texts: '1011' Overlapping (Mealy) Sequence Detector in Verilog

texts:
I'm designing a "1011" overlapping sequence detector,using Mealy Model in Verilog.
The FSM that I'm trying to implement is as shown below :-

Verilog Module :-
`timescale 1ns / 1ps

module seq_detector(
input x,clk,reset,
output reg z
);

parameter S0 = 0 , S1 = 1 , S2 = 2 , S3 = 3 ;
reg [1:0] PS,NS ;

    always@(posedge clk or posedge reset)
        begin
            if(reset)
                PS <= S0;
            else
                PS <= NS ;
        end

    always@(PS or x)
        begin

            case(PS)
                S0 : begin
                            z = 0 ;
                            NS = x ? S1 : S0 ;
                            $display(PS);
                        end
                S1 : begin
                            z = 0 ;
                            NS = x ? S1 : S2 ;
                            $display(PS);
                        end
                S2 : begin
                            z = 0 ;
                            NS = x ? S3 : S0 ;
                            $display(PS);
                        end
                S3 : begin
                            z = x ? 1 : 0 ;
                            NS = x ? S1 : S2 ;
                            $display(PS);
                        end

            endcase
        end
endmodule

Testbench :-
`timescale 1ns / 1ps

module testbench;
    // Inputs
    reg x;
    reg clk;
    reg reset;
    // Outputs
    wire z;
    // Instantiate the Unit Under Test (UUT)
    seq_detector uut (
        .x(x),
        .clk(clk),
        .reset(reset),
        .z(z)
    );

initial
    begin
        clk = 1'b0;
        reset = 1'b1;
        #15 reset = 1'b0;
    end

always #5 clk = ~ clk;

initial begin
        #12 x = 0;#10 x = 0 ; #10 x = 1 ; #10 x = 0 ;
        #12 x = 1;#10 x = 1 ; #10 x = 0 ; #10 x = 1 ;
        #12 x = 1;#10 x = 0 ; #10 x = 0 ; #10 x = 1 ;
        #12 x = 0;#10 x = 1 ; #10 x = 1 ; #10 x = 0 ;
        #10 $finish;
    end

endmodule

Simulation Output :-

The issue is that, I'm getting the number of '1011' detected to be correct (i.e. 3 according to the testbench). But the timing where the output is going high is wrong. The output 'z' is going high when '101' is being detected, when it's expected to go high when '1011' occurs. What's the possible modification that I'd have to do, so as to eliminate this error ?


texts: How to implement an isolated connection matrix

texts:
I need to implement a circuit for a researcher, which looks a little bit like this:

Description of the circuit:

There are two or more fully isolated biphasic current drivers, and N output pins. Any of the current drivers can connect to any of the outputs. On the diagram I have represented this part of the circuit as 4 plugs on flying leads which can connect to any of the 8 sockets. The connections will need to be changed dynamically and arbitrarily, perhaps up to 100Hz. The output voltage may need to be as high as ±80v, but the current will no more than 10mA.

What's my problem?

I have no problems implementing the fully isolated current drivers. What I'm not sure about is connecting the drivers to the outputs.

What have I thought of so far?

The only way I can imagine doing this is to use a 4x8 matrix of relays (or solid state relays). I could probably do this, but I'm aware that in the course of the project they're going to want to expand the number of outputs to 64, and the number of drivers to 4 or 8. This is going to mean a circuit containing 1024 relays!

Is there some alternative way I could approach this problem. I am open to any kind of suggestions.


texts:
I have a complex number s of the form s=[1/sqrt(NN\$_{t})] e^{j\phi_{k}}\$  S\$_{o}\$ is another complex number. It is given that |s-s\$ _{o}\$|<= \$\epsilon\$ where  0< \$\epsilon\$< 2

It is stated in the literature that this constrain can be written as
 $$ \phi_{k}=\arg s  \in\left[\gamma , \gamma + \delta \right]   $$
 where \$ \gamma \$ and \$ \delta \$ are given by \$ \gamma \$ =arg S\$ _{o} \$ - arccos(1- \$\epsilon ^2/2)\$
and \$\delta \$ =2arccos(1- \$ \epsilon^2/2)\$
  Can  anyone explain how is that possible?


texts: How can I extract the rms noise from the measurement's over all noise?

texts:
To clarify my question, here is an example: Let's say I have an opamp and I want to measure and quantify its output noise when its input is grounded. So after shorting the opamp's input to its ground, I couple its output to an oscilloscope and read the rms voltage. Call it \$V_\mathrm{RMS_{all}}\$.

Now some part of the the noise I read at scope screen is related to inherent noise from the scope itself. Call that \$V_\mathrm{RMS_{scope}}\$.

What is the practical way to extract only the opmap output noise (\$V_\mathrm{RMS_{signal}}\$) in this case? Should I short the scope inputs(and call the measurement Vrms_scope) and subtract it from the \$V_\mathrm{RMS_{signal}}\$?
Does the following formula make sense:
$$
V_\mathrm{RMS_{signal}}^2 = V_\mathrm{RMS_{all}}^2 - V_\mathrm{RMS_{scope}}^2
$$
Does such a method neglect common mode related noise?


texts:
I have a device which contains a USB chip which uses 19.2MHz external oscillator.

When I measured the EMI generated from the device, I got series of peaks ranging from 100MHz to 1GHz+.

The peaks have interval of around 3.2MHz.  Why do I have harmonics of interval of 3.2MHz instead of 19.2MHz?


texts: DIY LED lamp is less powerful than expected

texts:
I am making an LED lamp using an LED strip. The LED strip I am using is a 240 LED/m SMD2835 strip, which operates at DC12V, and is supposed to use 18W of power per meter.

My lamp is constructed as seen on the diagram: I cut it into 20cm strips, installed them on an aluminum heatsink and wired in parallel. I have tested each of the 20cm strips separately, and they draw around 0.3A of current at 12V, which is very close to the specification.

However when I wire everything together, the completed circuit draws only around 1.4A of current, which is 16.8W, while it's supposed to be around 28.8W (18W/m * 1.6m). I also noticed that each individual 20cm strip is not as bright, compared to when powered individually. I also measured voltage in the beginning and in the end of the strip - and it is much lower than 12V!

First I thought the problem is with my power supply - and I have tested it with different ones, ranging from cheap 12V 3A wall plugs, to bigger 60W bricks, but unfortunately - same result. Finally I tested it with an adjustable voltage power supply, and I noticed that when I set output voltage to around 14V, then voltage across the strip becomes around 12V and it draws around 2.5A of current, which makes it much closer to how much power it is supposed to draw according to my design (and it is much brighter, too - like when I powered 20cm strips individually).

I am very confused... Can you explain this behavior? Should I buy a power supply with a slightly higher output voltage, so that it drops down to 12V when connected to the strip? If so, how do I calculate how much output I need? Thank you.


texts: SPI problem in STM32 with defining new CS line. SPL F107

texts:
In my project, I connected two MCUs to each other (MISO->MISO, MOSI->MOSI, SCK->SCK). I define a new pin as the CS pin (PORTC.10). But in my receiver the sequence is wrong. Here is my code( For example I send 1234 but I get something else, sometimes works many times doesn't)

void SPI1_IRQHandler(void){
    unsigned long Input;
    if (SPI_I2S_GetITStatus(SPI1,SPI_I2S_IT_RXNE)== SET)
    {
        Input=SPI_I2S_ReceiveData(SPI1);
        MSG[Position]=Input;Position=Position+1;
        if (Position>=(PosMax+1))
        {
            Position=0;
            SPI_I2S_ITConfig(SPI1,SPI_I2S_IT_RXNE,DISABLE);
        }
    }
    if (SPI_I2S_GetITStatus(SPI1, SPI_I2S_IT_TXE)== SET )
    {
        SPI_I2S_ITConfig(SPI1, SPI_I2S_IT_TXE, DISABLE);
    }
}

void EXTI15_10_IRQHandler(void){
    if (EXTI_GetITStatus(EXTI_Line10) != RESET)
    {
        if (GPIO_ReadInputDataBit(GPIOC,GPIO_Pin_10)==0)
        {
            SPI_I2S_ITConfig(SPI1,SPI_I2S_IT_RXNE,ENABLE);
        }
        else
        {
            SPI_I2S_ITConfig(SPI1,SPI_I2S_IT_RXNE,DISABLE);
            if (Position>=PosMax)
            {
                Position=0;
                SendTest=MSG[2];
            }
        }
        EXTI_ClearITPendingBit(EXTI_Line10);
    }
}

In transmitter before sending the 10 bytes it makes the PORTC.10 low and after 1us start sending each byte. After sending 10bytes it makes PORTC.10 high again.


texts: How to control brightness of high power LED with PWM microcontroller (ATMEGA16)

texts:
Hi I am entirely new to the PWM concept. I have an AVR based ATMEGA16 microcontroller (https://robokits.co.in/control-boards/rhino-robot-control-board/rhino-robot-control-board-avr-based-with-quick-c-compiler) which I successfully tested by running DC motor having rating of 12 V, 7.5 A. I now want to use the same microcontroller for controlling brightness of 3 high power CREE LEDs whose ratings are 72 V and 2 A each. I tried connecting output of the microcontroller to a DC-DC converter (https://www.amazon.in/Matefield-Converter-Step-up-10V-60V-12V-80V/dp/B07KZSMHKJ) but it didn't work.

When I control brightness using DC power supply, the brightness varies properly (from 0 to 50K Lux) with voltage. I used a MOSFET and the brightness varied from only 18200 to 18900 Lux when duty cycle was varied from 0 to 100 %.

Kindly help me out. Thanks in advance.

What other components do I need so that the PWM signal can be amplified or boosted?

The 12 V supply is input to the microcontroller board I use. Didn't know how to add a microcontroller board in the schematic. So just drew a block to represent it.

simulate this circuit – Schematic created using CircuitLab

I was wondering if it is feasible to use a step-up transformer so that the 12 Volt PWM output of the microcontroller board is stepped up to 72 volt PWM which will be fed to the LEDs.


texts: Locking up a DC motor with constant supply a bad thing?

texts: I am working on a little pen plotter project and for one of my motors (which supports the pen) I have used a small DC motor obtained from an old DVD drive. I have noticed that if I supply a constant 5V to this motor, it "locks up" when the pen comes into contact with the paper and stays there whilst keeping a slight pressure on the pen (perfect for the application), but I am now starting to think, is this a bad thing?  If the DC motor has a constant supply to it and is held in the same position, should it be OK? It seems to be and isn't getting hot, so I just wanted to confirm.


texts: Do I really need resistors when controlling LEDs with Arduino?

texts: I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it really matter here? These LEDs are working just fine without a resistor.


texts: How do electric utilities determine the Load Demand on the network?

texts: Provided that electric utilities are tasked with ensuring that the load demand is always met, how do these utilities determine load demand to be met in the first place in real time rather than using some forecast?


texts:
Here’s the real dumb question:
If my battery is 24v and 40Ah which makes 960 Watts.
Now if i attach an invertor of 24v~230v how do i recalculate energy? Is it 230v X 40Ah or 24v X 40Ah ?


texts: How to measure energy stored in a battery

texts:
I have just designed a solar panel prototype, how do i measure the energy stored in the battery that is connected to it?
What device can i use?
i will place the solar panels with car battery attached in the open for 3 days. Thank you


texts: How do I get a chinese nRF51822 development kit running examples with an ST-link, Keil uVision?

texts:
I've been working at this for days with not much information out there to assist me in fixing my issues, so I figured I'd make a post here.

  I'm using a cheap chinese nRF51822 module and motherboard
  that I bought on AliExpress, and programming it in Keil uVision5 with
  an ST-link (or other non-JLink SWD device). How do I get the official
  Nordic Semiconductor examples to work and have the device show up on
  bluetooth?


texts: One Wire, 1-Wire, SingleWire, SDQ -- are they compatible?

texts:
There are at least three different manufacturers with "one wire" type memories:

Maxim/Dallas has "1-Wire"
Microchip has "Single-Wire"
TI has "SDQ"

Are they all compatible with each other?

I'm considering using the DS2480B to drive a 1-wire memory device with a standard serial port, but I don't want to be limited to Dallas/Maxim memory devices, as they are not the cheapest.


texts: Nodal Analysis in AC with different Frequency throughout

texts:
I am trying to solve this circuit for the voltage across nodes C and D. Now I think I know how to solve it mostly and would probably opt for loop analysis.  But what has me confused is that the current supply is operating at 3r/s while the voltage supply is operating at 5r/s

simulate this circuit – Schematic created using CircuitLab

The ground I can place anywhere I want but I figured the place it is in the diagram made the most sense.

Is there some simple rule I am forgetting on converting frequency so that I can more easily calculate the resistance of the inductors and capacitors?  If not how would I go about calculating the resistance of inductors and capacitors with two different 'w' in the circuit?


texts: Operational amplifier for higher slew rate

texts: what are the possible ways to improve slew rate of an operational amplifier in CMOS technology?


texts:
I'm using 4 layers PCB, with the following stuck-up:

Signal1
GND
VCC
Signal2

the GND layer flooded with GND
Not all the VCC layer flooded with VCC because I needed to route some nets there

I've some free spaces on layer 2&3&4... What should I do with it?

To flood with GND any free space? or can I just leave it without flooding...

There are more nets in the VCC layer:


texts: Does voltage and current have an inverse relationship in DC power transmission?

texts:
Let's suppose that we want to transmit a 1kW via DC generator with
the below voltage level. From this we can see that the relationship between the DC voltage and current is inversely proportional,

P = I x V

P=1000, V=110, I = ?, then I = 1000/220 = 4.54 amp.
P=1000, V=220, I = ?, then I = 1000/110 = 9.09 amp.

Hence, higher voltage in this case will lead to lower amp.

My issue here, is how can we combine this fact with what we learned in Ohm's law about the current being proportional to the voltage as long as the resistance is constant? As the theories are kind of conflicting in my opinion.


texts: Microchip Advanced Part Selector - Difference between CCP, PWM Outputs, PWM Channels

texts: I want to select a PIC with at least 4 PWM channels. I was looking at the Microchip Advanced Part Selector (MAPS) and I got confused with Digital Peripherals options, there was Max PWM Outputs, PWM Chan, Std PWM, CCP and others, whats the difference, also why there are two selectable values for each one, is this a range?


texts:
I designed a PCB with a microcontroller and a load that draws 3A on average with current spikes of up to 9A. The PCB is powered by a high-drain Li-Ion battery. I want to add a simple undervoltage protection feature to the firmware that cuts the load from the power supply when the battery voltage falls below a certain threshold. The microcontroller can measure battery voltage, but I'm unsure under which conditions to cut the load from the power supply. There are in principal two different approaches:

cut the load from the power supply when the battery voltage falls below 2.7V (or another threshold), independent from how long the battery voltage stays below this value
cut the load from the power supply when the battery voltage falls below 2.7V (or another threshold) for a certain time

I'm unsure which approach would be better. If the second approach would be better, what would be an appropriate time during which the battery voltage would need to stay below the threshold?


texts: Why are latching relays so popular in oscilloscope front-ends?

texts:
I've seen many latching relays used in oscilloscope front-ends, particularly the input attenuator section. Beside the merit of 'energy-saving' of a latching relay, are there any other advantages?

And what about its usage in harsh industrial environment, such as high magnetic interference?


texts:
I recently came across the term USB Host Device while reading how someone used a micro controller as a USB Host device.I haven't been able to understand the meaning of this term.

Could some one please tell me what it is in the simplest words possible?

Also

how is it different from a USB peripheral device?


texts:
I am learning CAN protocol. It is a dumb question about CANIDT register. What is the link between Tag Identifier and Message Object. Is it arbitrary set by the programmer or is it linked with actual data/message of the CAN page. I am using AT90CAN32. Link to datasheet:
http://www.atmel.com/images/doc7679.pdf


texts:
I came across a question:

  Electric field measured in the far field of an antenna at a distance r of 50 m = 1 V/m. Find the electric field at a distance of 500 m from the antenna.

The solution starts with - E is proportional to 1/r.

I know, E = V/r. Is it assumed that potential is the same at 500 m, to say that E is proportional to 1/r !? I thought E is proportional to 1/r^2, as per coulombs formula, if the charges are assumed to be constant. Where did I go wrong ?


texts:
I've wrote a small program  that runs on an XMEGA :

    #include <avr/io.h>
    #include <stdio.h>

    #ifndef F_CPU
    #define F_CPU 32000000UL
    #endif
    void system_clock_init(void){
        CCP = CCP_IOREG_gc;  /* allow changing CLK.CTRL */
        OSC.CTRL = OSC_RC32MEN_bm; /* Enabling the 32MHz RC oscillator */
        while (!(OSC.STATUS & OSC_RC32MRDY_bm)); /* wait for ready */
        CCP = CCP_IOREG_gc;/* allow changing CLK.CTRL */
        CLK.CTRL = CLK_SCLKSEL_RC32M_gc ;/* system clock is internal 32MHz RC */

    }

  int main (void)
    {
        // Insert system clock initialization code here (sysclk_init()).
       system_clock_init();
       PORTR.DIR = 0x02;

     while(1) {

        PORTR.OUTTGL = PIN1_bm;
    }
  }

the program should toggle an LED,  but when I use the scope I measure a signal of 2ms , which mean that uC clock is : 1 MHz  ?? which  wonders me because I think that the program is correct ?

and idea what am I missing here ?


texts: Phase locked loop for Grid synchronization

texts:
Is there any IC available to implement PLL for the single-phase grid-connected inverter?
one solution that I came across is using Texas instruments C2000 series microcontrollers and I also searched PLL ICs but I found digital PLLs but is there any IC specifically to implement analog PLL that generates sin wave for the grid synchronization?


texts: What should I do to switch off a P-Channel MOSFET as fast as possible?

texts:
I have a Power supply that powers circuit A (5V, up to 3A). When the power supply is disconnected I want to detect it and power circuit B with a battery (3.2V). I need circuit B to be powered on as fast as possible (it will keep alive part of circuit A) and want to keep the design as simple as possible.
To achieve this, I planed to use a P-Channel MOSFET where the gate would be connected to Vin (from power supply), source would be connected to Vbattery positive pole. and drain would be connected to circuit B. See Circuit
Here are my questions:

What should I do to switch off this P-Channel MOSFET as fast as possible (and power on circuit B as fast as possible)?
What datasheet criteria should I take into consideration when chosing the MOSFET ?
Well and of course, is there a better way to achieve this ?

Thank you in advance.


texts: with a L298N controller I need to "warm up" the motor to get it to run without stopping, why and how to do it with python

texts:
I understand that this will be a very trivial question but I cannot find an explanation online, probably because in my ignorance I'm asking the wrong question, to support my explanation I'm leaving code, draws , measurements and a video showing what is happening.

This is the scenario:

I have a L298N  controller (this one), with a 12v motor (this one) and a 12v power supply(this one), for some time I thought the controller was defective because it always "blinks" when it is on: the motor starts and runs as it should for like a second, then it stops and starts,stops,starts and so on for as long as I have it connected,this is how it looks like in my test:

in the scenario that I described above when I connect that 5v loose cable to the first or second pin the motor goes fast for like a second and then starts turning itself on and off in some sort of blinking effect, exactly the same happens if I turn that pin on with python (by sharing the GND and turning the selected GPIO pin to HIGH in a code like this):

import sys
import time
import RPi.GPIO as GPIO

mode=GPIO.getmode()

GPIO.cleanup()

Forward=26
Backward=20
sleeptime=1

GPIO.setmode(GPIO.BOARD)
GPIO.setup(Forward, GPIO.OUT)
GPIO.setup(Backward, GPIO.OUT)

def forward(x):
GPIO.output(Forward, GPIO.HIGH)
print("Moving Forward")
time.sleep(x)
GPIO.output(Forward, GPIO.LOW)

def reverse(x):
GPIO.output(Backward, GPIO.HIGH)
print("Moving Backward")
time.sleep(x)
GPIO.output(Backward, GPIO.LOW)

while (1):

forward(5)

reverse(5)
GPIO.cleanup()

but for my surprise at some point (while doing the test of the image) I realised that if I hit the cable a few times to get the motor started then I can leave the pin connected and the motor will keep going at full speed, so I feel like this motor needs to "warm up", but I still don't understand why.

I just took some measurements and now I'm even more confuse:

if I leave the cable on the pin the motor first receives around 3v, then it goes down to 1 and stays between 0v and 0.6v

if I hit the cable on the pin multiple times the voltage start building up, so the first time it receives 3v, the second 3.x then 4.x then 5.x and so on (so at some point it have enough voltage to work at full capacity)

I uploaded a little video to show what is happening, at first I leave the cable and it "blinks", then I "warm it up" and at the end it works as it should:

video

So my doubt is:

-Why does the motor do not receive enough voltage from the start?

-why does it work if I hit the pin with the cable 8-9 times before leave it connected? Shouldn't the voltage be totally independent of if the motor is running or not? (obviously not as if I disconnect the motor those pins receive 10v constantly,but mind tell me why?)

-If that "warm up" process is necessary how do I get this behaviour using python? Is there a "building volts" process that I should be following in my code?


texts: Use "real" condenser microphone element instead of electret condenser microphone

texts:
Apologies my original question was completely unhelpful, I'm trying to make a USB condenser microphone, and the tutorial I was trying to follow used two electret condenser microphones, which were wired like so:

I unfortunately was sold two "real" condenser microphone elements, which have three poles (V+, Ground and Output) and did not realise my mistake until I was home, making it impractical to return them.

I would like to know how to connect these three pole elements to the circuit instead of the two pole ones that are used.


texts:
I have a device with a RS232 communication port (3 pin,tx,rx and gnd).

When I connect it to a PC RS232, they don't communicate together.

I use hyper terminal on the PC side and all setting are correct.
Why it doesn't work? Do I need pull up or pull down resistors?


texts: Does anyone have a detailed dB A to db Z (or dB SPL) table?  I have found one at http://www.cirrusresearch.co.uk/blog/2011/08/what-are-a-c-z-frequency-weightings/ and at http://onlinelibrary.wiley.com/doi/10.1002/9780470869253.app4/pdf.  Is there one with values for 3000 Hz and 6000 Hz (and as many other values as possible)?  I know it is not possible to convert between dB A and dB SPL, but I am trying to look for a table of corresponding values.  Since Z-weighting subtracts 0 every time, a highly detailed A-weighting table would be good too.


texts: How does 3D Time-of-Flight (TOF) camera work?

texts:
This is my first post in this forum! So Point me if anything is not clear!

I want to know how TOF camera works? So I've done Google & read some nice explanation about How Phase difference between Transmitted & Received signals can be used to calculate the Depth of an Object from Camera with good example.

What i did understand:

How a light source(IR) can be modulated & demodulated ? Answer
How to filter the reflected IR signal having the same modulation frequency? Answer
Depth Can be measured by Calculating the Phase change of the Transmitted signal.

What i cannot understand:

How phase change of a continuous square wave signal can be used to Measure the depth?

Update: Here is a Nice Explanation about this.

Note: I'm talking about TI & Mesa Kind of TOF Camera's using IR Led


texts: LED emergency lighting - relay activated

texts:
I've designed the following schematic for my LED emergency lighting project;

I'm planning on building it soon, my knowledge in electronics is short right now (I started learning electronics by reading the book at "allaboutcircuits.com" two days ago).

I would like to know if my design is solid, correct and safe, should I add protection circuit, change the "Relay power OFF circuit", etc;

Do you have any suggestions on how can I make it better?

If changes are needed, could you please add a schematic for the change and how it should be connected to the existing circuit? remember that I'm a beginner.

LED emergency lighting schematics:

Purged delay circuit

Corrections, changed relay symbol to SPST

Changed parts designations

Former schematics
Deprecated-00

Deprecated-01

Deprecated-02

Design explanation:

The DC power supply is an old 5VDC-Output phone charger, it is going to stay connected to the mains 24/7.
It is essentially two separate circuits, one for the relay coil with power OFF delay and the other is to drive the LED's with 1.2V*4 AA battery pack.
Now the relay is connected directly to the 5VDC power supply as suggested;
when the Mains power goes out, the relay will close the LED's driving circuit.
The switch S1 is when I don't need the light anymore while it is being used as a flashlight.


texts: STM32F4 Systick timer HAL_SYSTICK_Config() clock value

texts:
In STM32F4 controllers, systick timer is configured to generate interrupt on every 1 ms. If clock frequency is changed, then the number of ticks requred for 1ms should be given as a parameter to the function HAL_SYSTICK_Config

This is what is done in the tutorial I'm following
SYSCLOCK = 8 MHz

HCLK = 4 MHZ

APB1 & 2 clock = 2 Mhz

Systick timer prescalar = 1

HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

According this if I want the Systick timer prescalar to 8 then code would change like this

HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK_DIV8);

But I don't think this would work. Here HCLK  is 4 MHz but the Systick timer clock is infact 500 KHz (4Mhz / 8).  For the first code, since the prescalar is 1, it wouldn't be an issue.

Shouldn't the prescalar configured before configuring the Systick and consider the prescalar value? Like this

HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK_DIV8);
HAL_SYSTICK_Config((HAL_RCC_GetHCLKFreq()/8)/1000);

I thought it could be a mistake from the side of instructor. So searched for STM32 HAl code, these are codes in HAL_RCC_ClockConfig function which configures systick timer

/* Update the SystemCoreClock global variable */
SystemCoreClock = HAL_RCC_GetSysClockFreq() >> AHBPrescTable[(RCC->CFGR & RCC_CFGR_HPRE)>> RCC_CFGR_HPRE_Pos];

/* Configure the source of time base considering new system clocks settings */
HAL_InitTick (uwTickPrio);

HAL_InitTick Function

HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)
{
  /* Configure the SysTick to have interrupt in 1ms time basis*/
  if (HAL_SYSTICK_Config(SystemCoreClock / (1000U / uwTickFreq)) > 0U)
  {
    return HAL_ERROR;
  }

  /* Configure the SysTick IRQ priority */
  if (TickPriority < (1UL << __NVIC_PRIO_BITS))
  {
    HAL_NVIC_SetPriority(SysTick_IRQn, TickPriority, 0U);
    uwTickPrio = TickPriority;
  }
  else
  {
    return HAL_ERROR;
  }

  /* Return function status */
  return HAL_OK;
}

uwTickFreq is 1.

you can see that this function is not considering the Systick timer prescalar? It calculates HCLK frequency and then passes that value to HAL_SYSTICK_Config function.  Isn't it important to consider the prescalar for this? Use it calculate what the Systick timer clock freqency.


texts: Getting more amps from a computer power supply

texts: Hey everyone I am new here and new to working on electronics. With that being said I am trying to figure out if wireing 2 of the 12v wires with 18 amps would give me 24 volts with 36 amps? I am trying to use a computer power supply to run a vape mod that is designed to run at 8.4 volts and 30 amps. I just need to figure out this part so I know what resistors I need to get and calculate the wattage. Thanks for any help! I am really looking forward to trying to get this to work


texts:
Alright, have another one which the solutions manual is vague on.

I have to reduce \$f =(x1+x3+x4)(x1+x2'+x3)(x1+x2'+x3'+x4)\$. Right in the first step, though, the solution does something I don't understand.

They go to \$(x1+x3+x4)(x1+x2'+x3)(x1+x2'+x3+x4)(x1+x2'+x3'+x4)\$. Where did that 4th term come from? I thought we could add a sum if it was the same as one of the current terms? How are they allowed to change the x3?


texts: How do you figure out an efficient battery setup?

texts:
I have a project where I need an arduino uno and 4 dc motors to run on batteries. My first thought was that I'll just hook up 3 or 4 AAs to the arduino and a 9V to the motor drivers.

I googled to be safe and the internet consensus seemed like that method would be very inefficient. Voltage wasn't the problem but apparently 9V have very low current and I'd be wasting money, and the arduino wastes current like a madman. Most solutions involved buying additional hardware. Is there a way I can efficiently power my project without buying more chips?

Even just guidance on how to calculate a better setup would be very appreciated.


texts: Is it ok to connect the output of buck regulator in parallel?

texts:
I am using MCP16322 buck regulator powered from 12V and outputs 5V and 2A. Is it ok to connect the output of two of these in parallel? Does connecting the outputs in parallel mess up the maximum capacitance values on the output of the regulators? Is it better to connect the outputs in parallel via diodes? The diodes will cause a .7v drop though which I rather avoid.

Here is the application circuit.


texts: Why would a "power switch" be designed this way?

texts:
This unit is an ARINC 429 bus analyzer, manufacturer "AIT" (Aircraft Interface Technologies), model "429A". Yes, it's confusing. Rated 115VAC/3A/60-440Hz. It has a 250W SMPS inside with several 3A fuses integrated. The power switch is a C&K 7201J1ZQE2 and claims 100k actuations @250vAC, 5A.  How it switches on and off has left me scratching my head however.
Mains power comes in, across a typical switch-mode supply, and to a front-panel board.  There, is a DPDT rocker switch, two resistors, and two SCRs. Closing the switch connects the circuit as shown:

What is the reasoning behind using these SCR's, as opposed to just using the DPDT switch across A/B directly?  Is it due to "skin effect" on contacts at 400Hz?
What determines the values of R1 and R2?

As far as I can tell from simulation, anything from 0-1kΩ will "work" as R1/R2 with varying success. Lower values seem better because the A-B voltage drop decreases. And above 1kΩ, the firing angle lags, reducing the RMS power delivered to the PSU.
The max gate current for the 2N6404 is 2A for 1µs, so that means 165vp/2A = 83Ω minimum (assuming the 72Ω intrinsic gate resistance does not factor in.)
R1/R2 seem to dissipate very little power in sim, but both failed open (1/4W), and their values are not readable. Any hint on a value, failure mode, and/or reasoning behind this bizarre circuit would be appreciated.


texts: Derivation of the transfer function form with the system type number included

texts:
A transfer function is derived from an ODE with the Laplace transform as following...

Some times though there is a different form of the transfer function, one that includes the system type number \$l\$.

How is that form derived? As I have listed the way we go from an ODE to a transfer function, how is the system type number came to be included in it?
g


texts: How does the voltage divider model a voltage source in this transistor bias circuit?

texts:
I encountered a text which says that the leakage current Ico (or called Icbo) adds up to the signal current hence causes thermal runaway because it causes temperature to increase and it also increases with temperature. Below is the related illustration circuit(I guess we are not in control of Vbe anymore):

As a remedy the text shows these alternatives:

What I understand from above alternatives is that it seems if we are in total control of Vbe(by using a voltage source at BE terminals), then the Ico will not affect the biasing circuit.

If my understanding is correct, how does the circuit on the right(with voltage divider) is equivalent to the circuit on the left(with voltage source)? How is this source transformation done in electric circuit theory? Somehow the author equalizes the voltage source to a voltage divider but how?

edit:


texts: IC capable of transmiting IR over multiple pins

texts:
recently I have been looking for a way to define a pin on the Arduino Uno. once I got that right I expected that I would be able to send IR signals over at least 5 pins.This would be because I had defined the other 4 pins to suit the characteristics of pin 3.

Below is an example of IR transmitting code for pin 3

 /*
 * IRremote: IRsendDemo - demonstrates sending IR codes with IRsend
 * An IR LED must be connected to Arduino PWM pin 3.
 * Version 0.1 July, 2009
 * Copyright 2009 Ken Shirriff
 * http://arcfn.com
 */

#include <IRremote.h>

IRsend irsend;

void setup()
{
}

void loop() {
    for (int i = 0; i < 3; i++) {
        irsend.sendSony(0xa90, 12);
        delay(40);
    }
    delay(5000); //5 second delay between each signal burst
}

These pins will be used to send the signal of an IR LED. My logic is that if I can  define pins then I can hook up multiple IR LEDs (one on each pin) and thus I can send a different signal to each LED.

Unfortunately This can't be done on and Arduino Uno alone. So I am looking for an alternative IC or microcontroller which will fit my requirements.

Is there any alternative microcontroller specifically built to do what I want to do here?

Here and Here are links to questions I asked on the Arduino forum related to this post.

Any suggestions and pointers will make me very happy thanks.


texts: Microcontroller soft off circuit not working - why?

texts:
I was making a board with an atmega328 mcu (to be used with Arduino libraries) to do some one wire communication stuff. Since I was etching the board anyway, I decided to try and implement a simple software off functionality, without putting much thought into it. Once I etched and assembled the board, my one-wire stuff works fine, but the software off circuit does not. I was poking around and I can't understand why it does not work.

The idea is that pushing a momentary push button (for 2-3 seconds), will connect the battery to the 5V regulator which in turn powers the MCU. The first thing the MCU does is set a digital pin high (line labeled PWR in the below diagram), to latch the N-MOSFET Q1 and bypass the push button switch. When the switch is released, the circuit should remain powered through the MOSFET.

What in reality happens is that pushing the pushbutton powers up the board as expected. The gate of the FET is driven to 5V by the MCU as expected, but as soon as the pushbutton is released, everything turns off. It seems that the FET is not bypassing the pushbutton for some reason, but I can not understand why? The FET Vgs is 1.8V, R6, R7 and D1 are there so I can use another push on the button to generate an interrupt on the BTN line, then drive the PWR line low and switch off the board.

So the question is what is wrong here? Why doesn't Q1 MOSFET stay latched once the pushbutton (connected to PWRSW header) is released? I'm certain it is not something complicated, but I just can not understand why - perhaps because I've been staring at it for too long...


texts: 5V Crowbar circuit using LM431 not triggering

texts:
I'm designing a crowbar circuit to to blow a 1A fuse, when the voltage increases above 5V. I'm using an LM431 and using the design in Figure 20 in the LM431 datasheet. I designed and prototyped the following circuit, but found it didn't work as I had thought.

I used R1=39kΩ and R2=33kΩ  as a voltage divider, intending to surpass the LM431 reference voltage of 2.5V when the input voltage exceeds 5.4V. When I tested it out, it didn't work as planned. With an input voltage of 5V, I measured the voltage over R2, and found it was measuring 0.8A, instead of the expected 2.3V. I took out the LM431, and found the voltage divider was functioning correctly without it in there.

So I figured my problem was with the value the value of R3. I replaced it with a 10K pot, connecting between one edge and the wiper, and tried finding a value where the voltage over R2 was greater than 2.5V. I found it stayed consistently at 0.8V, until the pot was less than 10Ω, and the voltage jumped to 4.5V, and the LM431 got very hot, before I shut it off.

I'm not sure where to go from here, I've tried replacing R1 and R2 with different values of resistors, both keeping the same ratio, and changing the ratio. As far I could tell, it didn't matter what value resistors I used, the voltage over R2 stayed at 0.8V.

I found another question on here planning on using a similar design, asking what values each of the components should be. The accepted answer has a more complicated circuit, including an extra BJT, and was wondering why that design was suggested over the more simple one from the LM431 datasheet.

Any help on the sizing of R3, or other possible problems in the circuit would be appreciated, I'm not sure what to try next.

UPDATE:

As suggested, I double checked the pinout diagram, and rather embarrassingly, noticed the pins were numbered differently to what I had set up. The pins were numbered 1-3-2, not 1-2-3. Anyway this has fixed the voltage divider issues, and now the voltage over R2 increases as expected until Vin=5.4V.

However, the fuse isn't being blown above 5.5V. Is this due to the vale of R3? I haven't tried varying this value. Does anyone know what this value should be? Or is it a problem with the triac?

UPDATE 2:

I realised that I didn't connect cathode of the LM431 to the gate of the triac when I changed the LM431 to be correct. Now that I've done this, I'm having troubles with my voltage divider not working correctly again; I get a reading of 0.8V over R2, when I expect 2.5. The voltage at the gate of the triac is 0.2V, and I'm using a SC141D triac.

It seems to me that the triac is causing some issues, as the voltage divider worked fine without it. Is there something I need to account for when designing a voltage divider?


texts: Trouble with meeting design specifications of a second order system using Matlab

texts:
I am trying to solve the following question.
Consider the transfer function $$G(s) = \frac{1.247}{s^2+9.76s+23.8}$$ is in the forward path of a unity feedback control loop. Assume that it is compensated using a static gain K in the forward path. Now I have to plot the root locus of closed-loop system and determine if it is possible to find a value for K such that the settling time is 0.7963 s and the rise time is 0.4445 s.
I know how to do it on paper. The overall closed loop transfer function become $$G(s) = \frac{K*1.247}{s^2+9.76s+23.8+(K*1.247)}$$
If I compare this with standard form of second order system, I can see that
$$2*\zeta*\omega_n = 9.76$$ and
$$\zeta\omega_n = 4.88$$
From the formula for settling time,
$$t_s = \frac{4}{\zeta\omega_n}$$
$$ \zeta\omega_n = \frac{4}{0.7963} = 5.02$$
Therefore, it is not possible to design the system by just varying the value of K. But my doubt is, is there any way to directly find it from the root-locus plot in Matlab. How do I plot the root locus in the first place without knowing the value of K?


texts: Voltage booster for an Arduino Uno waveform generator

texts: Recently I made a waveform generator using an Arduino. Its output is only 5 volts, but I need 113 kHz with 15 or 12 volt (I think) for an ultrasonic mist maker. Is there a circuit to increase the voltage without changing the frequency?


texts:
I'm trying to find ideas how to capture just the sound of the cymbal(s) of a drum kit - while the entire kit is being played. As cymbals are made of bronze, they are not magnetic and that rules out normal electromagnetic pickups. Optical systems probably struggle with the fact that there is quite a lot of movement when a drummer strikes the cymbal hard:

https://www.youtube.com/watch?v=kpoanOlb3-w

I do have access to normal microphones, but I'm looking for a different approach. The sound of the pickup does not have to be "perfect" or very natural. Any thoughts?


texts: Where does STM32CubeMX generate AF GPIO initialization?

texts: i was wondering where does CubeMX (when you export it to an IDE such as Atollic) generate GPIO initialization for alternate functions such as Timer capture pins, UART pin ect. (we are talking about HAL drivers) I've noticed it's not initialized in GPIO_Init nor the specific  initialization function used. I want to set pull up on an AF pin without having to import the project again. So where is it?


texts:
I have a large array of 8x8 load cells I'd like to monitor, and I'm looking for an efficient way to do that.

Obviously, one option is 64 independent instrumentation amplifiers, but that's expensive and involved. Another option is 8 instrumentation amps with 8 x 1:8 differential analog switches, or a single instrumentation amp with a 1:64 differential analog switch. These options reduce the total component count and cost, but still has a significant overhead. I'm wondering if it's possible to solve this with a matrix configuration, something like this:

simulate this circuit – Schematic created using CircuitLab

Clearly, there are parasitic paths here: in the configuration shown, SW1 measures R1+R4 in parallel with R11+R13, while SW2 measures R12+R14 in parallel with R16+R18. However, because the bridge is matched, the effect from the selected cell is twice that of any other signal. It seems like it ought to be possible, by measuring all the cells in the matrix and doing a little differential math, to extract the value of each individual cell.

Am I right about this? Is there a better configuration? And how do I go about determining the individual readings from the matrix of output values?


texts: Effect of splices on 120 Ω twisted pair cable impedance a.k.a correct way to attach stubs to the bus?

texts:
I am currently in the process of designing a wiring loom for a race car control system which must also connect a number of devices via a CAN bus.

This is my first encounter with CAN bus (J1939-15) systems which call for a 120 Ω UTP bus cable terminated by 120 Ω resistors on each end, and my question relates to the correct method for connecting stubs (device cables) to the bus.

Asking around within my industry, the solutions proposed by colleagues are the following:

Strip insulation only and solder stub connections onto the bus without cutting the cable.
Cutting the cable and using Y or T splitter connectors. (Amphenol and Deutsch seem to make J1939 specific Y-splitter connectors. No mention on either product datasheets about impedance matching however.)
Cutting and using 2-1 environmental splices instead of Y-splitter connectors (e.g MIL-S-81824/1 or Raychem MiniSeal splices).

Is there a better or correct way to attach stubs to the main bus?

If not, of the three above options, would the use of the splices linked in the third option adversely affect the network?

Note: In this instance the job specification does not allow me to use solder unless the joint is also encapsulated in a specified potting compound, and I would also prefer avoid the Deutsch Y-splitter connectors due to bulk.

The baud rate is 1 Mbit/s, and bus length is 20 ft (6 m). Stubs in most cases will be less than 1 ft (0.3 m) length.**


texts: Is there a standard way to extract the base addresses in Qsys SOPC info file into a VHDL file?

texts:
For an FGPA fabric AvalonMM master, it is very important that the base addresses be correctly defined in a HDL source file so it can make use of them. The base addresses can change easily as we make some modifications in the Qsys system.
The base addresses are stored in the .sopcinfo file which is basically a XML file by the look of it. Although I can come up with my own tcl or python based solution to extract the base addresses from this sopcinfo file, is there a standard way to extract the base addresses into a VHDL/Verilog/SystemVerilog file e.g an already existing tcl, perl or python script that can be executed as soon as the user presses the compile button in Quartus and update the HDL file from the existing sopcinfo file?
Updating the base addresses manually by reading them from Qsys and writing them into a HDL file is prone to errors and is not reliable.


texts: DC/DC converter/eFuse maximum output capacitance

texts:
I have some doubts about the design of this DC/DC converter circuit/PCB circuit:

On the left side there is a 400V to 12V DC/DC converter (Vicorpower DC/DC Mini, 300W). The maximum output capacitance of the converter is calculated with 833.3µF. (Datasheet: "The capacitance value is not the absolute maximum value, but the value for which general application of the converter can be deemed appropriate. Testing will be required to ensure that the module is stable if this value is exceeded. Approximately 10X the value calculated will cause the converter to go into current limit at turn-on.")

On the 12V output side of the converter there are several PCBs. Each of them has some DC/DC converters and some capacitors at different voltage levels. Also, each PCB has an eFuse of the type TI TPS2592AL (programmable SoftStart control). The DC/DC converters on the right hand PCBs are of the type TI TPS6213X (buck converter, programmable Soft Start).

Now I have two questions about this case:

The Vicorpower DC/DC converter has a maximum output capacitance of 833.3µF. Does this only mean I have to add the capacitor values on the 12 V line in front of the eFuse? Or do I also have to add the capacitor values on the 5V/3.3V line of the PCBs for the total output capacitance?
For the circuit calculation of the eFuses I have to figure out the "Load capacitance" of the eFuses. Similar question: Do the capacitors behind all DC/DC converters count? Or just on the 12V line?

Thanks!


texts: When we say the term 'setting time' of an LO,what exactly do we mean by setting time here ?


texts: Are op amp and voltage current converter same

texts:
I am trying to create a constant current output for my project between 0 - 10 mA.

I read we can convert voltage to current by using op amp
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-8/voltage-to-current-signal-conversion/

but I also found IC
http://www.ti.com/lit/ds/symlink/xtr110.pdf

so for voltage current conversion do I have to use a IC like xtr110 or can I just use a op amp?

Also, xtr110 seems to only output 4-20 mA, is there a IC that can output 0-10 mA?

My output signal is 5-30v square wave and I am trying to convert to 0-10 mA.


texts: Dimming CCFL:s with PWM or amplified analog voltage

texts:
First post here. I have been trying to get this project going for a while, but I now think it is time to ask for help.

I want to build an array of cold cathode fluorescent lights (CCFL:s). The brightness of each of the lights should be individually controllable with a digital signal (serial or DMX), to be able to control them like a screen with tubes as pixels.

So far, I have been successful in dimming the lights with a 16-bit DMX to PWM-interface, but the solution is quite bulky. I am modulating the 12V DC signal that goes into the CCFL inverter. I want to know how I can improve this solution by considering different options.

Normal DMX with 8 bit resolution does not create a nice enough effect with the dimmer I am using (it is in fact meant for dimming LEDs). The different steps are too noticeable. I have so far been able to get a nicer effect by using 16 bit PWM-drivers, but the desired dimming effect occurs just over a small portion of the resolution. Could I get the desired effect from a PWM-dimmer that uses a different dimming “range”?
Instead of using PWM, I have been thinking about dimming the lights with an analog signal between 0-12V, as is done in this video. There are two ways that I have thought of that could make analog dimming possible. One is staying with DMX and getting DMX to analog converters, or getting serial DACs to provide the desired voltage dimming. The problem in both of these cases are the amperage limit of conventional DACs and DMX to Analog-converters. The converters usually can withstand about 20mA, and the CCFL:s require about 150mA each to be fully powered. What components or circuits can I use that can supply an analog voltage signal at this amperage level?

While reading up on the above I have come in contact with electrical components called “emitter-followers” and “op-amps”, but I would be happy to be pointed to some resources where I can read up on specifically how to use them for this kind of applications.


texts:
Determine the current passing through R3.

Given:

R1=5Ω

R2=5Ω

R3=10Ω

V1=100V

Is2=5 A

Attempt to solve this :

Using Mesh current analysis:

Mesh 1:

-V1+R1(I1-Is2)+R2(I1-I2)=0

100+5(I1-5)+5(I1-I2)=0

10I1-5I2=125

Mesh 2:

5(I2-I1)+10(I2-Is2)+5i'=0

i'=I1-Is2

This would give us I2=Is2=5A

Hence I1=15A

The current going through R3 would be equal to I2-Is2=5-5=0A

However this answer doesn't seme logical , I can't imagine that there's no current going through R3 since the current i' should obviously split into R2 and R3.

I'd be grateful if someone could point out any mistakes in my calculations.


texts: How to find the total resistance of this circuit

texts:
Without giving resistor values, what are the steps to breaking down this circuit to find total resistance?

Edit:
Like this?


texts:
I have been working on this circuit many days. I just would like to know how it works. In my opinion, the key is in the feedback in the 2º CMOS, but I do not really know how to manage it.

All the information I have about the circuit is in the figure.


texts: Linearization of Non Linear State Space Model

texts:
Im designing a PI controller for a Maglev experiement but im a little stuck on how to linearize the non linear state space model. I have developed the state equations (seen below) and i know the equilibrium point of interest below. But im stuck on the maths behind linearizing it.
Nonlinear State Space Model

Equilibrium Point

Any help is greatly appreciated


texts: Can de-ionized water be used instead of distilled water to prepare lead acid battery electrolyte?

texts:
I have a couple of Yuasa and Power Sonic conventional lead-acid bike batteries that I recently purchased for a very good bargain price from a seller. They are new and never used. But unfortunately, the seller did not have the battery acid packs in his possession. So, I have to end up preparing that myself.

I know that I'll need to prepare a 36-38% concentrated sulfuric acid solution (this is what manufacturers usually use) using my concentrated acid which is a 95-98% ACS reagent sulfuric acid.

Now I know that they usually use distilled water to prepare them. But I was thinking if it's possible to use ultrapure de-ionized water instead.


texts: Understanding Differential Mode Voltage of a Floating Circuit?

texts:
I am currently trying to work on studying for the ECE NCEE FE exam, but I came across the problem and don't quite understand the answer.

Essentially we have an ideal transformer with an arbitrary load on the secondary side, along with the knowledge that the secondary side is floating, and there is a 120V, 60Hz source on the primary side. Now the question is asked "at which of the following points has the highest risk of electrical shock if a person were to touch the circuit?" (Assuming the person is standing on the ground)
A: Primary side before transformer
B: Primary side GND (after transformer)
C: Secondary side after transformer and before load
D: Secondary side after transformer and load
Now the solution is point A - as point A has an established ground and voltage source (and a shared ground between the circuit and person), so touching point A basically creates a short in the primary side of the transformer, which causes the full source to flow through the person touching it.
What I don't understand is the elaboration of the solution:
"...The transformer is ideal, and the load is floating. A fault condition does not exist. Therefore, there is no differential voltage to ground at point C or D."
What I don't understand is how is this possible? Doesn't the transformer provide power to the secondary side, thus creating a flow of current and potential across the load? Wouldn't grabbing point C also be dangerous as well, and possibly D since that node isn't common with earth/person ground - as the potential difference again is basically creating a short when the person touches point C to where they stand?
Basically my confusion is to how the floating side is somehow harmless when you have energy being input from the primary side and creating a potentially dangerous, unknown voltage across the load? I've always been taught that floating circuits are dangerous, not harmless.


texts: Use 2 of the 8 cables of an existing ethernet connection

texts:
There is an Ethernet cable that runs from a server room to an office. That cable is connected to a router. There are times when we need to reset that router and I will like to do that remotely. There is only one Ethernet cable that runs to the office I wish there was one more.

I will like to place an arduino or raspberry pi at the office that will be responsible for turning off and on the router with a relay.

I need to send a signal from the server room to the arduino located at the office.

I have tried using the NRFL01 and other radio signals but the distance is to far and the signal is lost because there is a lot of walls in between.

I want to use 2 of the existing Ethernet cables just like a Poe switch uses some off the wires to inject power. Instead of injecting power I will like to insert a signal. What cables can I use of the internet cable. I know very little about networking. Does it matter if it's a cat5/cat6? Can I do something like that?


texts: What makes same wattage led light bulb brighter than the other?

texts:
I noticed that one 10 W LED light bulb was 800 lumens and the other 1000.
Both were warm white, 4000K, 80 CRI.

What exactly makes one brighter than the other?


texts: Identify whether PCB 1/4" audio jacks are balanced or unbalanced

texts:
I have a Fostex 2016 line mixer and was trying to see in the manual (https://www.fostexinternational.com/docs/tech_support/manuals.shtml) whether the 1/4" inputs and outputs are balanced (TRS) or unbalanced (TS).

Finding no information in the manual, I took the unit apart to look at the PCB. See the two images below:

I see the sleeve soldered to the ground plane (is that the right term?) which makes sense.  Then I see the tip soldered to pads that are clearly connecting to audio lines, which also makes sense.  I believe the soldered pad in between the two is for the ring, which in this case seems isolated (meaning it is an unbalanced connector).  It seems like a super-basic PCB so I am guessing that there are no interior layers but just wanted to confirm.  I am also confused why there are five lines going to the 4 line-out connectors (the two other connectors are for aux sends, I believe, and the single black pin is GND.

I appreciate any help clarifying the answer to this question and maybe even educating me on some analog audio electronics at the same time ;).


texts:
I have a pressure sensor which is working in the feet of a person which senses the pressure. I'm using nRF processor for sending just ON/OFF signal to the motors. The problem is I'm using a battery which it should last for one year, it can't be recharged nor replaced.
My idea was to use a nano Amperage comparator which senses at certain threshold the signal, if it's above the limit, it wakes up the micrcontroller and sends back data to the motor.

The inside comparator of nRF costs 5uA which I think is too high for a 12 months device, also it depends on the how much the pressure sensor is used.

Please note that in the future I would need an nRF uC because of future features that need to be added.

My question is there any other ideas or alternatives to let the battery work for 1 year giving the above conditions. Hardware or Software solution would also be an option.


texts: How to remove non-square noise from Pierce oscillator?

texts:
Because I am working on some AVR microcontroller projects that will have multiple processors sharing clocks, I wanted to create a solid, reliable circuit to provide a clock after changing the AVR fuses, just in case. ;)

I created a Pierce oscillator at 4.096 MHz and it gives a decent signal and near-perfect frequency with a very good vertical slope to the edges, but it has a lot of non-square jiggles in it:

Here is my circuit:

And its realization on genuine Veroboard:

The question is: What can I do to remove most or all of the "spiky" signal components when the signal is high?  Are there additional components I could add to condition that out and still have a usable square wave for clocking an AVR that is dependent on an external clock?


texts: In general, construction wise, what makes a speaker more or less sensitive to mid tones?

texts:
I bought a second hand vintage boombox and the left (full-range/'woofer') speaker has gone so I replaced both speakers with some Sony ones. The Sony ones are taken from of cabinets lying around (the only ones I have that fit inside the boombox).

The Sony ones sounds nice however they are more sensitive to mid-tones. I noticed this before when inside the original cabinet (cabinet taken from), no filters at all are used (boombox and cabinet). It seems it is a characteristic of this speaker.

I understand it is a different speaker with other characteristics but what makes it more sensitive especially to mid-tones? The mid-tones on these speakers are pretty intense.

In general, is it the type of materials, foam and paper type, stiffness, depth (paper angle), cone size, coil diameter, coil windings, magnet (size or strongness)...... what makes it more sensitive to mid-tones (again, no filters are used)?

Any thoughts on this?


texts: Can you bypass a Rectifier diode from AC to DC

texts:
I am trying to find out if I can bypass the AC rectifier diode and connect DC voltage at the + and - terminals to power a audio amplifier board.
If not then I also need to find out why does the circuit board requires dual AC inputs. 25v-0-25v

I am a beginner when it comes to electronics.
Many thanks.
This is the part Amplifier


texts: Protecting a comparator's input from overvoltage during power up/down

texts:
I'm designing a board which uses a 15V supply for most of the circuitry but also includes a high voltage (HV) adjustable supply that can go as high as 140V. For safety reasons I'd like to detect when the HV supply is higher than 50V.

The circuit to do this is straightforward: use a comparator powered by the 15V supply to check the output of a resistor divider on the HV supply, and set the output to go high when the HV supply is above 50V.

The only problem is that both the 15V and HV supply will be powered on (and off) at the same time. It's possible that the HV supply will reach its final value before the comparator is fully powered by the 15V supply, in which case the voltage of the comparator input that is connected to the HV resistor divider may temporarily exceed the comparator's supply voltage.

One solution is to connect a Schottky diode from the comparator input to its supply pin (this solution is mentioned, e.g. here). The resistor divider also serves as the current-limiting series resistor. Below is a schematic with this solution:

simulate this circuit – Schematic created using CircuitLab

My concern with this, however, is that I've only seen this solution used when the device that is being protected is already powered up. If the diode starts conducting because of an overvoltage on the input then the comparator will be powered up through the diode instead of the 15V supply. This could lead to an unusual startup sequence for the comparator, which seems like a bad idea. Are there any pitfalls to protecting a comparator from overvoltage while the comparator is being powered up by connecting a diode from its input to its supply pin?

I've also come up with an alternate solution to protect the comparator input. The idea is to disconnect the comparator input from the HV resistor divider until the 15V supply is near its final value. The comparator input is disconnected by a solid state relay which is open until the 15V rail nears its final value. The SSR is implemented in the below schematic as the \$D_2\$ LED controlling \$SW_1\$. A 12V Zener in series with \$D_2\$ ensures that the SSR doesn't close until the 15V rail reaches about 13V:

simulate this circuit

(Note that \$R_6\$ is connected to the comparator input to provide a path for the input bias current when the SSR is open. It does affect the divider ratio but the resistor values in the schematic are rough values right now anyway.)

Component cost and board space is not a problem for this application so I'm inclined to go with the SSR solution, but I'm reluctant to turn down the diode solution because it's so simple. Is the diode solution sufficient for this case? Can either solution be improved? Is there another, better solution?

Additional notes:

I'm flexible on the particular comparator used. I'm using the TLV7211 elsewhere on the board so that's one possible choice for simplicity, but I'm not forced to use it.
Both schematics are set up for a DC sweep simulation of the worst case (HV supply set to a constant 140V and the 15V supply ramping up from 0V to 15V). Feel free to play with the simulation.


texts: I was searching  a lot for understanding what is gain  and phase matched cable. Can somebody explain on what is gain and phase matched cable


texts: Zeros and poles in the following bode plot

texts:
According to the definition, zeros are the frequencies which make transfer function to be zero, and poles are the frequencies which make transfer function to be infinity.

The definition can be seen MIT handout, and Wikibook.

But considering the following transfer function $$H(i
\omega) = \frac{(i \omega)(2+i \omega )  }{(1+i \omega )^2}$$

But according to definition, $$i \omega$$ is an imaginary number, but 1 and 2 is a real number, How is it possible to make transfer function to become zero or infinity.

When plotting bode plot, it is like below:

The pole is 1, the zero is 2.

Why?

Can anybody provide a mathematical explanation?


texts: TDA2030 strange startup noise problem suppression

texts:
As a newcomer in electronics as a hobby field, before starting, my humble request to everyone is to not get annoyed by my questions which sometimes may be little silly.
So lets get started: I have started studying a little about opamps for audio amplifying and the IC I am using is a TDA2030. In previous circuits, I used to have a potentiometer to control the gain of the opamp, and that method worked very well,
Then I realized that I can't use a potentiometer everywhere to control gain of this IC so I found another formal way to do this; the diagram is shown below:

simulate this circuit – Schematic created using CircuitLab
When I start this circuit up, I get very high noise for a few seconds from starting time, every time. The noise goes away automatically after a while; it takes almost 1-2 mins to get pure sound without any noise. So what I want is: as soon as I start the circuit, the noise is removed.
First Question:
Am I missing some other components which is making it behave so? If yes so what are those and please explain their functionality. And what is the cause of this startup-time noise?
Last question:
When I discharged the Capacitor C1 before running the amplifier, this produces same noise for few seconds again. Why so? Does the capacitor's charged or discharged state matter here? Or is it the original functional procedure of the IC?
Thanks for your precious time, and please always put a schematic with example for my better understanding which will be more preferable to me.


texts: motor controller requiring a battery in parallel with DC power supply

texts:
I have a 36V 800W DC brushed motor (MY1020).
It is controlled by a 10-50V 40A motor controller (Cytron SmartDrive40) and an Arduino UNO.
I use a 36V 34A 1200W power supply (AC/DC).
the user's manual of the driver says the following:

"If a power supply that cannot sink current is being used (example: bench top and AC to DC switching power supply), the input voltage will rise when the driver is regenerating (motor is slowing down). Thus, it is important to connect a battery with same voltage in parallel with the power supply to absorb the current generated by the motor. Else, the input voltage might rise to a level where Enhanced SmartDrive40 will be destroyed permanently or the power supply trigger protection mode."

I wonder why a battery is adviced instead of a resistive load or something similar. I don't want to buy an expensive 36V battery just to use it as a " buffer tank for the brake energy". Also, powering a battery permanently is not good to me.
Is there any shields that could do the job? Would it work with 3 old used 12V batteries?


texts: When do we need an external crystal for an Atmega chip?

texts:
I have created a microcontroller circuit, based on the most used circuits I could find on the Internet -- which use an external crystal. As I know, Atmega16 has an internal oscillator which operates at 1 MHz by default. So, the microcontroller can be used without an external crystal. But now I am confused -- do I need an external crystal for my microcontroller circuit? I am just using ADC, USART, and LM35. I don't know if the internal oscillator is enough, good, or etc to be used.

So, when do we need an external crystal for our microcontroller?


texts: What is the anatomy of a noname touch panel?

texts:
I would like to add touch support to my 17 inch monitor (the computer runs Ubuntu).

A quick DuckDuckGo shows some interesting results: http://cgi.ebay.com/17-inch-USB-Panel-Kit-Set-Add-Touch-Screen-Function-/160626649602?pt=Computer_Monitors&hash=item2566182a02

I am a total newbie in electronics and drivers, so here are my questions:

Does the installation of such a panel depends on:

the display manufacturer?
the operational system used in the computer and the presence of drivers for this kind of touch panel?

Is it difficult to DIY this enhancement overall?

Are those panels reliable?


texts: TinyFPGA A Series Board programmer compatibility

texts: Since the TinyFPGA programmer writes configurations to the Flash memory of the FPGA chip, can I use that programmer for A series boards on any LCMXO2 chip? Or can I at least use it for the same chip with a different package?


texts:
I'm trying reverse-engineer a circuit on an espresso machine water boiler. I was looking at this post: Water Sensing Circuit

which seems to be essentially the same idea. Really the only differences are:

*I'm only working with one probe. The other "probe" is actually just the surface of the boiler, which is grounded. I've measured roughly 2Mohms across the probe and ground when water is touching it.

*I'm trying to run low voltage AC instead of DC, to avoid corrosion. The original circuit produces a square wave at 1kHz, 3.6V Peak to Peak. I figured I could easily produce a similar signal with a microcontroller and circuit similar to: Changing a Signal's DC Offset

Is there an AC equivalent to a circuit controlled by a PNP transistor?


texts: What type of connector should I use for multichannel(16) RF analog signals? Can I use HDMI?

texts: I need to select a connector type for 16 pair of wire. The signal is analogic and in the frequency range of 1 MHz. I prefer not to use 16 SMA connectors, however I am fine to use 4 blocks of connector or less. The connectors would be preferably shielded.


texts: Has anyone programmed a bare nrf52832. I have the ebytes e73-2g4m04s1b module. Nordics devzone suggest using segger j link and stuff. But I don't have access to any of those. Can I use Arduino Uno to programme ? Has anyone done it before ? Can u guide / point to some resources.


texts: Optocoupler high side vs low side switch

texts:
I have a NPN Darlington Optocoupler that I have been using for low side switching. I was wondering if it would be okay to also use as a high side switch?

Optocoupler Datasheet

simulate this circuit – Schematic created using CircuitLab


texts:
EDIT: I have been investigating in this problem for quite some time. It turns out to be a way more difficult project than I thought and not something for beginners. This requires expensive hardware (microphone & amplifier) and some sophisticated audio analyizig on the microcontroller. Even a complete microphone with amplyfier circuit does not provide the desired results (according to the comments on this product)

I am entirely new to the Arduino (but I'm familiar with programming). In order to built a VU meter, I want to put a microphone to the analog 0 pin of the Arduino and display the value via the serial connection.

I googled and found this circuit:

... and I tried to build it with this result:

(I'm now using the circuit suggested by Oli Glaser in his answer)

The values on the serial monitor don't change depending on the music volume.

What is the easiest way to measure the volume on the analog input of the Arduino?

Also, I have a TDA2822M, but I don't know if it is helpful for this project.
The caption on the microphone reads XF-18D.

Edit:
My arduino code:

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println(analogRead(0));
  delay(300);
}

The serial output:
1023
1022
1022
1022
1022
1023
1022
and so on

How can I check if the microphone works at all?
Is it directional?

Edit:
I am now using a S9014 transistor.
The ADC and the serial connection work (I tested them with a potentiometer).

The serial output is now around 57.

Also, I don't have a multimeter or oscilloscope.
I have a multimeter now.


texts:
Can I have a case statement without a always block like an inline if condition does not need a always function?

assign WORD_OUT = (SELECT_BIT_IN) ? WORD_IN1 : WORD_IN2;

but if I try this,

assign WORD_OUT = case (SELECT_BIT_IN)
    4'd0 : WORD_IN0;
    4'd1 : WORD_IN1;

or this

case (SELECT_BIT_IN)
    1'd0 : assign WORD_OUT = WORD_IN0;
    1'd1 : assign WORD_OUT = WORD_IN1;

It gives me an error.

I am trying to avoid using any registers.


texts: Let's say I have a 60 Hz sine wave, and I want to create a second wave of the same frequency, but with a phase difference controlled by another analog input voltage, - 10 to 10 V for instance. Is there a chip or simple circuit that can do this? I want to control the shift from 0 to 360 degrees


texts: Streaming video using BLE or classic Bluetooth 4.0?

texts:
BLE only has a data payload of 100Kbps so I was wondering if it is possible to stream a live video using Bluetooth Low Energy?

Classic Bluetooth 4.0 has a data payload of 2Mbps which makes it easier to transmit the video but I am more concern about the total power so want to implement the BLE. Can I get the same result when I use BLE to stream the video?


texts: 5v power switcher: Uninterruptable power source

texts:
I know there are a few other questions similar to mine, but after looking through the answers, it does not seem like it's what I need. I've also looked at the Arduino Due/Uno circuitry, and they aren't quite what I'm going for.

So I have a load that is requires 5v, with a maximum current draw of 500mA, ~250 typical. I also have a backup 3s lipo battery stepped down to 5 with a switching regulator. My circuit must always have 5v; I'm running a flight controller, any brief power loss initiates a full reboot (not handy whilst flying). The FC is usually powered via USB, however, the for my applications this USB power source has the potential to loose power. What I'm looking for is a circuit that can switch between the USB and the LiPo/5vReg in the event of a USB power loss, while maintaining a constant supply of voltage & current.

Prior Research:

Having two power sources joined together after a diode on each source will not work. My entire circuit is built around a 5 volt reference, and even a small 450mV forward voltage drop from a schottky diode will not work.

Mosfets: I tried using a P-channel FET with a very low RDS-on. My first attempt looked something like this:

The theory behind this was the 5v from the USB would hold the FET "off", and once the USB power source was lost, R2 would pull down the gate, turning it the FET on, allowing 5v to flow from the backup to the load. Of course this doesn't work, because the 5v flows back to the USB input, through what is now a voltage divider, and keeps the fet in some weird half-saturated state. I was getting ~3v on the output. (I know I didn't provide specifics).

So I figured in order to stop that, just put a schottky on the 5v USB, easy enough right?

This worked in the sense that the FET remained on, however, takes me back to my original problem, there is still a voltage drop across the diode while I'm using USB power. So that won't work.

After more brain draining, I was thinking I could use a NAND gate, thinking that when I loose USB power, the NAND output would go high, turning on my FET. I still have the same problem with the previous FET circuit, I would need a diode on the 5V USB line to keep it from deactivating the NAND gate (by backup 5v flowing into the USB input gate). Basically this is just a waste of extra circuitry anyways.

Yet another problem remains to be solved, if I use a FET to switch sources, I need a capacitor to provide constant power during the switching period, I cannot have even a few milliseconds of power loss. I also do need a switcher. Conserving battery power is quintessential. If I have USB power then I do not want my battery being drained.

So that's what I'm struggling with. I look forward to your responses! I hope I provided enough info/research into this question.

UPDATE:

I cooked up the circuit below, will be testing here shortly. The idea is that once the 5.5v backup powered, it will turn off the USB FET, keeping voltage from flowing back into the USB. The diode is to keep the USB from turning itself off. Whether this actually works or not I'm not sure, testing begins shortly. Any feedback on this circuit?


texts: Common way of describing a "double-sided wait"

texts:
Is there a commonly used name to describe a "double-sided wait" data transfer protocol?

This is a uni-directional scheme in which data is transferred on the clock edge if both the sender and the receiver (alternatively called producer and consumer) indicate that they are ready for the transfer by asserting a corresponding ready signal.  If only one side is ready for the transmission, it normally must enter a wait state.

"A Double-Sided Wait" is the title of a section describing this scheme in the book "Logic Design and Verification Using SystemVerilog" by Donald Thomas, but I don't find that name used elsewhere.

I believe that this is a very commonly used transaction protocol, but I don't know where to look for additional descriptive text on the topic -- or how to refer to it when trying to communicate about it.


texts: Does an SD card in SPI mode respect chip select/slave select? Seems to be resetting in my application

texts:
I have an application where I have a microcontroller (NXP LPC1343) which is connected to an FPGA via 16-bit SPI. There is also an SD card using the same SPI port (MISO/MOSI) but with a different CS/SS pin (both are active low, as per the SPI specification). One of the things I need to do is write data from the FPGA onto a file on the SD Card using FAT32, and this is the job of the microcontroller. The microcontroller is running FatFS, which I have gotten to work reliably by itself.

Because the microcontroller only has a small amount of RAM, only a small amount of data can be buffered at once. Hence, the micro has to read a buffer from the FPGA, change the SPI mode to 8-bit, and then write that data to the FATFS. Recall that in order to configure the SD card for SPI mode, a command must be sent while the SPI bus is running at 400 kHz, and a certain amount of waiting has to happen. Therefore, I would like to have to only perform the initialization once.

However, performing transactions on the FPGA even while holding CS high on the SD card seems to put the SD card into a weird state such that it needs to go through initialization again. This of course is undesirable, since the initialization may take several milliseconds, in order to write just 4 kB or so of data (again limited by the small RAM capability of my micro). As I need to write several megabytes as quickly as possible, this reduces performance from about 500 kB/s to less than 100 kB/s.

I'm aware that SD cards aren't technically fully SPI compliant, but how can this problem be fixed?


texts: Extending the range of a Remote Keyless Entry RKE key fob

texts:
If it possible to amplify the RF emitted from my key fob to dramatically increase it's range when attempting to remote start my car?  My wife is a nurse and leaves the hospital late at night.  She'd like to remote start her car (especially in the winter) to minimize the amount of time she spends in the parking lot.

Any ideas?

Even if it's something she has to carry in her purse that's OK.  Other people have RKE systems that operate over a longer distance and they can start their car OK, but my wife's is not powerful enough.  Tried changing the battery, but that didn't help.


texts: STM32L4 LPTIM as pulse counter of intermittent pulses fails when initializing with no pulse

texts:
I'm working with LPTIM as a Pulse Counter on a STM32L432KC, I have a rain gauge connected to LPTIM1 (PB5) and a anemometer to LPTIM2 (PB1). Both configured on STM32CubeMX as Standalone: counts external clock events and pins assigned as LPTIM?_IN1 using LSE clock.
To simplify, let's just use the anemometer but the symptoms is happening on the rain gauge as well.
Initializing the counter:
HAL_LPTIM_Counter_Start(&hlptim2, 0xffff);

This returns HAL_TIMEOUT when there's no pulse (no wind). If I turn the anemometer with my hand or is winding, when the device is initializing, it returns HAL_OK and it works just fine after that.
Troubleshooting, I found where it's timing out. On stm32l4xx_hal_lptim.c, HAL_LPTIM_Counter_Start function, you can find this code:
  /* Load the period value in the autoreload register */
  __HAL_LPTIM_AUTORELOAD_SET(hlptim, Period);

  /* Wait for the completion of the write operation to the LPTIM_ARR register */
  if (LPTIM_WaitForFlag(hlptim, LPTIM_FLAG_ARROK) == HAL_TIMEOUT)
  {
    return HAL_TIMEOUT;
  }

There's application note AN4865 related to use LPTIM as a pulse counter and it doesn't say anything about LPTIM_ARR register neither LPTIM_ISR waiting for ARROK flag (4th bit). Also, on the example code, they expect a constant pulse signal arriving so this problem never happens.
If I comment if (LPTIM_WaitForFlag... block, it works perfectly.
I'm not sure if this is a bug or not, and if is, how to report to STMicroelectronics.


texts: Can I read passive RFID tag (125/134 kHz) with a NFC tag reader, like the one on Samsung Galaxy S3 ? If not, why: maybe because of the different frequency of the NFC reader (13,56 MHz)? Any way to to excite passive RFID tag with NFC reader?


texts:
I am trying to learn to use this software called FlatCAM that converts gerber files into gcode.
The problem is that my plotting area is completly black, and when I open the gerber files, I don't see anything:

What is going on?
It should look like this:

I am using version 8.993. I don't know if maybe it is a bug or maybe I need to press a button to activate it. Since I am new to this software, I don't know. Could someone with more experience help me?


texts: PIC microcontroller not working without PICKIT3

texts:
I was trying to program a PIC microcontroller with MPLabX 5.1 and PICKIT3. I'm having a weird problem. After flashing the program, with PICKIT connected, the MCU works fine but after disconnecting it from  PICKIT, making it work standalone, the MCU stops working. I have no clue what's going on. I have previous experience with AVR and new to PIC world. Please help me solve this issue.

Thanks!

Update

MCLR is pulled up, debug bit is turned off in the config file in order to make PICKIT work as a programmer rather than a debugger.

Does work with PICKIT connected, Does not work standalone i.e., with external supply connected with PICKIT disconnected.

MCU is - PIC18LF45K40 (PDIP)

The circuit does not have much going on,Power supply and Pull up resistor is connected and Pin-3 is supposed to give out pulses. Configured to work with internal oscillator. MCLR pin is pulled up with 10K resistor.


texts: What is the use of two power supplies in an opamp?

texts: I am learning about opamps. Now I want to experiment with them but the problem is with -Vee (that negative power supply). I felt like I couldn't design it so opted for ground instead of negative supply, as I heard about single supply. Now anyone please elaborate what is the use of two power supplies also the consequences of making the -ve supply as ground. My college course prefers IC 741 OPAMP.


texts: STM32G474 signal generation with DMA + DAC using STM32CubeMX HAL

texts:
I am trying to generate a periodic signal with the DAC on the STM32G474 using DMA. There are tons of examples of this, and I´ve done the same in the past with an STM32L4 and F4 with no issues. However, I´m not sure if there is a problem in the STM32G4 line or a bug in the libraries/HAL code generation. I set up a simple example, just with a circular buffer of 2 samples at a slow rate, but I never get anything out, it generates on start a DMA transfer error and disables DMA.
I have tried different pins and channels. In the STM32G4, the DMA streams are multiplexed so you can use any as long as you are not using the same for other peripherals. I tried starting the timer first, including delays, calling HAL_DAC_Start() before HAL_DAC_Start_DMA() (which is redundant). Setting a value manually to the DAC works with no problem. I have tried also using Timer2.
I´m using STM32CubeIDE 1.3.1 and the code is generated with STM32CubeMX 5.6.1, the latest versions.
The main.c is here, it includes all configuration:
https://pastebin.com/F90s3iBz


texts: Saving to cassette with 80s BASIC calculator, TI-74

texts:
This 80s calculator, a TI 74 has a function that lets you save BASIC programs to a cassette tape. But, I don't have the cable to connect to a tape deck (or MP3 recorder?) So, I put my oscilloscope on the contacts (The ground pin and 6th pin): this shows that the digital signal is easy to detect. Can I run this through an amplifier and record it? Or do I need additional hardware?

UPDATE
I soldiered together an audio cable and this video shows what the TI-74 sounds like when saving a program to tape. I was not able to load the program back on to the TI-74 using this sound file, I think I need to adjust the pinouts.

https://www.youtube.com/watch?v=q_TumkmldJk&feature=youtu.be


texts: Is there any risk in leaving a Li-ion connected to a solar panel with only step-down converter?

texts:
I have a 18V solar panel which is connected to a step-down buck converter, which drops the voltage from 18V to 3.5V. When clouds block the sun, the voltage drops to less than 3.1V. I have added a diode on the positive terminal to make sure that the battery doesn't give back any current, but I was wondering if there is any risk in having such a fluctuation. Li-ion is sensible to trickle-voltage, and I am worried that this kind of of fluctuations will destroy the battery. Is this fear motivated by reality?

Right now, I'm only connecting the wires to the battery when it is full sun, because I have a constant voltage more or less. Can I keep this connection all the time or do I need other components to keep the battery safe?


texts: What if ddr4 Termination is done at last word component

texts:
Memory Component : MT40A256M16

Controller : Xilinx MPSOC - PS Side

Question :
I have mistakenly provided the DDR4 termination resistances at the first data lane and the layout engineer has completed the routing feeling it as last device.

layout was done properly for address lines, driver->comp1->comp2->comp3->comp4->vtt termination

but the data bus is connected in reverse fashion as shown in figure

does it affect my ddr4 performance ?

logically i dont feel anything has gone bad,

but is it compulsory that when we say last device "it is the device carrying last DQ lane of 64bits of data ?"


texts: What is a "phase reversal" choke and why is it used?

texts:
I was recently looking at the circuit for an HF radio amplifier called the "Packer" amplifier. It's a typical HF amplifier that puts out about 35 watts.

The final output stage uses IRF510 MOSFETS connected to a "balun", which is basically just an isolation transformer at RF from what I know.

There is one aspect of it I do not understand:

The points labeled "SWV" are just the supply rail (DC voltage). C4 and C9 are isolation capacitors. What I don't understand is T2 and how it works or what it does. In the documentation it is called a "phase reversal choke". I'm familiar with common mode chokes found in appliances and what they do, but the topology of how this is wired really confuses me.

Wouldn't current just flow from SWV to Q2 as it turns on, taking a path through T2 at terminals 1 and 2 ? Why would any current be present in T1 at all?


texts: Is there any generalized symbol for an electrolytic or electroplating cell?

texts:
Is there any symbol for an electrolytic cell? An electroplating cell, for instance?

(There are commonly used symbol for electrochemical cell (battery symbol). But symbol for electrolytic cell not seen. Neither in electricals , nor in electronics )

I've seen a symbol for a kind-of electrolytic cell, the Voltameter, ( that was used for chemical arithmetic (stoichiometry) and charge-calculation.

But the use of this symbol is so-rare (I've seen this symbol only in a few school textbooks, and this website containing the image below).

The bottom portion of the image from that website also contains the symbol, labeled as "voltameter".

The school textbooks also used this symbol in some small circuits also.

But I did not find this symbol in standard-sources or encyclopedias, etc.

So I want to know,

Could I use this symbol to indicate any-kind of electrolytic cell  (such as electroplating cells? ) or it is the symbol for only that measuring device?
If not, then, is there a more general symbol, applicable for any-kind of electrolytic cell?.
Is there any standard source where this symbol is described properly?


texts: How do I get my Arduino to reset another board?

texts:
Let's say I have another micro controller board. It has a 2 pin header on it. If you momentarily connect those two pins together -- either shorting them out with a jumper cap, or hooking them up to a button and then pressing said button, and so on -- the board will reset.

Now let's say I want to set up my Arduino so that it can trigger this reset when a certain condition is met -- received a command over a wireless link, a counter passed a certain value, whatever.

How would I hook this up? What additional components would I need, if any? Do I just hook both pins of the reset header to Arduino pins and digitalWrite(PIN, 1) them?

Sorry for this admittedly newbie-sounding question, but I am still fairly new to electronics.


texts: What kind of device is this LT6251 MBR...CT?

texts: Can't find any specs on this device (LT 6251 MBR10100CT or is it MBR|0|00CT or MBRI0I00CT). Can't find datasheet for it.


texts:
I'd like to try interfacing a fast (80 MHz) ADC with a microcontroller system.  The ADC (ADC12DL080) connects to a buffer flip flop (SN74LVTH162374) which then drives the MCU data pins about 6 cm away on a daughterboard.  The clock output on the ADC is inverted, so I used an inverting buffer to flip the polarity and then route to the flip flops and the MCU clock input:

Questions:

If the MCU clock is positive triggered, then I would have a race condition depending on the propagation delays, but if it I set it to be negative triggered does it latch the D-flip flop outputs correctly?

The inverted clock on the A/D is a little confusing to me.  Is the idea that I should clock the flip flops have a cycle after the A/D and not using the inverter?  Right now I'm relying on the delay for the buffer to let the A/D data outputs settle, which I'm not sure is a good idea.  Should I move the inverter after the flip flops so that the A/D, buffer and MCU are each 1/2 cycle apart?

Edit:  The MCU in this case uses the ADC clock to know when to latch in data from the data pins.  It does not clock the rest of the MCU off of the clock, just the data input latch.


texts:
If two batteries are connected such that positive terminal of one is in contact with negative terminal of other then we add the potentials so the potential will then be their sum.

Similarly if a battery is connected to a pn junction diode such that positive terminal is connected to negative side of junction potential
(ie.connected to p type) then why don't we add their potentials?
Isn't junction potential similar to the second battery as in the first case?

Please explain it at level of a high school student.


texts:
I am trying to repair a PCB that controls a camping fridge, in the process of reverse engineering the circuit I have got stuck at the device in the top left of the below photo marked K17h I believe this is either a transistor or op-amp used to amplify the voltage drop from the large shunt to the right.

Is there any way I can identify this component, and ideally find a pinout? I have searched for K17h but turned up nothing. Is there a database of these SMD codes kept anywhere for reverse engineering purposes?


texts: Why does my bandpass RF filter complain about Ts in Simulink?

texts:
I am doing a basic amplitude modulator, and I'm using as input signal for now a Gaussian noise generator, then I modulate it with a carrier fc=2e9Hz. When using Simulink along with a RF bandpass filter, I got an error saying that there is missmatch between the filter sampling time (Badnpass filter Ts = 2.5e-9) and the input signal the noise I guess (Ts= 2.5e-11), as it can be seen in the picture attached.

I have tried as well to set the same sampling time in the gaussian generator and in the filter, but then I got another error saying that the sampling time in the filter is to low compared to the center frequency... Which I don't know what it does mean, since if I set it lower, then I would have aliasing issues.

May someone enlighten me a bit?

Thanks in advance!

Regards


texts: What is the difference between a 0 Ohm Resistor and a piece of wire?

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As I was browsing through parts listings for a 3D printer project, I stumbled upon a resistor listed as "0 Ohm". Fittingly, it had a single band in the center: a black band. Because of \$U_t=R_tI_t\$, this piece immediately felt rather silly to me, as it wouldn't change the outcome of a series after Kirchhoff (\$R_t=\sum R_i\$) and would be a short in a parallel design: \$U_t=U_1 \& R_1=0\Omega \rightarrow I_1=\infty\$

What difference does this nill resistor have to just a piece of wire put in its place? Is there a special application where such a piece is used or is it just some kind of novelty?


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I have what I think to be a DPST switch. My problem is when I plug it into my circuit, it seems to be closed regardless of whether I press it or not. I have tested with another of the same type of switch but with the same results, so I think that either my circuit is wrong or I don't understand how to use this switch properly.

The text underneath the switch reads:

ZYCF
181

Attached are photos of the circuit, the switch and its packet.


texts:
I am a noob in this.

I would like to amplify a 3MHz modulated sine wave coming from a frequency generator. That is 5Vpp 50ohm ie 0.5W. Or it can be 10Vpp and High Z.

I would like to achieve 2-10W output. Preferably adjustable but fixed 3/4/n/8W would be OK too.

Because I have been obsessed in the last month to find out the answer for above, please help me what are the properties and or maybe the exact name ;) of the device I am looking for?

Thanks in advance


texts: How to convert pixel map to voltage/angles?

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My end goal is trying to get something rendered using lasers and a MEMS scanning mirror. There are not that many resources online for this, but it seems like the basic idea is pretty applicable to general embedded systems principles. I am building the driver from scratch and having trouble with part of it, and hopefully can get some direction on what to learn and make sure my thought process/approach is correct? The idea is straight forward:

Render a element and generate a ppm file to define each pixel value
Convert that to a set of voltages for the DAC
Based on the data sheet I can generate a look up table for voltage -> angles for the mirror

My main question is figuring out how to generate those sets of voltages. Is that even the correct approach? It seems like it will be a very similar approach to how LCD screens work with refresh rates.
HV_A (X+)
HV_B (X-)
HV_C (Y-)
HV_D (Y+)

HV_A = ((x_in / 8) + 1.25) * 56
HV_B = 140 - (((x_in / 8) + 1.25) * 56)
HV_C = ((y_in / 8) + 1.25) * 56
HV_D = 140 - (((y_in / 8) + 1.25) * 56)


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Here I asked a question why to have the capacitors:

FT232R chip and capacitor

But now the problem of their proper setup arises i.e. how to include the excerpt at the bottom of the picture in the whole circuit? Also I have a fundamental question here. Isn't it so that when I connect capacitors in a parallel way I could simply use 1 equivalent capacitor with Ceq = C1 + C2 + C3? Thus in my case I would have only 1 capacitor with C = 10nF + 100nF + 4.7uF =~ 4.8 uF. Also why are 10nF and 4.7uF capacitors polarized and 100nF is not? I read that it's more of a technological requirement that larger capacitors ~1uF+ have to be polarized. Why then 10nF is polarized? Thanks.

The picture is from
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf


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I'm trying to use an LT8500, which comes in a curious and interesting package: 6x6mm QFN with 0.55mm pitch, a second row and an exposed pad:

There is 0.25mm of empty space between pads. Can I still route that on a two layer board, or should I switch to four layers and use microvias? Is there an option I've missed?


texts: Voltage Threshold Gate Circuit from 0-5V Input

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Background:
I have a circuit in which when Vin is applied, the super capacitors have to be charged before anything else in the circuit can be utilized (otherwise I will undervolt the devices I am trying to power and they will not turn on). Therefore, I am trying to figure out the best way to prevent Vin from getting to the Load until Vin stops charging the caps and is at the normal 5.4V level.

Vin Characteristics:
Vin starts at around 1V for x amount of time then quickly jumps to 5.4V once caps are done charging.

The circuit below is my attempt to make sure no voltage gets to the Load until Vin is at least 5V. On paper, and in circuit lab, this works.

simulate this circuit – Schematic created using CircuitLab

My question is:

Is there a better, more efficient way to handle this?
Is there a risk that when the OpAmps are at a negative voltage output (on the labeled OpOut2), will that cause a problem in the circuit?

Thank you for any input!


texts: How do I limit the maximum power, delivered to a heater, through a triac?

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I am using the following circuit to turn ON/OFF a heater. Works like a charm. However, I would like to limit the maximum power delivered to the heater. The reasons for this are:

the heater is a fire hazard when running full on
the triac has to be sized for quite large current when powering the load full out

What is the simplest (fewest added components) way to limit the power, that a triac delivers to a resistive load?