whats the cheapest protection circuit for this test equipment?

texts:
I am designing a piece of test equipment that has a DAC output.  The test equipment might be used to troubleshoot UUTs that are damaged or malfunctioning.  Therefore I want to add a protection circuit to the DAC output.  The DAC circuit itself is already designed.

The question is what's the cheapest protection circuit for this test equipment?

I already looked at the Bourns TBUs but the smallest ones they had had a
current limit of 100mA (which is too large).  They also had rather
large output impedance.
I already looked at PTC poly-fuses, but I couldn't find any that were rated
for > 100V, had a hold current > 3mA, and a trip current < 10mA.  Also poly-fuses with very low trip current have very high output impedance.
I came up with this circuit, using two depletion mode MOSFETs to form
a bi-directional current limiter.  I then reduced the apparent output
impedance using an op-amp.  This seems to work but it costs several
dollars and I was hoping to do better price-wise.

These are the design goals:

1)  The output range of the DAC is 0.0V to 5.0V.

2)  The DAC output bandwidth is 1KHz max.

3)  The protection circuit sits between the DAC output and the connector pin on the test box.

4)  The voltage present on the output of the protection circuit should track the input to within ±2.5mV when the output current is within the range of ±3mA and the input voltage is between 0.1V to 4.9V.

5)  When the input voltage is outside the range 0.1V to 4.9V then the protection circuit output voltage is not required to track the input voltage.

6)  When the output current is more than ±3mA the output voltage is not required to track the input voltage.

7)  The DAC output should survive a direct short to +33V DC indefinitely.

8)  The DAC and protection circuits should survive intermittent voltage spike of ±100V occurring for less than 1 second not more than once every 10s at the UUT pins.

9)  During a fault the protection circuit shall not allow more than 10mA to pass through the connector pin on the tester for shorts up to ±100V.

10)  After an over-voltage or over-current fault is removed from the pin the protection circuit should be un-damaged and revert to normal operation within 10 seconds (faster is better).

11)  The box is sealed and the user cannot open it to replace any parts or disposable fuses in the protection circuit.

12)  ESD is handled separately and not considered here.

13)  Protection circuit should not occupy an area larger than 20mm x 20mm on the PCB, and it shall not be more than 20mm tall.

I already have supplies 3.3V, +5.0V, and ±15V available for the protection circuit to use.  For cost and space reasons I would like to avoid having to add extra power supply voltages in the tester.


texts:
i want to understand the thought process and ideas behind these:

see the schematic

http://www.pololu.com/catalog/product/2124

1 - what is the n-FET and diode (Q1 and Q2) component means?

2 - why the 4.7kOhm resistors used instead of 10kOhm like in the datasheet here (also applicable to other circuit,this is just an example to help me understand) Datasheet

3 - how designers verify that the component values used will yield the desired result? i mean they are only provided with IC and its datasheet,sure they need to do simulations to verify the circuit. do they model the IC?How's the simulation done for e.g?

4 - any tut/books to help me understand better how to connect IC with external components?like from a pin of an IC with sensor/op-amp,choose values,what to consider, how to verify etc.
in short how to use the IC pin as a driver or input from other components.


texts: Should I use an asynchronous or synchronous reset?

texts: I am programming a Microsemi M2Gl005 FPGA and wondering which type of reset I should use. I currently have an asynchronous reset implemented, but I wanted to make sure that the part didn't prefer a synchronous reset. I checked the datasheets and found not much mention of it. Any thoughts?


texts: Do capacitors and inductors have initial voltage or current in small signal approximation problems?

texts: I'm trying to solve a small signal approximation problem. The operating voltage for the capacitor is 2 volts. I simplified capacitor by a linear one. In solving this problem should I consider the initial voltage of the capacitor 2 volts or 0?


texts: Is it possible to measure the distance of a WiFi access point from the receiver?

texts:
I have signal strength in dBm and frequency in MHz is is possible to find the distance??

Any idea about how to do it?


texts: 2 bit RF control without microcontroller

texts:
I would like to wirelessly transmit 2 bits without a microcontroller (basically control 2 LEDs wirelessly...), as having several receiving nodes the cost of the project would be driven very high.

I thought of using cheap AM RF modules (such as the Quasar QAM-TX1 coupled to the QAM-RX2), then code the 2 bits on the frequency output of an astable 555 and count it on the other end, but the system gets quite complex, difficult to implement (I am currently struggling to a. get a frequency which is multiplied by 2, 4, 8 from 2 switches only).

Am I neglecting an easier option?


texts: Simplest LED-transistor switch LED being on in switch's off-state

texts:
I'm very, very new to EE, so this might be a really basic question. I am trying to make a very basic LED-switch using a bipolar NPN-transistor. The circuit I use can be seen below.

simulate this circuit – Schematic created using CircuitLab

Now, when I prepare this circuit on the breadboard, the LED will dimly emit some light even when the switch is open. When the switch is closed, the LED turns fully on, as desired.

Does anyone know why the LED is on, even though the switch is open?


texts:
Everytime i run modelsim altera i get the output with 'z' in it and i dont know what is causing this.

Modules:

module orgate(
                input [3:0] a1,
                input [3:0] b1,
                output [3:0] w1
                );

assign w1 = a1 | b1;

endmodule

module xorgate(
                input [3:0] a2,
                input [3:0] b2,
                output [3:0] w2
                );

assign w2 = a2 ^ b2;

endmodule

module comparator(
                input [3:0] a3,
                input [3:0] b3,
                output reg [3:0] w3
                );

always@(*)
begin

if( (a3^b3) == 0 )
w3<=1;
else
w3<=0;

end

endmodule

module sumator(
                input [3:0] a4,
                input [3:0] b4,
                output [3:0] w4
                );

assign w4 = a4 + b4;

endmodule

module mux4(
                input [3:0] in1,
                input [3:0] in2,
                input [3:0] in3,
                input [3:0] in4,
                input [1:0] sel,
                output reg [3:0] out_mux
                );

always@(*)
begin

case(sel)

0: begin out_mux = in4;end
1: begin out_mux = in3;end
2: begin out_mux = in2;end
3: begin out_mux = in1;end

endcase

end

endmodule

Top module:

module top(
                input [3:0] a_top,
                input [3:0] b_top,
                input [1:0] sel_top,
                output [3:0] out_top
                );

wire w1_t,w2_t,w3_t,w4_t;

orgate P1(
            .a1(a_top),
            .b1(b_top),
            .w1(w1_t)
            );

xorgate P2(
            .a2(a_top),
            .b2(b_top),
            .w2(w2_t)
            );

comparator P3(
            .a3(a_top),
            .b3(b_top),
            .w3(w3_t)
            );

sumator P4(
            .a4(a_top),
            .b4(b_top),
            .w4(w4_t)
            );

mux4 P5(
            .in1(w1_t),
            .in2(w2_t),
            .in3(w3_t),
            .in4(w4_t),
            .sel(sel_top),
            .out_mux(out_top)
            );

endmodule

Tb module:

module circuit_tb();

reg [3:0] a_tb;
reg [3:0] b_tb;
reg [1:0] sel_tb;
wire [3:0] out_tb;

top T(
        .a_top(a_tb),
        .b_top(b_tb),
        .sel_top(sel_tb),
        .out_top(out_tb)
        );

initial begin

a_tb=5;
b_tb=13;
sel_tb=0;
#100

a_tb=9;
b_tb=13;
sel_tb=3;
#100

a_tb=9;
b_tb=4;
sel_tb=2;
#100

a_tb=9;
b_tb=15;
sel_tb=1;
#100

a_tb=15;
b_tb=15;
sel_tb=1;
#100

$stop;

end

endmodule


texts: Is it possible to control a PWM computer fan with a resistor? If yes, how?

texts:
I have a video card that is loud while idle, because the fan curve appears to be set rather aggressively. Unfortunately, this can not be changed via software.

The fan is connected with a regular 4-pin PWM header (black, red, yellow, blue).

I have some low-ohmage resistors (20-40 Ohms) and would like to try to limit the voltage supplied to the fan to find out if it solves the issue.

Normally, such adapters are available for 3-pin fans with a resistor on the positive lead. However, I am unsure if the same is possible with a PWM-controlled fan.


texts: What are fast and slow decay timings in the Allegro A3201 low voltage meter?

texts:
In the A3901 Low Voltage Meter Driver datasheet Figure 8 on pg. 10 shown below indicates what the output "IOUT 2/3-4" will look like given input "IN1/3 or IN2/4".

But Figure 8 does not mention anything about how long it takes for the output to rise from 0amps to +Ireg nor is there any mention about how long it takes when it falls from +Ireg to -Ireg (when it switches from Foward / Fast Decay to Reverse / Fast Decay).

The same question applies for rise / fall times for Forward / Slow Decay and Reverse / Slow Decay.

Am I not reading this figure correctly or has Allegro not provided rise / fall times?

Is there any way I can discover the rise / fall times myself? How?


texts:
I have done some soldering in the past but I have never taken any course or had proper training on how to use a soldering iron, but I need to be able to start soldering more regularly. My soldering tip has turned completely black within about 2 hours of work. I was tinning and wiping it with a sponge as I was working but at some point it became unexpectedly black and started to repel solder. I can not tin the solder to the tip anymore and it is completely black. I have tried using a damp sponge and adding flux but neither of things things work. Any suggestions?

EDIT: This was resolved by buying .03" solder, brass solder tip cleaner, and  "tip tinner".


texts: Performing small signal ac analysis with non-linear components

texts:
I have written a circuit simulator that uses Kirchoff's voltage and current laws to solve linear circuits containing capacitors, resistors, inductors and op-amps (where the op-amps are assumed to be linear), but I'd like to add support for diodes and transistors and I'm a bit lost as to how to do it.

My program is essentially an implementation of modified nodal analysis - using the user's specified circuit, I build a series of simultaneous equations into an admittance matrix and solve it for the circuit's input using a sparse solver. It works well for performing small signal ac analysis to calculate transfer functions and noise.

Diodes and transistors are of course non-linear, and must in the latter case have negative feedback applied by the circuit to linearise them. They do not have a (simple) frequency dependent resistance dependency like the passive components I have already implemented, but rather a transconductance set by the bias in the circuit, so my admittance matrix approach doesn't really work for circuits containing diodes and transistors. I think SPICE handles non-linear components by first finding the "dc operating point" of the circuit, then it replaces the non-linear components with equivalent impedances (perhaps with e.g. parasitic capacitance as well) but I don't know how to do that. In my current program, I do not need to calculate the dc operating point because this is implicitly zero due to the presence of only linear components. If anyone can describe the process of calculating the dc operating point of circuits with diodes and transistors, or if they could point me towards any documents or texts that describe how to perform such an analysis (or perhaps some source code in a high level language), I'd be grateful!


texts:
I was just wondering what is the function of the *EP pin on most TQFN package chips?

It says I should connect EP to ground, what happens if I don't ground it (I forgot)?


texts:
I have used digital Isolators before in unidirectional Designs. I am now faced with isolating a bidirectional digital signal line.
Specifically I would like to isolate the 2-wire debug interface of an STM32 and the STlinkV2. I have found a circuit that claims to be able to do this for a generic ARM Cortex. It uses an SI8662 6-ch, digital Isolation IC.

Here is my schematic:

I have implemented the design on a prototype pcb. The unidirectional CLK signal arrives in quite a good condition after the isolator. The bidirectional Data signal however is severely degraded. Obviously this is due to the chain of the two isolator channels that feed back into the signal with a delay.

Here is a scope image of the Data line after the isolation IC:

My understanding of the cicuit is, that the 4k7 Resisors dampen the feedback signal and therefor the feedback should not be visible if the line is not driven at  the outher side of the isolator. Is this correct? If so, how would one choose the values for these resistors?

If this is bad way to do it, is there any other approach to isolate bidirectional data lines?


texts:
I'm using an H-bridge (L298n) to actuate two motors, so I've connected up a battery pack to the supply voltage in, to power the motors, and I've connected the logic supply voltage in to the arduino 5v out. (All are grounded.)
When the arduino is off but the drive power is connected to the H-bridge, the power goes up the logic line, and tries to power the arduino from its output.

Is this normal H-bridge behaviour, will it damage my board, and how can I stop it?


texts: Can ultrasound be used to determine distance without line of sight?

texts:
Is it possible to determine the distance between 2 devices (using phase shift, time of flight or any other method) without line of sight?

In the affirmative case what's the precision and accuracy for distances below 50cm, and where could I get good information about that particular method?


texts: Why should we choose to go for a smaller motor (4.5 kW vs 6 kW) for go-cart?

texts: We are thinking of using a 4.5 kW motor and not a 6 kW one. Due to some constraints and rules, the maximum power a motor can have is 6 kW. So why is it recommended to use a smaller motor? And does it have any performance benefits or drawbacks?


texts: Identifying this "IC”, Trying to reverse engineer a board

texts:
Part 1: the board and how it's connected

I'm looking at a headphone sound amplifier that is used to help experts detect pests in palm trees when a microphone is placed on the trunk of the palm tree. Here's what the board looks like on the front,

On the left side are 9V battery wires coming in to supply the whole circuit . Top right is ( i presume ) microphone pre-amplifier circuit  which has input from a microphone ( silver Wire is the Signal Line while the bare wire is ground ) , the output of the BJT microphone circuit (brown wire) gets through a potentiometer to the input of the unknown IC (red wire) , the IC is then connected to the purple and blue wires which go to the headphone . The yellow and green are 9V Lines that are connected / disconnected through a switch .

Part 2: my conclusions for far

Here's my guess,

The BJT circuit is a microphone preamplifier circuit .
The IC is some sort of a special purpose Audio-ish amplifier .

Part 3: schematic of the board

Part 4: my questions

What is the IC Model/Type/Category .
BJT Circuit drawn earlier ( Preamplfier ? ) .


texts: Should I use Multi Transaction Translator?

texts:
I'm designing a board which has two USB 2.0 Full-Speed (12 Mbps) USB-UART controller (CP2108).
These controllers will be communicating with the PC via an USB2422 HUB.
This hub has got a Single Transaction Translator, but it's cheap and doesn't need a lot of external components.
I have a bit of doubt that this design will work properly with this hub.
Is it possible that there will be communication and speed problems? Maybe I should use another hub which has multi Transaction Translator?


texts:
Circumstances :

The power supply to our home is faulty and runs very low. Sometimes as low as 138V, most of the time 170V,  but never 220V as it should. (We are in South Africa)

Sometimes the UPS from my computer alarms like when there is a power failure, but actually it is still on.

My question is how low is the power when this happens?


texts:
I have a Power Supply of 24 volts and 2.5A.

I need something like that:

http://i.imgur.com/z4oJukD.png

I need a power supply of 24V and almost 1500mA and another of around 8 volts and 500mA (to suplpy an Arduino). It is possible with this connection? Or I nees something like http://www.amazon.com/LM2596-Converter-Module-Supply-1-23V-30V/dp/B008BHAOQO/

How much the resistors would be?

Thanks!


texts: Can poor PCB fabrication process / assembly, and the type of solder used cause thermal EMF (seebeck on PCB) problem? Is it affected by the type of the material used? For example, quality of plating, vias, use of different metals such as gold, tin, copper etc?


texts:
I am working on a personal project that will involve driving a latching 9V/DC solenoid from an arduino. The circuit I've come up with is dependent on two things, that I haven't quite figured out yet:

1) The arduino needs to provide a DC voltage for a timed interval. This is to power a SPDT relay during whatever time it takes to charge a capacitor.

2) Same as in 1) but the DC voltage needs to be of reverse polarity.

I understand the use of MOSFETs to boost voltage and I know that H-bridges can be used to reverse polarity, but how do I combine these two elements?

I know there are tons of ICs, motor drivers, shields and the like out there that would provide an easy solution; I would however like to keep things as low-level as possible in order to learn something from it.

Thank you.


texts: Why touchpad starts acting weird when connecting a cheap USB-C charger?

texts:
I recently bought a cheap USB-C power delivery charger and 2m USB-C cable for my Surface Go.
When I connect it, everything seems to work fine, it charges at full speed, etc, but there's one weird thing:
The touchpad starts acting weirdly, as if it received random signals. Touchscreen seems to work fine though.

My question is, what could have caused this?
I'm not looking for a solution, because that would obviously be to buy better charger, rather for explanation what exactly might be happening.


texts:
I need to run 12v motor with using Raspberry Pi. I made a circuit which works but then I noticed a "little" problem. Pi's software PWM signal is only 3 volts so BUZ11 doesn't open enough.

I found this schematic:

Is it possible to somehow crank my PWM signal up? Ex. Using that schematic given with inverted pwm? Or can I just use transistor before FET to raise pulse voltage?


texts:
I am working on a project in which I have to simulate a heat activated alarm. I have attached two images. One of which is a Proteus circuit image that i have made. When i start its simulation the speaker attached in the circuit doesn't play any sort of sound. Even if i raise the temperature to 150 degrees. The circuit diagram that i am following for this circuit has also been attached.
I guess there must be some thing that i am missing. Can anyone help ??
Regards,
-Rehan


texts: Why transistor is non-linear in Cutoff & Saturation mode?

texts:
I am imagining Linearity in the sense that

F(ax+by)=aF(x) + bF(y)

Now suppose I have BJT characteristic curve :

In Active region, The response is : Ic = F(Vce) = const. So it is linear.
In Cut off region, Response is : Ic = F(Vce) = 0.
- No matter how large the increase in Vce, Ic is still zero. It is Similar to Air gap. So it should be linear as well.
In Saturation region, Response is : Ic = const * Vce. With const being the slope of the curve. In reasonable Vce, I see this slope is of a straight line (not of a power function). So it is also linear in this region.

What was wrong in the above argument that I applied to BJT ?

Edit: Actually , function : y = b is non-linear map


texts: How loop gain is related to complete transfer function?

texts:
I am trying to understand how loop gain of system determines the stability of a complete system.
Loop gain is given by 1+GH where G is forward transfer function (TF) and H is feedback factor.
If we make loop gain stable then how it is possible that my transfer function is also stable? because  the poles of H becomes zeros of transfer function. So the complete systerm response changes?
How I can determine the transfer function shape from loop gain/Characteristic equation?


texts: I have designed a memory system that has 10KB ROM followed by 6KB of RAM. The ROM begins at 0000H. I had to use two 4K x 8bit ROMs and one 2K x 8 bit ROM. I also have to use one 2K x 8bit RAM and a 4K x 8bit SRAM. The SRAMs have to have two input controls , CE and OE and WE. Is this diagram correct , how can I produce WE in this diagram?


texts:
I was wondering Where I could find the derivation for the complex power formula, S=VI*/2, where S, V and I are complex phasors.

I've seen a whole bunch of verifications where people sub stuff into the equation to show that it happens to work.

Here's what I know so far,
If \$ V=V_{M} ∠ \phi _{V} \$ and \$ I=I_{M} ∠ \phi _{I} \$ and \$ S = V_{RMS} \cdot I_{RMS} \$,
then \$ V_{RMS}= \dfrac{V_{M} ∠ \phi _{V}}{\sqrt{2}} \$ and \$ I_{RMS}= \dfrac{I_{M} ∠ \phi _{I}}{\sqrt{2}} \$ and S = Vm∠ø_v*Im∠ø_i/2 \$ S = \dfrac{V_{M} ∠ \phi _{V} \cdot I_{M} ∠ \phi _{I}}{2} \$


texts: Create a CMOS circuit from a logic function

texts:
I have to create a CMOS circuit from the logic function: F= ~A + B (notA or B). I made the truth table but I'm stuck here trying to make the CMOS circuit. Any ideas anyone? Thanks!

I know it's the CMOS circuit for the NAND gate. I tried to change to get the results I want but I'm stuck.


texts: Why the don't the theoretical and practical output of comparator match for small input?

texts:
I have been using TL084cn IC which is basically an amplifier IC.

I was giving the input to it of amplitude around 450mv.

This IC is capable of providing a slew rate of 13.

The Vcc given to it was 5V and -Vcc was GND also the inverting terminal was grounded so basically the opamp was being used as comparator.

Theoretically the output should have been 5v for positive half cycle of the input however the output was only 3.6 V.

Why is this so?

Datasheet of TL084CN


texts: How would I go about reverse-engineering RF lights?

texts: I have some ceiling fans and lights throughout the house that we control with RF remotes. I'd like to be able to automate these lights with my raspberry pi, but in order to do that I'd need to figure out the frequency and how the remotes communicate. Advice?


texts: LTC2498 Temperature Sensor Chip Code via SPI

texts:
I would be very grateful for your tips for my present problem definition:

I have a microcontroller ATmega128RFA1 with integrated Zigbee with UART-USB(TTL Converter) attached to the PC.

From the ATmega128RFA1 I have connected via SPI a LTC2498 Temperature Sensor Chip.

I need to read The Temperature from LTC2498 on The Terminal Program in my PC.
The scheme is as follows:

LTC2498--SPI--uC(Programmed with code Read_ltc2498)--UART_USB--PC.

The code with which I am working is as follows:

#include <avr/io.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <util/delay.h>

#define DD_MISO 3
#define DD_MOSI 2
#define DD_SCK 1
#define DD_SS 0

void uart_init()
{
    uint16_t temp = ((8000000)/(9600.0*16)-1); //Berechnung Übertragungsgeschwindigkeit

    UBRR0L = temp; //Übertragungsgeschwindigkeit übermitteln
    UBRR0H = temp>>8;

    UCSR0B |= (1<<TXEN0)|(1<<RXEN0)|(1<<RXCIE0); //Senden und Empfangen freischalten

    UCSR0C |= (1<<UCSZ00)|(1<<UCSZ01);  //Übertragungsformat: 8-Bit

}

int sendestring(char *s)
{
    int i=0;

    for(i=0; s[i] != '\0'; i++)
    {
        while bit_is_clear(UCSR0A, UDRE0); //warten, bis UDRE0 = 1 (Senderegister frei)

        UDR0 = s[i]; //ein Zeichen senden

    }

    return 0;
}

void SPI_MasterInit(void)
{
    //Outputs: MOSI, SCK, SS
    DDRB = (1<<DD_MOSI)|(1<<DD_SCK)|(1<<DD_SS);

    //Enable SPI, Master-Mode, set clock rate fck/16
    SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
}

int SPI_MasterTransmit(char MOSI)
{
    //start Transmission
    SPDR = MOSI;

    //wait for transmission complete
    while(!(SPSR & (1<<SPIF)));

    //returned data from slave to master
    return SPDR;
}

int main()
{

    char str[20];

    // Thermoelement an CH0 und CH1
    char masterOut1 = 0b10100000;

    // interne Temperaturmessung:
    char masterOut2 = 0b10000000;

    char result;
    uint32_t masterIn = 0;
    uint32_t Temp = 0;

    uart_init();

    SPI_MasterInit();

    for(;;)
    {

        _delay_ms(500);

        //CS des Thermochips auf low
        PORTB &= !(1<<DD_SS);

        //Byte1
        result = SPI_MasterTransmit(masterOut1);
        masterIn = (result & 0b00011111);  /*last 3 bits lost/*
        sendestring(str);

        //Byte2
        result = SPI_MasterTransmit(masterOut2);
        masterIn = (masterIn<<8) + result;

        //Byte3
        result = SPI_MasterTransmit(0);
        masterIn = (masterIn<<8) + result;

        //Byte4
        result = SPI_MasterTransmit(0);
        masterIn = (masterIn<<8) + result;

        //CS des Thermochips auf high
        PORTB |= (1<<DD_SS);

        masterIn = (masterIn>>5) & 0b00000000111111111111111111111111; /*Last 5 bits lost/*

        sendestring(" masterIn: ");
        sprintf(str, "%ld", masterIn);
        sendestring(str);

        //bei interner Temperaturmessung: Temperatur in °C berechnen laut Datenblatt Seite21
        Temp = (masterIn*4/1570)-273;

        sendestring(" Temp: ");
        sprintf(str, "%ld", Temp);
        sendestring(str);

        _delay_ms(2000);
    }

    return 0;
}

I have tried change in SPI function the 4 modes for CPOL and CPHA bits in the SPCR Register but doesn´t work.

With the next chars I have LTC2498 configured as follows:

32 bits:
Byte1= 10100000;
Byte2= 10000000;
Byte3= 00000000;
Byte4= 00000000;

The results are around this:
result1: 11111111 masterIn: 16777215 Temp: 42471

masterIn = DATAOUT according to the LTC2498 DataSheet has to be around 80000, so is too high.

Could anyone help me with this problem?


texts: I have a simple question. I need to make the PFET or PMOS FinFET weaker than minimum size when nfin=1. So Can I change its length from default  to l=2n in the netlist for simulation? It worked but I want to see if this is actually doable in fabrication.


texts: High level present in a pin of a non-powered IC can damage it?

texts:
I'm using a TXS0108E to convert from 5V to 3.3V and vice versa. The schematic is below:

In the datasheet, in section 6, I read the following:

Voltage applied to any output in the high-impedance or power-off state, VO:

A port :

     MIN: –0.5V
     MAX: 4.6V

B port:

     MIN: –0.5V
     MAX: 6.5V

Voltage applied to any output in the high or low state, VO

A port:

    MIN: –0.5
    MAX: VCCA + 0.5 V

B port:

    MIN: –0.5
    MAX: VCCB + 0.5 V

Some of pins in B port are energized when the IC is not powered at all. So I was wondering, would this be a problem ? Normally it is a problem to ICs, would this IC be a exception ?


texts:
I have a Leeson 3/4 HP motor available to me, which I want to turn a pulley on my lathe and control voltage via a Penta KB Power KBWM-120.
I am a little lost on how best to do this or if I have the right combination of devices.  I am going AC 110V into the KBWM device, which has two DC outs (L1 and L2).  The motor wiring diagram has L1, L2 and L3. What would L3 be in this situation?

Also, the motor has settings for 208 or 230v, but my KBWM outputs 0-90V. Would I need to get a 240V controller to run this motor?


texts: Serial port from PC not reaching the MCU

texts:
I'm trying to send some data from the PC to my STM32L432KC Nucleo board using UART.
Transmitting data to the PC works just fine, I'm receiving data through the STLink Virtual COM Port which I can see using any Serial Monitor like TeraTerm or others.
The problem is with RECEIVING the data from the PC. I've tried sending data using TeraTerm and Hercules and I also checked with Serial Data Monitor if the data is being sent and it looks like it is. But nothing shows up on the UART RX pin (checked with an oscilloscope)
For clarity - I'm not posting any code because the signal doesn't even reach the RX pin so it's not a problem with processing that data.
My process:

Connect the board to PC:

Board configuration in CubeMX:

Sending data through COM3 using TeraTerm or Hercules software:

As I click "send" I'm checking with an oscilloscope if anything shows up on pin A2(PA3) (which is the UART RX pin) - nothing shows up there
Additional info: Sending data from the board to the board works just fine. The problem is with PC->Board


texts: I'm trying to calculate the power of a signal and my tutor has given me this formula to do it. I've spent the past while building a program and now the foundations are there it's time to implement the maths side of it. The problem is I can't actually read it. Would someone be able to transcribe it and explain it to me?


texts: Do I need to put a resistor in series with relay coil?

texts:
I need to design a circuit to drive a relay and I have some doubts.

Do I need a resistor in series with relay coil, I mean, between
transistor and relay coil ?
Why I always find relays with 12V, can I use a 5V source to energize the coil?

Unfortunately, I don't have current specification neither a relay model. My doubt is about functioning, I'm afraid to fry the relay or the transistor.

simulate this circuit – Schematic created using CircuitLab

:


texts: Is it safe to use a stripboard for a 22V 10000mAh LiPo circuit?

texts: I have a circuit that acts as a switch between 2 LiPo batteries. I tested the circuit with 3.7V batteries on a breadboard. But now can I implement this using 22V 10000mAh LiPos on a stripboard or is the current too much ? Should I get a custom PCB instead?


texts: How to choose PCB manufacturing technology/factory?

texts:
I have sent some PCB designs to factories for prototyping. The price, however, varies greatly. Some ask 200 USD for a four-layer 5*10 cm PCB prototyping, while some only ask for 50 USD. I assume that there are differences between these two factories. However, I could not find the differences. Could I ask for some advice here?

My application:

Mixed signal circuit, with precise analog circuit(10 pA precision) with MCU runs at 168 MHz with internal clock. It uses a 20 MHz SPI.
Long term stability is a concern.

Questions:

What are the criteria to choose an appropriate PCB manufacture?
Should I care the plating? I noticed different processes using tin/gold/Pb and etc.
What else kind of parameters should I check?
How could I know the quality of a PCB?


texts: Help for find Camera Datasheet or interface to st32f103

texts:
I want to use of S302's Camera(the S302 is a mobile phone with a good camera) and interface it st32f103 but, unfortunately I can't find any datasheet for it. Also, I can find the schematic of Phone and can to some things of it but I think it's not enough.

Where can I find the datasheet of the camera? If we can't find the datasheet then help me until to use of it. On the back of camera wrote:

SAGEM

I think I can to use I2C for interface it because you can find some I2C's pins in the schematic. look:

Any suggestions?


texts: Do Peltier and heater make a good combo for thermostat?

texts: I want to achieve 0.05C stability in closed space to fit 24 bit ADC and voltage reference. Is it a good idea to use Peltier and heater together ?


texts: Implementing a multiplexer for a given function

texts:
I am a Little bit stuck here. Lets say we have the function $$Y=BC+\overline { A } \overline { B } \overline { C } +B\overline { C } $$

How can I can implement this function with just a 4:1 multiplexer?


texts: Power MOSFET gets hot while driving Peltier by step-down buck voltage converter

texts:
I have a TEC1-12712 Peltier element, which I am driving using Arduino microcontroller through IRFZ44N and buck step down converter (to smooth PWM).

Overall, circuit consists of:

12V, 8.5A max DC power supply
5V, 40mA, 1kHz PWM square wave signal from Arduino microcontroller
Totem pole gate driver to drive IRFZ44N gate (stolen from here)
IRFZ44N power mosfet with heatsink and ventilator (49A Id)
Buck mode step down converter (stolen from here)
TEC1-12712 Peltier element (1 Ohm, non inductive load)

After powering on and giving 5V to the gate driver input, the MOSFET becomes immediately hot (to touch), even when PWM is in full cycle (no pulse).
Is that normal? It is rated to handle high currents (Id = 49A) and gate should be fully open (totem pole gate driver).

I was able to keep it running a few times already for 30 minutes without burning it but I am worried if there is something wrong and if it survives for a long time.

BTW: When I apply PWM signal (50% duty cycle, 1kHz) the buck converter gives interesting, quiet buzz. I was unable to record it since fans cover it up. Is that normal or a sing of something being wrong?

Could you please suggest an improvements or point to a mistake I could have done?

Disclaimer: I am an absolute & total noob and this is the first circuit I ever build. So please forgive me if I even phrased something inaccurately.


texts: Countdown to ON timer switch for appliances?

texts:
I have an unusual application for a countdown timer switch.

I need to turn OFF a refrigerator for a  limited amount of time and have it automatically turn back ON after the timer expires.

The purpose of this is to ensure there is not an annoying hum from the compressor while watching TV near a wine refrigerator.

The wine is going to be just fine with the compressor disabled for a couple of hours but I don't want to ever forget to turn it back on after I'm done watching my movie or whatever.

I've been searching for a countdown timer switch that can do this but so far have only found switches that will turn the power ON temporarily and then turn it back OFF after a specified amount of time.  I need the opposite.

Is there such as thing as a countdown timer switch that counts down and switches ON rather than OFF after the timer expires?

If not, is there anything analogous to a NOT gate for appliance-level AC power which when powered switches another circuit OFF and when unpowered, switches another circuit ON?


texts: Programming flash in manufacturing environment using Codewarrior TAP

texts:
I would like to use the Codewarrior TAP to program flash on boards in a manufacturing environment.

My target is a P4080 CPU w/Flash memory. I am currently using an Abatron BDI-3000 for this, but that device is now EOL and I will eventually need to find another way to program the flash. It looks like the Codewarrior TAP can do it, but I can't find any solid clues for how to do this.

I suspect it can be done because some engineering folks in my org have used the "Codewarrior IDE" to program flash. However, I would very much like to avoid using the IDE in a factory. I know that I can telnet to the TAP, but there doesn't seem to be any analogous CLI commands to what I used on the BDI-3000. There's some words about the TAP having support for gdb, but I am not sure of the capabilities of gdb.

My tasks are very simple...

Erase some memory range. BDI command was "erase 0xeff80000 0x20000 4"
Program a binary from a tftp server. BDI command was "prog 0xeff80000
/path/in/tftp/server/MyBinary.bin bin"
Verify the binary was programmed correctly. BDI command was "verify
0xeff80000 /path/in/tftp/server/MyBinary.bin bin"

The problem is I don't see the equivalent of any program, erase, or verify commands in the Codewarrior TAP manual. Moreover, there doesn't seem to be a way to specify a TFTP server which contains binaries to write to the target. But if I need forget about TFTP and put the binaries on the host PC, that's OK too.

Can anyone help me get started with this? I just need to get pointed in the right direction. Alternatively, what other tools can I use to program this flash in a way that is automation/factory friendly?


texts: OP-AMP Positive/Negative Feedback together

texts:
I've read several articles about the application of OP-AMP negative feedback. As far as an application for positive feedback, I came across hysteresis and it makes sense.

Are other uses for positive feedback other than hysteresis?

I am also not sure why in some applications they use both the positive and negative feedback path?

I've leanred that if the net gain on the negative feedback path is more than the net gain on the positive feedback path, then it acts as an OP-AMP with negative feedback, and vice versa.

If we tend to get an overall negative feedback or an overall positive feedback, then what is the point of using both paths at the same time, at the first place?
Why do we even bother ourselves to use both paths, if at the end all we care about is to have either a net positive or negative feedback?


texts: Trouble using Noyito TTL to RS232 mutual converter module

texts:
I need pixhawk to read a novatel gps which has rs232 output. So I purchased a noyito TTL to RS232 mutual conversion module, assuming the word mutual means it can work as rs232 to ttl converter as well.
https://www.amazon.com/NOYITO-Module-Conversion-Arduino-communicates/dp/B07BJJC3R6
The Novatel GPS outputs data in NMEA format, but the Pixhawk doesn't seem to recognize the GPS. When I wired it to an Arduino to see if the messages are making it through, I was unable to see anything on the serial monitor. (I connected the VCC,GND,TX,RX pins to the 5V,GND,TX,RX pins on the arduino). I'm wondering if:

The TTL converter I purchased is a one way converter

If issue has something to do with nmea data I'm passing through

Here is how I have wired it:
From the converter, I have VCC, GND, TX, RX going to the +5V,GND, TX,RX respectively on the Pixhawk. (see image below). The GPS is connected to RS232 side of the converter.


texts: Is the DDR3 specification required to implement DDR3 modules

texts: The DDR3 specification maintained by JEDEC costs approximately 6k USD annually. Is it absolutely required? If this is the wrong place to ask this I apologize.


texts: Back-to-Back PMOS high power dissipation

texts:
I have created a circuit in LTspice to switch between two power sources (10s Li-Ion batteries).

V1 and V3 resemble the power sources which vary from 30-42V. V2 and V3 are output pins of an µC. R3 is a the load.

U1-8 are BBS3002 PMOS with pin1=Drain, pin2=Gate, pin3=Source

It seems to be working, with the exception of a strange high power dissipation in the PMOS (* BBS3002 is the PMOS*) in the following state:

V1=42V, V2=0V, V3=30V, V4=3.3V --> Pd in U1= 8.1 KW

I think it is due to the low voltage drop over U1 and U4, which will open the PMOS in this spice model, altough threshold is at least -1.2V.

Can someone explain to me, what is happening here ?

edit: added PMOS specs (sorry for bad symbol, this is the model from On Semi)


texts: Waterproof Fan Failing In A Chamber With 100% Relative Humidity

texts:
So I've built a aeroponic tower that uses an ultrasonic atomizer instead of spray nozzles. This approach is called "fogponics" across the hydroponic community.

My Problem is that I have to run a fan within the atomizing environment which requires the fan to be in contact with 100% humidity at all times. The fans purpose is to recirculate the generated vapor continuously. This of course brings into question the need for a waterproof fan.

I bought 2 from ebay recently and was advised to run them at 12V instead of 24V to keep the current from going too high due to the added drag of the water that would kill the driver if it was running at 24V.

Here's what I bought: http://www.ebay.ca/itm/40mm-20mm-New-Case-Cooling-Fan-24V-Waterproof-to-IP55-2-Wire-Ball-Brgs-376-/382060138074?hash=item58f48f0e5a:g:IE4AAOSwBOtZAQxW

The 2D image below shows my implemented design (Right) and an older version that better illustrates how the air circulates(Left)

Here are a few shots of my prototype:

The waterproof fan lasted around 55 hours cycling on for 2 mins and off for 1. I noticed that the sound changed towards the 40 hour mark; It started to lower in pitch and would fluctuate irregularly between it's original pitch the lower pitch every 2-10 seconds.

The fan would not start again after it's untimely demise.

What do you folks think is happening? I could really use a solution or suggestion to help me through this because I'm at my wits end and thinking about a redesign is disheartening when I'm so close!


texts: Calculating the model complexity for wireless sensors

texts:
I am coming from geoinformatic background and I do not know anything about the electrical issues.

I have a model for outlier detection for wireless sensor and I want to assess the energy complexity in terms of computation and communication and storage.
My model uses the data that were stored before and fit the model and observe every 2 minutes data and aggregate them and send massage to other neighbor point when identify outlier.

I have proposed to use a piece of information plz guide me to interpret these information in order to calculate the complexity.

TICC2420 is programmable in eight levels (from  approximately –25 to 0 dBm)
Mac layer   IEEE 802.15.4
Transmit bit rate   250 kbps
Operation frequency     2.4 GHz
Packet size 128 bytes
Radio model TI CC2420
Transmit current at 0dBm    17.4 mA
Transmit current at -25dBm  8.5 mA
Receive current 18.8 mA
Supply voltage  (1.6 – 2.0 V)

E=P×T

P=I×V

T=(Packet Size)/(Transmit bit rate)


texts:
I have tried to understand how to match my 50 ohm pcb trace, which is carrying a high-speed data signal, with a digital chip's input pin.

The problem is that I don't understand why the calculations explained in this note from Texas Instruments are correct or even usefully.

http://www.ti.com/lit/an/slyt413/slyt413.pdf

On page 9 the characteristic impedance of the pin is calculated, and it seems that this should be used to match my series termination with the transmission line using the standard Zseries = Zo - Zout.
They state that this formula defines both input and output impedance of the pin.

I assume that the transmission is longer than the raise/fall time of the output driver for my questions, and that there is no termination at the receiver, so a wave of double voltage is reflected, which I think is normal for series termination.

Now for the questions:

If the drivers MOSFET is ON, this would cancel the effect of C_COMP in the IBIS model, so does the reflected wave returning form the receiver really see the calculated impedance (+ the series termination) ?
If the pin is configured for input, I don't see that the characteristic impedance has any use. Say that we have calculated the pins characteristic impedance to be 50 ohm, it would be perfectly matched the line, but when configured for input, the wave has no where to go but back towards the driver, since the L-C circuit is reactive ?

But what am I missing...


texts: SD card reader, had to add 1k resistor to make it work, why?

texts:
I was having a problem making my sd card reader work with Arduino Mega, I tried a lot of things to no avail until I read somewhere that I should try putting a 10k or 1k resistor in series with the MOSI and SCLK pins but for some reason in my case I had to put a 1k resistor in series with SCLK and CS pins to make it work. What exactly is the reasoning ?

Waveshare microsd card reader:

SD card reader schematic

Out of curiosity I added a level shifter too since the sd card module doesn't have one on it and that didn't work, so the Arduino and sd card reader pins must be connected to each other with no level shifting !


texts:
I have seen and used non-contact soap dispensers and water taps in public toilets for a long time already, but only recently have I begun wondering, what kind of sensors they use and how exactly those work. Many of those devices seem to feature some kind of infrared light source, but how do you cheaply measure distances using light without measuring travelling time? Because I guess that would be too expensive and complex for such devices. Or do those sensors not measure distance? And are there any technologies, that don't use infrared light?

EDIT1:
Thanks for all the answers so far. They cover most of the devices I have had a look at. I'd now just like to know, whether there are any other technologies to do this, that do not use infrared light. Because there is this one non-contact hand dryer in my university, which does not seem to feature any IR equipment. Or maybe it is just very well hidden.


texts: How to correct Warning : array subscript has type 'char' [-Wchar-subscripts]

texts:
Hi I write a function to reset a Character Array in Atmel studio as below:

char PacketData[50];
void Reset(){
        for (char i=0; i<=50;i++)
           PacketData[i]='\0';
    };

But Always get warning when compile the program:

  Warning       array subscript has type 'char' [-Wchar-subscripts]

Anybody know how I remove this warning?


texts:
The picture below is on page 7 of the datasheet of TL497, it is a switching regulator that I use as an inverting regulator (it has an inverting mode) to generate -24V from 12V in input, in the first designing equation on this page I have 2 unknowns "I(pk)" and "Io max" I don't know how can I find their values ?? In the datasheet it is wrote that I(pk) maximum value is 500mA so if I(pk) in the equation means 500mA why they didn't write 500mA simply unless of I(pk) also I(pk) max value is 500mA it can be lower than that and if 500mA means the "Io max" then I(pk) value will be 3A for VI=12V and |Vo|=24V which is impossible because I(pk) max =500mA. I hope I explained well.
datasheet:http://www.mouser.com/ds/2/405/tl497a-405896.pdf


texts: Measure CMRR of amplifier in a single HSPICE simulation?

texts:
So far I measured CMRR by first obtaining the open loop gain and exporting the wave, and then doing the same with the AC source in common mode, but this adds the need for additional software, and make the process difficult automatize.

I don't think there's any easy way, since the two test circuits are different (basically with the AC source connected as common or differential input), but I wondered if there is any HSPICE trick to make it work.


texts: Randomize PCB trace generation with Altium Designer

texts:
We are trying to create a tamper mesh as a flex PCB. This tamper mesh will consist of around 10 signal traces in order to detect a tamper.
One crucial point is that this tamper mesh should be different each time we generate it. This way it makes it harder to probe the protected circuitry without tamper detection.
Altium has its autoroute, there is also the interactive Lenght tuning tool.
Does anyone know if there is a tool to randomly fill out a PCB area with the given traces?
Thank you in advance!
Edit: Something like this but without dead ends.
The Taces have a start point and an endpoint each with its own Pad to connect to a MCU.


texts: Standard SPI uses single-ended signals. Is it possible that a communication uses SPI protocol but the signals are physically LVDS?


texts: In a car, what is the difference between a 12-V and a 24-V system?

texts: As I understood, 12-V car system refers to automotive system that runs with a 12-V battery. What are the basic differences between a 12-V and a 24-V (actuators, ECU...) ?


texts:
While taking a look at some other peoples PCB designs I noticed something that I haven't seen yet.

In some designs, I see regions marked by unconnected, small dots on the signal layers. Here are two examples from completely different projects:

Question: What is the purpose of these markings?


texts: What exactly is a potential barrier in transistors?

texts:
Here it says that:

  When a transistor is OFF, there exists a potential barrier between the source and the drain..

I don't know exactly what a potential barrier is. If I had to make an educated guess, it would be a barrier that an electron has to overcome in order to reach the drain, from the source. If you don't want the electron to reach the drain (i.e. the transistor is "off"), you make the barrier harder to overcome. However, this guess raises questions (the foremost being whether or not the guess is actually correct):

What kind of barrier is this? Obviously, a 'potential' barrier, but how does this work?
Is this barrier removed if you want a transistor to be on?


texts: What is this schematic symbol with two arrows?

texts: I'm trying to figure out what this schematic symbol is. At first, I thought it was some kind of diode but I don't know if that makes sense. The symbol is highlighted in yellow below:


texts: 3 phase voltage problem when connecting to servo

texts:
I have 380V 3 phase with the following line to neutral voltages: L1: 238V, L2: 234V, L3: 224V. The system has a single phase servo driver that takes in L3 and N, however when hooked up L1, L2, and L3, change to the following: 394V, 400V, 0V. I'm not sure why this discrepancy is happening.

Thanks in advance!


texts: Sparks on grounded metal bodies on lighting strikes in the nearby (two miles)

texts:
I have a strange phenomenon in our mountain cabin, on the Italian alps: lightning strike on the nearby (not so near: < 2 miles) causes audible / visible sparks on:

electric / fire wood water heater pipes (very frequently)
LED spotlights (rarely)

Both have the bodies grounded.

Details:

In the dark I also see LEDs lighting up (just a weak flash)
The nearest lighting I saw was > 1/2 miles from cabin so I cannot say how the phenomenon is affected by distance from strikes
Electric system and ground are new and tested. I already asked to our electrician but he says that our ground is good, and he don't know what can cause the phenomenon (this is why I write here :)
It seems that sparks occours only with metal bodies physically attached to a wall that has the ground on the other side (the cabin is on a slope; the ground level on the back is about 4 meters higher than on the front. Wall is made of stones and concrete, about 30" width)
The cabin is one of the last one of the electric branch on which we are connected
Water heater has a metal exhaust pipe (about 10 feets long) that run inside the masonry flue

For my knowledge strikes are too far to have a direct role, so I tend to thinking about spikes on the power line (the last mile is underground);
but a spark means a LOT of potential difference - and not destructive ones + no failure on the electronic devices I have plugged in 365 days/year means very little current, so I tend to exclude the power line.

Yes, I'm confused :)

Thank you very much

Ps: I found a video

https://www.youtube.com/watch?v=DuNLm284m80

You can hear the sound of / see (indirectly) the flash of the spark, but in this case the lightning is in the nearby, I can expect that could induce a lot of EMF; in my case lightnings are a lot far away (also > 10 seconds between lightning and thunder)


texts: Shielded cable, to ground or not, in amplifier

texts:
I have been looking for an answer on the net about this question but not found it fully answered. The topic has been up here a few times (see links below) as well but I find the answers lacking.

My application is a vintage amplifier (Tandberg TR-1040), where the 30V AC supply cable pair run over the amplifier circuit on it's way to the rectifier and large caps and cause a weak hum. My idea is to improve it's performance thru shielding these AC cables somehow. The machine is not grounded to earth, neither is the chassis. So what would one do? To leave the shielded cable with the shield not connected to anything? Or using unshielded but twisted cables that I route somewhere else inside maybe. But my question is mainly - what happens if you have a shielded cable here but the shield is not connected to ground?

I want to avoid the AC supply to 'leak out' to the sensitive signal circuitry. That is all.

The question was put forth by Jensen68 but unsatisfactorily answered here: Cable type and decreasing EMI/RFI
It was also asked briefly here:
ungrounded chassis shielding
And here:
Does an ungrounded shielded cable shield at all?

Help to explain this will be much appreciated!

Unconnected shielded cables seem to be unorthodox or inefficient, nowhere have I found that using them in this way is mentioned.

I am also unsure of if twisted cables not only decreases absorbed interference but also decreases interference 'radiated out' from the twisted pair. In a case like this it is a vital point.

Photo of the inside of my Tandberg TR-1040 with problematic cables marked

Here is a video on youtube that measures radiation from an AC power cable and what happens when it is shielded by a metal sheet and the shield is 'floating' (measures at about 5:00 into the video). Not sure if it is reliable or applicable here.
https://www.youtube.com/watch?v=EeAcGell_cg


texts: So, I'm sitting here looking at a chewed up extension cord that I just unplugged from the wall out of fear. Both the neutral and hot sides (no ground) have been chewed to (and part way through) the bare copper. My rabbit is nuts, I know, but did she really continue to chew while receiving 120 volts AC for her trouble? This is throwing everything I thought I knew about electricity into a tailspin. Maybe she wasn't grounded well, but I've been shocked myself when I was probably less grounded. Any help greatly appreciated!


texts: Why does resistance reduce when a conductive fabric is stretched?

texts: I just purchased some conductive fabric and noticed that stretching the fabric reduced its resistance. This seems counter-intuitive since stretching a wire leads to an increase in its resistance. I have also found this video where you can see this happen. Why is this happening? How does stretching the fabric lead to drop in the resistance? and is there any relation between the two?


texts:
I have implemented an SD/FAT combination on a Renesas RL78/G13 processor. The SD card is being driven using SPI.

The code has been proven to work on two custom target boards using a 2GB card - the SD can initialise properly via the FAT middleware and a file can be created on the card and written to. The result can be confirmed by plugging the card into a Windows machine and reading the file.

Suddenly, as if by magic, the SD card stopped working recently. Using a debugger, I tracked the problem down to the first time the FAT initialisation sequence tries to do a data read operation.

The sending of CMD17 (Read Single Block) and its response are handled correctly, but when the data packet is clocked-in (dummy 0xFF clocked-out on SO), the processor seems to reset (I get pre-main code being run, which I can confirm through my debug log).

I am wondering whether SD power is an issue. Due to other aspects of the board design, we're seeing ~2.9V for SD power and SPI comms. I can only ever see references to 3.3V for SD SPI, but does it really need to be exactly that? Could this be causing the issue, or is this a red herring and there's another reasoning?

Any help would be greatly appreciated.


texts: Can I connect a PSU to the Ramps 1.6+ and the USB to Arduino at the same time?

texts:
I just want to connect the Ramps to the power supply unit and upload the Marlin firmware to the Arduino. I found three possible outcomes

1. Problem

I found one person here who says that we should not use external power for the Ramps and plug the USB to the Arduino at the same time because the board could burn:

  I was constantly hooking & unhooking my Arduino from my PC while the printer was plugged into the mains. At some point, it had enough & it released some "magic smoke". Later on, I found out this was the power regulator on the Arduino.

  You shouldn't need to plug in the USB and the external power to the Arduino at the same time, but if you did, it is smart enough to only use one.

  That being said, by default the RAMPS passes 5V straight to the Arduino to power it (using the Vin pin).

But the person who had asked the question wrote a new comment to this answer:

  I fixed the problem. Actually the diode D1 was creating that problem. I removed the diode D1 and now everything is working well.

I have read that the diode D1 (they may different boards, but I assume that the function of the diode is the same):

  According to the schematics of the board, there is a diode (D1) between the VDD5V and the VDDUSB net to prevent any current flowing back, towards the laptop's USB port.

If the other guy removed the diode could damage his laptop, right?

2. No problem if I take care of the grounds and rest of connections

An Electric Engineer also said in the comments of the same question

  As an EE, there is no specific problem with what you tried, provided that all supplies are properly isolated. Before burning another Arduino, reconnect the parts you have now one at a time, check for unexpected voltages. In particular, check that the ground levels are at zero or near-zero potential difference before connecting. Also, be sure that all grounds are tied together. The motor supply ground must be connected to logic ground. Grounding is a large subject, and someone will justifiably pile onto this answer with concerns about ground loops and noise, but if your grounds are not common, you risk sneak paths and destructive voltages when you interconnect systems.

I am a little confused about this. The ground in the PSU is clear (I use 12V and 15A):

But where is the ground if I connect the Arduino by USB? Is my laptop adapter ground?

3. No problem at all

Finally I found a video where one guy connect both things at the same time. I think that's the only way to make the Pronterface work and move the motors directly or send some G-code instruction in the command line.

Socket

I have this kind of socket in my house, they just have Single Line (brown cable) and Neutral line (blue). So I wondering what happens if I don't have ground and if this could make burn some board.

Question

So my question is. Is it so common to burn the Arduino connecting both (PSU and USB)? Or the guy of the first question is just an exception? Should I worry about that? Do I need to do anything with the diode D1?

Update

@Russell McMahon says I should connect all the grounds (negative terminals) together, from USB the supply and the PSU.

So I would like to know if instead of breaking the USB cable I could use any of the grounds that appear in the Ramps shield. I show here its diagram, as you can see there are many of them:

In the past, I have used Arduino and an external power supply and I could use the GND pin in the Arduino, that's why I am asking.


texts:
This is the practice problem 8.9 of Fundamentals of Electric Circuits 5th Edition.

Can someone help me with this question? I need a more detailed solution of this problem. Especially, what are the initial conditions. I though, by turning of the independent source, it should be i'' + 7*i' + 10*i = 0, and the initial conditions should be i(0)=0, and di(0)/dt=0.

But my solution turns out to be incorrect. Where did I make the mistake? Thank you in advance!


texts: Transformer vs capacitive vs both coupling to speaker

texts:
I have seen various configurations in my lifetime on how an 8-ohm output speaker is connected to amplifier circuits.

Currently I'm doing a project using an LM386 amplifier and I capacitor coupled the output as shown in circuit A below, but it didn't work right because when a nearby transmitter (about 4 inches away) was transmitting data, I could hear the data through the speaker.

I read online that what I'm experiencing is a ground loop problem and using transformers can help stop that. So I figure my best bet then would be to choose circuit B, C, or D. But which one will be the absolute best for delivering the audio from the amplifier without anything at all causing interference to the speaker? and why?

Also in these schematics, disregard the part number for the amplifier shown and assume the resistor is capable of handling the required output wattage and assume all capacitors are electrolytic and 100uF


texts: How long would an original gameboy last on a modern lithium battery?

texts:
The original Gameboy was famous for it's battery life on 4AA batteries. My HTC One smartphone can last about as long as the GB did back in the 80s.

So how long would an original gameboy last if powered by a modern lithium phone battery?


texts: How to boost my Lipo battery automatically when connected to a load?

texts:
Ibam using a Lipo battery to boost the voltage from 3.7V to 10V using a MT3608 module.
Since the MT3608 module always boosts the voltage no matter if I connect the load at 10V. Is there a way where module starts boosting automatically if a load is connected using any transistor?
If there is a possibility using a transistor, where should I connect the transistor and what all connections should be changed?
P.S : I am trying to boost the voltage from 3.7V to 10V to control 3 LEDs (each LED with a forward voltage of 3.3V and forward current of 30mA.?


texts: Supply one device with two power supplies

texts:
i would like to ask if my schematics is ok.

I have one (or more) device (here symbolic as "R") which are supplied by a main power supply. I would like to support them also with an usv for the emergency case when the main supply is down then the the devices should be supplied from the usv.

I suppose that there should be some management device which would switch between the two power supplies but this schematics is much simpler.

But i have concerns:

For reasons i have not under control i can´t provide a common ground for the two supplies so i suppose that the (not existing) common ground could cause problems.
Is it possible that there will flow something like an offset or "balancing" current between the separated systems?
while there are diodes with different characteristics is would be difficult to define which power supply will supply the devices. It could be that the usv will supply the device (R) the whole time, then the first power supply would be useless

Is there a other way, some schematics or devices to manage the switching better than with this primitive schema?


texts: Simulate center-tap transformer using two transformers?

texts:
I have a PCB that takes 3 input terminals: V-, GND and V+. On the manual, it is stated that the inputs should be two 6V outputs from a center-tap transformer. I do not own a center-tap transformer, so I'm curious whether I can simulate a center-tap transformer using the following configuration:

Consider two 6V transformers A and B.

Connect:

A- to V-
A+ and B- to GND
B+ to V+

Would that be electronically sane?


texts: Computing short circuit current of transformer

texts:
Update: My 500Va is just an example. What I wanted to compute was the short circuit current of utility pole transformers because I want to estimate how large an arc flash that can be produced.

Assuming the pole utility transformer is 100kVA, and the primary voltage is 12,000 volts. Then the computation is like this? 100kVA/12,000 volts/0.02= 416A only.. or do you use 100kVA/120 volts/0.02 = 41,666A?

original:

How do you compute for the short circuit current of a transformer? Is the following correct?

Assume the transformer is 500VA with 2% impedance.

Then 500VA/120v/0.02= 208.3A

This means if the secondary side of the 500VA transformer is short circuited. Then there will be 208.3A short circuit current produced?

How does this relate to whatever is the step down
voltage?


texts: How would you go about identifying an irreducible circuit? By irreducible, I mean combining resistors whether in series or in parallel to reduce the circuit.


texts:
I'd like to measure 0-800VDC using the ADC of a PIC18F and opto-isolated from the high voltage. Since optocoupler's CTR is variable and non-linear, I'll use the IL300. Checking this application note, I've found the following schematic:

That's the schematic I've made:

From that, I'd like to understand what parameters I have to check to choose the right op amps for this application. Any general purpose rail-to-rail 12V single supply would fit the project?
Also, is IL300 the best option for this?


texts: How to Cascade Filters and Audio Volume Control

texts:
I am trying to output PWM from an MCU, filter it with a LPF to form an analog signal, cascade an audio volume control that allows for smooth control between silence and a somewhat amplified signal, and output the result to headphones (Z ~ 32Ω).

How can I cascade the stages so that the audio volume control circuit (which would use a digital potentiometer) doesn't impact the impedance of the LFP and mess with the cut off frequency?

I would also like to minimize the impact of the external load (from the headphones) on the cut off frequency of the LPF.


texts: Tantalum capacitor as bypass for digital IC

texts:
I am reading the MCP4725 digital-analog converter datasheet and they recomend to use two bypass capacitor at supply voltage:

  The power supply at the VDD pin should be clean as possible for a good DAC
  performance. This pin requires an appropriate bypass capacitor of
  about 0.1 μF (ceramic) to ground. An additional 10 μF
  capacitor (tantalum) in parallel is also recommended to
  further attenuate high frequency noise present in
  application boards. The supply voltage (VDD) must be
  maintained in the 2.7V to 5.5V range for specified
  operation.

What is the advantage of using a tantalum capacitor in this application?
A 0805 or 1206 10μF ceramic capacitor is even smaller than usual tantalum capacitor.
Can I use just two ceramic capacitor, 100nF and 10μF?

One additional question: Is it the output voltage of this DAC stable enough for a voltage reference? Or could it require some kind of filter?


texts:
So I've been attempting to create my first development board and layout. I'm first working on the decoupling capacitors, power and ground portions of the layout.

The MCU I'm trying to properly decouple is an STM32F411RET6 running at 100Mhz. According to the STM Application Note a single 0.1uF capacitor at each Vdd pin is adequate. Of course it also says at least one Vdd pin should have a ferrite bead in series with the capacitor. Am I reading this correctly?

I plan the following:

1- 2 layer board

2- Top and bottom layers will have ground pours

3- Components on top layer

4- Traces on both bottom and top as needed

5- Decoupling capacitors sized 0402 .1uF close to pin and 0805 10uF caps further away

I am just a hobbyist trying to create my first micro-controller board and layout and want to make sure I get everything correct before getting too far into things.

Is it worth the additional cost of a four layer board so that I can more easily do proper decoupling by having separate GND and Vdd layer? Or should I stick to two layers and use top layer for GND + traces and the bottom layer Vdd + traces?

The image below ( sorry, created using MS Paint ) is what I hope is a good layout strategy for decoupling capacitors. I'm sure working with 0402 sized caps will be a treat, but it's been suggested a much better size for decoupling caps. The image isn't meant to show proportions or pad sizes properly. Just trying to show my idea for where I want to put the part and traces.

Is this a reasonable layout for decoupling capacitors? Or should I put the capacitor near the pin parallel to the IC instead of perpendicular?

And can anybody recommend a good part number for the decoupling capacitors?

Thanks again,
Jim


texts: How to design a binary up down counter using D flip flop's and the 'up' or 'down' count will be controlled by another flip flop?

texts:
I have to design a 4bit Binary Up Down counter using D flip-flops .  But here is the catch I cannot directly use a switch to control whether the counter will count up or down, I have to do that using a D flip flop. Any help on how I can solve this?

N.B. I can design an up down counter , but I need to know how to use another D flip flop to control the whether I want up or down count


texts: Whats going on with my transimpedance amp?

texts:
Pulling my hair out with this design. I have the following design which was done using analog devices Photodiode Circuit Wizard tool so it should work. The current source in the schemeatic is the photodiode UV-035EQ. the op amps are powered by +-5V.

This setup is for more measuring low level UV light. But as soon as I place the photodiode into darkness I get a horrible waveform with a peak/trough of about +-2V
https://drive.google.com/open?id=18lMKfpOSzvvhQ3yqGymRFszVO9QUYHl7

Lookig at the photodiode it looks like its working fine I've tried multiple ones and they all seem the same.

simulate this circuit – Schematic created using CircuitLab


texts: Problem with 7-segment display: dimly lit when off

texts:
I'm driving two large seven-segment displays using two shift registers (74HC595). The displays have a forward voltage of 12V and a max forward current of 20mA.

I'm feeding data and 5V of power to the shift registers from the my Arduino and I used used an external 12V supply for the displays, but I was planning to use a larger (18V) supply later. I hooked 12V + to the common anodes of the two displays, then connected the segments to the proper pins on the shift registers. I put a 330 ohm resistor between the SR pins and the segment cathodes. My plan was to use 18V, so I figured that 330 would limit my current to 18mA per segment. When running with the 12V supply, I expected the segments would be dimmer, but work fine.

So, all of my prototyping with 12V worked fine. When I switched over to using 18V (from two 9V batteries wired in series) I noticed that one of the displays seems to be dimly lit even when all of the segments are supposed to be off. (They still light up as they should when on.)

FWIW, it appears to only happen to the display that's connected to the first shift register - i.e., the first one in the chain that receives data directly from the Arduino. The other display (driven by the second SR) seems fine.

I'm a bit of a newb, so I would not be surprised if I'm making some mistakes here. Any suggestions?

--

UPDATE: Schematic added below that represents the current (flawed) design.

So, I'm hearing two possible solutions to reduce the voltage flowing across the segments when "off" - the first would simply reduce my 18V to 12V. Others have suggested putting two darlington arrays (e.g., ULN2803) in, which I assume would sit in-between each 74HC595 and the resistors that lead to the individual segment cathodes. Is that right - would it look like this?

(I'm just showing one assembly of a shift register, darlington array, resistors, and 7-segment display. Also, ignore the stray resistor at the top right.)


texts:
I am looking to  generate a moderate frequency sine wave around 1kHz with amplitude and dc offset control. I plan to use an Analog Discovery 2 tool to generate the sine wave (max 5V) and use an external power supply to boost it (to around 10V). I would be needing a summing amplifier for that.
My question is, should I choose an inverting or a non-inverting amplifier? For that frequency, any suggestions as to what model Op-amp to use?
Thank you.


texts: Can I read programmed content inside any sort of non-volatile re-programmable memory device with Microscope, X-ray, etc.?

texts:
Non-volatile re-programmable memory like NAND flash, NOR flash, and etc. stores information in forms of electron charges and doesn't change in structural forms that can be inspected with X-ray or Microscope.

Then is there a way to inspect content of the memory when it cannot be addressed with normal way?


texts:
I am a confused about linear and non linear fir filter.

I have this depiction of the solution space for linear-phase and
nonlinear-phase FIR filters for a given set of specifications.

Region 1 represents the set of all linear-phase FIR filters that meet
the specifications. Region 2 represents the set of all linear and
nonlinear-phase FIR filters that meet the specifications.

If in non-linear phase FIR filter that meet the specifications, what is the difference between specifications of linear and nonlinear case?


texts:
I am attaching two boards I have just designed in Eagle and would appreciate if any expert around here willing to take a quick look would flag any obvious errors in the design.

There is one board that would serve as a light switch PCB, sending a CAN message over the CAN bus. There would be plenty of them (I plan about 40-ish).

The other board is the final relay board. There would be just two, one for each floor. And SSR boards I already bought would be connected to the relay boards (which in turn would switch the lights in the house on and off).

I will also connect my USB interface to the CAN network (to the USBTIN 3 pin header in the relay) to be able to debug it (and in the final version also control from an ODROID over a web application). For pure debug purpose of the Microchip pins I have the DEBUG 5pin header in each board too.

Any hints or questions WRT to the design would be much appreciated. I plan to use a Cat 5 cable with RJ45 plugs. The switch boards therefore have double RJ45 plugs on them, and they all would be powered up on the bus line directly (only the relays have the power jacks). I know that is out of spec for CAN, but I plan to run al low baudrates, and right now I have 50 kbit/s in the code (see the link above), but more than happy to go way down.

Perhaps a question is WRT to the terminating resistor. I have been reading mixed recommendations on this one. Obviously the datasheet suggest using two 60 ohm resistors connected via a SPLIT pin. That assumes a 120 ohm cable, which I do not plan on using, I plan to use plain Cat 5 (which is said to be 100 ohm if I got this right). Then others propose using a resistor to match the cable impedance, which would mean two 50 ohm resistors instead.

I went for a bit of compromise so far (also because the local shop does not actually have 60 ohm resistors) and plan to put 56 ohm resistors there now. I do have oscilloscope too and plan to play around with that too if needed.

I indeed plan to play with this way more once built on my table before putting it out in our to be built house :) So far I only played with this setup on a breadboard.

For those interested in more background of what I am doing, check my GitHub account here (all the boards are there as well): https://github.com/PoJD/can-pcb and https://github.com/PoJD/can


texts: how to connect multiple proximity sensors to a PIC to work together on a single port

texts:
Here is the proyect, making a failsafe autonome Baby Cart

believe me my life is at risk here, im in high school studyng mechatronics so im still learning how to make some stuff but i know the basics the thing is an aunt wants me to make a baby cart for my newly born cousin that can be radiocontrolled or moved by the baby and stops automatically if there is a fall when the baby is in free roam mode.

Using a PIC for the proyect, the circuit uses 2 voltage lines, a main 5V supply is for powering the PIC controller, sensors, output relays, the logic circuit and the RC control (borrowed from a RC car), the secondary 12v power supply is used for the motors for the wheels and the motors on the deployable legs (for stopping the cart if the baby wants to go off a cliff and the sensors stop dettecting ground).

i want to connect 8 sensors but the pic only has 6 input ports and 2 are used for the RC control is it plausible to connect 2 sensors to each port while passing by the same "not" gate?

if the baby falls im going to be dead


texts: Enabling Freescale IMX6 pull down registers on an input pin

texts:
I'm looking for a way to enable the pull down resistor on a Freescale iMX6 MCU.

I'm running a Linux distribution on it and usually interact with the hardware using a higher-level language, so I'm not 100% familiar with the stuff below.

From what I read in the i.MX50 Applications Processor Reference Manual, resistor pull up / down options are configured using pad control settings, in particular using the following functions

PULL_KEEP_CTL (4 bits pull up/down and keeper controls)
PUS (2 bits pull up/down configuration value)
PUE (1 bit pull/keep select)
PKE (1 bit enable/disable pull up, pull down or keeper capability)

I found the pin definition in arch/arm/plat-mxc/include/mach/iomux-mx6q.h I found the definition of the pin I'm interested in (it's for this pin where I want to enable the pull down resistor).

#define _MX6Q_PAD_DISP0_DAT10__GPIO_4_31    IOMUX_PAD(0x04AC, 0x0198, 5, 0x0000, 0, 0)

The IOMUX_PAD definition contains the following

#define IOMUX_PAD(_pad_ctrl_ofs, _mux_ctrl_ofs, _mux_mode, _sel_input_ofs, _sel_input, _pad_ctrl)                                  \

_pad_ctrl_ofs - hexadecimal offset of the control register, which selects the electrical circuitry (from page 2336 in IMX35RM.pdf)
_mux_ctrl_ofs - hexadecimal offset of the MUX control register, which selects the function of the pin
_mux_mode     - bits 2..0 in MUX control register
_select_input_ofs - SELECT_INPUT register offset (see table 4-11 IOMUX_CTL Register Addresses from 0x07A8, IMX35RM.pdf)
_select_input - see table 4-12 Daisy Chain List, IMX35RM.pdf
_pad_ctrl     - bits to be set in register _pad_ctrl_ofs for configuration selection

I'm wondering if changing the _pad_ctrl value would do the trick.
Would changing the definition of the pin, rebuilding the kernel and restarting the module with the new kernel enable the pull down resistor ?

#define _MX6Q_PAD_DISP0_DAT10__GPIO_4_31    IOMUX_PAD(0x04AC, 0x0198, 5, 0x0000, 0, (PAD_CTL_PUS_100K_DOWN | PAD_CTL_PUE | PAD_CTL_PKE))

Are there other ways to change the pad control values without rebuilding a kernel and restarting the module ?


texts: How to reduce Timer error of Atmel 89S51 microchip?

texts:
I wrote a simple code counting 30 seconds using Timer 0 (Mode 0, it's 13-bit counter) of Atmel 89S51, and I used Proteus to simulate. After 30 seconds the LED light should be turned on.

I found that the LED light would be turned on at about 31 second, that seems to be an error of 1 second. I think this error is not acceptable since I only count 30 seconds.

In this picture you can see the simulation result:

Here is the code:

#include <reg51.h>
long i=0;

main()
{
  EA=1;       //Enable EA bit
  ET0=1;      //Enable Timer 0
  TMOD=0x00;  //Use Timer 0, Mode 0

  TH0=(8192-1000)/32;  //Count 1ms
  TL0=(8192-1000)%32;
  TR0=1;      //Start Timer 0

  while(1);
}

void T0_int(void) interrupt 1
{
  TH0=(8192-1000)/32;
  TL0=(8192-1000)%32;
  //if i==30000，30000*1ms=30s
  if(++i==30000)
   {
      P1=~0x01;
   }
}

Did I miss something or is there any way that can reduce this error?


texts: Max10 LVCMOS input setup and hold timing

texts:
I am struggling to find the minimum setup and hold timings for single-ended 3.3V LVCMOS inputs in the datasheet. I'm especially puzzled that the datasheet and handbook differentiate between low-speed and high-speed pins without stating the actual difference between the two.

I really would like to have some ballpark numbers prior to coding.


texts:
I have an system that has a signal that swings to logic level 0(on)-12v(off).

That i'm reading with an Arduino.

The signal is normally held at 12v.

Using a simple circuit like so:

The blue line is the one that swigs.

My question is, why is the Arduino burning out? Issent the diode preventing the 12v from going backwards and hitting the board with 12v? and the ground should draw the 5v away from the board reading logic level 0.


texts:
This image is an example of a wire wrap label that lists multiple AWG numbers.
What does it mean? How could it be anything but a single specific gauge?


texts: Identification of a sot363 dual transistor

texts:
Could you please help me in the identification of the 6 pins dual PNP transistors below.
Thank you in advance.


texts:
I have Setup like this for my application. I have Transformer which gives out 12V 1A & 5V 500mA output.I have used isolated ADM2483 design where power galvanized isolated. Primary side 5v &gnd taken from 7805 regulator  where 12v input comes from transformer. same ground used by MCU/ADM2483 side
Where as secondary 5V/ground ADM2483 taken from 5V/500mA source. this way I have total isolation in primary side.
My unit working well with Aux 85-270vAC/Dc &12V DC standby upto 10 device without any disturbance using lap cable for 1000 meter.
By seeing circuit it understood that communication works only when Aux 85-270VAC supply is given.
since 12Vdc Supply from battery given. product wise it will it work on 12v dc not communication.
Issue:

i have introduce battery charging unit and it stop communication. if remove battery charging unit it start working.

2)i have tried grounding Communication ground and secondary side of ADM2483 ground common. In this case also it not communicating.

I have used terminator resistor 100E but it didn't solved issue.

I have same product which having non isolated rs485 trans receiver, where it work on all prospect battery, aux supply, battery charging unit where  i used same transformer but it non -isolated design.
When i bring isolated design in daisy chain with non-isolated design without battery charging unit. it stopped communication.here i made ground common for communication/isolated/non-isolated ground.


texts: How does this Miniature Solid State Tesla Coil work?

texts:
Here are the schematics

What is the use of>

-Transformer (I assume it is providing higher voltage? and what does it do)
-Transistor (Is it common emitter? and what does it do)
-LED (What does it do?)

I do not need this for homework, I was just curious to know what is happening in the circuit.

How I think it may work The resistor and led form voltage divider for the base. The voltage is equal to the voltage of the led drop in reverse bias ~4V. Then the transistor switches on and off bcs. only changing voltage can pass through transformer. These are my thoughts about how it works, but I would like to know more.

The answer fulfills my thoughts.


texts:
I am designing a transimpedance amplifer to run at 10mA in 100uS to detect proximity of an object (low power application)

I am intending to use the VSMB1940ITX01 IR LED and the VEMD6110X01 IR photodiode.

I am looking at using the standard transimpedance amplifier in either passive or active configuration. The output current when illuminated is in the uA range but what determines the max voltage I can get from this in choosing my load resistor?

Also does using an active over a passive configuration help? I've had a look at multiple application notes but to little avail.

Any help greatly appreciated!


texts:
Question:

  Consider one set of \$Mod-14\$ digital-counter having input clock frequncy \$19kHz\$.If another input clock frequency as first one is cascaded then final output clock frequency of the composite counter will be?

  \$(A)1kHz (B)4.75kHz (C)0.28kHz (D)2.1kHz\$

As the \$mod-n\$ counter will divides output frequency by n.So output of first counter will be \$19kHz/14\$,which is fed to another counter of mod 14 ,then  it will again divide output by 14,So

\$\frac{19\times10^3Hz}{14\times14}=96.93 Hz\$

But here no option is matching.


texts: What makes lead-free solder harder to use?

texts:
Soldering in a RoHS-compliant way normally means using a solder that does not contain lead - the metal that made up most part of common solder before.

Handsoldering using lead-free solder seems to be harder.
Possibly it also makes industrial soldering methods "harder" (as opposed to just different)?

What are the practical difficulties that arrise in comparison to using "classic" solder?
What causes these difficulties?
How can they be handeled or worked around?


texts: How to do a transient simulation using LTspice?

texts:
I have the following circut that resembles a CMOS inverter. Now I want to do a transient simulation on this circut but I am not sure how to do it.
I always get a straight line! Not sure why. I tried everything.
In this transistor I have VOH=5V, VOL=0V
I tried changing the voltage in the advanced settings and to put pulse but I didn't undertand how to set the values?
Any help?


texts: Usually AC quantities have the x-axis as time, but phase shifts are done in angles. How is there not a unit conflict?

texts: This feels like a very specific and stupid question, but I have studied AC circuits for a while already. I just didn't think about it that much, but why is it established that the x-axis we use for graphs is time but we get to be able to shift the sinusoid by the x-axis in terms of an angle? I mean, they really aren't the same units. Time is in terms of seconds commonly and angles in degrees or radians. Why does it work? How do they coexist, being able to read phase shifts and measure periods using the same axis?


texts: Pull-up and Pull-down Resistor Usage on Input or Output MCU Pins

texts:
Are pull-up/down resistors (whether internal or external) only needed for MCU INPUT pins? In contrast, an MCU pin configured as an OUTPUT "knows what level it's at" because it does the driving - a "floating" MCU OUTPUT pin tied to some input of another circuit doesn't make sense, because the state of the MCU pin can only be high or low... do I have this right? Now, upon MCU bootup or failure, it may be beneficial to have a pull-up/down tied to this "MCU output to IC input" line to ensure that the input to some IC is never floating.

Maybe I just answered my own question here... pull-up/down resistors can be used on both input and output pins, depending on application?


texts: Circuit direction of flow according to tutorial

texts:
I'm following an introduction in circuit electronics, and there seems to be a contradiction in its explanation of the direction electricity flows. First it says that electricity is the movement of valence (outer shell) electrons from atom to atom, and that the negative pole of a power source (being of like charge) will push electrons from the negative pole and electrons will flow from the negative pole to the positive pole, which attracts flowing electrons.

Then I've come across this description:

  the positive side will have a higher voltage than the negative side,
  which is exactly what we want. In fact, when we measure voltage, we
  usually say that the negative side is 0 volts, and the positive side
  is however many volts the supply can provide.

  What have we learned so far?
  *Electricity will flow from a higher voltage to a lower voltage.
  *DC voltage sources always have two sides, called positive and negative, with the positive side a higher voltage than the negative
  side.

The bolded part especially seems to contradict what was said earlier about the flow being from negative to positive.

Here is the link to the site

Could someone explain how the electricity in one explanation flows from negative to positive, and in the other explanation from positive to negative?


texts: How Do You find The Cutoff Frequency of a Low Pass Filter?

texts:
A lowpass filter exists around R1,R2,R3 and C2 but how would you find the cutoff frequency?
I think that you have to first find the Thevenin equivalent circuit and this is what i got:
RTH = (R1//R3)//R2 = 960.6 Ohms.
Then cutoff frequency is
Wc = 1/(2piRC) = 1.66 Hz
I think this is wrong because it is extremely small, can anyone help me understand.


texts: Detecting ground with Atmel/Arduino and waking up from sleep

texts:
I'm building a small board which should start working when it is touching ground.
I want the battery to last (without a physical switch) so I put the board to sleep. However I would like to wake up the Atmel processor when it is touching ground.

I made the following sketch, but as I'm unfortunately a electronics newb, there's bound to be faults with this sketch/logic.

Would it leak a lot of battery current for example? Does it work like this at all?


texts:
Multitasking is important these days. I wonder how we can achieve it in microcontrollers and embedded programming. I am designing a system which is based on a PIC microcontroller. I have designed its firmware in MplabX IDE using C and then designed an application for it in Visual Studio using C# .

Since I've gotten used to using threads in C# programming on the desktop to implement parallel tasks, is there a way to do the same in my microcontroller code?  MplabX IDE provides pthreads.h but it is just a stub with no implementation.  I know there is FreeRTOS support but using that makes your code more complex. Some forum says that interrupts can also be used as multi tasking but I don't think interrupts are equivalent to threads.

I am designing a system which sends some data to a UART and at the same time it need to send data to a website via (wired) ethernet. A user can control the output through the website but the output turns ON/OFF with a delay of 2-3 sec. So that is the problem I am facing. Is there any solution for multi tasking in microcontrollers?


texts:
I want to reverse the polarity of my current source, which is a capacitor in this case, in the middle of discharging phase. Also the capacitor bank is being discharged through a coil to make a short time electromagnet. What I want is to reverse the polarity of that magnet in middle of discharge. How can I achieve this using MOSFETs or other fast switching components?

Below is the single polarity simple circuit. Also I'm using polarity sensitive capacitors in my capacitor bank.

I know that H-bridge would be the component in this situation, but I'd like to build my own "H-bridge" using n- and p-type MOSFETs to handle these high currents.

simulate this circuit – Schematic created using CircuitLab


texts: Understanding stepper motor voltage and torque relationship

texts:
The specs of this Stepper Motor say at a voltage of 3.36 V and phase current 2.1 A, the maximum holding torque is 65Ncm. I'm confused though as on the datasheet there is no voltage mentioned, only a max phase current of 2.1A and same holding torque. I know that voltage applied to a stepper, directly affects torque though. Say I have a 12 V supply to power this stepper, will the stepper draw the same 2.1 A but give a greater torque output or is it saying that 3.36 V is the maximum voltage for this motor?
(3.36 V seems way too low to me)


texts: Can't Resolve Multiple Constant Driver[Verilog]

texts:
Can't Resolve Multiple Constant Driver

Error (10028): Can't resolve multiple constant drivers for net
"NumOfPixCF[31]" at Pixel_Tracking.v(30)
Error (10028): Can't resolve multiple constant drivers for net
"NumOfPixCF[30]" at Pixel_Tracking.v(30)
Error (10028): Can't resolve multiple constant drivers for net
"NumOfPixCF[29]" at Pixel_Tracking.v(30)

And so on.
Anyone knows how to solve this? I'm an amateur in Verilog coding.
module Pixel_Tracking(
    input[15:0] r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,
    input start,
    input clk,rst,
    output reg[5:0] Object_Shift=0
);

    reg[15:0] R1,R2,R3,R4,R5,R6,R7,R8,R9,R10;
    integer i=0;

    integer NumOfPixCF=0,NumOfPixNF=0;
    integer reposition = 0;
    reg[15:0] AreaCF = 0,AreaNF = 0;

    always@(posedge clk )
    begin
        if(rst)
            begin
                reposition <= 0;
                Object_Shift <= 0;
            end
        else
            begin
                for(i=0;i<=15;i=i+1)
                    begin
                        NumOfPixCF = NumOfPixCF + R1[i] + R2[i] + R3[i] + R4[i] + R5[i] + R6[i] + R7[i] + R8[i] + R9[i] + R10[i];
                        NumOfPixNF = NumOfPixNF + r1[i] + r2[i] + r3[i] + r4[i] + r5[i] + r6[i] + r7[i] + r8[i] + r9[i] + r10[i];
                    end
                if(NumOfPixCF > NumOfPixNF)
                    begin
                        Object_Shift <= 6'b000100; //Object moved away
                    end
                else if(NumOfPixCF < NumOfPixNF)
                    begin
                        Object_Shift <= 6'b001000; //Object moved forward
                    end
                else
                    begin
                        AreaCF = AreaCF + R1 + R2 + R3 + R4 + R5 + R6 + R7 + R8 + R9 + R10;
                        AreaNF = AreaNF + r1 + r2 + r3 + r4 + r5 + r6 + r7 + r8 + r9 + r10;
                        if(AreaCF < AreaNF) //Object moved to the right
                            begin
                                Object_Shift <= 6'b000010;
                                //reposition <= 1;
                            end
                        else if(AreaCF > AreaNF) //Object moved to the left
                            begin
                                Object_Shift <= 6'b000001;
                                //reposition <= 1;
                            end
                        else //Object did not move
                            begin
                                Object_Shift <= 6'b000000;
                            end
                    end
            end
        reposition <= ~reposition;
    end

    always@(reposition,start)
    begin
        if(start == 1)
            begin
                R1 <= r1;
                R2 <= r2;
                R3 <= r3;
                R4 <= r4;
                R5 <= r5;
                R6 <= r6;
                R7 <= r7;
                R8 <= r8;
                R9 <= r9;
                R10 <= r10;
            end

        if(reposition == -1)
            begin
                NumOfPixCF <= 0;
                NumOfPixNF <= 0;
                AreaCF <= 0;
                AreaNF <= 0;
            end
    end
endmodule


texts: Modifying SMPS power supply to produce a negative voltage

texts:
In SMPS power supply that uses a single transistor to generate the switching signal ( no control IC), which component must be modified so the output voltage could be negative?
I tried to reverse the polarity of the output shotkey diode and I connected a 100w lamp in series with the line for protection,after a few seconds the lamp turns on, and the MOSFET got so hot.
,


texts: AC current amplifier with pwm current control

texts:
I'm starting to build a piece of test equipment to test a trip device for switch gear breakers.  I need to amplify an AC current source.  When the breaker is in service the trip device receives its current sensing from the secondary of the ct on the breaker.

I want to be able to control the current via PWM as I plan on using a TI microcontroller for the brain of the system.  I'm struggling with the AC amplification section.  I am trying to find the LED drivers that have a external MOSFET and try it as I would have current sensing and could PWM control it.  Then I could use the MOSFET I need as I need to be as close to 60 amps as I can be.

What do y'all think?

Thanks!
Jake


texts: What is the difference between neutral and ground? I do not understand the difference.


texts:
I'm going to use the following stepper motor drive chip:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00255075.pdf

And I have choosen the following AC/DC converter:
http://www.farnell.com/datasheets/1766195.pdf

The output voltage of the AC/DC converter is 12V, the motor supply voltage should be 8-45 V.

Is it necessarily to use a voltage regulator to stabilize the supply voltage? (For example switch-mode power supply.)
Or can the output of the AC/DC converter directly used to supply the motors with the drive IC?