texts: For decoupling an IC's power supply pins, is there any reason to use multiple capacitances when all the MLCCs have the same package size?

texts:
A PCB I'm working with has three decoupling capacitors on an IC's Vdd pin - 0.01uF, 0.1uF, and 1uF. They are all in 0402 packages.

I understand that capacitors of multiple sizes are often used because parasitics tend to scale with size, but I was under the impression that this was generally because of different package sizes, not the actual capacitance values themselves.

I also understand that putting multiple capacitors in parallel will increase the overall capacitance while decreasing parasitic values, but I don't see why one would use varying capacitances for that rather than just using the largest value possible for each capacitor.

Is there any reason to use multiple decoupling capacitors with the same package but different capacitance values?

Here's a screenshot of the relevant portion of the circuit schematic (C1, C2, and C3 are all 0402 MLCCs):


texts:
I'm routing a 4-layer PCB with a DP83640 chip on it. The layer stack is signal-GND-PWR-signal. The datasheet recommendate use bead or 0 Ohm resistor to isolate the VDD.

  6.4 Power Supply Recommendations The VDD supply pins of the device should be bypassed with low impedance 0.1-μF surface mount capacitors.
  To reduce EMI, the capacitors should be places as close as possible to
  the component VDD supply pins, preferably between the supply pins and
  the vias connecting to the power plane. In some systems it may be
  desirable to add 0-Ω resistors in series with supply pins, as the
  resistor pads provide flexibility if adding EMI beads becomes
  necessary to meet system level certification testing requirements (see
  Figure 6-17). It is recommended the PCB have at least one solid ground
  plane and one solid VDD plane to provide a low impedance power source
  to the component. This also provides a low impedance return path for
  non-differential digital MII and clock signals. A 10.0-μF capacitor
  should also be placed near the PHY component for local bulk bypassing
  between the VDD and ground planes.

Because there multiple VDD pin for the chip, so the easies way is to split the power plane. But then I will have signal wires crossing the slots :). I don't think it's a good idea.

Any good suggestions?


texts:
I'm not sure the cause but I'm having troubles getting a consistent voltage reading from the ADC pin of my STM32F103(actual bluepill and not a knockoff). Here is the serial output from my board (each averaged over 200 sample points). When I measure using my multi-meter I have a value of 2.22V with almost no variability. How can I solve this variation in my ADC data? I've tried a draw down resistor, increasing the number of sample points, increasing the time span between each individual measurement, and nothing seems to work. Any ideas? (code included below)
2.206412
2.223868
2.499660
2.224902
2.493302
2.515666
2.415408
2.291376

//Includes//
//------------------------------------------------------------------------------
#include <Arduino.h>

//------------------------------------------------------------------------------

//Constants definitions//
//------------------------------------------------------------------------------

#define flow1_Sensor    PA6
#define green_LED       PA11    // External LED-Green
#define LOG_INTERVAL    200     // mills between outputs

uint32_t  timeold;              //initial time
int reps=200;                     //number of adc values to be averaged
double flowrate1=0;

void collect_flow_data(int flow_sens_pin, int reps, double* flowrate1) {
  double sum_flow=0;

  for(int i=1; i<=reps; i++){
    int val_flow = analogRead(flow_sens_pin);
    delay(20);
    sum_flow = sum_flow+val_flow;
  };

  double avg_flow=sum_flow/(double)reps;
  *flowrate1 = (avg_flow/4096) * 3.3;
};

//------------------------------------------------------------------------------
//Main Setup
//------------------------------------------------------------------------------
void setup() {
  Serial.end();

  //Indicator LED
  pinMode(green_LED, OUTPUT);
  digitalWrite(green_LED,LOW);

  //start Flow Sensor Pin
  pinMode(flow1_Sensor, INPUT_ANALOG);

  timeold = millis();
  //setup serial connection
  Serial3.begin(9600);
}
//------------------------------------------------------------------------------
void loop()
{

  if ((millis() - timeold) >= LOG_INTERVAL)
  {
    collect_flow_data(flow1_Sensor, reps, &flowrate1);
    Serial3.println(flowrate1,5);
    digitalWrite(green_LED, HIGH);
    delay(100);
    digitalWrite(green_LED, LOW);
    timeold = millis(); //update times
  }
  else{}
}


texts: I need to make a PCB, and the only software I have is Eagle. All the other parts are listed in my libraries, but where can I find a library that has DIODES INC. - MMSZ5226BS (Zener diode)?


texts: Why use decoupling capacitor with Servo S2309S and how does it work?

texts:
I read the following statements in Arduino Projects Book, explaining about the use of decoupling capacitor in a circuit connected to a servo.

  When a servo motor starts to move, it draws more current than if it
  were already in motion. This will cause a dip in the voltage on your
  board.

3 things that I want to know about:

By Ohm's law, increase in current should be proportional with the increase in voltage, no? How can an increase in current causes a dip in voltage?
The dip in voltage referred by the book, is it the voltage between ground and the main power or ground and the control pin of the servo?
Can we observe this dip in voltage in action? I tried to remove the capacitor and still can't see how it affects the movement of the servo.


texts: What other material could replace copper in an electric motor?

texts:
In the discussion about a "what if?" question in the Worldbuilding StackExchange, I claimed that it would be near impossible to build an electric motor without copper. Other people think that any conductive metal would do, including iron, although with a lower overall efficiency.

I seem to remember that the point of having an iron core in the electromagnets was to have an high density of the magnetic field, and therefore having iron coils would disrupt the field and make the motor non functional.

Am I right ?


texts:
I'm just working through some textbook exercises and have been stuck on this one for a while.

The question is:

The current in an AC circuit is represented by the phasor \$I = I_0 e^{j(120\pi t + \pi/3)}\$. What is the physical current in the circuit. What is the period. What is the signifance of \$\pi/3\$.

I know that this can be rewritten as:
\$I = I_0 [\cos(120\pi t + \pi/3) + j\sin(120\pi t + \pi/3)]\$.

Therefore the period is 1/60 and the the \$\pi/3\$ just represents a phase shift.

But I have no idea how to find the physical current.

Any guidance would be greatly appreciated.


texts: What does negative impedance mean in the context of miller's theorem

texts:
Miller's theorem states that for a linear circuit of two nodes with voltages $$V_1,V_2 $$ which are connected by an impedance, $$Z$$in series, circuit could be represented by an equivalent one with two grounded impedance. The first impedance written as $$\frac{Z}{(K-1)}$$ and the second as $$\frac{ZK}{(K-1)}$$ where $$K=\frac{V_2}{V_1}$$
Suppose V1=2V and V2=3V. The impedance of the linear equivalent circuit according to miller's theorem would be negative for the first impedance since 1<3/2 and positive for the second part since 3/2>. Similarly, suppose V2=2 and V1=3, the first impedance would be positive and the second impedance would be negative in the resulting linear circuit.
Blow is schematic

simulate this circuit – Schematic created using CircuitLab

My question is, what would the negative impedance mean in both cases?


texts: Is there a way to buffer current for high usage periods?

texts:
I am using a USB port as a power source(500-1000ma) for my latest design(Wireless Comms and lots of LED's) and most of the time things work perfectly. However at times I do get spikes where the current draw can go higher than the supply and restart the MCU.

Is there a solution to store extra current?

I know a battery might solve this but I prefer to not go that way... Any other options?


texts: "Net Antennae Violation" on Pad -> Via -> GND plane connection

texts:
I just started routing my first PCB on Altium. It is a simple 2-layer board with bottom layer as dedicated GND plane.
I started out placing GND vias for GND pads of the top layer SMD components like this:

But Altium gives me a "Net Antennae Violation". The Altium documentation states:

  This rule operates at a net level in the design to flag any track or arc end that is not connected to any other primitive and thus forms an antenna. The specified value is the set tolerance of how long a stub must be before the rule will flag an error. Default for this rule is set to 0.

So I understand that a Via is no primitive and I could just disable the design rule. But I would like Altium to still warn me about something like this

while suppressing the GND via antennae violation.

Is there any way to achieve that?


texts:
I am controlling the speed of the motor and measuring RPM using IR module.

The method I used works fine (I rotated the motor manually). I am facing problems when I connect the motor to the power supply. I just want to stop the motor once the speed reaches a certain limit. I am counting the pulses for 5 seconds, once the number of pulses crosses 11. I stop the motor.

However, when I provide voltage to the motor, the timer never reaches the end (overflows).

Power supply for motor: 48V.

//This code is for ATMEGA 16

#include<avr\io.h>
#include<avr\interrupt.h>
#define F_CPU 1000000UL
#include <util/delay.h>

int del;
int x,x1,z,z1,a;
volatile int rpm;

int main (void){

DDRA = 0x00;
DDRD = 0xFF;
DDRC = 0xFF;
DDRB = 0xFB;
ADCSRA = 0x87;
ADMUX = 0xC0;               // Selecting ADC0

TCNT1H = 0xAC;              //5 seconds timer for rpm
TCNT1L = 0x54;

TCCR1A = 0x00;
TCCR1B = 0x04;

MCUCSR = 0x40;
GICR = 0x20;                 //Enable interrupt 2
sei();

    while (1)
{

    ADCSRA |= (1<<ADSC);
    while ((ADCSRA & (1<<ADIF)) == 0);
    {
        x = ADCL;
        PORTD = x;
        x1 = ADCH;
        PORTC = x1;
        del = ADCL;
        del |= ADCH << 8;       //ADC value from pin 40 (throttle)
        del = (del-512)/50;

        if (del >=7)
        {
            PORTB = 0x08;   // if throttle is completely turned, rotate at
                            //full speed
        }

        else if (del > 0)  //if throttle at midway, send PWM pulses
                           //accordingly
        {
        PORTB = 0x08;
        _delay_ms(del);
        PORTB = 0x00;
        _delay_ms(10-del);
        }

        if (del < 0)
        {
        PORTB = 0x00;     //motor stopped when throttle is at initial
                           //position
        }
    }

    if ((TIFR & (0x1<<TOV1)))    //if timer flag HIGH
    {

        if (rpm >= 11)   // if rpm is greater than 11 during five seconds
        {
            PORTD = 0xAA;
            PORTB = 0x00;   //stop the motor
            PORTC = rpm;
            _delay_ms(2000);
            rpm = 0;
        }

        else               //else continue
        {
        PORTD = 0xFF;
        PORTC = rpm;
        _delay_ms(1000);
        rpm = 0;
        }

        TCCR1B = 0;      //restart the timer
        TIFR = 0x1<<TOV1;

        TCNT1H = 0xAC;
        TCNT1L = 0x54;

        TCCR1A = 0x00;
        TCCR1B = 0x04;
        PORTD = 0x00;
        PORTC = 0x00;

    }
    }
}

ISR (INT2_vect)
    {
        rpm++;
    }

IR sensor is at pin 3.
I am using the module as it is:https://www.amazon.in/VEEROBOT-Infrared-Proximity-Obstacle-Detecting/dp/B0115NCT4U/ref=sr_1_3?s=industrial&ie=UTF8&qid=1517231322&sr=1-3&keywords=ir+sensor

I am using this circuit to step the voltage down for Atmega16. hobby-hour.com/electronics/lm2576-5v-buck-regulator.png The mosfets work fine. I have already checked them with heavy load and long runs.


texts: What is a single conductor temperature sensor called?

texts:
What is a conductive temperature probe called? They're relatively massy metal rods (5-8mm thick, 5-15cm long) that have a single conductor (NOT 2 conductor wire) to connect to the thermostat.

The connecting conductor wire is reasonably thick to (presumably) conduct the heat effectively to the measuring device.

I replaced one in my oven, and my spa has one too.

(I ask, because I broke the wire on my spa one, and searching the internet without a technical continually brings up thermo couples and other sensors)

Updated to help others: I'm looking at something like this is the sort of thing:


texts:
In the Atmel SAME70-XPLD board, there is a 2MB (2 bank x 2K row x 256 col x 16 bit) SDRAM (ISSI IS42S16100F-5BL).  It is connected as follows:

I don't understand why the A0 pin of the SDRAM is connected to ADDRESS2 of the MCU.  Since this is a 16-bit wide memory, shouldn't this be ADDRESS1 so that each address is 16-bit aligned?

The schematics for the board can be found here (page 48 is the SDRAM):
SAME70-XPLD User Guide


texts: Why does current change when adding in an LED?

texts:
In the following diagram:

The current is 1 mA from:

V = IR
R = 1 / 1000 = 1 mA

However, when I add in an LED with forward voltage 1V:

Why does adding in the LED drop the current as well? Does an LED have resistance as well? (I thought an LED only causes a voltage drop but doesn't have resistance). How does that work?


texts: Why is HV kept open in OC test of transformer? Also, why is LV shorted in SC test of the transformer? (Generally this is preferred - why?)


texts:
I'm looking for a good beginner book for ARM microcontrollers. It should cover the CPU architecture and the boot sequence and ideally also assembler, C and peripherals.

I have a book like this for AVRs and there seem to be several good choices for Atmel chips. The ARM landscape is is more complex with multiple vendors and several classes of chips. A look on Amazon did not reveal a clear favorite. Would appreciate some recommendations.


texts: 3.3V to 5V logic level shifter with 3.3V microcontroler board and 5V arduino sensor

texts:
I would like to use logic level shifter like the one above.
3.3V logic level would be connected on NodeMcu 3.3V microcontroller board pin, while 5V level would be used for Arduino sensor.
What troubles me is the current flow.
I don't think I understand properly current flow.
When 3.3V logic level is LOW, will some current flow back towards 3.3V microcontroller pin through R1 or through R1 and R2 combined towards 3.3V pin?
Should I worry about that?
I would appreciate if someone could help me understand a bit more about current flow in this circuit?


texts: Why does USB type-C use multiple voltage sources?

texts: USB standard-A uses a single VBUS, but type-C seems to have two. Why is that?


texts: Can you damage a tantalum capacitor by mounting with heat gun?

texts: I just mounted some 47uF tantalum capacitors to a logic board. I used a heat gun at 325°C to heat them up so the solder under there would melt, and then they would sit down on their pads. They did successfully mount, but I was concerned about the heat gun damaging the caps because they became very hot, and one or two of them became discolored (slightly toasted :D). The machine boots fine.


texts: Access elements randomly in RAM based FIFO VHDL FPGA

texts:
The thing is: new data is being generated every "time step" that can be few clock cycles. So I want to store the data generated for few time steps in a "buffer". The data must be stored like in a queue. That is, the latest datum goes at the end of the queue and the first one is discarded. All the rest are moved one step ahead. That is, the second becomes the first, the third becomes the second and so on.

I want to avoid registers to save circuit area. That is why I am thinking of using on-chip memory like SRAM.

It can be understood as a FIFO based in RAM in which I could access any stored element by means of an address.

Something like:

entity special_fifo is
  generic (
    WIDTH : natural := 8;
    DEPTH : integer := 32;
    WIDTH_DEPTH : integer:=5
    );
  port (

    clock      : in std_logic;
    reset      : in std_logic;
    wren      : in std_logic;
    ren     : in std_logic;
    address    : std_logic_vector(WIDTH_DEPTH-1 downto 0);—-This is the thing that I would like to have
    data      : in std_logic_vector(WIDTH-1 downto 0);
    q       : out std_logic_vector(WIDTH-1 downto 0)

end special_fifo;

Can anyone clarify if it is doable?

Another way to ask the question could be:

Is it possible to shift the elements stored in RAM as if they formed an array. Something like this:
RAM(address)<=RAM(address+1).

The number of clock cycles required does not matter in principle.

Edit: The data does need to be moved in the ram. It is data that has to be updated (thats why the latest is incorporated whereas the oldest is removed). Every single element of the current data must be accessible by means of the address. It is like updating a matrix row by row.


texts: What is the limiting current for a stepper motor having a resistance per winding of 20.5Ω, an inductance winding of 45mH and an operating voltage of 12V?


texts: Should continuity test be performed when the device is off? Why?

texts: Can an electronic circuit which is passing currents be tested by a multi-meter's continuity test? Would it be meaningful or harmful? Why?


texts: Does crystal leads have to be same length?

texts:
I have always managed to keep the length of crystal resonator leads at the similar length. In the application I am working atm however, I noticed it would be suitable to place the crystal in a way, that one of the leads would be significantly shorter than the other. Since this connection is not a differential pair and the crystal can be treated just like an RLC model, I see no problem in that. But to be sure, I rather ask because I might miss something. So, does it matter either the leads are the same length or not?

I would appreciate all help regarding this.


texts: How to calculate voltage drops and power for a current dependent current source in series?

texts:
So the question goes as follows:
For the circuit in the figure below determine: a) the loop current, b) voltage drops across all the resistors; c) voltage of the dependent current source, d) power associated with each element and whether it is absorbed or delivered.

I don't need the entire answer done, just maybe the first step to get started.

Thanks to everyone that told me to do the KVL, but I'm stuck trying to express the dependent current source. I know it is 5 times the current of I, but this is where I get stuck. VR1 + VR2 - VIs + VR3 + E1 = 0


texts: ADC of TM4C123GH6PM( 1 Msps as given in datasheet ) is not reading any data if sampling frequency is increased beyond 250Khz

texts:
I need to sense a signal at 500kHz.
According to the datasheet of the TM4C123GH6PM it is able to sample up to 1000Khz.

The code is already written with sampling frequency at 90Khz. Whenever I change the sampling frequency to 500Khz, the ADC is not reading any data. Also, in the code they have used SS0 Sample Sequencer (p. 802 of datasheet).

If I change the sample sequencer to SS3, will it help? Or what can be possible solutions?

DAtasheet : http://www.ti.com/lit/ds/symlink/tm4c123gh6pm.pdf


texts:
I need to replace a pc-fan 2 pin(80X80X25mm).
The only details it has are:12V/0.14A.(no RPM/CFM details).
Will those details(voltage/current)enough and i can pick any
80X80X25mm 2-pin pc fan which has the 12V/0.14A value or it might be
a case,that the rpm/cfm of the replacement,will be different in
spite of the identical voltage/current?


texts: Is there any relation/leak between two sections of LM358 op-amp?

texts:
I want to use section A of an LM358 OpAmp to limit the current and section B to convert Arduino PWM to analog, and then connect output B to non-inverting input of input A as reference voltage.

The LM358 VCC is not going to be lower than 12V or higher than 16V.

Is there something like "leakage" of current/voltage or anything else between two sections that can damage the Arduino or two sections are isolated from each other?


texts: How to do series connection of DC/DC converters?

texts:
I am using Traco Power TEN 5-1223 which has +12V input and +-15V output.

I am trying to connect 4 +12V DC/DC converters in series.

How can this be done? What are the connections to be made and to what pins?


texts: MOSFET Driving On The Cheap And Cheerful

texts:
I need (unless I'm XYing) to high side switch a FET pair from a (PIC16) microcontroller in the simplest way possible. They are switching an audio line with significant current (presently the output of an LM386 running at 5V single rail). I've been noodling about trying to think of the simplest way to do this with the lowest part count/cost/board space etc. The switching does not need to be fast and will only happen occasionally when my device switches modes due to different audio sources being connected. This isn't audiophile level concerns. It's running headphones mainly for speech of telephony quality.

So, high side switching with current in the potentially low hundreds of mA needs a good voltage on the gate above the 5V. So, a voltage doubler. For reasons stated above and also somewhat a matter of taste I want to avoid yet another transistor in the mix. So I realised a simple voltage doubler (with which I have little practical experience) seems to be the answer. After fiddling with that, I realised I could actually use the FETs' gate capacitance as one of the capacitors in my doubler. So, this circuit-

D1 and D2 are the doubler diodes, C1 is the cap that isn't the FET gates. V2 represents a microcontroller pin running at about 100kHz for a clock. V3 is another pin which goes high or low to enable the output to drive fully up to 9ish volts and down to nearly zero. M1,M2,C3 and RLoad are the FEts and their load. R2 discharges the charge pump when it switches off. The FETs are actually switched by a combination of (a) the charge pump running and (b) V3 going high. According to the simulator btw, if I change my diodes to 1n5817 Schottkys, their reverse leakage is sufficient to not need R2, so that's another component saved. The output looks like this-

So what I'm primarily asking about here is R1 and R3. Their only purpose is to limit the current pulsing out of the MCU pins. With them in circuit, the spikes are entirely within the PIC spec at a few mA. Worst case is (not surprisingly) when the charge pump starts running.

If I take them out of the circuit, I save 2 resistors but the current now looks like this-

Ouch. However, this are extremely short spikes of current going into a capacitance of 4.7nF (plus the gate capacitances).

...the spacing being 5 microseconds (100kHz) and the spike pulse length being about 50ns. Basically I'm not sure how much an MCU pin can cope with short capacitive spikes like this before blowing; or over what time interval (if any) the current rating holds good.

Can I get away without the resistors? Any other thoughts on this? Are MCUs tolerant of capacitive loading? Am I in Rube Goldberg territory? I'm in that situation where the circuit I'm working on in general (of which this is only a part) is just looking too complexificated and I'm trying to pare it down.

I've had a good read of the datasheets for the PIC but I can't find a spec for capacitive loading of the pins.

NB yes there is a particular circuit reason I want to switch the amplifier's output before the 220uF DC blocking capacitor, by the way.


texts: Solar -> Supercapacitor efficiency considerations

texts:
So, basically, using high voltage series solar-solar panel arrangements and a buck-converter to step down to 2.7V for a supercap array.

Vs

Using a parallel solarpanel arra with a voltage close to a series supercap array and using a buck-boost converter.


texts: Does USB-PD prevent power banks not to fall asleep?

texts:
I'm playing around with PD board (SparkFun's DEV-15801, programmed for 9V) and power bank (Anker PowerCore 10000 PD) and observe the following behavior:

When I connect PD board to USB-A port of the powerbank, it provides 5.2V for two minutes and then shuts off.
When I connect PD board to USB-C port of the power bank, it gives 9V indefinitely (at least overnight)

I learned that power banks typically turn off without substantial load, and wanted to investigate this phenomenon, so this permanent voltage over PD was a surprise. This power bank has a Low Power Device Mode feature, but I definitely didn't activate it.

The board also doesn't have the logic to simulate load to explain it.

I'm wondering, does USB-PD protocol make power bank aware that the sink still needs power and thus not switch off?

Can I expect other PD to behave the same way, or is this just a property on the model I'm using?

Thanks for your help in advance!


texts:
I've got a 5V supply, which I need to pass through an LDO to get 3.3V. The max current that the I need the LDO to support is 1A (at 3.3V). I'm looking at the TI LM3940. Using the DDPAK/TO-263 package, I can see that the junction-to-ambient thermal resistance, \$R _{\theta JA}\$, is \$ 40.9^oC \$.

Further down in the datasheet we have the following image:

There's also the following equations:
$$ I_{IN} = I_{OUT} + I_G$$
$$ P_D = (V_{IN} - V_{OUT})I_{OUT} + (V_{IN})I_G$$

We're told that \$T_R (max) = T_J (max) - T_A (max)\$ (max allowable temperature rise is equal to maximum allowable junction temperature minus maximum ambient temperature).

We can calculate the maximum allowable value for \$R_{\theta (JA)}\$:
$$R_{\theta (JA)} = \frac{T_R (max)}{P_D} $$
As long as \$R_{\theta (JA)}\$ is \$\geqslant 40.9^oC W^{-1}\$, then there's no need for a heatsink.

If we assume that \$T_A (max) = 25^o C\$ and we're told \$T_J (max) = 125^o C\$ we calculate that \$T_R (max) = 100^o C\$

Planning for worst case conditions, let us say that (values from datasheet) \$I_{out} = 1A, V_{in} = 5.5V, V_{out} = 3.13V\$. The bit I'm stuck on is \$I_G\$. Is that the quiescent current? The value of which, for worst case, would be \$250mA\$?

I calculate:

$$R_{\theta (JA)} = \frac{T_R (max)}{P_D} = \frac{100}{3.745} = 26.7^oC $$
\$26.7^oC W^{-1} \leqslant 40.9^oC W^{-1} \therefore \$ a heatsink is required.

Is my understanding correct and calculation correct?


texts: Eliminating Signal Race Hazard in an IC dynamic latch/register!

texts:
I work in MAGIC Integrated Circuit software at layout-level.

I got an 8bit dynamic register made of 1bit dynamic flipflops that write input on the positive edge of the signal:

(Note: I used Transmission gates as switches instead of just NMOS, for robustness. Inverters are normal CMOS inverters.)

So it basically has 8 of these flipflops, connected to the same CLK. However, when I just do simple CLK and notCLK propagation, my register works on BOTH the positive and negative edge of CLK, while it should work only on positive edge. My TA told me it's because of the Race Hazard, where at one point both CLK and notCLK are at high logical level, during transition. This was correct when I simulated, so I eliminated Race Hazard with this circuit:

And indeed, with this there was no overlapping of logical '1' for CLK and notCLK. Of course, there was overlapping of the '0's, but that's inevitable, and it shouldn't affect the circuit, right?

However, I still have the 8bit register writing input values at BOTH positive and negative CLK edges! Why does this still happen? It works correctly apart from this fact. Here's the signal diagram:

As you can see, t2clk and t2nclk are my CLK and notCLK outputs of the race eliminator circuit, and it successfully eliminated '1' overlapping. However, it still writes values on negative edge of signals!

Heres my layout of the whole 8bit register, if its of any use:

If you need detailed layouts, I'll give, but I can guarantee they are faithful to my explanations! :) Help ASAP plz, deadline tomorrow!!! :)

EDIT: Could the addition of Transmission gates instead of NMOS' be the reason for malfunction?


texts:
I'm a newbie to eletronics but have a circuit diagram that uses a 2N3904 transistor to drive a relay rated at around 320ohms.
However, I already have a relay that is rated at 720 ohms which I would like to use and need to know the value of the new base resistor required.
The circuit is supplied from a 12 volt DC car battery through an LM7812 (12v out) voltage regulator. The relay I want to use (OMRON G6A 234P) is 12 volts, with 720 ohms coil and 16.7mA current rating and will have an IN4148 diode across the coil connections.
Would really appreciate it if one of you experts here could let me know what base resistor I need for the 2N3904 in this circuit.


texts: Does socket orientation have an effect on sound?

texts: Is it possible that the socket orientation (in Europe: one pin 230V, the other ground) can have an effect (albeit very small) on the amplifier behavior of a very old stereo sound system? What is, if any, the underlying reason ?


texts: What is this canister at the top of a utility pole?

texts:
I'm currently in Manuel Antonio, Costa Rica. I'm living in a relatively off-the-beaten-track house and at the top of some of the utility poles leading to my house are these canisters (the light grey thing with "IC" on it):

What is that? Is it a super localized transformer for the light fixture? Is it something else?

On the 5m walk from the main road to my house, there are many instances of these.

NB: this is in Costa Rica, not the US.

So, a second question is... what is the equivalent of this in the US? Or is it common in more rural parts of the US? (I live in a city, normally).


texts: How can you work out the internal resistance of a rectified 3 phase generator?

texts:
If there is a star topology 3 phase generator such as this-

Connected to a full-wave diode rectifier such as this-

Can you approximate the circuit to this-? (assuming steady state, DC load)

If so, how could you calculate R_G?

How would R_G relate to the resistance measured when you place a multimeter between the generator pins R, B, Y ? (e.g. resistance between R and B, resistance between B and Y etc.)

Images references-

https://circuitglobe.com/star-connection-in-3-phase-system.html
https://www.electronics-tutorials.ws/power/three-phase-rectification.html
https://en.wikipedia.org/wiki/Electric_generator#/media/File:Generator-model.svg


texts: What low power RF Transmitter to use for crowded signal area

texts:
Hi I'm fairly green when it comes to RF technology in circuits.

Here's my problem: I need a low power RF transmitter module (3 - 5v) for my application. It's a small embedded device and all it does is broadcasting a short ID to a base station.

My circuit is very small, it's a battery powered AVR. The AVR holds the unique ID to be broadcast when a certain logic criteria is met.

And to make things complicated, There will be multiple of these broadcasting their IDs to the base station, probably up to 1000 devices broadcasting once per 5 seconds which is 200 times per second. I need the range about 500ft or more.

I'm guessing something that broadcasts in the ISM range will work but I'm open for any design ideas.

So long story short; What TX/RX chips would be good to use? Also, how what would be the best way of getting a message through in such a crowded network?


texts: LVDS Termination - Not sure what it accomplishes

texts:
I am looking at the following schematic where there is an LVDS to LVDS connection. The common mode and swing are a little different between the output and the input.
I am use to seeing 100 ohm differential at the receiver. I understand that the common mode and swing are different, so I thought that the designer would do something like this:

Does anyone know how this termination is working?
Thanks!


texts: Pulse width stretching of the 0 pulse with a constant T

texts:
I have a digital output with varying pulse sizes and I want to design an IC to stretch the 0 output for a constant T+ "0" pulse time (as in attached picture).

I have tried using a monostable multivibrator with a NAND gate but the problem I got is that the length of the pulse remains constant, which could be a problem if the pulse width is greater than the multivibrator output so how to add this time constant to the original pulse width instead?


texts:
I am replacing my auxiliary light switch of my car.

on the switch assembly, it has a positive, negative, and ground.
I am replacing it with a pololu pushbutton power switch with an oem switch that is a momentary type.

Here is the switch: http://www.pololu.com/product/750/pictures

Positive to Vin
Negative to Vout
There are 4 grounds on this circuit board, so which one is the correct one to connect to the right ground?

Or am I completely wrong?


texts:
I power my 3.3V circuit with step-up power converter. Input to the converter should be  from two Ni-MH 1.2V batteries or alternatively from two 1.5V alkaline batteries.

I need to indicate low battery (by eg. LED blinking) and when the voltage reaches critical level the circuit should be disconnected. Probably I'll need some LVD (Low Voltage Disconnect) solution. Ideally if I could adjust which voltage should be indicated as warning and which to trigger circuit disconnection.

In my project I am using Arduino Mini Pro (3.3v) so maybe I could use it to measure the input voltage of the converter and warn if it is low.

Could somebody please propose me which circuit to use as LVD to fit my needs? Or any other solution?


texts: Simulation of photodiode in Micro-CAP 12

texts:
I am beginner in simulation S.P.I.C.E. and I use the simulator Micro-CAP 12 to simulate an electric schematic.

I want to simulate the photodiode PIN InGaAs IG17-series and to monitor graphically the rectangular electrical impulse, at an amplitude of a few volts generated by the photodiode depending on a period of time in ns.

Please give me any advice. I do not know how to begin. The schematic is below.


texts:
I've been looking for 115v primary 9v secondary 3.2va power rating PCB transformer and couldn't find any to replace the one that was fried. All I find is dual one, instead for example 4 pins it has 8 pins, and 220v once.

Could I use 220v primary 9v seconday 3.2va even the input is 110v?
It's for coffee machine Saeco.

Can I use the dual output and just use one pin?

Here is a picture of a transformer I need (size and shape)

Thank you


texts:
I'm interested in building a portable bluetooth boombox, but I don't really know anything about audio.  I am going to follow this forum (http://techtalk.parts-express.com/forum/speaker-project-gallery/62234-1st-boombox-project-the-madeleine?242898-1st-Boombox-Project-The-Madeleine=) for the build, which I can easily follow except for one part.

The guide gets kind of vague when he starts to talk about the audio crossover design, but there are some pictures he includes of the PCB and parts.

My question is: Is my below schematic correct?  The connections in red are directly from the first picture of the physical PCB, but the blue connections are what I'm unsure of.

If you need any additional information like speaker frequencies or PCB component values please let me know.  Thank you.

UPDATE:
I've found a picture of the bottom after scouring online for a while.  I've posted an updated schematic with what I think is accurate based on the pictures.  Do you think this is indeed a correct schematic?


texts: High frequency signal using low frequency micro-controller

texts: How do micro-controllers running at slow clock frequency (under 100 MHz) produce high frequency radio signal (2.4 GHz for example)? For example - ESP8266 runs on a clock speed of 80 MHz but is capable of wifi communication which requires a 2.4 GHz signal.


texts:
What kind of components are these?

It shows:

GA
62A
And a symbol

Does anybody know what specs these can have?

(note: updated the question since they were not capacitors).


texts: How to change ferrite core of transformer

texts: we want to replace EE20x10x6 ferrite core to FED 25 to reduce height of transformer.This is for LED driver ,we have all data for EE20x10x6 means turns for input,output,and auxiliary winding with inductance.please help me how to do this


texts: NPN low transistor voltage in emitter despite high voltage collector

texts:
I'm having a problem running fairly easy transistor case. I'd like to feed 12V to a short (9 diodes) LED strip using a signal from 3.3v controller. However after reading multiple articles on transistors, I can't wire this up correctly.

In this curcuit I'm using 2N3904 NPN transistor.

So I placed R1 so that there's 1mA current going to collector's base pin.

Collector is wirred directly to 12V and collector has:

R2 as a pulldown resistor, so that it's grounded
a short SMD5050 white strip (so that it doesn't exceed 200mA)

My intention here is to simply control 12v led stripe with a low voltage microcontroller.

simulate this circuit – Schematic created using CircuitLab

The problem with this design is that I have only 2.7V on emitter when the button (SW1) is pressed - which looks like as if the base was used as a collector but I have checked the wiring with transistor datasheet multiple times.

I think I'm missing something very obvious, any ideas?


texts: I have to implement a phase error model to see effect of phase errors on antenna patterns. However, the distribution of phase errors isn't provided to me. I am not sure whether to assume the phase errors to be gaussian distributed or uniformly distributed. Does anyone have any idea regarding the nature of phase errors in electrical/antenna related systems?


texts: Difference between (s-Omega) and (1+s/omega) transfer function representation

texts:
In my lecture notes the transfer functions are represented as:
$$ T(s) = k \frac{1+s/\omega_z}{1+s/\omega_p} $$
Where $$ \omega_{z,p} $$ represent the zeroes and the poles, respectively.
What's the difference and how do I convert this format to the usual
$$ T(s) = k \frac{s-\omega_z}{s-\omega_p} $$
Can I just use the same frequency between either format?


texts: How to partially drive a load with respective impact on my electricity meter?

texts:
I want to optimize the use of my photo-voltaic production by redirecting the remaining unused energy to electric heaters in winter, or something else in summer (given that fans are inductive loads and would make the problem worse). Note due to the (insulting) comment below: I obviously do not want to waste energy uselessly! My panels covers at most 75% of my needs, so I do have a use for the energy I produce cleanly!

The question is how to drive variable loads in such a way as to achieve a near-zero net meter reading. To be clearer if I can: if my smallest heater is 1000W, and the remaining power I have from my panels (after driving whatever I could fully) is 800W, then I want to feed them to the heater, without having to pay for the "missing" 200W. The net energy shows zero, and I am fully using my solar grid.

On/off strategy: easy but non optimal

Until now I only used on/off modes. I compute the best combinations of heterogeneous heaters to use my production in the best way. This is a classic packing problem, and the effect is easy to understand on my electricity bill.

But when the solar production is lower than the smallest load I have (<800W), then my best option is to give it for free to my electricity provider (which resells it to my neighbors... huh). Else I would be paying by importing energy.

So I need to be able to drive loads more gradually and have my energy meter integrate the kWh correctly (from my viewpoint!).

Skip half mains cycles: would it really improve my bill?

I could skip half mains cycles by driving a TRIAC or a solid state relay thanks to a Bresenham algorithm (i.e. switch it on only for N half-cycles out of each repeated M half-cycles).

But I doubt that such uneven AC waveform use would work on my electronic meter. May be it would if it was integrating my need over a significant time interval, like the old spinning disk meters.

Instead, I suspect that every peak I use would still overshoot my instantaneous production, count as an import of energy, and be detected as so (which is fair). But during the cycles I do not use I would again over-produce electricity for free, back into the public grid.

Switching the load at high speed (chop the AC)

I can otherwise rely on a much higher switching frequency (e.g. hashing the 50Hz AC waveform with a 100KHz PWM). Technically, it should still be fairly easy with a microcontroller and a TRIAC.

But still, I wonder if the electricity meter would count it the way I would like. As a side note, even with a zero-cross detection, would I pollute the mains with electromagnetic noise (even for resistive loads? my micro-inverters are quite sensitive to noise on the AC waveform and may shutdown as a protection!).

More complex control?

Still in order to use my excess of energy, as measured by my electricity meter, I could also try and drive the heaters with variable voltage instead of chopped AC.

It may be the only real way to have the electricity meter behave as I expect (instantaneous P=UI ?). But I have no clue how to do this with loads up to 2KW . Would adding high power coils smooth the chopped AC waveform?

So far my weirdest idea would be to try and add a servomotor to set the potentiometer of a 4KW AC motor controller in order to drive my heaters... but this sounds like a bad idea :D


texts: I have a RN 41 (Roving networks) bluetooth module, have no breakout board, want to connect it to Arduino duemilanove, can anyone please help with the circuit diagram and the components required to connect module to arduino


texts: Circuit and schematics - grounding diode

texts: I've never seen such connection before and I was wondering why the diode is grounded in that configuration.


texts: How can I limit the current in a 12v car battery to be safe for my 25a motor driver?

texts:
I have a 25amp Sabertooth Motor controller that can be powered by my 12v car battery. I have big 24v wheelchair motors attached to the motor controller.

I do not know how much current that the motors consume. However, I installed 20amp fuses to make sure that my motor driver does not get damaged in case of current overflow or a motor stall.

Having that said, the fuse blew out several times when I test-ran my robot. Everything works fine, except the motors consume very high current from the battery.

Can I possibly connect a resistor in series with the motor driver to make the circuit "safer" to avoid blown fuses? Will a voltage regulator help? OR does anyone have any other suggestions? (please be specific)

Thanks


texts:
I think I may have overwritten the reserved bits when messing with GPIO on my board.
Now when I try to connect with OpenOCD it gives an error.

Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : clock speed 950 kHz
Info : STLINK v2 JTAG v24 API v2 SWIM v0 VID 0x0483 PID 0x3748
Info : using stlink api v2
Info : Target voltage: 3.260948
Error: init mode failed (unable to connect to the target)
in procedure 'init'
in procedure 'ocd_bouncer'

Is there any way to erase the memory in flash without being able to connect to the board, or Have I bricked my board.


texts: Why changing the potentiometer affects the whole circuit?

texts:
simulate this circuit – Schematic created using CircuitLab

I have the following simple circuit where the potentiometer is used as a rheostat.

9V battery (-) --- 0.470K Resistor --- LED --- 1K Potentiometer --- LED --- (+)

When I turn the shaft of the potentiometer both LEDs change their brightness.

My problem arise from my own understanding that electric charge flows from (-) to (+) so whatever happens after the first LED should not affect it (should not matter).

Where is the problem in my mental picture?


texts: Sending ground along with digital connections between boards

texts:
I have been wondering for quite a while whether it's good practice when connecting two boards together (powered from the same power supply, although each has its own regulator) to send ground connections along with the digital connections.

For instance, I had a board which contained a AVR atmega microcontroller (controlling an external ADC) connected directly to a FTDI USB to serial converter. This worked well. Now, I'm splitting the boards into an ADC board with the micro+ADC components and a board containing only the FTDI chip. The connectors on these boards are screw terminals, and I'm going to use SIP pins to connect the terminals together instead of wire. This ensures minimum distance the 8 logic signal has to travel between boards. The rise time of these signals are on the order of ns, and are running at 1MHz.

The question I'm having is whether it's good practice to add more pins for ground connections between boards. I understand that giving each digital pin its own ground pin will reduce coupling between pins and provide better ground return paths. However, that will add to the pin count. Also, I'm worried it will feed back noise between the boards.

Previously, when sending wires between other boards I've had capacitive coupling between them. So I'm trying to find what the standard practice for such a situation is.

Thanks in advance,
M


texts: USB mouse with a PS/2 adapter for FPGA PS/2 interface

texts:
I'm designing a PS/2 mouse interface for BASYS 2 FPGA board. As you might know to communicate with a PS/2 mouse you need a protocol, so if I write my VHDL program for the PS/2 protocol and then connect a USB mouse with a PS/2 adapter will it work?

I don't really know what happens inside a mouse but logically I think it shouldn't work or maybe the adapter does all necessary protocol changes? My adapter looks like this PS/2 Male to USB Female Adapter but it's a Microsoft adapter as is my mouse.


texts:
I know that the capacitors store energy by accumulating charges at their plates, similarly people say that an inductor stores energy in its magnetic field. I cannot understand this statement. I can't figure out how an inductor stores energy in its magnetic field, that is I cannot visualize it.
Generally, when electrons move across an inductor, what happens to the electrons, and how do they get blocked by the magnetic field? Can someone explain this to me conceptually?

And also please explain these:

If electrons flow through the wire, how are they converted to energy in the magnetic field?
How does back-EMF get generated?


texts: Total copper loss in parallel operation of dc generator

texts:
While calculating total copper loss of two dc generators connected in parallel which is valid approach?

calculate resultant resistor of two parallel connected generators then use
ohmic loss formula with total load current.
calculate two individual copper loss (current delivered by individual
generator and its own resistor), then add up both copper losses.


texts: Can you use reverse as regenerative braking in a 2 quadrant motor?

texts:
I'm having trouble understanding 4 quadrant versus 2 quadrant drive for a 3 phase permanent magnet brush-less motor.

Let's say you are riding a scooter with such a motor at a certain velocity forward and slam it into reverse.  The scooter will slow to a stop and then start accelerating backwards.

What is the difference between doing this and using regenerative braking (besides the obvious fact that you continue backwards after stopping)?

Does using reverse to brake the scooter as described above put energy back into the battery the same as regenerative braking would?

For drive manufacturers that sell drives with optional regenerative braking capability, what is really the difference between a 2 quadrant version of the drive?  Can't the 2 quadrant version be used for regenerative braking with reverse?


texts: VHDL: Getting a part of the actual input in a variable

texts:
I am writing a VHDL code for implementing a cipher on FPGA.

I am passing a hexdecimal value to a signal as an input

input :  in  STD_LOGIC_VECTOR (63 downto 0);

I get the value in input but further I want to use only 1st 8 digits in for loop.

In other words I just need to get a sub-string out of the actual input I receive.
So can I achieve this in VHDL syntax. If yes, can any one provide a hint, or provide any pointer about this.


texts: Do CMSIS libraries also handle GPIO registers?

texts:
I'm currently exploring embedded programming with ARM processors. My embedded systems class has us programming on an Atmel SAMD20 (Cortex M0+). Our lab manual explains in detail how to utilize an Atmel library to access the registers on the processor to control GPIO pins.

What I've been trying to learn on my spare time is how to get up and running on my own with a different microcontroller, knowing that the code will be somewhat different. I read about CMSIS which seems like a convenient way to start programming on new microcontrollers using the same ARM core. However, different silicon vendors will have a different number of GPIO ports/peripherals connected to the microcontroller. How can CMSIS keep consistency between these GPIO ports when they are different between different chips? Or does CMSIS not handle GPIO ports and only things pertaining to the ARM Core?

If the latter is the case, does this mean I must look at vendor datasheets to understand how to code a specific microcontroller? I am looking at STM32 microcontrollers at the moment and am having trouble locating anything that documents their header files. I am a little lost and overwhelmed at the moment, so any advice and direction would be appreciated.


texts: How can I slow down the switch time of a MOSFET?

texts:
I have an NMOS that is switching too fast for my application. Into the gate I am sending a logic-level square wave (PWM). Unfortunately for me, as expected, the output is also a near square wave.

How can I get the Vout to be more trapezoidal? Or said another way, what is the simplest modification I can make to decrease the slew rate at the output?

Note: (Vin) is the voltage applied at the gate of the NMOS & (Vout) is the voltage seen at the drain of the NMOS.


texts: Issues with CP2102 USB bus-powered and esp8266

texts:
I currently have some problems getting the cp2102 and esp8266 to work together on my board and was wondering if some of you can spot the problem or have some hints for me.
The issue is, that I'm not able to upload anything to the esp8266 ( timeout cant detect flash config ), but the cp2102 is being recognized by my pc and the esp8266 modules are also working (tested with a spare nodemcu board, switched the cp2102 around aswell). The voltage on the pins seems to be fine aswell, except for gpio0, which hovers around 2V (while it is at 3.3V on the nodemcu board).
I suspect it has something to do with the cp2102 being used in USB Bus-Powered mode, since I can measure 2V on gpio0 and 0.9V on VCC while the tps61021 is powered off, but I'm not sure.

Edit:

The tps61021 is powered by two aaa batteries and outputs 3.3V.
The board is a 2 layer design.
I used an external FT232RL programmer (connections: rst->RTS, dtr->DTR, rx-TX, tx->RX and gnd->gnd) on a working previous iteration (without the onboard cp2102)

This is my current schematic :


texts: RTOS: Micrium uCOS vs Mentor Graphics Nucleus

texts:
We're working on a wearable IoT device, and I'm hoping for some guidance on  the common commercially available RTOS, such as what's the difference between the two. As of current I'm leaning toward Mentor (their marketing and easily available info on their website is very grabbing), but my associate is insisting on uCOS. I believe uCOS is more popular, and has a lower minimum footprint but I'm not entirely concerned about these.

Nucleus looks like it has more modules/stacks ready to go, am I wrong?
Furthermore, someone convinced me that have a POSIX layer is important, which Nucleus seems to natively have. Does this make sense?

Some of the stuff we need is, i2c; M4, M0 support; USB OTG; BLE (CC2564)


texts: Right way to couple DGND to Chassis ground

texts:
So we all know certain things:

DGND (and subsequently AGND) needs to be coupled to Chassis ground, or Earth at one position, at least, in a device.
The Earth is otherwise considered as a hazardous source of stray current and noise - and needs isolation from the electronics.
The System ground and earth are usually capacitively coupled.

Questions:

I have seen AGND and DGND coupled with ferrite beads - primarily to reduce HF coupling yet keeping the DC bias the same. So capacitively coupling the DGND to Earth is to make sure DC power does not flow into the system but the HF components flow out of the system?

Usually its a 100nF or 10nF cap that i have seen be used for this purpose - is that the general rule of thumb, or does the value of the cap change based on the application/design of the system?

What about HF transients on the Earth coming into the DGND through the cap - is protection from such events implemented in hazardous environments? (Read electricity substations, lightening towers, etc.)

Are there any other recommended EARTH to DGND connection schemes recommended other than capacitive for special needs/applications?


texts: DC electromagnet strength: voltage or current?

texts:
Is the strength of a DC electromagnet more determined by current or voltage?

For example: if I had one battery at a fixed output that I could step up or down, would it be better to have a higher voltage or current?

I don't want loads of equations as this doesn't have to be accurate. I just need to know if I should step up or down my power?

P.S: and do you have a recommendation where I can find out how to create a circuit about stepping up or down DC. I've had a look around but I don't know what is best or now as this is not something I usually do.


texts: The circuit in the image is to detect AC mains is present when the wall switch is ON. When wall switch is in closed position the DC current will pass through it and return to the circuitry.Th e transistor circuitry will help to switch ON the LED bulb when mains voltage (230v) is not available. Each LED will require 3.2V and consume 25mA. I am planning to use two 2N3906(PNP) transistors and one 2N3904 (NPN)transistor. Can somebody suggest your feedback on this circuit.


texts: How to secure components to a wire-wrap board

texts: I used to use a breadboard, and it would hold the components put into it. A wire wrap board is different. The components are don't seem to be secured to the board. How are they supposed to be secured to the board?


texts: I have been looking for this on google and couldn't find it, what does the schematic look like for a 3 pin IR reciever (ground, +5v, out)?


texts: How does a change in base current affect collector current once the transistor is biased

texts: Let us say I bias my base emitter region so that the depletion region is reduced (Vbe=0.7 volts) so the the base emitter region conducts. Now if I apply a small base current why does it result in a large collector current since I already have the base emitter region forward biased . Does the base current inn some way cause a change in the collector base depletion region? In what way do I have to look at this to be able to understand?


texts: Can an Arduino Pro Micro act as a USB hid and usb host device at the same time?

texts:
I know that the Pro Micro can act as a HID device.

As far as I understand the Pro Micro can also act as a USB Host using a usb-host adapter (shield) - right?

Now can the pro micro be both a device and a host by using 2 usb ports (the one from the pro micro for hid and the one from the usb-host shield for usb-host)?

Thanks


texts: Fast circuit breaker on low side of mosfet driven led circuit

texts:
I have some high power CREE COB LED's CXA1304-0000-000C00A20E8, which I turn on for 0.5 ms using a MOSFET on the low side. The signal comes from an optocoupler.
I experienced some burned MOSFETs from shorts in the LED circuit. I am looking for a short circuit breaker, which I could add next to the MOSFET.
So far I checked the datasheet of TI's eFuses but they are to slow in building up the target voltage(23.9V/1.6ms)
In the best case the LED's circuit will stay open if 2 Amps get exceeded until reset. A fault indicator pin would be nice also.
Edit: R1 (Voltage drop around 9V) is allocated in the lamp, not next to the MOSFET. Nominal current is about 1A. The rise time should be less than 10 µs. The shorts arise from imperfections during build/install/use. For example all LEDs are shorted.


texts: Auto power off for 220 V AC cable breaks

texts:
Can anyone suggest a circuit to automatically cut power when 2 core 220 V AC cable tied on poles powering 12 V SMPS at different locations breaks between any poles? There is lot of monkey menace.

__________________________________

EXAMPLE ONLY of use case:

There is lot of monkey menace

Sumatra, 2009.
:-)
Genuine photo(s)  but badly edited.


texts: Synchronous reset within always block - BLOCKING vs NON-BLOCKING assignment

texts:
I am trying to use synchronous reset within an always block for a Moore FSM.
Following are 2 blocks of code implementing the same, one uses Non-Blocking assignment and other uses Blocking assignment.
always @(posedge clock, posedge reset) begin
 if(reset==1)
     current_state <= Zero;
 else
     current_state <= next_state;
end

vs
always @(posedge clock, posedge reset)
begin
 if(reset==1)
     current_state = Zero;
 else
     current_state = next_state;
end

What would be the difference in outputs between these 2 blocks of code?


texts:
We have some PCBs that were designed to drive high-power ultrasound transducers. There was an issue with the boards early on that resulted in several of them blowing diodes.

I have since fixed the issue on the remaining boards and am trying to repair the dead boards to solder on some new diodes.

However I have run into an interesting issue that I have never seen before, which is that the lead frames of the QFN packages seem to have metallurgical bonded themselves to the PCBs. This is presumably because they are copper lead frames.

The board is 4-layer with 1oz copper and a large number of thermal vias - there is normally a large heat sink on the reverse side which I have removed it during the rework attempts.

Below is an example of a diode that I've tried to remove. To heat, I am using a hot plate (Weller WHP200) to bring the board up to ~150*C and then a heat gun to bring the diode up to ~350*C. However on all five diodes that I have attempted I seem to be only able to remove the package - the lead frame seems to be stuck fast. Even heating to ~400*C doesn't seem to allow it to budge.

I also have a 120W soldering iron to hand (Weller WXP120), and have tried it out as @Sphero suggested. However even leaving it on the copper slug for a good couple of minutes at 380*C (board hot enough that solder on the RS1 pad in the picture was wet), the slug won't budge.

Has anybody come across this issue before? Do you have any suggestions for how to remove the lead frame?

I don't mind experimenting on the boards as if they can't be fixed, they are scrap anyway. So if you have any ideas you'd like me to try, I'm all ears.


texts:
I want to power two opamp rails with +-12V.
For that I want to use this component to obtain +/-12V split supply from a 24V single supply.

But I came across the following statement:

  TLE2426 splits the opamp rails and references signal ground but not
  output ground.

What does that mean? Can I use use TLE2426 to power rail-to-rail opamp rails?


texts: How do I correctly power a USB 2.0 while decoupled from signal?

texts:
I'm building a switch that will power on / off a bunch of USB 2.0 ports. In order to avoid overloading the USB hubs (as has been an issue in the past) I would like to power and switch my peripheral device separately from the USB socket. The connection would look like this:

I'm worried that there will be a difference in common mode voltages between the gnd / 5V from my power supply, and the D+/D- data. I have done some searching but I'm not sure what an allowable common mode voltage drift is, and how I could mitigate it.

Specifically my questions are

How much do I need to worry about this common mode voltage?
What should I do to compensate / protect this circuit, especially the USB socket?

EDIT: Thanks to the responses below, I will instead use this as a circuit:

Hopefully this isn't pulling too hard on ground and overloading the USB socket!


texts: Using rotary encoders with no interrupt pins

texts:
I little background first..
I have 4 separate wheels in my robot and an encoder on each wheel. I am using an arduino mega 2560 which only has 6 interrupt pins, every code that I've seen either uses 2 interrupt lines per encoder or 1 but then its not that precise.

My idea:
My idea here is that the encoders tick at around 300Hz at maximum speed for my robot so I'm using a timer overflow interrupt to read all of the inputs that encoders are connected to at roughly 1kHz which also gives me plenty of time (1 ms) to check if the inputs changed and do my calculations and then return from the interrupt.

My question:
Is my thinking correct? Will I be able to read properly the encoder position and changes? Is there anything better I could do? Are there any caveats that I should take into account when dealing with this?

Update:
From the discussion in the comments and answers I currently have the two following alternatives:

Stick to the polling idea (increase frequency when necessary)
Use a "shared" interrupt available on every pin (didn't know it was possible)


texts: How to Set Background Color of Editor in MPLab X?

texts:
New to MPLab X, and just trying to navigate between bugs and getting used to it.  I've already found that 'C' formatting is apparently not part of 'All Languages'.

In Mac, I've found:
mplab_ide >> Preferences >> Fonts & Colors icon >> Syntax tab.

But there doesn't seem to be a way to set the background color of my editing environment.  The white is just a little intense on this monitor and I'd like to take it a bit darker if I'm going to be looking at this code a lot.

Thanks.


texts: I have completed an Altium PCB design and now I want to change the footprint of one component. The "Import Changes from " button is inactive. How can this be enabled?


texts: Transfer function of phase change controlled with capacitance

texts:
We have an RLC series circuit with sinusoidal voltage source of frequency \$\omega\$. The normal transfer function of current to voltage is:
$$ G(s) = \frac{I(s)}{V(s)} = \frac{1}{R+s L+ \frac{1}{s C}}$$

We would like to find out the transfer function for phase shift of current to the capacitance. We can control the capacitance and therefore also control the phase shift.

$$ G(s) = \frac{\phi(s)}{C(s)} = \,? $$

The nonlinear function of phase shift from vector diagram is
$$ \phi(C) = \arctan\frac{\omega L- \frac{1}{\omega C}}{R}$$

We could linearize this function with Taylor series, but this equation doesn’t have any dynamics.

Is there a way to get the linearized transfer function (how small step change of the capacitance changes the phase shift of the current) so we can do the stability analysis for a control loop?

We have a black box with a value of capacitance as input and phase shift of the current as the output with RLC circuit inside. Lets now try to do identification of this system. I can set a value (operating point) of the phase shift with the value capacitance. Now I will do small sinusoidal perturbation around the operating point of C at some frequency range, and measure the amplitude and phase shift of the output phi. I know it's confusing phase shift if phi is the phase shift of the phase shift. What I get is the Bode plot and from this, I can approximate the transfer function. This is the transfer function that I want to drive mathematically.

This is a classical PLL

The VCO is controlled with voltage \$ V_{cont}\$, the output frequency of VCO is
$$\omega_{out} = K_O V_{cont},  $$
where \$ K_O \$ is the gain coefficient [rad/s/V] and the output phase is
$$\phi_{out} = \int \omega_{out} dt = \int K_O V_{cont}.  $$
The transfer function VCO is then
$$\frac{\phi_{out}(s)}{V_{cont}(s)} = \frac{K_O}{s} $$
Instead of the VCO is the RLC circuit. I also can’t control the frequency like in the VCO, only the phase shift.
This is the block diagram of the control system

This is the working principle scheme

Here \$ C(s) \$ is the compensator (regulator, loop filter)

The PLLs are used for measurement of the currents in the main and auxiliary phase, they also have AGC (automatic gain control) to ensure the same amplitudes of the current signals, because I only want to compare the phase difference. What I want to control is the phase shift of the current in the auxiliary phase to the current in the main phase, let's say to get 90 degrees phase shift. I have tested this in a simulation and it works.


texts: How to calculate the node voltages for this circuit using the voltage divider rule

texts:
I am working on the following circuit:

Simplifying the circuit:

After simplifying, my answers do not match that of values I get from simulating the circuit in multisim. Here's my calculation:
$$Voltage V_B$$
$$V_B=6(\frac{5000}{5000+(32.35714286\times10^3)})$$
$$V_B=0.8030592734V$$
$$6-0.8030592734=5.20V$$

$$Voltage Vc$$
$$V_c=5.2(\frac{(32.35714286\times10^3)}{5000+(32.35714286\times10^3)})$$
$$V_c=4.50V$$

The simulations I did on multisim show that the voltages for Vb and Vc are:
$$V_B=5.161V$$
$$V_c=5.035V$$

I don't know if its the simplification I'm doing wrong or my approach towards the voltage divider rule. I need help.


texts:
I'm thinking:
If I have two fuses of same type and rating in parallel, the current would split approx 50/50.
If one fuse have a lower resistance, then more current will flow in that, it will get hotter than the other.
Then the resistance will rise, to the point where both fuses will carry the same current.
So two fuses in parallel will blow at (almost) the double current.
Am I wrong?


texts: Door Phone / Intercom interface to arduino and power from dc bias?

texts:
This is my very first post on a challenge I have been struggling with for a year. How can I build a extender to my door phone (Brand Fermax) while protecting the inputs on the arduino and avoiding more power sources than necessary ?
This post only care about converting a 24v dc biased audio signal into 0-5v readable by the arduino.
What I have come up with are two options:

A simple diode protected opto isolated circuit using 4n35. This will both protect the arduino and enable reading a 0-5v signal but I assume the DC bias will in reality mean the audio signal get very compressed to voltages that only vary between 4 and 5v? See image.

Therefore I have considered another circuit which first removes the 24v dc bias, then adds a smaller bias into a opamp that drives the input of the optocoupler. The issue here is that the opamp and audio signal needs a voltage source. And here I try to use the dc bias to power the opamp.
See circuit from EveryCircuit. Note! this simulation is emulating input to an optocoupler. Ignore everything to the right of the led as EveryCircuit doesn’t support optocouplers as default.

Some additional information:

The signal from the door phone seems to be a 24v DC shifted AC signal (audio) with amplitude +/- 5v. Meaning the signal seem to vary from +22 to +27v. The signal is a square wave when the door bell rings and the spoken audio when someone is talking in the outdoor microphone.
I have no idea how much current the door phone DC component (in contrast to the AC audio component) can support. I don’t know how I can find out since I don’t have the original schematics. I have only used an handheld oscilloscope to try to find out the signal.
The plan is for the arduino to read an analog (+/- 5v) signal through the A0 pin. I will in software detect audio over a given volume threshold, which will trigger sending a package of data to a remote arduino over NRF24L01 (Audio and “open door request” signal). The remote arduino has a button which will trigger an “open door“ command, which will be transmitted back and trigger a relay on the arduino connected to the door phone. Everything already works except the interface to the actual door phone

Which option is best and what would a better choice be?


texts: What is difference between LP and ALP series of HM628128 SRAM?

texts:
I ordered HM628128ALP-10 on aliexpress, got instead HM628128LP-8.

When I checked datasheets from internet, it look like -8 is little faster then -10 and LP version takes little more current that ALP to feed inputs (like 2uA instead of 1uA) - not that it matters for me, as I just want build variant of SAP-1 computer with "little more" RAM and some exra features, but it is hobby project and would run on some small frequecy, so all LEDs displaying registers would be visible blinking, not just dimmed lit.

It just catched my interest, but I could not found anything about what the LP and ALP means - I suspect, that it is something like different derivate families in 74xxx series https://en.wikipedia.org/wiki/7400_series#7400_series_derivative_families , but could not found any similar good reference for it.

Can somebody explain or point me, what the difference actually means?


texts: Timing Constraints for Forwarded Generated Center-Sampled Clocks?

texts:
Problem Description

I am trying to figure out the "correct" way to constrain (in .xdc format - this is in Vivado) a forwarded source-synchronous clock that is generated (by division) from the system clock and center-sampled at the receiving module. The situation is as such:

We have an ADC that our FPGA is sending data to. The interface to the ADC is source-synchronous: we forward a clock along with the data. It is also center-sampled in that we generate the data (at the FPGA) on the falling edge of the forwarded clock, and capture the data on the rising edge of the forwarded clock. To add to the complexity, this forwarded clock is generated by dividing the system clock. We want to be able to set the output delay of this forwarded clock/data so we can specify the setup and hold times of the ADC. The issue is that we are unsure how to specify the multicycle constraints such that Vivado figures out the correct launch and capture edge.

In real life, our forwarded clock is only divided by two from the system clock, but we want to know how to do this in the most general case, and so we'll set the division rate to eight for the sake of example.

Visualization

The big issue is figuring out the correct multicycle constraints. There seems to be no intuitive way to specify that data is launched on the falling edge of the generated clock and captured by the rising edge. The main issue is that the data is actually generated by the system clock - an FSM (that creates the generated clock) ensures that new data is only launched on edges where the generated clock falls. The "launch clock" is thus the system clock, while the "capture clock" is SCKO.

Below is a drawing of the system.

Attempted Solutions

We were able to quite easily solve the question of multicycling with regards to setup: in this case we set:

set_multicycle_path 4 -setup -from [get_clocks sys_clk] -to [get_clocks SCKO] -start

This makes sense - our capture edge is 4 cycles from our launch edge, so we push the setup time forward hold cycles. These 4 cycles are in terms of the system clock, so we make sure to use the -start flag so that the setup multiplier is in terms of the launch clock.

The question is: what should we do for the hold multicycle path, and why?

Research

For research, we can consult Vivado's UG903: Using Constraints. Of particular use is the section on multicycle paths - specifically the "Multicycles Between FAST-to-SLOW Clocks" section on page 117. But this only tells us how to handle an extended datapath - we don't understand how to apply this to our project, where we need to make sure Vivado knows that data is only launched on the falling edge of SCKO (which is NOT the clock that generates it - sys_clk generates it, but only certain rising edges of sys_clk...).

We've tried cycling through different hold multipliers, but we're not sure what the correct way of doing this is. For our "divide by 2" example, we found that setting a hold multiplier of 1 would work - the path report seemed to indicate something we could convince ourselves was the right answer (namely, it started the "source clock" at one period after the "launch clock" - this would correspond to the launch path starting at the falling edge of the forwarded clock and the capture path starting at the rising edge of the forwarded clock.

We've also looked at several parameters for our generated clock, output delay, and set multicycle path constraints. We've looked at the "-clock_fall" flag, but this tells the tool that we want to capture on the falling edge (when we actually need to tell it to launch on the falling edge... but of a different clock). We've also looked at "-rise" and "-fall", but haven't been able to really figure out what those do or what effect they have.

Question

In short: what is the correct multi-cycle constraint to put here, and why?


texts: What impedance should I get when testing a volume control?

texts:
My newly purchased house is wired for audio in 7 rooms. There is a distribution hub in the basement, and an impedance matching volume control in each room. The first time I hooked up my amp to the speaker wires I blew a fuse (in the amp, not a breaker). So now I'm individually testing each room. It works fine with 1 room connected, and I measured the impedance of the speakers in that room independently of the volume control and it was approximately 7.8 Ohms (I assume they are 8 Ohm speakers which is the most common in the US.) Then I measured the impedance from the point of view of the amplifier running through the volume control with different impedance matching settings on the volume control, and this is what I saw:

1X = 3.8 Ohms
2X = 5.1 Ohms
4X = 6.5 Ohms
8X = 7.8 Ohms

I thought that was strange because I was expecting approximately:

1X = 8 Ohms
2X = 16 Ohms
4X = 32 Ohms
8X = 64 Ohms

Is my expectation wrong?


texts: Arlec grid connect bulb and power points DC convert smart WiFi hack

texts:
These devices works off 240V AC.
I was looking to convert them to run off DC and keep the grid connect app function.
https://www.bunnings.com.au/arlec-9w-950lm-4000k-grid-connect-bc-smart-globe_p0136183
I don't really want to play with live AC so any help would be good.
As far as I can, see U2 drops around 320DC to 6.5DC but I don't understand were to next. The LEDs seem to run at 40-50VDC on dimmer.
Right now I am hoping to understand a schematic just get it to power on by DC to the network, then maybe use the output to do something different.


texts: Why does ATtiny85 example code bit-shift zeros?

texts:
The ATtiny85 datasheet provides the following example C, on page 18.

1  void EEPROM_write(unsigned char ucAddress, unsigned char ucData)
2  {
3     /* Wait for completion of previous write */
4     while(EECR & (1<<EEPE))
5       ;
6     /* Set Programming mode */
7     EECR = (0<<EEPM1)|(0<<EEPM0);
8     /* Set up address and data registers */
9     EEAR = ucAddress;
10    EEDR = ucData;
11    /* Write logical one to EEMPE */
12    EECR |= (1<<EEMPE);
13    /* Start eeprom write by setting EEPE */
14    EECR |= (1<<EEPE);
15  }

(I added line numbers to the code above.)

In line 7, why does the example code not just read:

EECR = 0;

Why bother with all of the bitwise operations for something that ultimately resolves to zero?


texts: Why would bridging a varistor with the multimeter leads on any setting have caused the unit to turn on?

texts:
So I've been working on fixing this window AC unit for a while, and when I started I knew next to nothing about circuits. At present today, I know a bit about circuits -- enough that i at least know what the various components are for, plus how to use the multimeter, but I am faced with a mystery I was wondering if anyone else might be able to put an educated guess on, because this puzzling event happened back when I DIDN'T know what I was doing, so the details meant nothing at the time. Now that i'm more knowledgable, I am unable to reproduce the same result.
Some background: Our apartment suffered an overvoltage event, which fried all of our surge protectors as well as the two appliances that were plugged directly into the wall: the AC unit being the more valuable.  Upon taking the thing apart, i noticed that the board had a burn mark on the back side which corresponded to where an MOV varistor was mounted on the front.
Here is the point where I wish i knew at the time more about what I was doing, because when I first saw this I pulled out my cheap dollar store multimeter, which I had no clue how to use, and put it on SOME SETTING and put the leads to each side of the varistor, which suddenly caused the AC unit to jump to life and begin working! Without knowing what the purpose of the varistor was, I immediately ordered a set of new ones with the goal of soldering a new one on.  I used wire cutters to remove the old varistor off the board.
Now about a month later, I understand what a varistor does, and so am at a loss as to how bridging its leads on ANY SETTING on the multimeter would have caused the entire unit to suddenly turn on.  I also can no longer reproduce whatever it was that I did, and any attempts to bridge the leads now results either with A) nothing or B) it immediately blowing the 3.15A fuse placed in series next to it.
So here is the puzzle.  What possible reason would it, when i original bridged the two leads of the varistor with the dollar store multimeter, have caused the AC unit to turn on? From my understanding of varistors now, it seems like the only possible results of putting something other than a varistor in between those two points in a protected circuit would either A) short it or B) do nothing, passively.  I don't understand how the circuit would be turned on by doing something to the protected side in parallel.
Anyone have any thoughtful guesses? I am at a loss.


texts: Max Charging Current for AGM batteries in parallel

texts:
I have 3 identical 125ah AGM deep-cycle batteries, all purchased at the same time. They will be charged with solar, through a charge controller. I have them connected together in parallel.
They are rated for a max charge current of 30A. I just want to confirm whether connecting them together in parallel raises that max charge current to 90A, or if it stays at 30A. I won't be getting anywhere near 90A in reality... but I will go over the 30A mark unless I re-arrange my solar (which I really would prefer to not do...)


texts: What does an internal or external loop filter do for this clock IC?

texts:
For the CDCE62005 clock generator IC, what does the internal or external loop filter accomplish?
Thanks in advance for any input.

Page 44 of datasheet, and pages 1-2 and 6 or the eval board user guide.

CDCE62005 Datasheet: http://www.ti.com/lit/ds/symlink/cdce62005.pdf

CDCE62005 Evaluation Board User Guide: http://www.ti.com/lit/ug/scau024/scau024.pdf


texts: ways to generate (small amounts of) electricity

texts:
I'm searching into ways of generating very small amounts of electricity, by small I mean enough to light a couple of leds, nothing more

The main idea is to have toys that my daughters (2 and 4) can play with.

I started with a pet project that, installed on the steps of the stairs, would light a led when step on it (using a piezo; does pavegen uses the same piezo principle?), and then went on investigating other means of generating electricity.

know of any?


texts: How termination resistors work; what happens if I use lower values?

texts:
I am going to try to interface low-speed 8bit DDR2 chip to FPGA, and I've got some questions crucial to make it work :-)

Is that correct that the idea of termination resistor is to sink most of the signal to GND, so that only small part of it reflected back? Have anyone tried to put let's say 2-3 resistors of smaller value so that multiple remining reflections will be out of phase & cause less interference?


texts: Using Micrologix 1400 (1766-L32BXB) FET outputs to control frequency input to ST-M5045

texts:
There is a minimum current requirement in order to use the FET pins on the Micrologix controller of 21mA, and the output voltage of the pins are 24V. The ST-M5045 stepper driver data sheet says in order to use 24 volts as input a 2k resistor must be placed at the input. This will drop the current consumption below the 21mA requirment of the controller. Could a voltage divider placed between the driver and controller handle this problem? Maintain a voltage of 5V at driver input pin and draw 21mA current from the controller.

Micrologix 1400 installation manual (pg 32 bottom table)

stepper driver data sheet (contains diagram of controller and driver)

Optocoupler datasheet

image of input circuits to control inputs


texts:
I’m currently using a sysWORXX USB-CANmodul1 to communicate with a Maxim MAX3051 CAN Transceiver on a custom PCB of mine. I've been having issues with the modul1 losing connectivity with the board. The CAN lines are short (~1m) and terminated at both ends with a 120 Ohm resistor between CAN_H and CAN_L.

It's my understanding the CAN Bus should have a recessive state voltage of ~2.5V and a dominant state voltage ~3.5V and ~1.5V for CAN_H and CAN_L respectively.

However when I measure the CAN signals from each device with a scope that's not what I'm getting. See below

I've poured over the datasheets of both of these devices to no avail. Links to those are below.
My main question is does anyone know what is going on here?

https://datasheets.maximintegrated.com/en/ds/MAX3051.pdf

https://www.systec-electronic.com/fileadmin/Redakteur/Unternehmen/Support/Downloadbereich/Handbuecher/L-487e_02_05_USB-CANmodul.pdf


texts: Start off with embedded C with ATmega32 (ATmega AVR series)

texts:
I have a ATmega32 board laying around and I figure it would be perfect to start off with microcontrollers. I once did some babbling in embedded C (thats when I got this board) but the flow was stopped due to some things. Now I have two questions:

What is the best free resource to start off with C for the avr series. I know of AVR-GCC but was looking for some tutorials or free books to start me off.
Should I directly jump to C or go through ASM first? I see there are many asm books around. So what is a better option?

While searching the Internet, I found the Arduino bootloader for ATmega32 here http://retrointerfacing.com/?p=30 but the problem is I a hesitant to do some tinkering with the fuse bits and all.  Is it safe to do so?


texts: Is it misleading to say "holes in semiconductors jump to the other side"?

texts:
I'm getting a little confused with the convention of saying that "holes in a semiconductor will move from p-side to n-side and electrons will move the opposite way". I have no trouble with the concept itself, it just seems to me that an electron moving from one side to the other would mean it left a hole behind where it used to be?

Am I understanding it correct that we just think of electrons leaving behind holes as "holes moving" or do I actually misinterperet the way this works?


texts: Will enclosing a brushed DC motor significantly reduce it's lifetime?

texts:
I designed a 3D printable LEGO-compatible enclosure for an inexpensive brushed DC motor.  The intended use is outdoor holiday decoration, so I fully enclosed the motor to weatherproof it.  LEGO Technic motors are fully enclosed in plastic as well.  But I recently learned that enclosing a brushed motor is a bad idea since the ablated brush material will eventually short the motor.  This is why brushless fans are used around electronics.

Is my understanding correct?  Should I not enclose such a motor?  (Perhaps the LEGO Technic motors are brushless.)


texts: What is the practical probability of a bit getting flipped during transmission?

texts:
We know that Coding Theory depends on the fact that the probability p of a bit flip must be less than 0.5. From Fundamentals of Error-Correcting Codes (pg.39), it states

In most practical situations p is very small.

Using the technology we have in 2020 such as Fiber-optic cable, other types of cables, or wireless medium, what is the practical probability a bit encountering a flip during transmission?


texts: Can't set P74 of my PIC24F Development Board to HIGH

texts:
I have a PIC24FJ1024GB610 Development Board (Explorer 16/32).

I am trying to do a simple project where I would set P74 (PORTC RC14), and D3 LED at P17 (PORTA RA0) to HIGH.

This is the code for my project

#include "xc.h"

#pragma config FWDTEN = OFF
#pragma config ICS = PGD2

int main(void)
{
    TRISCbits.TRISC14 = 0;//output
    TRISAbits.TRISA0 = 0;

    LATCbits.LATC14 = 1;
    LATAbits.LATA0 = 1;

    while(1);

    return 0;
}

However, when I build the code and program it into the DB, I can see D3 LED to be lit, but when I bring a multimeter and try to measure the voltage at P74 I get a 0V. I thought maybe the Pin Header was defective and measured the voltage at the +3.3V pin with reference to GND and found out it was +3.3V.

I really don't understand, if there is nothing wrong with the code, or the pin header isn't defective, then why don't I get +3.3V at P74?


texts:
I'm controlling a device  that needs 12v and uses maximum of 2 amps (car fuel pump suction control valve). I'm using esp32 together with IRLZ44N logic level mosfet. I'm sending PWM signal with 1khz frequency to the gate from esp. It's very basic setup I used often with arduino. The mosfet is however getting very hot after about 20 seconds and melts breadboard. The esp32 also gets hot after few minutes and eventually stops working. I tried few different mosfets and already burned two esp32s.

simulate this circuit – Schematic created using CircuitLab
At first I thought the gate threshold is too low for this mosfet but turns out it's Vgs is as low as 2V to fully open. That wouldn't explain esp burning though.
What am I doing wrong here?


texts: Does the Atmel-ICE Debugger work on ATtiny MCUs?

texts:
I've looked on the interwebtubes and could not find out if the Atmel-ICE debugger works with ATtiny MCUs.

In theory, since the debugger supports debugWire and SPI modes, it should, but the official page doesn't list them as supported devices and the internet doesn't seem to know.

I'd like to know for sure before I dish out the cash: my AVR Dragon self destructed and I need an upgrade.

Many thanks.


texts: A difference amplifier with a non-grounded non-inverting input

texts:
My question is simple.

Let's say Vin1 = 5V and Vin2 varies from 0 to 5V.

What is Vout, if the non-inverting input is not connected to ground (with or without a resistor between the + input and ground)?

In the case of a difference amplifier, standard texts always show the non-inverting input connected to ground via a resistor (Rg). In that setup, Vout is trivial, but what about the setup shown below?

Your help is appreciated!

Note: Assume that the + and - supply terminals (2 and 5) in the diagram are wired up.


texts: How do inductor specifications impact their effectiveness in a boost converter circuit?

texts:
I've been trying to understand how to select an adequate inductor for a boost converter circuit.  I'm a hobbyist so I'm not always sure what to look for, so I haven't been able to find something that helps me understand holistically wether or not an inductor is adequate for a given step-up DC/DC converter circuit.

My question is what are the relevant specifications for an inductor, how does changing each one impact it's capability in the converter circuit, and how do you figure out what makes the inductor inadequate?

Examples

Inductance

The inductance seems to "set" the ripple current.  The higher the inductance, the lower the ripple current.  This appears to be desirable.  If the datasheet recommends a 1uH inductor, can I substitute a 2uH inductor?  What about 470uH?  How do I know how much ripple current is acceptable?

Maximum DC Current

The DC current rating seems like it's related to how much current I can draw on the supply side.  If I think I'm going to pull 3A from the power supply, can I use any inductor, ceteris paribus, with a maximum DC current greater than 3A (plus some amount of derating)?

Maximum DC Resistance

The maximum DC resistance seems like smaller is better, but how do I know how high the DCR can be before it negatively impacts the converter circuit or battery life?

Self Resonant Frequency

The self resonant frequency has to be greater than the frequency of my switching circuit right?  But, can I pick just about SRF that's greater than the switching frequency (plus some margin)?

Are there other factors that impact the inductor selection that I didn't consider (other than price and footprint . . . which is why I'm asking the question in the first place)?

This turned out to be a pretty incredible resource

http://www.ti.com/lit/an/slva372c/slva372c.pdf


texts: Purpose of capacitor in melody generator IC

texts: What is the purpose fo the capacitor in the following circuit?


texts: How to control 220 volts without using relays?

texts: I have a fan in my house, It has an electronic PCB that responds to a remote control. The PCB has a voltage dropping capacitor so, I think it is supplied with a very low voltage such as 9 or 12 volts. There is no relays on the PCB nor inside the fan, How can the PCB control the 220 volts AC induction motor ?


texts: How can I link two pins in the same route using EAGLE

texts:
I'm creating a board that has a ACS712 as current sensor. This little CI has two pins that actually has the same function and are linked internally. What I'm trying to do is link this two pins in the same route using EAGLE as the image below.

Does anyone know if there is some feature to do this in EAGLE?


texts: Will a 300A HV connector fail before a 600A fuse does?

texts:
I know this is a silly question but I cannot find ant data indicated it will not. The HV connector rated at 300A @ 85C and it is a 600A fuse, I cannot find a connector with a higher current rating.

The contentious current is 100A, however if

contentious current is 600A at 50C, is my connector under spec'ed?
if peak current is 1200 for less than 5s, is my connector under spec'ed?
if there is dead short (400v), will the connector fail before the fuse does?

Connector:

https://www.te.com/usa-en/products/connectors/automotive-connectors/intersection/amp-hvp-1100-high-current-connectors-and-headers.html?source=header-match&tab=pgp-story

Fuse:
https://www.littelfuse.com/~/media/electrical/datasheets/fuses/semiconductor-fuses/l70qs_high_speed_fuse_datasheet.pdf

Connector derating curve:


texts: SPI sensor wireless transmission using nrf24l01+ but without microcontroller

texts: I have a tiny sensor which has SPI signal. The sensor has only two lines (other than power and ground) and it takes clcok signal from a board and sends the SPI signal back to the board. I want to take this sensor away from the board and send the signal wirelessly. The whole system doesnt need arduino as the signal is already an SPI. I just need to transmit it.


texts: I'm using a 27MHz oscillator and trying to measure its voltage level and waveform with oscilloscope. But I have no idea how to match the impedance of oscillator and oscilloscope, since the data sheet of the oscillator doesn't specify its output impedance. Could anyone please tell me which values I may assume?


texts: Got very low current from PWM in Arduino

texts:
Arduino pin6 is in PWM mode, writing values from 0 to 255. This is connected to the base of a BJT NPN and then the emitter is connected to a led.

I don't understand why if I use a multi meter to read the current between pin6 and the base I get so low amps, like 40 micro amps for nearly to 5v(221 value in analog write).

Circuit in 123d


texts:
I'm looking for some advice on which components to use for this application.

The problem:  We'd like to measure the amount of "noise" in a warehouse and display this on a LCD/monitor/whatever.  When the noise reaches a certain threshold, it will be suggested that employees put on their ear protection headsets.  The sensors (microphones) need to be wireless (RF/Wifi would be preferred!  A wired RS-232/485 solution would be considered as well) and need to send samples at least every second.  Having a dedicated PC to gather and display the samples is also being considered.  For now we're only thinking of one sensor but would like to expand this to many in future.

I want to know what components you would use to accomplish this.  I'm looking for a very easy way to gauge noise so maybe decibel samples would be good.

Any hints very welcome!

Thanks


texts: Measuring Voltage and Curent Simultaneously with Probe?

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I have very little experience with electricity, but I am doing a project in which I need to measure power output of solar cells.

I am currently using this:
http://www.pasco.com/prodCatalog/PS/PS-2115_pasport-voltage-current-sensor/index.cfm with GLX software to measure voltage/current over time/temperature.  When I measure either voltage or current, the values are correct - as checked by a multimeter.

However, when I try to measure both simultaneously - which I must do - the values seem to equalize at around 0.5 for each - incorrect for both values.

I know I can just use a multimeter and record that way, but I need to be able to do this hands free and simultaneously.

Is there a circuit or something I can use or setup that will help me measure both accurately and simultaneously?

Kinda embarrassed to post this, but i guess I'll never learn otherwise.

simulate this circuit – Schematic created using CircuitLab

The battery is supposed to represent the PV cell.  The voltmeter/ammeter next to each other are supposed to represent the probe with its dual function.  Can you suggest any other way to set it up and/or is there major problems with what I am doing (probably numerous).


texts: Increased current at the output of a switch

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I am forcing a current at the output of a switch up to 25mA.

The switch can handle only a limited current depending on its size.

Question: Where will the rest of the current come from? What does the negative voltage at the output of the switch mean in practice?

The switch is a transmission gate.


texts: Reducing the tolerance of resistors manually

texts: All the resistors available come with a finite amount tolerance. This is undesirable particularly in highly sensitive systems. While we can use resistors with the least tolerance available, I want to know if there are any methods (something like designing a special setup to bring down the tolerance) using which we can manually reduce the tolerance value to the minimum that we may require?


texts: Can anyone help me to find the relation for sensitivity of wheatstone bridge using transfer function or any other methods. And why is a wheatstone bridge more sensitive when all resistors have equal value? I think what matters is the ratio of resistances and not their individual values.


texts: Protecting 0 to 5V Arduino pins from +/- 10V oscillating input

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Background:  I want to connect a Eurorack Synthesizer Low-Frequency Oscillator, which can range from -10V to 10V, to an Arduino pin which can only accept 0V to 5V.  I don't mind if the negative portion of the voltage just gets cut to zero as all I need to do for this project is measure the period of the LFO.

Here is the circuit I had in mind:

simulate this circuit – Schematic created using CircuitLab

At the left is the LFO which can range from +/- 10V.  This connects to a 10K series resistor at the front of my circuit (so that's "in").  After that in parallel are two BAT85 diodes; the upper one is intended to pass voltage spikes greater than 5V onto the 5V rail of the Arduino, the other is intended to pass negative voltages to ground.

At the right is the Arduino pin itself, represented by a 100M resistor (the "out" for my circuit is a digital pin https://www.arduino.cc/en/Tutorial/DigitalPins).

So, starting with a detail question:  I know that there can be issues with dumping current onto the +5V rail through the upper diode when that goes forward biased (stress on the power supply, etc) but is there a corresponding risk to having the ground-connected diode allowing current to flow when it goes forward-biased to cope with a negative spike?

My fundamental question is: Will this work?

(I ran it on a simulator and it looked OK, with the voltage at the pin going from 0-5V as the LFO cycles, and just a steady trickle of reverse leakage through the diodes flowing from the +5V to the ground, so in normal usage it seems like the diodes aren't dumping current to either rail.)


texts: Is debounce necessary when detecting voltage on a relay switched lamp?

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I'll be using an Arduino to "read" the parking light wire on a car.

I was wondering if debounce is necessary here? I want to think that the factory bulb will act as a debounce to smoothen out the signal...

I will be using the interrupt function to read the state change of the parking light wire. In particular, I will enable some function if the state changes twice in a particular time frame, so therefore I can't have false reading from switch bounce.

The diagram shows how I tie into the factory wire.