texts: Complete alternatives to the Arduino IDE?

texts:
I'm not that big of a fan of the official Arduino IDE (in terms of visuals), so I've started looking for nicer alternatives. However, most of the projects I've found are in alpha/beta and are generally incomplete.

I'm 100% new to circuit board programming and I've never used an Arduino before, but from what I gather the Arduino IDE is just a wrapper for an avr library which does the actual writing to the board. Are other "arduino-like device" IDEs a possible option?

Again, I'm very new to this so user-friendly-ness would be nice.


texts:
Attached you find photos of a Li-Ion battery's PCB. I'd like to know what this component is called and what its use is.

The component in question is the three pin stretched silver "bridge". The white blobs seem to be glue, while the black things you see are ICs. There is nothing beneath the brownish center of the component.


texts: Sampling many low voltage analog signals

texts: I'm trying to sample 128 low voltage (a few millivolts) analog signals at around 800 samples/second. My original idea was to hook up 128 instrumentation amplifiers to 128 ADCs, but that turned out to be too expensive. My next idea was to try switching the signals (sample 16 of them, then sample another 16, and so on), but I'm not sure how to do that at low voltages without using relays (expensive/slow). I'm at a loss what to consider next. Any suggestions?


texts: 12V PWM to Analog DC converter for car cooling fan

texts:
I’m installing two 12V 80W cooling fans in an old BMW which originally uses a PWM electric fan.

This original fan has a three pin connector (constant 12v, ground and PWM signal from the ECU). I gather it has a controller built into the fan which actually controls the voltage that the motor sees.

How can I use the PWM signal from the ECU to control the speed of my two new fans (identical and rated at 6.6A)?

Not sure if a low pass filter would do the trick or something else is required.

Thanks in advance!


texts:
I am developing a PCB for an analogue sensing application. It uses the internal ADC on a PSoC3. As usual, the application is very space constrained (11mm x 21mm), so I have had to make some compromises in the PCB layout which I would not have done on a larger PCB.

The board is supplied by regulated 6v, and contains two 5v linear regulators. An MCP1702 for the digital supply, and an MIC5205 for the analogue supply. The board is sensing five A1324 Hall effect sensors. Each Hall effect output signal is filtered by a 100nF + 1k RC filter. One sensor is on the PCB itself (bottom right). The other 4 plug into the right hand 6-pin connector.

The chip is acting as an SPI slave, but ADC samples are always taken between SPI transactions, so the SPI should not interfere with the analogue signals.

Sadly, I am still seeing some noise (about 1.5 LSB at 12-bits) on the analogue signals, and I wonder if there is anything I could have done differently in the layout to improve it.

Please open the image in a new tab to see it in higher resolution.

Added:

Other PCB designs I have done using the MCP3208, and the same dual 5v supplies, same sensors, and same RC filters have achieved no noticeable noise at 12 bits.

The ADC on the PSoC3 is a delta sigma type. This version of the PSoC is limited to 12 bits, but another part number has a 16-bit ADC (although with a lower sample rate).

I do care about the noise, and would really like to push it a bit further towards 12 ENOB. The reason is not accuracy, but velocity measurement. Currently this level of noise is making it impossible to do accurate position and velocity control on a robot.

Added:

Schematic. Sorry it's a bit cramped, but you can just about read the values.


texts: LD1117V33 voltage regulator heatsink, thermal paste needed?

texts:
I want to screw a heatsink to my LD1117V33 voltage regulator. It's a normal 3mm screw and nothing inbetween. Do I need to use thermal paste or something like that?

It will be regulating 12V down to 3.3V to power an ESP-12F which will controll three MOSFETs to control my LED strips.

Thank you!


texts: finding the output resistance of bjt folded cascode

texts:
I am being asked to find the output resistance of following BJT cascode amplifier, from "Microelectronic Circuits" by Sedra and Smith, 7th edition, problem 8.80.a on page 588.

Now I decided to simplify the circuit down using the convention of opening the current sources and shorting the dc voltages to ground. Afterwards, I used the equivalent T-model to find the output resistance. I utilized the fact that the output resistance of Q1 is r_o already. Therefore, to find Ro my circuit would simplify to the following:

simulate this circuit – Schematic created using CircuitLab

Here is my analysis
\begin{equation}
\\KVL\quad outer\quad loop\\
v_o=r_o\left(i_o+g_mv_{\pi }\right)+r_oi_1\\
now\quad i_o+g_mv_{\pi }=i_1+i_e\\i_e=\frac{g_mv_{\pi \:}}{\alpha }\\therefore\quad i_1=i_o-\frac{g_mv_{\pi \:\:}}{\beta }\\now\quad substituting\quad v_o=2r_oi_o+r_og_mv_{\pi \:}\left(1-\frac{1}{\beta }\:\right)
\end{equation}
Here utilizing the outer loop of ro and re, we get:
\begin{equation}
v_{\pi }=r_oi_1\\v_{\pi }=r_o\left(i_o-\beta g_mv_{\pi }\right)\\Therefore\quad\\v_{\pi \:}=\frac{r_o}{1+r_o\beta \:g_m}i_o
\end{equation}
Now using these relationships and substituting, we get
\begin{equation}
R_o=\frac{v_o}{i_o}=2r_o+\frac{r_o^2g_m\left(\beta -1\:\right)}{\beta \left(1+\beta \:r_o\:g_m\right)}
\end{equation}
Here, am using the following values for the parameters:
\begin{equation}
V_A=5,\:\beta =100,\:I=0.1mA
\end{equation}
Unfortunately, am using these values and am coming up with a 100.5K ohms. I know there is something wrong with my analysis, because the answer should come out to 3.33M ohms. but I can't figure out what it is. Can somebody please point me to where the mistake is in my analysis. Thank you.

** Also, the transistors are matched, parameter values are the same for Q1 and Q2


texts: LTspice .ac analysis - expressions don't work or work inconsistently

texts:
In .ac analysis I would like to use expressions to calculate and plot the result of a combination of sources.
I understand that the results of .ac analysis are complex numbers.  Is there any guidance on which expressions work with these and which do not.
I find that adding and multiplying works, but that more complex expressions do not.
For example I would like to use the max or min expression. These don't give an error, but give the wrong answer in a behavioural model.  Trying to use them in waveform arithmetic generates an error.
I also find that division works in waveform arithmetic, but not in a behavioural model.
I have not been able to find any information in the help, on the undocumented section of LTspice wiki or generally across the www that gives any guidance on this.
Specifically, in the simulation below

B3 gives an answer of 0 at all frequencies, but plotting the expression V(Eq2)/V(Eq1) works.
B4 gives the wrong answer.  It results in the value of V(Eq1) at all frequencies.  Trying to plot the expression max(V(Eq2),V(Eq1)) throws up an error.

Plotting the expression Im(V(Eq2)) gives the same result as plotting V(Eq2).
Plotting the expression RE(V(Eq2)) gives 0 at all frequencies.
Im and Re do not work in expressions in the behavioural models.
Any insights would be greatly appreciated.


texts: Capacitive load of digital driven transmission line

texts:
I was looking at a design and started to wonder, how to analyze and verify the design.

A digital microphone has the output (SD) specified with a maximum Load of 150pF.

How do I translate this information, if I want to connect the SD output to a 50 ohm transmission line, using source termination ?


texts: Decreasing voltage without decreasing the current

texts:
I have got two 12 V 7.2 Ah lead-Acid batteries, which are connected in Series (26 V after charging). The batteries are connected to a step-up / boost module which have to be 2 V higher than the input. So the min. output is about 28 V

I want to use this to power an "mobile Amplifier", which is based on the compounds of an Logitech Z323 Speaker System. Now, my problem is, that the amplifiers input have to be between 14-18 V, but I can't get a lower output voltage from the boost module than the input voltage. In my opinion I could use a resistor combined with ohm's law. But the problem is, that the current-consumption of the amp (max 3 A) depends on the volume which is adjustable by a potentiometer.

Is there a way, to lower the output voltage to 14 V ignoring the actual current flow?


texts:
I'm working on a TTL to RS485 transceiver which is part of a bigger project (arduino based) and I came up with the following design:

I have a few questions:

1) I have seen very different values for the resitors R23 and R25 from 1K up to 20K. I have decided to use the most common value I have seen in other designs 4.7K but I don't really know if it's a good decision and how to calculate a proper value.

2) D11, D12 and D13 are used to protect against transition voltages, are the choosen ones correct? I have seen some designs including fuses, is it a good idea for extra protection?

This project is arduino based and it will be a network of 32 devices conected via RS485 so any idea to improve and protect the communication will be a great contribution.

Updated schematic to reflect the suggested changes:


texts: Maxim 7219 - how do you adjust the current going into each segment of a seven segment display

texts:
I planning on having  8x seven segment displays driving off a single 7219. The vcc is 5v. I was wondering how does the 7219 divide the power amongst the displays? Not decided yet but I probably only want 5 ma for each segment so 40ma for each seven segment display. The datasheet doesn't explain it in a way I understand.

Is it just usual way of working out a resistor for an led ? if so how is it able to guarantee the same amount for every one of them


texts:
Referring to the photo below, in direct-mapping cache design, why we need a comparator to compare between the tag in the address and the tag in the cache?
Isn't a valid bit enough?


texts:
I am currently in the process of designing an automotive (motorsport related) fuse-box as a side project to my studies. I've not had much luck searching for fuse holders (20 position) however while searching I came across fuse holders for printed circuit boards. I'm wondering whether a PCB design would be out of the norm for a fuse-box?

The advantage I see is that I can have it custom to the size I'd ideally want. Though I'm not to sure whether the same PCB can be used to house the relays (micro). I'd like to have one PCB which houses the relays, fuses and regulators my existing design


texts: FM Transmitter Amplifier — Maximum output power with non-customized parts?

texts:
I would like to build an FM transmitter on my own and I found a nice circuit that acts as a USB sound card to transmit low power FM signals. http://tipok.org.ua/node/35

My plan is to add another amplification stage with an additional device, commonly called FM Booster / FM Amplifier. There's one around fmuser.org that claims to amplify input signals from 0.2 to 0.4W up to 30W.

Unfortunately the output of FM Stick is only up to 0.1W. They use a transistor circuit around BFG541.

I really would like to use of-the-shelve parts only (like FM Stick does). At the same time I know that this will limit the maximum output of the circuit. But to what extent? What's the maximum RF output possible if one sticks to readymade parts?

I could not find any other circuit in the interweb, that does not rely on handmade coils.

Thanks in advance & Regards,
Hans


texts: Floating traces on MCU dev boards bad for noise?

texts:
When you have development boards for microprocessors with every GPIO pinned out on headers around the edge of the board, is the board more susceptible to picking up noise than a board without all those unconnected lines?
For example say you were using the ADC on the board but everything else is disconnected (like in the image):

Would the signal being read be noisier than if all those pink unused traces didn't exist if the board was placed near noisy things like SMPSs?


texts: Atmega4809 Asynchronous USART doesn't trigger data register empty interrupt - iom4809.h error

texts:
TLDR ATmega4809, mis-labelled ISR in iom4809.h. How can I define an ISR without using these mis-labelled predefined values from iom4809?

Using the ATmega4809 Xplained Pro eval board, I'm setting up asynchronous USART transmission, using the data register empty interrupt to always send the next available byte. If there are no more bytes to send, I disable the interrupt. I'm using the example USART project from MicroChip, directly from the Atmel Studio project generator.

/* Interrupt service routine for Data Register Empty */
ISR(USART1_DRE_vect)
{
     // I need to handle this interrupt.
}

int8_t USART_0_init()
{

    USART1.BAUD = (uint16_t)USART1_BAUD_RATE(9600); /* set baud rate register */

    USART1.CTRLA = 0 << USART_ABEIE_bp    /* Auto-baud Error Interrupt Enable: disabled */
                   | 0 << USART_DREIE_bp  /* Data Register Empty Interrupt Enable: disabled */
                   | 0 << USART_LBME_bp   /* Loop-back Mode Enable: disabled */
                   | USART_RS485_OFF_gc   /* RS485 Mode disabled */
                   | 0 << USART_RXCIE_bp  /* Receive Complete Interrupt Enable: enabled */
                   | 0 << USART_RXSIE_bp  /* Receiver Start Frame Interrupt Enable: disabled */
                   | 0 << USART_TXCIE_bp; /* Transmit Complete Interrupt Enable: disabled */

    USART1.CTRLB = 0 << USART_MPCM_bp       /* Multi-processor Communication Mode: disabled */
                   | 0 << USART_ODME_bp     /* Open Drain Mode Enable: disabled */
                   | 0 << USART_RXEN_bp     /* Reciever enable: disabled */
                   | USART_RXMODE_NORMAL_gc /* Normal mode */
                   | 0 << USART_SFDEN_bp    /* Start Frame Detection Enable: disabled */
                   | 1 << USART_TXEN_bp;    /* Transmitter Enable: enabled */

    USART1.CTRLC = USART_CMODE_ASYNCHRONOUS_gc /* Asynchronous Mode */
             | USART_CHSIZE_8BIT_gc /* Character size: 8 bit */
             | USART_PMODE_DISABLED_gc /* No Parity */
             | USART_SBMODE_1BIT_gc; /* 1 stop bit */
}

No matter what I tried, I couldn't seem to get the data register empty interrupt to fire. I figured out that there was an inconsistency between the datasheet and the library that defines the interrupt vector.

From the 4809 datasheet:

  26 0x1A 0x34 USART1 - Receive Complete

  27 0x1B 0x36 USART1 - Data Register Empty

  28 0x1C 0x38 USART1 - Transmit Complete

From iom4809.h

This doesn't match!! It is interrupt number 27 in data sheet and interrupt number 26 in the iom4809 library.

#define USART1_DRE_vect_num  26
#define USART1_DRE_vect      _VECTOR(26)
#define USART1_RXC_vect_num  27
#define USART1_RXC_vect      _VECTOR(27)
#define USART1_TXC_vect_num  28
#define USART1_TXC_vect      _VECTOR(28)

How can I define an ISR without using these mis-labelled predefined values from iom4809?


texts:
Consider an AC voltage source is placed in series with a complex impedance (z) and a load impedance. The maximum power transfer to the load impedance occurs when the load impedance equals the complex conjugate of the series impedance (z).

What I want to know is what is the (mathematically rigorous) derivation of this?

I've looked through my electrical engineering textbooks and can't find a good derivation. If you could provide one, I would be very appreciative.

Thanks in advance for your help.


texts: LED lamp lighting with only 1 pin connected to earth which isn't connected to anything

texts:
Anyone can help figure this out?

Yesterday, while connecting my LED lamp projector with an AC plug, I noticed when one of the 2 pins was connected to the earth pin of my AC extension cord, it would light up slightly. A really weak light but still light.

The extension cord is 20m long but not rolled in a tight coil. It could be somehow like 10 turn of AWG10 wire but I have no idea if that has any impact. The hot wire and neutral are connected but earth is floating.

So now I'm wondering how it's even possible. Could the extension cord induce current and push it into the lamp projector AC-DC transformer enough to light the led slightly? Like the floating earth is acting like an antenna.

I also noticed for a few weeks that my neighbor's lamp is always slightly turned on when turned off. Not sure if it could be related.


texts:
I need to read temparature and rh values from sht35 sensor. here is the datasheet

I am using stm32f0 and I have 2 different sensor. problem keep occurs with both sensor. Address pin connected to the ground so i2c address must be 0x44 but my code stucks at the while loop below. I am using keil, and cubemx to generate configurations. I watch sda and scl lines with a scope and everything looks right.what could be the possible problem of failure? ps: I tried checking out of the while loop too, nothing changed.

while(HAL_I2C_IsDeviceReady(&hi2c1, 0x44, 2, 100) != HAL_OK);

my i2c init function is here

static void MX_I2C1_Init(void)
{

  /* USER CODE BEGIN I2C1_Init 0 */

  /* USER CODE END I2C1_Init 0 */

  /* USER CODE BEGIN I2C1_Init 1 */

  /* USER CODE END I2C1_Init 1 */
  hi2c1.Instance = I2C1;
  hi2c1.Init.Timing = 0x2000090E;
  hi2c1.Init.OwnAddress1 = 0;
  hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
  hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c1.Init.OwnAddress2 = 0;
  hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
  hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  if (HAL_I2C_Init(&hi2c1) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure Analogue filter
  */
  if (HAL_I2CEx_ConfigAnalogFilter(&hi2c1, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure Digital filter
  */
  if (HAL_I2CEx_ConfigDigitalFilter(&hi2c1, 0) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN I2C1_Init 2 */

  /* USER CODE END I2C1_Init 2 */

}

edit:

HAL_I2C_IsDeviceReady(&hi2c1, 0x44, 2, 100)

waits for an ACK signal from i2c bus, I can't see any ACK on scope too.


texts: How does the comparator work internally?

texts:
I'm currently working on LM339 comparator. It says "If IN– is lower than IN+ and the offset voltage, the output is high impedance" on the datasheet. I'm wondering how does the comparator makes it go to high impedance internally?

From my understanding, high impedance means zero current at the output, which means zero current at the collector of the NPN. Like how do we make Ic=0 (this might be a basic NPN question)?


texts:
I have encountered several terminals, sockets, cables, and similar components which are rated in either DC or AC voltage, but not both. I sometimes want to use an AC rated part with DC or vice versa. Is there a way to identify when this is obviously unsafe?
For example, I know not to use something rated for 12VDC with 125VAC.
To give a specific case, I want to know if I can use this https://www.grote.com/electrical-connections/trailer-connectors/heavy-duty-7-way-connectors/82-2145/ 40a @ 28 VDC rated socket with a 10a @ 125 VAC load. Thank you.


texts: Generating a short pulse after a delay on ATmega 328/P

texts:
I am trying to use one of the hardware timers on the ATmega 328/p (arduino uno) to generate a short pulse some number of microseconds after receiving a pulse on an input.

Currently my code looks like this:

uint16_t pulse_delay = 12000; //half-microseconds
uint16_t pulse_length = 20;

void setup(){
  pinMode(8, INPUT);
  pinMode(9, OUTPUT);
  TCCR1A = 0;
  TCCR1B = _BV(ICNC1)  //input capture noise cancel
      | _BV(ICES1) //positive edge
      | _BV(CS11); // /8 prescaler
  TIMSK1 = _BV(ICIE1); //enable input capture interrupt
}
void loop(){}
ISR(TIMER1_CAPT_vect){
  TCCR1A = _BV(COM1A0) | _BV(COM1A1); //set OC1A on match
  TIMSK1 |= _BV(OCIE1A); //enable match interrupt
  OCR1A = pulse_delay; //pulse begin time

  TCNT1 = TCNT1 - ICR1; //TCNT1 now contains time since input pulse, even if
                        //the interrupt isn't run immediately
}
ISR(TIMER1_COMPA_vect){
  TIMSK1 &=~ _BV(OCIE1A); //disable match interrupt
  TCCR1A = _BV(COM1A1); //clear OC1A on match

  OCR1A = pulse_delay + pulse_length;
}

This code should theoretically do the task, but it doesn't produce any output at all - to my oscilloscope it looks like the output pin just stays low.

However, if I replace the last line (OCR1A = pulse_delay + pulse_length;) of the compare match interrupt with the following two lines, it outputs a pulse just fine. The issue with this is that it uses significantly more CPU time, and it can only count time from when the interrupt starts so if the interrupt is executed late the pulse will be longer.

  delayMicroseconds(pulse_length);
  TCCR1C = _BV(FOC1A); //manually trigger match event

All that the first version is doing differently is triggering the match event via an 'alarm' set on the timer, rather than waiting to trigger the match manually.

Why does the first version not work, and how can I make it work??


texts: Continuous servo "misbehaving' with arduino uno

texts:
I've recently got a TowerPro MG996R 360 degrees Robotic servo and after many tries I still can't get it to work properly. Using the Arduino's Servo library I wrote a simple program that writes a value to a servo and displays it through serial:
#include <Servo.h>

Servo test;

void setup() {
  test.attach(9);
  Serial.begin(9600);
  test.write(90);
}

int input;

void loop() {
  if(Serial.available())
  {
    input = Serial.parseInt();
    test.write(input);
    Serial.print(test.read());
    Serial.print("\n");
  }
}

So the two problems that occured to me are:

When I input something servo runs for about a second and then stops. In the serial monitor the value read from servo just resets to 0.
The way servo reacts to the value written to it is all over the place. Above 100 it works fine, but whenever I type something below that it acts weird. For values between 80 to 50 it just turns for about one degree and stops. For values below that it turns at full speed.

I have no idea what could cause these issues. The servo is powered separately by a 5V 3A power supply (I have also connected the supply's ground with arduino's ground pin). Does anyone have any ideas?


texts:
I'm an electronic & electrical engineering student in first year of university. I have had to use a few core programs as part of my course for programming and simulation software. However I came across AutoCAD Electrical and struggling to understand the use of the application.

It being an electrical CAD software, I assumed that I'd be able to carry out similar tasks as Micro-Cap (which I use to analyse AC, DC circuits) or Proteus (which I use to simulate code for PIC micro-controllers). However I've yet to find any tutorial that says that AutoCAD Elec does any of those.

If not, then I would like to know the essential point of it? If drawings is the main use of it, can't I just continue using Visio, which I had to map a fuse-box design for a side project. It is pretty fiddly on Visio, but if all AutoCAD Elec is, is a drawing tool, in what way would it excel Visio for the kind of drawings I need (all car related: looms, fuse-boxes, motors)?


texts: high voltage multiplexer for battery cell monitoring

texts:
I'm working on a battery management solution with 50.4V battery (36 cells in series with 1.4V a single cell voltage) for automotive application.
i'm planning on using multiplexer and differential amplifier to monitor the voltage of these cells with a microcontroller.
The problem here is that a multiplexer maximun voltage input is 36V/40V from what i found.
so is there any automotive multiplexer able to handle this voltage (50.4V)?
If not can i use a voltage divider for the cells with a higher voltage than 36V ? in this case i'm a little bit worried about the accuracy and the precision of the measurement.


texts: Isolation of CAN-High and CAN-Low signals

texts:
I have to isolate the signals CAN-High and CAN-Low on a CAN bus.

Is there an isolated CAN repeater (something like IXXAT's CAN-Repeater - 110 × 75 × 22 mm) which would be possible to mount on a board?

I mean a component CMS or through hole that I could solder on a printed circuitry. Or at least something much smaller than the one I posted.


texts:
I have 2 identical 12 V 100 Ah lead-acid batteries in parallel. I used to keep them fully charged with a mains charger, one with a built-in algorithm for these kind of batteries.

I recently hooked up a 50 W solar (PV) panel to maintain them fully charged instead.

The PV panel is connected to a solar charge controller, the charge controller has a gel charging algorithm, claims overcharge protection, and is set to use PWM.

My problem is this:

Everyday around 09:00 AM the batteries get charged to 16 V+ and the charge controller displays an overcharge error. When I measure the voltage at the battery poles with a multimeter, it displays pretty much the same voltage as the one shown by the charge controller.

Now, I'm pretty sure that this is a spurious reading - when I disconnect the PV panel from the charge controller, the voltage falls to 13.3 V within a few seconds.

The batteries also seem to be quite happy - there is no discernable increase in temperature from the outside, irrespective of how long the overcharge voltage is measured.

Is there some explanation for this?

I'm thinking, maybe the batteries have some built in circuitry to prevent overcharge as well and disconnect the input, so that the charge controller gets confused?

Or could there be some obscure battery chemistry at work, perhaps on a very small scale at the poles?


texts: I have a chip cellular antenna from Pulse W3544B. In the datasheet it is said to make the transmission line 1.34 mm thick which I feel is too huge and also I wanted to make a strip line for impedance matching and according to online calculations the thickness of the strip line is determined according to my dielectric and layer properties. I got 0.325mm. I'm confused which to use?


texts: LSD NiMH cells that provide reasonable capacity even in subfreezing temperatures

texts:
Sanyo claims that 2000 mAh Eneloop LSD AA NiMH batteries provide about 1400 mAh at -10 °C (-15 °F).

I wonder if only Eneloops provide reasonable capacity in the cold, or if the competition does too. Do any other low self-discharge AA NiMH batteries, not made by Sanyo, also provide reasonable capacity in below-freezing environments?

Edit:

I've found some tidbits which don't answer my question but are helpful.

"patrat" uses body heat and a high-drain device to keep batteries warm: "My [flashlight] is in my pocket, picking up body heat until I use it. If I use it at medium or higher, it stays warm once removed from pocket."

"Battery Guy" writes: "When it comes to low temperature performance for NiMH cells, it is safe to assume that the better the high current performance is, the better the low temperature performance will be."

Russell McMahon writes elsewhere: "I'd expect lower capacity batteries within a given size range to have somewhat improved low temperature operation, all else being equal. For example, 1500 mAh AA better than 2500 mAh AA. But the increased initial capacity may cancel this out. (Larger capacity batteries squeeze in all possible active material at the expense of electrolyte volume et cetera)."

Energizer Recharge NH15 AA 2300 mAh claim to work at temperatures as cold as 0 °C (-32 °F).

Duracell Rechargeable StayCharged DX1500 AA 2000 mAh claim to work at temperatures as cold as -10 °C (-15 °F).


texts:
I've got a small red laser pointer from a chinese ultrasonic distance meter, which has a small regulator circuit (6mm x 7mm) with SMD components.

I guess that is a constant current to drive the laser, but I was unable to understand the circuit.

I've used a microscope and a continuity tester to check all connections several times, as I was thinking I got some wire incorrectly attached. But I was not able to find any error.

The transistors are labeled L6 in a SOT-23 package, and I assume they are KST1623-L6 or 2SC1623-L6, both similar NPN transistors. I was not able to measure the capacitor without desoldering it, and I'm not confident in being able to take it apart and put it back being so small (~ .5mm x 1.4mm).

I powered the circuit using my Arduino regulated output at 3.3V during about 10 seconds, and the laser lights up, without any overheating observed.

I don't understand how Q2 works, as the base is attached to GND with 39 Ohms resistor, so as far as I know, ideally, it should be in cutoff mode. I'm curious how this circuit can work and why they decided to use it.


texts: basic math question about voltage, ohms, resistance

texts:
total n00b here. After working on several projects by copy & paste from other people's schematics and code, I'm finally digging in and learning some of the math to know what I'm doing.

If I have a pushbutton (this one, to be exact) that lists max amps as 50mA, and I have a 9 volt battery, the math for the resistor that I need is 9/0.05 == 180ohm, right?


texts: Will RS 485 to RS 232 converter change the half duplex mode to full duplex mode?

texts:
I am using an RS 485 serial connection through which I need to send S19 files for my boot loader project. Since it is a half duplex mode of connection, I need to toggle a dedicated pin before sending and receiving. I am using this terminal application. I got the desired output when I sent a string.

But I couldn't get any output when I try to load a file (s19 file to be specific).
Is it because of the Half-Duplex connection I use ?
Will an RS 485 to RS 232 converter change the mode from Half duplex to Full duplex ?

UPDATE

I am working on Freescale's MKE02Z64VLD2 microcontroller. I just now found out that there is no RTS CTS pin in my controller. (Check Comment Link 1)

This is the Serial connection which I use,

And the Terminal application is not a boot loader GUI, I found it in this site. (Check comment Link 2)
Thanks for helping.
I am posting the Links in the comments section because I dont have enough reputation to post more than 2 links


texts: How to identify replacement transformer?

texts:
I have a DVD player that is apparently working fine but the power supply makes a loud whining noise. The noise comes from, or from very close to the transformer. Upon close inspection, I see that there is a crack in the frame. The section is still held mostly in place by the wrapping tape but it is possible to shift the outlined section slightly.

I assume the transformer needs to be replaced.

I have the schematics. Additionally, not visible on the picture, the side of the transformer says "TNY267P / HY 0419" (but that appears to refer to the switcher IC). I have another DVD player with a similar PSU, a label of the transformer in that says "P 2472.0001A / 300?9706 / 23105Z / VDE".

How can I identify a compatible replacement transformer?

(Doing this to learn, and to make landfills slightly smaller :) )


texts: 4 bit subtractor using 2's complement of an adder

texts:
currently having problem with my carry in to carry out.

i have used this for my LSB
    assign S=A^(~B+1)^Cin;
    assign COUT=(A&~B)|((CIN+1)&(A^~B));

and this for my 3 higher bits.
    assign S=A^~B^Cin;
    assign Cout=(A&~B)|(Cin&(A^~B));


texts: Is Atmega8L-8PU compatible with Atmega 328 on arduino UNO?

texts: I have an arduino UNO running my code perfectly. Now I want run the same code on an Atmega8L-8PU which is connected on a breadboard. Is it perfectly reliable to use this Atmega8 instead of the Atmega328 (if the compiled code is less than 8kb)? Also please tell me how to easily transfer the compiled code to this breadboarded Atmega8?


texts: How to drive brushless motor with Arduino?

texts: Is it possible to drive a brushless motor directly with Arduino? Or should I revert on controlling a brushless motor ESC with PWM pulses?


texts: Why can't the error in proportional control system be closed by increasing the gain?

texts:
Proportional control is a closed loop system in which error is fed back for reaching a particular value. However, if the error is too small, it can't make a correction.

I think that this problem will be solved when we get proper gain.
If we want to get a signal which has magnitude 10, and the error is 1,
then the real value of the signal is 9. So if we make a closed loop which has gain 1 then the signal will reach 10.

I know this is wrong but I don't know why.


texts: Identify microcontroller pins for CAN interface

texts: I am using DSPIC33FJ64GP804 in my project. And the datasheets can not tell me which pins are used as CAN tx and dx. Maybe it is pin 21 C2in- and 22 C2in+? Or maybe any two pins can be used?


texts: LM324 Pre-Amp For Mic (to PC) Not Working

texts:
I don't have much experience in circuit assembling or designing but I wanted to create a pre-amp for my microphone(Philips SBC MD110 Dynamic Microphone which I directly connect to my PC) to boost the signal levels. So I created one by refering this 2 mins video https://www.youtube.com/watch?v=1wbgbbbILc0

So this is the circuit diagram(screenshot from video):

This is the circuit I actually made from the above diagram:

This is the underside of the board:

That's it. But its not working. When I connect the output of amp to pc's mic socket, all I can hear is a noise and nothing else.

The Vcc (~5V) is reaching the Vcc-pin of opamp IC as my multimeter shows that. Also I've used the 1st opamp of the IC (+ve input is 3rd pin, -ve input is second pin and Output is from 1st pin).

What I am doing wrong here?


texts: Double pulse test drain current not reaching peak

texts:
I want to have a double pulse test for the MOSFET. The drain current needs to reach 17 A peak. So to choose the capacitor and inductor I did the following,
DC Bus voltage = 400 V
$$L\dfrac{di}{dt} = V_{DCBus}$$
Taking $$L = 400 \mu H, di = 17, V_{DCBus} = 400V$$
the time is 17 microseconds.
And taking $$C\Delta V_{DC} = 0.5I_{pk}(\Delta t)$$
I get C = 36 uF. (Taking voltage ripple as 1% of DC Bus voltage).
But the simulation the drain current does not reach 17 A, and the dt time does not match either. What am I doing wrong here? My main aim is to get 17 A drain current of the lower MOSFET.
This is the drain current.

The blue is the VGS of lower MOSFET.

EDIT:-
I tried using 340V, L = 100 uH, C = 12.5 uF which should give 17A peak current for the MOSFET being turned on for 5 microseconds, but I got this, (blue is the drain current).


texts: Can a 74AHCT IC be a drop-in replacement for 74HCT IC

texts:
I have a circuit in which I interface a radio module running on 3.3V indirectly from a 5V supply.

I use a regulator to provide the 3.3V module VCC and the data is exchanged between both circuits through double-inverters (74HCT04).

This setup does work, but I read that if I used 74AHCT parts in place of 74HCT then the speed of operation will be 2-3x faster.

If I exchanged the 74HCT04 with a 74AHCT04, would the part still work or would there be special clamping diodes (like in the 74HC series) that would prevent the voltage conversion on the data signals to take place?

The data being exchanged between the radio module and the rest of the circuit is continuous and digital at the speed of 38400bps.


texts:
I have a technical question asking how to use this IC in my application.
I am converting 0 to 5Vdc from a potentiometer to a 12-bit digital representation using a 12-bit parallel output ADC IC. This IC is an LTC1273BCN. :I have attached the datasheet in this link.
I am reading these 12 bits with 12 digital inputs on a FPGA. The IC is powered with 5Vdc.
But I don't understand some pin connections on the IC. Below is my understanding of the IC:
Pin 24: +5Vdc supply
Pin 23: Ground
Pin 1: Analog input from potentiometer
Pin 3: Ground from potentiometer supply
Pins 4-11 and 13-16: ADC output 12-bits
What are the rest of the pins used for (pins 2, 19, 20, 21 and 22)?
How are these used in the ADC process? I would like the ADC chip to continuously convert the analog output without being told to do so by the FPGA. Or is this how the IC is designed to function?
Thanks


texts:
Suppose I have a scheme defined by the following equation:

\begin{align} z = \frac 1 {\frac1 {4R} - j* \frac {1}{wL}} - {j*\frac1{wC}}\end{align}

I need to find a vector diagramm of the scheme, which show the phase angle between current and voltage.


texts: MPLAB 8: Hotkey for "Program Target Device"

texts:
I am looking for a hotkey that will have the same effect as "Program Target Device" from the toolbar or menu.

Programming Target (4/7/2012  7:55:43 AM)
PIC24F16KA101 found (Rev 0x8)
Erasing Target
Programming Program Memory (0x0 - 0x143F)
Verifying Program Memory (0x0 - 0x143F)
Programming Configuration Memory
Verifying Configuration Memory
PICkit 2 Ready


texts:
I'm having problem with my verilog code when I synthesize it. It shows multiple drivers error. I think may be it's because of multiple always blocks I'm using in it. So how can I fix it!!? Here it is:

module check(csx,dcx,wrx,rdx,clk,d_out,res);
input wire clk,res;
output reg csx,dcx,wrx,rdx;
output reg [7:0]d_out;
reg [2:0]count;

always @ (res)
begin
  if (res==1)
  begin
    csx=1;
    wrx=0;
    rdx=1;
    dcx=0;
    count=0;
    d_out=0;
  end
end

always @ (posedge clk)
begin
  count=count+1;
end

always @ (count)
begin
  repeat(3'h5)
  begin
    if((count+res)==3'h2)
    begin
      d_out=8'h28;
    end
    else if(count==3'h3)
    begin
      csx=0;
      wrx=1;
    end
    else if (count==3'h4)
    begin
      wrx=0;
      csx=1;
      d_out=8'h11;
    end
    else if (count==3'h5)
    begin
      csx=0;
      wrx=1;
    end
  end
end

endmodule


texts: Modify Ring Contact Sensor in a series of wired security reed switches

texts:
After reading the instructables post on the simplisafe sensor I modified the ring sensor and tried to integrate it with my wired sensors. This is what I found:

testing with a spooled wire about 20 feet worked fine

When I added the ring sensor into an actual wire run to a door I was able to register the door closing if the circuit was originally open but then after that the ring sensor would always display closed even when the door was opened

I saw the comments about adding resistors to the leads so I did that and I was able to register the door opening and closing successfully.

I then tried to add another 2 door sensors in series and the initial problem came back. So I had to add another resistor

So now I have 3 4.7k resistors and I am able to monitor 4 doors total.
But on my second zone of sensors wired in series I cannot get it to work. This zone has 5 sensors but I have also tried it with 4 and tried to wire it the same as the first.

The problem on this zone is the first 2 sensors in the series will register an open and close fine, and the last sensor will register fine, but if I open the 2 windows in the middle the ring sensor will still see it as closed.

I have searched and found a few posts of people saying that they have had success by adding a capacitor to the circuit but I am unclear on how exactly they did this. Here are all the links I have found and maybe someone else can explain this better.

https://simplisafe.com/forum/customer-support-forum/installing-and-using-simplisafe/hard-wired-existing-door-sens#comment-604970
https://www.reddit.com/r/Abode/comments/6ny9w9/options_for_using_hardwired_sensors/
https://www.reddit.com/r/Abode/comments/5sclaf/connecting_hard_wired_sensors/

What these people are saying is there is AC voltage induced into the circuit and adding a capacitor somehow fixed their issue.

I don't understand why the sensors in the middle of the circuit will not register the opening of the circuit. I know this is a strange issue but maybe someone else has knowledge that will help solve this problem. If this is AC voltage from surrounding wiring how would a capacitor be wired into the series circuit to fix the problem?

I originally had this as an answer on a related post Integrate residential hardwired alarm zone with modern wireless sensor


texts:
I'm trying to build a simple low-power water level alarm such that it could run continuously for at least 4 months on just 3x AA batteries. I've found this schematic which uses the 555 timer:

However, the 555 timer has a minimum power consumption of around 30mW, which would be too much. Would it be a good idea to modify the circuit such that the water's conduction supplies power to the 555 like so:

Is water conductive enough for this to operate?

Would it be a better idea to just use a low-power MCU like MSP430 and raise an interrupt when the probes short by water's conduction?

Any thought appreciated.


texts: DRV8860 - Open drain output with 1.4k internal pull-up - How to understand this low value

texts:
I'm going through the Datasheet of DRV8860 and got confused by the pull-up setting of DOUT.
In the Datasheet the block Diagram shows the pull-up as follows:

In the "Electrical characteristics" table it is stated that the pull-up resistance is typically 1.4k Ohm and connected to an 5.7V internal voltage.

So my questions:
What's the reasoning behind this configuration?
Why for example they would not put a high value ("weak") pull-up there instead? Then the user could still oversteer it with a lower value pull-up resistor. But with this configuration, the voltage is pretty much fixed to 5.7V.
Or am I missing something?


texts:
I'm wondering if anyone knows the accuracy of measuring uA current with a cheep (~25$) DMM? I need to measure some low power circuits (10-500uA) and I'm deciding whether I should get an analog uA meter or use my DMM.

My guess is that the DMM will not be very reliable? I can test it with a dummy resistor load and attempt to verify with a scope I suppose.

Update:
Accuracy I'm looking for: good question, I would ask the same. within 2.5% is good enough, what I want to try to avoid is disturbing the circuit...

Also The op-amp + shunt idea is one I had, I wanted to get peoples opinions first before I invested the time into that.


texts: Why does 4T SRAM have very high pull-up resistors

texts: I was just wondering why do 4T-SRAM cell designs always have extremely high resistance (~GΩ). Is it because of the constant static power consumption?


texts: How is solar power consumed before grid power

texts:
This one has been on my mind for a while now...  I recently installed rooftop solar panels with micro-inverters.  While I was informed I would be using the solar power first, and any remaining needs would come from the grid, as well as sending any excess to the grid, I didn't really understand it.  Now that I'm using the system, I can clearly see (by watching the meter) that I truly do use the solar power first.  This raises a plethera of questions, some of which are:

If I have two sources of power which are phase synced, why aren't they consumed at equal rates?
In my mind, the utility power source is monsterous compared to my solar panels, how is it they 'overpower' the grid source to actually push power onto the grid?
What would happen if solar generation exceeded power consumption on the entire grid?

However, as the title indicates, right now I'm mostly curious on how I'm consuming my solar power before consuming any grid power...  Must be magic ;)


texts: What material should I use for the plates of my homemade mica capacitors?

texts:
I recently acquired some mica as i want to build my own high voltage (50 kV if possible) capacitors. The problem I am encountering right now is that the surface of such a crystal isn't perfectly flat but rather uneven. My plan was to simply use aluminium foil as the conducting plates but it doesn't fill said indentations.

I thought about melting a material directly onto the surface but what is a suitable substance for this task? If possible I would prefere to not buy some special equipment. I have a gas soldering iron whose flame is supposedly 1300°C hot. That should be enough for thin sheets of  metals with a low melting point.

Do you know about a suitable material or possibly another solution?

By the way it should not release any toxic gases as I want to produce the capacitors at home.


texts: Is there any repeater with power amplifier?

texts:
I installed sensor module connected with controller. Those are connected with 6-wire cable, and it consists of 2-wire power(5V & GND), 4-wire signals(0~5V analog). First time, I thought distance will be at most 15m. But the distance can be decided depends on the field. Sometimes it can be over 60m, long!

I tested with 40m cable I have. I saw voltage drop in power line about 0.4 ~ 0.5V, and it makes trouble with proper operation. I wonder if any related device for power amplifier with repeater for amplifying receiving signal like this case.

I searched some device store, but couldn't find proper options. If I cannot do that, gonna modify the design.

Jiwon


texts:
I have some questions regarding this system that is supposed to take in an input signal and move the load according to this signal. The current load position is feedback to the CT, which compares the current position to the desired position and produces an error signal that is amplified by the amplifier. I understand the processes involving the CT being connected with the CX and comparing it to produce an error signal but am unsure about other things. CX is a control transmitter and CT is a control transformer
1.What type of feedback inductive position sensor component is used and how does it work? Or is the CT THE feedback component

How exactly does the amplifier amplify the error signal that makes the load move to the correct position. Quite unclear about this

Any help is appreciated thanks


texts: Convert from VGA 9 pin to RCA (manually - old machine)

texts:
I'm in a trouble. Can someone help me?
I have a very big machine where I had mounted an IBM 5151 monitor by VGA. The VGA cable was connected to the card below (see attachment), by 4 wires.
Now the monitor is broken and I'm in  trouble. Can anyone help me?
I want to connect a single RCA wire (the yellow) directly in the card in place of the 4 wires of the VGA (wires grey, green, pink, white, to be clear.) The RCA cable has 2 wires, one yellow and one black.
What can I do?
Please it's really important.


texts: can't read&store in global variable in function OR can, but get error reading ds18b20 sensor

texts:
I'm using Atmega8 with CVAVR 2.05.0 and trying to slightly modify the way ds18b20 library works. I want to store temperatures from sensors in global array and start conversion for all sensors at one time - so i can avoid useless delays and do something usefull.
For now in "Project Configure - C Compiler -Code Generation - (s)printf Features" are set to "float,width,precision".

I found a problem (tested it in Proteus 7.7 SP2 and on real atmega8) - if i call tempature reading in function inside printf like this:

    printf("t%i read=%.4f \n\r", i, ds18b20_read_temperature(&rom_code_ds18b20[i][0]));

it works fine, except it can't read global variable inside function. But if before that print i put any assigment to global float array like this:

    temperatures[i] = i + 0.275;
    printf("t%i read=%.4f \n\r", i, ds18b20_read_temperature(&rom_code_ds18b20[i][0]));

i start getting errors (-9999) for every read for 2nd and 3rd sensor, no matter what is in asigment - if it is assigment to global varible. But it starts reading from global array right values.

Firs I tried to read global float array in main - it works fine. Then i tried to do same temperature reading in main - again, inside printf it works fine, but if i try assign result of reading to local variable t1 and then printf those t1 - i get zero.

Here is example for "good" output (no assign before prints, but no global variable read in function):

Here is example for "bad" output (put assign before prints, global variable starts reading normally, but 2&3 sensors are lost (see those -9999?) ):

Where is the problem?
Or there is something i should know about defining or using arrays and/or in functions?

About global variable i found only about problems inside interrupts, there was recomended to use volatile. Tried volatile - no effect. Also tried pointers (i'm not familiar with them, but with help of friend...)  - the same thing - no reading global in function and "loosing sensor readings".

Also after compiling project i get warnings:

  Warning: C:...\my_reading_ds18b20\my_reading_ds18b20.c(261): array index is out of range
  Warning: C:...\my_reading_ds18b20\my_reading_ds18b20.c(263): array index is out of range
  Warning: C:...\my_reading_ds18b20\my_reading_ds18b20.c(265): array index is out of range

I checked that variable number_of_sensors=3 (with printf), so i don't understand why i get this warning. Maybe because this varible is set with preprocessor?

Here is my .c file: watch for lines 80, 251, 252

https://app.box.com/s/8e3no26kfetoutiaqt6vn1rvsxq7wo2n

(with comments and "debug" printf. if anything isn't clear - ask me)

And here (if needed) .prj file:
https://app.box.com/s/52oo40bvo0fx02dshmjaw0nsv1mlywco

I draw your attention that it is NOT about reading dsb18b20 - those function is from library and works well, but about problems got from global float variable. I really need to store those values for later use!

UPDATE1: Seems the problem in everything except t1..t4 was in setting variable number of sensors, because if change initializng array float temperatures[number_of_sensors] to float temperatures[4] all previous problems are gone. So it seems i can't get number of sensors defined by way i used. Is there any other way except automatically change number of sensors depending on used options?


texts:
I have my application
bootloader appilication
    void bootloaderJumptoUserApplication(void)
{
    void (*bootloader_application_reset_handler)();
    printMessage("BL DEBUG MSG: Called bootloader_jump_to_user_application() \n");
    uint32_t mspValue = *(volatile uint32_t*) FLASH_SECTOR2_BASE_ADDRESS;
    printMessage("BL DEBUG MSG: MSP Value: %#x \n", mspValue);
    __set_MSP(mspValue);
    uint32_t resetValue = *(volatile uint32_t*) (FLASH_SECTOR2_BASE_ADDRESS + 4);
    printMessage("BL DEBUG MSG: Reset Value: %#x \n", resetValue);
    bootloader_application_reset_handler = (void*) resetValue;
    bootloader_application_reset_handler();
}

user application
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
      printMessage("hello from the user application__huhuhuu\n");
      HAL_Delay(1000);
   }

system_stm32f1xx.c
#if defined(VECT_TAB_SRAM)
#define VECT_TAB_BASE_ADDRESS   SRAM_BASE       /*!< Vector Table base address field.
                                                     This value must be a multiple of 0x200. */
#define VECT_TAB_OFFSET         0x00000000U     /*!< Vector Table base offset field.
                                                     This value must be a multiple of 0x200. */
#else
#define VECT_TAB_BASE_ADDRESS   FLASH_BASE      /*!< Vector Table base address field.
                                                     This value must be a multiple of 0x200. */
#define VECT_TAB_OFFSET         0x00008000U

but my bootloader does not jump to the user application


texts:
I want to make a ATMega-based module to record several parameters of a go-kart while driving - pedals position, speed of the wheels and g-forces. I have a problem with choosing how to measure gas and brake pedals position. I was thinking about putting a small neodymium magnet on the pedal and magnetometer connected to the module on the floor. Is it a good way to do it? The pedal movement is just few inches. I don't to use resistors and movable parts because I'm worried it might break and block the pedals, which isn't a good thing when driving flat out.

Also, is the an easy way to measure angle of the steering wheel?


texts: How to power gate device without voltage drop

texts:
I'm designing some electronics and I want to be able to control a HC-05's power without having the 0.7V transistor drop.  How could I do it? Are relays the only trick?

Thank you

John


texts: What is the impedance value that means it is a low ESR capacitor?

texts:
I need to select a 300uF capacitor and it is mentioned in the datasheet that it should be a Low ESR capacitor. However, it is not mentioned the impedance range or how much it should be.

How can I know if the impedance value is low or high ?
If I find a capacitor with 0.5 ohm impedance at 100kHz, is it Low or High ?!


texts: PCB layout of buck converter: capacitor placement

texts:
I'm designing a PCB for an IC that includes a DC/DC buck converter (MP2617). This is my first PCB, so I've been using the following resources for the layout: 1 and 2 (PDF files, the first one is a general layout guide for buck converters, the second one is a datasheet for another buck IC that has an extensive layout section).
I'm puzzled by an apparent contradiction between the two documents:
Document 1 says (page 7, paragraph 2):

Because high frequency of several hundred MHz is loaded on ground of input, so placing ground of CIN and CO 1cm to 2cm apart is recommended. If they are close to each other, high frequency noise of input may be propagated to output through CO.

whereas document 2 says (page 20):

The (–) plate of COUT should be closely connected to PGND and the (–) plate of CIN.
...
The point at which the ground terminals of the VIN and VOUT bypass capacitors are connected makes a good, low noise reference point.

Who should I believe here?


texts:
I am working with a small team designing a complex logical circuit using Proteus like this:

Each member designs sub-circuits and then we connect them together. The problem is that every sub-circuit is designed in a different file so then we want to copy the sub-circuit and paste it in the final design we are creating, but when we do that the sub-circuit is copied but not the circuit that is inside it, I mean, only the symbol of the sub-circuit is copied but the internal circuit is not copied.

How we can copy the entire sub-circuit? I tried copying the circuit inside the sub-circuit but then we have problems like duplicate references (U20 already exists, etc)


texts: I was searching the web to get full knowledge of IR remote controls. My satellite receiver (Humax)'s remote control got ruined. So, I unscrewed the remote control took a look inside it.  I know IR operates on 36KHz but what modulation techniques is being used. I just need to know the circuitry of the transmitter.


texts: Simple rectified voltage regulator not giving enough power

texts:
I tried to build a simple stabilised voltage supply for basic use to operate a maximum of 2 PC fans (0.15A and 0.45A) and also a 12V DC LED (0.5A) eg: http://www.led-slt.com/Spotlight/139.html.

Using parts I had around, I built a simple circuit based on an ac transformer (WDB4109 with o/p: 16.7Vac), a schotty rectifier STPS30 (giving 25V dc); an 18v zenner to drop the voltage to 18V which are fed to a voltage regulator L78S12, hoping to have a stabilized 12V dc. I've supplied a circuit diagram.

Without load, I have 18.2V after the zenner and a nice 12V output. When I connected the 0.13A fan, it rotated very very slowly as if there is no power.

Why I have very limited power in this circuit?

For your info, the transformer circuit is as follows:


texts: Sketching the voltage waveform of a capacitor

texts:
I'm currently learning about capacitors,

Question:

Ignore the fact that it says voltage on the figure, the question reused the waveform of a previous question.

Since I = C(dv/dt), and C = 1 F, i assumed that the waveform of the voltage is the integral of I(t). However drawing the waveform it looks discontinuous, which shouldn't happen. How should i solve the question?

Here is how i tried finding the waveform. I apologize for the crude writing, as it is pretty late right now.

I stopped halfway because i checked if it is already discontinuous through online graphing (GeoGabra), and it is as shown:


texts: LED Brightness or Luminance is additive or not?

texts:
Let us say I have an LED whose brightness or luminance value is 50 Cd/m2.
If I lit 10 same type of LEDs with same conditions of current and voltage then will the brightness of these 10 LEDs will add up to 500 Cd/m2 or will it give some other value?


texts:
Whilst looking for test rigs to experiment with tuned circuit filters, I came across the following article (http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1991/12/page29/index.html).
The author suggests a test setup including an interesting micro-wattmeter circuit that I've been studying.

Here's my version; the RF amplifiers have been replaced, but the rest is the same.

I understand most of it, but the biased diode detector is still something of a puzzle.  Is it correct to say that the biasing of this diode is critical to how this circuit operates?

It seems like the point is to place the diode in a region below the knee (square law area).  Since the op amp meter driver is lifted off the ground by the same diode with the same biasing, zero output from the RF amps produces zero output on the meter (after adjusting the zero POT). Any output from the RF amp(s) will slide along on the diodes characteristic curve and is amplified (a little) by the op amp.  In the square law region of the diode the output is proportional to the square of the input, so the meter is detecting power (not voltage).

Do I have that right?  I'm intending to place this detector downstream of a step attenuator, but even at that I'm guessing it wouldn't take much to overload the diode detector.  Has anyone built anything like this and how useful was it?  Are there any potential pitfalls to this design?

EDIT: one other thing, I realize the schottky's in my design wouldn't work well (the biasing on the RHS of the meter is designed for a greater Vf for starters!).  They won't be used in any final build - I'll be using proper low capacitance RF schottky's instead (1N5711).


texts: No Current Flowing From 12v Solenoid Pins

texts:
I have recently designed my first PCB (forgive my poor understanding of electronics) and I'm having an issue with the pins that are supposed to be powering the 12v 2A solenoid.
Everything works as expected except I am getting no current from the 12v solenoid pins. When hooking up the boards power supply directly to the solenoid everything fires as expected, but when trying to power the solenoid through the board, I get 12v across the solenoid pins, but no amperage.
I tested the resistance of the pins and I have a connection from the 12v supply positive to a solenoid pin, I also have the expected ground connection from the 12v supply ground to the MOSFET Source pin. The MOSFET is also working as expected and closing the ground connection when 3.3v is applied to the gate pin.


texts: How can I make a PC look like a thumb drive for reflashing devices?

texts:
I'm working with a legacy embedded system that uses a USB thumb drive to bootload new firmware.  The system powers up, mounts the drive, loads code, etc.  All is happy.

I'm looking to reuse this platform to use for multiple products and I'd like a way to keep the factory line from having to juggle thumbdrives and remember which one is the right load for the right device.  The device's bootloader is very skeleton and can't be configured with a type ahead of time (so it could pick the correct file off the thumb drive).

Using one of those magic USB A-to-A adatpers and a cheap Linux laptop (or PC running Vbox), is there some way I can make the laptop look like a thumbdrive to something plugged into it?


texts:
I have read in the Internet that in the most cases people prefer using INS (accelerometer + gyroscope) + GPS sensors. I have read they can compensate each other errors, but is it possible to obtain the same result using accelerometer + magnetometer + GPS sensors? Or accelerometer + gyroscope + magnetometer?
I have also read that gyroscope requires lot of battery, so my question is: what is the system which can give me the same result of IMU + GPS, without using gyroscope? If it is not possible, can I just use 9 axis system without GPS?

I know that it depends on the application I want to use, but just let's consider I would like to realize a medium/high level application, so I need it to be precise, but I can afford to have some (very) small errors.
If there is a paper which compares the performance of the system I mentioned, please link it :)

Thank you in advance for your answers.


texts: Confusion with RCD principle of operation

texts: I understand that an RCD is a device that interrupts an ac circuit (usually in outlets) if current between live and neutral/ground is not the same, indicating something is wrong with the circuit.   It is in a closed state (the power is connected to the circuit) when two wire coils (live and neutral) on the same core oppose each other (as they normally do), cancelling out their magnetic fields.   However when these coils do not oppose each other or vary enough to produce a net magnetic field they trigger a sensor which opens relays that disconnect the circuit.   In practice this could be done when someone touches the live wire for instance and are connected to ground (which is connected to neutral on most modern systems).   But my question is in an ac circuit wouldn't shorting out or allowing current flow between the two wires not vary their relative currents because they are already connected in the ac generator and the electrons that pass through the person (or connection point) would just join the alternating flow that already exists (at higher currents but still at the normal 60hz oscillation/opposition between live/neutral)?


texts: Wireless communication over long distances

texts:
Would like to communicate between an Arduino and a PC but over a
distance of 2500+ feet outside in the open, wirelessly. What would be
the best way of doing this? The communcation devices I have found
(xbee,...) dont go the distance.


texts: Which area of physics deals with principle of work of BJTs, diodes and other semiconductor elements and which book do you suggest covering this?

texts:
Which area of physics deals with principle of work of BJTs, diodes,...?

I'm familiar with equations that describe operation of these elements but I have no idea how they work "internally". I started learning Digital electronics and I'm trying to understand how different TTL implementations of logical gates work but I have hard times in learning this, probably because I learned only equations that describe these elements but I have no idea how they work.

Which book covers this field? I need some introductory book to this field because I'm complete beginner.

EDIT: I would not go in quantum mechanics, I'm not physics student. I'm electrical eng. student. I want to learn principle of working to be able to successfully use these devices as Electrical Engineer.


texts: Can we use nodemcu in real-time projects

texts: I have been working on some small iot projects using nodemcu. So  I have an idea to make those nodemcu projects into real-time . The places like home, office, school


texts: Is it possible to use a DRV8825 to drive higher current stepper motors?

texts: I know it's rated to 2.2A per coil, but I need to drive more than double that.  Can additional circuitry be added to this, or does the driver require accurate current sensing?


texts: Does paint affect EMI ability of enclosure?

texts:
This could be a very stupid question, but when it comes to RF you never know.

Does painting (non-conductive) over the top of a grounded metal enclosure affect its ability to absorb/block RF interference? At the mechanical fixings, the enclosure is not painted and has a good ground connection.

I was wondering because I remembered that RF currents travel on the surface of conductors. Would they just travel "beneath" the paint?

Thanks.


texts: What is the type of this surface mount transistor?

texts:
I have a no frost freezer which stopped freezing efficiently and after some research and trials I found the problem to be related to control board. And as of now I am pretty sure the problem is with this obviously burnt transistor that controls the compressor's relay.

Using a multimeter I figured it's a pnp type (Negative probe to base gave me a reading in diode mode) however the check was done on this other one that looks exactly the same and so I confirmed the type.

The burnt one did not give me overload when I touched either probes to base however it gave me a much lower reading for (probably B-C, I couldn't confirm C-E pins) than it read for (B-E). 24 , 420 respectively.

Now if my logic is correct, I want to know how can I figure it's precise model so I can change it? Marking reads A4t 95, as you can see, but a search on google was futile and I couldn't reach anything so figured asking here may return something.

Thanks in advance and sorry for my english.


texts: Measure capacity of Lithium by Coulomb counter method while charging

texts:
I'm learning to design a module to measure capacity (percent left) of ebike Lithium battery. Lithium cell ' specifications are 48V-13Ah, it's built from cell pin 18650- 2600mAh. I choose the Coulomb counter method to measure SOC. As the photo below:

Step 1: Initially, K1 and K2 open. When I connect the battery, K1 closes and K2 opens. Discharge current will be calculated by hall sensor for a short time (~3s) and the duration from K1 close will also be counted too. So, it means left percent of the battery is:

 %battery_1= (Ct - Cd)/Ct ; which Ct(Ah) is 13Ah, Cd(Ah) is discharge current x time

Step 2: K1 opens, K2 closes. The battery is charged from the adapter, charge current is also calculated through hall sensor integrating with the time.

 %battery_2 = %battery_1 + Cc/Ct ; which Cc() is charge current x time

This is my method I intend to measure %battery while charging. I hope someone can give me some recommendations about it. Thank of all you.


texts: "Tricking" ethernet cable it's disconnected

texts:
I have been looking for a solution to "disconnect" an ethernet cable from a port without physically disconnecting it.

I'm doing this since I want to reduce power consumption in a project I'm working on which includes an FPGA with an ethernet port. Physically disconnecting the ethernet cable is the only way of turning of the ethernet port on the FPGA, which consumes a pretty large amount of power.

I haven't found anyone doing something similar when looking for an answer. I might have a solution and were just wondering if it's viable or if someone has a better one.

What is the drawback of simply letting the ethernet cable going through a transistor? If the switch activity is low, the parasitics of the MOSFET shouldn't be a problem, or am I wrong here?


texts: Determine what voltage brings \$ V_{in} \$ in the saturation region for the following circuit?

texts:
Hi I need some help with my homework, I am trying to find \$ V_{in} \$ when the circuit is saturated.

Here is my circuit:

simulate this circuit – Schematic created using CircuitLab

Here is what I know B = 125 and Ic = 27 mA. So using:

Ic = BIb
Ic/B = Ib
27 * 10-3 / 125 = Ib
Ib = 2,16 * 10-4 = 0,216 mA

Then I tried to calculate \$ V_{in} \$ with this formula

Vin - Vrb -Vbe(SAT) = 0
Vin = Vrb +Vbe(SAT)
Vin = 33 x 103 * 0,216x20-3 + 0,2
Vin = 7,328

But it is not the correct answer \$ V_{in} \$ is suppose to be 7,84 what did I do wrong or what am I missing?


texts: Meeting Setup/Hold Time according to time analysis

texts:
I am trying to interface an IC with an FPGA. Both the IC & FPGA run at 66 MHz with no clock skew between them and the propagation delay of the data lines is negligible, since the length of the PCB traces that connect the 2 chips is very short.

The IC has a setup time 1 ns and hold time 4.8 ns, while the sampling of the data is performed at the rising edge of the clock.

According to the I/O Timing Analysis report of the FPGA software, which is created after the Place & Route so I assume is the absolute final report, I have a Clock to Output delay of around 10 ns.

If the FPGA outputs data at the rising edge with the system clock period being 15 ns and the clock-to-output delay 10 ns, new data have arrive 3 ns before the required setup time so I respect the setup time, which is 1 ns. At the same time, in the next cycle, since the clock to output is 10 ns, the new data will become available after 10 ns, so I have respected the hold time as well, which is 4.8 ns.

Is my reasoning correct?

Thanks in advance.

Edit:

FPGA is MachXO2 by Lattice (TQFP-144) while the IC in question is FT601 by FTDI, which is USB 3.0 to FIFO Bridge. Since clock-to-out is 10 ns, and the next output will become available when the rising edge comes, I assume to have a hold time of 10 ns (5 ns before the rising edge arrives plus 10 ns after the rising edge, which is the clock-to-output delay, totaling 15 ns).


texts: I'm planning to use two 6v 0.6W solar panel in series to supply a cheap tp4056 module with builtin cell protection in order to charge a single li-ion battery. In order to regulate the voltage to 5v for the module input I would use a buck converter. Since the module input range is 4.5-5.5v what will happen when in the night the panel voltage drop near 0v? Can the module be damaged? Should I use a cutoff voltage circuit?


texts:
I'm eager for help in figuring out why all the microcontrollers I'm using are dying randomly. At first, I was using LPC810Ms and LPC1114FN28s (both DIP packages on a breadboard), so I overlooked the problem since plugging in a new one was no big deal. But now, I'm using STM32F437s (100 QFP package soldered on a prototyping board), which at $17 a piece, and requiring a fair amount of soldering, makes replacement pretty expensive.
My power supply is pretty unconventional. It's an Antec HCG-850M computer power supply with the under voltage & over current protection removed, so I can run RC car motors without tripping. As a result of removing UVP & OCP, I noticed turning off the switch results in a very gradual voltage decay (takes > 10s for the voltage to reach 0). Could this be breaking the MCUs?
In general, the only peripherals I have connected are a Segger JLink for ARM debugging and a UART.
Symptoms:

LPC810, LPC1114FN28:
The chip gets very hot, eventually burning out. Surprisingly, I can still program and run things.

STM32F437:
The ARM SWD interface becomes inoperable. I can no longer program or run. No signs of overheating. I remember exactly that it broke right after I cut off the power, which happens very slowly as mentioned above.

I'm not expecting a too specific answer, so please share any relevant experiences.

Update
Correction: the voltage doesn't take 10s to die off (that was a guess based on how long it took the lights & fan to turn off). Instead, it drops instantly after 5 seconds.
I've measured the power supply on/off transient behavior several times and don't see any spikes. Here's the waveform when turning on:

This is within the allowed range (1.7V <= Vdd <= 3.6V).
Pictures/Diagrams:
(only colored pins are connected)

Update2
Finally, I've found the problem! but not the real cause. Thanks to clive1 on the ST forum thread, STM32F4 - Discovery fail, I resurrected the chip by switching the BOOT pin to 1, so it boots from RAM, instead of Flash. So it wasn't dead - just bricked (don't understand why the debugging interface depends on working Flash)
So now I'll make my question more specific: Why is the MCU's flash memory getting corrupted on powerup, powerdown, or resets? Also, forget about the LPC MCUs.


texts: Soldering RoHS components with Pb-Sn solder

texts: How is soldering RoHS components with good old Pb-Sn solder different from soldering non-RoHS components? I'm talking about hand-soldering, not wave or reflow.


texts: What is the difference between "SMD/SMT" and "Straight" about Mounting Direction?

texts:
I'm looking for a tactile switch for mounting on a PCB.
I use Mouser to find them.
https://www.mouser.jp/Electromechanical/Switches/Tactile-Switches/_/N-5g2m?P=1z0z7pt

In that page, there is Mounting Direction filter, and there are 3 options: Right Angle, SMD/SMT, and Straight.

I know the meaning of Right Angle, but I don't know the difference between SMD/SMT and Straight when I select SMD/SMT with Mounting Style filter.

I thought there are no differences in terms of the way to mount and actuator orientation, but actually, the number of search results are different.

What is the difference?


texts:
I am fairly new to electronics and all of that good stuff, but I have been doing some research on triggering a series of events that would simulate a movie bomb defusal. I've got an idea for four stages. I have some diagrams I've made in circuit lab, and I have a base idea for what I want, I just would like some tips and insight from a more experienced person and learn what values I need for resistors and such.

Diagram 1: Essentially what I'm trying to do in this diagram is; when the sensor wire is cut, it will allow current to pass through to an led and continue to let 12v of power from the 8 D cell batteries through the wires. If the wire isn't cut, it will not allow power through to the led. I've looked at some diagrams and done what I could to try and replicate that.

When the wire is cut, I want to power an led. I also want a key switch, that when turned, will turn on yet another led, and power a relay with 12v of power. This will, in turn, power an arduino powered keypad. Complicated, right?

Diagram 2: This diagram shows one of the three wires that is not correct. If this wire is cut, I want it to let power through to power a red Led, a 12v piezo siren,(https://www.amazon.com/gp/product/B00HR6P9QU/ref=ox_sc_act_title_1?smid=A1THAZDOWP300U&psc=1), and, if possible, a 9v activated smoke grenade THAT CAN BE REMOVED and the circuit will still function. (http://sportsmoke.com/smoke-grenades/electric-fire/tactical-smoke-grenade-electric-fire). I know. I'm needy. I want to have two incorrect wires, and I'm wondering if I could power all three wires off of the same power source, because 8 D batteries is already a lot to fit into a case.

Diagram 3: What I want happening here is a key switch, when turned, will trigger the smoke, led, and siren. This one can be powered by separate power source, like AA batteries in series. Also, I'd appreciate if we could power the same smoke grenade by all sources.

Ok! That's all the stages


texts: MATLAB about generating and analysing noisy signal

texts:
I have an assignment about Signals and Systems. I am completely new to MATLAB so i need extreme help on the assignment below:

Generate a noisy signal with sinusoidal components defined at 100 Hz and 300 Hz (3rd Harmonic)

a) Calculate (slow) its time and spectral variation
b) Calculate frequency resolution (deltaf)
c) Design a low pass filter to remove the 3rd harmonic and check its performance.

I need the code and the graphs to do this assignment. Any help is appreciated. Thank you.


texts: Can a MAX232 IC be used for RS-232C standard?

texts:
I have a GT01 Panasonic LCD which it's interface is RS-232C.

I have read that the difference between RS-232 and RS-232C is their voltage level which it's ±5 V in RS232C.

Can I use a MAX232 IC to communicate with this LCD?

I'm worried that MAX232'c Voltage level (±25 V) harms the LCD.

If not, would you please propose an IC which is capable with RS-232C?


texts: Trying to understand directivity of an ultrasonic sensor

texts:
I am trying to understand this plot of directivity from the following link:

http://www.nicera.co.jp/pro/ut/pdf/T4010B4(ENG).pdf

How do I read this plot? I can say that at 0 degree , the energy would be  0 db, at close to 60 degree , this is close to -10dB. Am I right ?

But then what is the meaning of  -6dB Full Angle : 100°, I do not see 100 degree anywhere. Even if I imagined I am not able to visualize how it will go to -6dB. Also why they did not show the energy at 100 degree in this plot.


texts:
I have a code on Arduino to read the data from MPU9255 with no libraries, using it direct through I2C. I am trying to do the same on Keil uVision with Bluepill, just to learn how to use I2C with HAL Drivers.

I don't know What I am doing wrong, here is the code:

uint8_t adressMPU = 0x68;
uint8_t i2cData;
uint8_t* receive_buffer = 0;

i2cData = 0x6B;

HAL_I2C_Master_Transmit(&hi2c1, adressMPU, &i2cData, 1, 100 );  //Starts MPU
HAL_I2C_Master_Transmit(&hi2c1, adressMPU, 0, 1, 100 );
while (1)
{
    i2cData = 0x43; //adress of the register to read Accelerometer x axis
    HAL_I2C_Master_Transmit(&hi2c1, adressMPU, &i2cData, 1, 100 ); //set the register address

    HAL_I2C_Master_Receive(&hi2c1, adressMPU, receive_buffer, 2, 100); request 2 bytes from the register
    HAL_UART_Transmit(&huart1,receive_buffer,sizeof(receive_buffer),100); // send it to serial port

    HAL_Delay(500);
}

My code in Arduino that is working:

Wire.begin();                 //inicia I2C
Wire.beginTransmission(MPU);  //Inicia transmissão para o endereço do MPU
Wire.write(0x6B);

Wire.write(0);
Wire.endTransmission(true);

Wire.beginTransmission(MPU);      //transmite
Wire.write(0x43);                 // Endereço registrador do Gyro
Wire.endTransmission(false);     //Finaliza transmissão
Wire.requestFrom(MPU,6,true);   //requisita 6 bytes
mediaGyroX += Wire.read()<<8|Wire.read();  //GYRO EIXO X

Surely I am doing something wrong, but I can't see the error. Can somebody help me?


texts:
I have a device in which there is a SPI flash and a I2C EEPROM, W25Q256JV (32MB) and AT24C1024 (1MB) respectively.

The MCU writes data packets in the flash fifo and saves its read write pointers in eeprom.

Sometimes the data read from flash is bad data = 0x3F instead of valid data.

I am trying to find reasons what is specific about "0x3F"? Where can it come from?

Just in case the read pointer went awry to some unwritten location then I should get "0xFF" instead of "0x3F".

Or possibly that wrong data was written during write operation. In this case where can "0x3F" come from in the MCU? If its some uninitialized array even then it should be "0xFF".

Or is it possible that the data gets corrupt during SPI read or write communication? Is there any chance that "0x3F" comes from some power supply problem during this read or write operations?

This values "0x3F" is consistent and every time whenever I get bad data it is always "0x3F".

I am interested to know at an abstract level what could be the phenomenon of this "0x3F" showing-up in the data?


texts: Transfer function for six-pulse controlled rectifier

texts:
I need to determine the transfer function for a six-pulse bridge rectifier, implemented with thyristors.

More precisely, I need to determine the relationship between the output voltage (pulse) and the firing angle (or the conduction angle) of the signal applied to each thyristor.
Obviously, the trigger signal for each of the thyristors is equal, and synchronous with the corresponding supply voltage.

Can anyone suggest a line of research?


texts: Why is DC voltage biasing applied to a capacitor in distortion pedals

texts:
I've been looking at some distortion pedal schematics and many of them are a variation of the same circuit, such as these two:

and

I know that most of these pedals are used with 9V batteries or power supplies, so a 4.5V bias is needed in the circuits, however whats the purpose of appliying the bias voltage to the C3 capacitor in the first image or C2 in the second image?, why not connect it directly to ground?, the capacitor would block any DC applied to it. I also know that the capacitor is probably there to achieve unity gain at DC, and a different gain for AC, but I still cant figure out why the DC voltage is applied there aswell.


texts: Question for Linear opto isolator circuit

texts:
-I want to have the same potential or linearity in opto isolator's input and output

Pic below there is my previous circuit ,sketch and Changed Sketch(the last pic),but it's not linear with PC817.
I have thought about using HCNR201,TI staff recommend me to use AMC1311,but i don't know how to used it .
Hope all kind of advice and suggest or recommand another IC for it

Thanks All First


texts:
Can we say anything about the program counter by looking at the size of a memory chip?

I think the program counter is part of the microprocessor and memory is external. How can we comment about the program counter by looking at the size of the memory?

For example, I had a question in one of my tests:

  A memory chip of 8kB has a data bus of 4 bits. What will be the size of the program counter?


texts:
I'm trying to test my 20A Hobbywing skywalker ESC.

For that I bought this servo tester from ebay

I'm a bit confused about the servo tester input. Shouldn't it be just supply power? Then what is that third pin (signal) in the input side?

Also can I check the ESC without supplying it power and connecting any motor?


texts: Why is the serial connection faster than the parallel connection?

texts:
As a software developer the concept of parallel processing usually meant faster processing because it meant things don't have to wait for the other processes to finish if they don't need to.

So how come the serial connection is looked at (arguably) as the future  while the parallel one as a thing of the past?


texts: What is the output voltage in this case?

texts:
What happens when the output voltage of an op-amp (say in a voltage follower/inverting configuration) should be higher than a certain amount (say 10V) and on the output I place a 5V zener diode in reverse, followed by GND?

simulate this circuit – Schematic created using CircuitLab

On the one side, it should be Vin, right? But I think it must also be less or equal than 5V because of the Diode


texts: What is the difference between an H-Bridge Motor Driver and Dual motor driver board?

texts: I don't understand the difference between a motor-driver like this IC H-Bridge Motor Driver and a motor-driver like this Dual Motor Driver Board. When reading about them they do the same thing but the second one is obviously much more complex and more expensive.


texts:
Respected members,
     I want to use a sorting technique which sorts N numbers using Verilog taking minimum clock cycles(less Time Complexity) as possible.

Thus, I want to get some help regarding the methodology and the Type of sorting technique I should follow.

Regarding the application, it is somewhat similar to shuffle image pixels  for e.g. I want to sort 64 image pixels for 256X256 image extracted at a time which equals 1024 times. So sorting of 64 8-bit data 1024 times which is the requirement.

Lastly, If I use radix sort, will be fruitful in order to achieve O(n) time complexity (for N Keys N clock Cycles)?


texts: STM32F2xx: Data from SPI Slave to Master

texts:
I have a STM32F2xx connected to a FTDI UM232H using SPI, STM32F2xx will be configured as SLAVE and FTDI will be configured as MASTER

My scenario is this, I am getting data in STM32F2xx, and when I received data I would like to send it to my FTDI using SPI

But, how can a slave SPI send to Master??? since to initiate the communication, it needs the SCLK, which is controlled by the master

So how can I do that?

Or my master needs to constantly read the SPI Slave??? (like polling method) or is there any better way to do ti??

My current configuration for my SPI is:

2 line duplex
1 Mhz clock
MSB
8 bit
Phase = Low
Polarity = Positive
Hardware: 4 lines connection, CS, SCLK, MOSI, MISO


texts: Is it possible to account for motor dead-band in a Laplace model of a feedback DC motor system?

texts:
For practical DC motors having dead-band effects, where the output angular speed of the DC motor remains zero until a large-enough DC voltage is applied to the motor system --- is it possible to approximate the DC motor as a first order model?

For example, input is voltage, output is angular velocity, so the first order DC motor approximation has a transfer function output_velocity/input_voltage is something like \$\frac{K}{(s+a)}\$.

And if we purposely include an integrator next to the first order model, we would get a transfer function \$\frac{K}{s.(s+a)}\$.

If we then incorporate that transfer function within a unity negative feedback system, then the closed loop feedback system would become :

closed_loop_transfer_function = \$\frac{K}{s^2 + as + K}\$, which has the form of a general second order system transfer function.

Apart from the issue of DC motors are really second order systems, there is also the issue of motor deadband, where the motor's speed remains zero until a sufficiently large-enough voltage is applied to the motor to get it moving.

My assumption is that the motor dead-band effect is not accounted for in the second order system transfer function. So there is expected to be issues when attempting to model and design the practical (actual) DC motor system with Laplace models.

Does anyone know if it is actually possible to use such approximations and Laplace system models to design the feedback system with real DC motors?

I think I have to sort out a few problems here, and one of those problems is to try understand whether or not the motor dead-band effect is going to be an issue. Or is it just not even possible to base this feedback design on a general second order Laplace system?

The original idea is to simply have a basic model of a basic DC motor (such as \$K_v\$ and \$a\$, where \$K_v\$ is approximate linear output velocity to input voltage slope relation, and 'a' is just related to the time-constant, to give an approximate \$\frac{K_v}{s+a}\$ transfer function for the DC motor - input is voltage, output is angular velocity). But, once again, I assume one of the barriers is going to be motor dead-band effect, or how to account for it.

The original idea is also to simply be able to scale (alter) the \$K_v\$ constant (with a multiplying factor), that will alter damping ratio, overshoot for step response. But at the moment, I don't know how to account for motor-deadband with the basic Laplace system model.

Thanks for any help and recommendations in advance! Thanks all.


texts: What file formats do oscilloscopes export?

texts:
Many digital storage oscilloscopes can export data for further analysis.

What kind of file formats do oscilloscopes use to export capture data over USB, Ethernet, or on a USB stick?  Which oscilloscopes produce which formats?


texts: How to protect low-voltage hardwired device against 120 V AC miswiring ? (I need a resettable solution)

texts:
I need to protect a hardwired device, made for AC low-voltage transformers (e.g.  doorbell), from miswiring to a 120 V AC power line. It actually occurs no matter how many warnings I put everywhere.
The space for the circuit is small (must be slim 8 mm x 9 mm, but can be long e.g. 40 mm). The device is between 4 W and 8 W depending on the configuration. The maximum acceptable voltage drop is 2 V.
All solutions I found have at least one of these problems:

Large parts (it must be compact)
Overheats (must be kept under 125 °C)
Works only with lower voltages i.e. protects 5 V input from 9 V

I think of first passing the input voltage through a full bridge rectifier, to deal with positive voltage only. But at 170-180 V, I can't figure out how a small MOSFET or BJT can make that possible.
Any ideas, or help please?


texts: Why are relays still used in electric ovens?

texts:
I bought a new electric fan oven recently. It has a digital thermostat and control system. Yet much to my surprise, I can hear a relay clicking on and off inside it to control the power to its heating element. The oven is rated at 4kW (230V).

I would have expected it to be using a triac to turn the power to the element on and off. So why not?

I don't think that the answers here duplicate the question about using relays in automobiles. The design criteria for switching 230V AC are very different for 12V DC. To start with, LVDC would use a MOSFET whereas mains AC would use a Triac. Considerations concerning voltage drop across the semiconductor device and dissipating the waste heat are different. Safety regimes are different. The operational environment is different. And so on.


texts: Why is 10V a common range for Data Acquisition or Benefit of increasing signal amplitude in the transmission line

texts:
I've been thinking about the reason why \$ \pm 10V\$ is a common voltage range for commercial DAQ cards. I think that using 10V instead of 1V on the output of the external sensor board would give +20dB of SNR in the transmission wires (considering two equal lines subject to the same external conditions), but is this true? Does a higher voltage in the transmission line provide better SNR?
I plan to design a board with AD7641 for data acquisition (part of a system which will be powered by a 12V battery, probably)  and I don't know if I should add more gain at the sensor amplifier to have 10V in the cables and then attenuate the signal on the ADC card, or just output in the \$ \pm 2.048V \$ range of the adc (internal reference) directly.


texts: Altium 15 BGA Fanout option is not working fully

texts:
I'm trying to fanout and route a 0.5mm pitch BGA component by creating a ROOM and setting a sepcific BGA rules for that particular component.

I followed this video below
https://www.youtube.com/watch?v=jUSi4rxBhsY

The compoenet I'm working on is this
http://www.ti.com/lit/ds/symlink/afe4403.pdf

The rules I used are as follows and considered from TI recommendations link below:
Clearance : 3.2mil
Width: 4mil and/or 8mil
Via: 10/5mil

http://www.ti.com/lit/an/sprabb3/sprabb3.pdf (see page 11,12 for 0.5mm pitch BGA)

I tried exactly as shown in the above video and also tried changing couple of options in FANOUT prompt. But what ever I try the output is only applying to specific pads in outer rows and not all the nets are pads are fanned out.

Please guide me. Thanks.


texts:
This is a Sallen-Key second order notch filter(bandstop filter) :

This filter attenuates the frequency at \$f_0=\frac{1}{2\pi RC}\$. But I don't get how. How should I analyze this kind of circuit?
What I only understand:

At very low frequencies the signal reaches the noninverting input due to caps being open
At very high frequencies the signal still reaches the noninverting input due to caps being shorted.
Lastly, the R/2 acts as positive feedback

Do analyzation of this circuit needs knowledge of transfer function? (since I haven't taken that subject, yet)


texts:
I am designing a PCB with a couple of transmission lines. I have already calculated the thickness and width of my traces based on the substrate height and dieletric to have a 50 ohm transmission line, so I think I have that covered.
But the question that now come to my mind is, is there any requirement on the distance between this transmission line and another traces present on the board? I will surround my TL with GND traces to avoid noice problems, but I have no idea on the distance I should left between my TL and the GND traces.
Is there anyway to calculate this or anything else I should consider?

Many thanks!


texts:
I want to ask you about the following graph exactly the added resistance after the rectifier and the filter. Is it ok to add this resistance to make sure that the filtered voltage will occur on the resistance and then goes to the buck converter?

note: I don't mean the load resistance, I mean the resistance in the middle of the graph.


texts: Eagle UI: updating silkscreen of library component

texts:
I just finished a schematic in the free version of Eagle that contains 20+ 0402 resistors and about a hundred 0805 capacitors.

I switched over to the board layout and found that the footprint of all these passives contains the part value, which I don't want as there isn't room on the PCB.

So, I edited the library and removed the ">VALUE" text. I then ran library->update all. However, the value text was not removed from any of the footprints.

If I right click on the component -> "open footprint" it shows me the updated footprint with silkscreen text removed. But the actual footprint in the board layout is not updated.

How do I fix this without having to manually change every. single. footprint?


texts: Electrical conductivity to determine reservoir water level to switch on/off pump

texts:
Did a survey of the commercial products available in the local market, which are broadly classified as 'Automatic Water Level Controller' or 'Automatic Pump Controllers', and found that all of them use a float-switches.

This got me wondering as to why the commercial products do not use 'electrical conductivity' of water as a test, to determine water level in the reservoir. If one uses something like 12VDC of periodic pulse to check for conduction via the electrodes at various levels, there should be no worry of electrical shock. So why don't the commercial systems use this, extremely inexpensive solution ? What is it that I might be missing ?

EDIT

To add a bit of context, what surprised me in my survey was that the price of spare float-switches was about 20% of the price of entire system (including 2 float switches). The cost of installation is about 2x the system price. And every time the float-switch is to be changed there's some labour cost as well (unless the unit is under an Annual Maintenance Contract, which cost 15-20% of the unit price). This is in a rather price sensitive market (India). Which is why the super simple "conductivity" test, seemed like a very cost-effective solution.


texts:
I would like to interface Arduino over SPI but need a way to decouple the system with an optoisolator. Any pointers in which optoisolator to get?

Everything works on 5V.

I've tried to connect with CNY 17-3 but it didn't work.
Maybe CNY 17-3 is too slow, or something.

Datasheet CNY 17-3:

PS:

One more note, I don't need any transfer from slave so only one direction.
CS, MOSI, CLK lines are needed.


texts: Minimum number of complementary CMOS to implement \$F=ABC+\overline{(A+B+C)}\$?

texts:
Minimum number of complementary CMOS transistors pair will be required to implement function,\$F=ABC+\overline{(A+B+C)}\$ are?

  \$(A)6\$

  \$(B)7\$

  \$(C)8\$

  \$(D)9\$

I tried like this but I am getting 7 CMOS pair but answer key says its 9 CMOS pair.whats the mistake I am doing?


texts: Why does sampling interval affect system response quite drastically?

texts:
I have been given a 2nd order transfer function in continuous time domain and been asked to design a feedback regulator and an observer for it.

The initial closed-loop system's transfer function is:
\$\frac{{\;\;\;\;\;\;100s + 500}}{{{s^2} + 105s + 506}}
% MathType!MTEF!2!1!+-
% feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca
% aMe8UaaGjbVlaaysW7caaMe8UaaGjbVlaaysW7caaIXaGaaGimaiaa
% icdacaWGZbGaey4kaSIaaGynaiaaicdacaaIWaaabaGaam4CamaaCa
% aaleqabaGaaGOmaaaakiabgUcaRiaaigdacaaIWaGaaGynaiaadoha
% cqGHRaWkcaaI1aGaaGimaiaaiAdaaaaaaa!4EA5!
\$

To discretize the system, I can select whatever sampling interval I like. However, selecting a different sampling interval, will change overal system's response significantly. For instance, this is my system's response with sampling interval T=0.1 sec to a unit step input:

The overal system's transfer function is (including feedback regulator and deadbeat observer):

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Compared to this one with T=0.0001:

The overal system's transfer function is:

My question is how to justify the differences in responses.

(Above plots are simply step responses to mentioned transfer functions)
Regards


texts:
I can't quite wrap my head around the power requirements for a CNC setup i'm building.
I'm using 3 x Easydriver 4.4 for driving the Sparkfun Stepper Motors. I previously used a 22 V 800ma Power supply which blew up one of three of the easy drivers. Any explanation as to why ?

will a 12 volt 2A power supply be sufficient to power the entire setup or will it damage it?
I'm really new to this and would really appreciate your input.

Edit 1: Added link to the original easydriver page with correct data.


texts:
I am building a class d amp circuit with base design from Great Scott's Class D amp which is found here.
I am trying to build and simulate the circuit in LTSpice with difference being I won't be using MOSFET Driver IC and will be inverting the signal and feeding it to another half bridge to make a full bridge amplifier.
Here is the Circuit and simulation files:- https://drive.google.com/drive/folders/1_B0tQIh58_niOk3M4CdICHCKTr6wPS08?usp=sharing
I am experiencing some wierd oscillation at the start of the circuit for a few milli-seconds. Can anyone point out the reason and/or a fix. Will the circuit get damaged if I build it as it is?
Here is the output of the simulation:-

The oscillation occurs on both of the half bridge after passing through lc filter. The blue line is the load resistor current. (In reality, the current would be half tho. I am using 1 ohm load in design while in reality I have 2 ohm subwoofer)
Also note, the circuit will only be used for sub frequencies, so don't point out that voice will get lower as frequency increases and also, it gets distorted at higher frequencies.


texts: Are digital signal processors categorised in ASIPs?

texts:
Reading Wikipedia, it seems like DSPs use short instruction sets specialized for digital signal processing with hardware designed to specifically accelerate these instructions (e.g. multiplying, accumulation etc.)
Going by definition of ASIP on Wikipedia (Which I don't understand well), DSP seems to be an ASIP. is this true?
DSP on Wikipedia
ASIP on Wikipedia


texts:
I am designing a device that operates on Li-io battery back. I want to be able to charge the battery while its plugged into a computer usb and at the same time do uart comms with the pc. The issue with FT232 is that the output current from the 3.3v output is limited to 50mA. I require larger  than that around 500mA to run other tasks run by the microcontroller. The VCC of the FT232 has to have a voltage 4.2V, thus this cannot be run by the battery as its voltage will drop after some drainage. My question is, how do I run the ft232 directly from the usb bus, and also be able to obtain current level higher than what the ft232 3.3v outputs?..I am attaching a schematic what I have done so far...

Assuming this is correct, this will still result in unintentional switching on of the FT232 when the device is operated via battery through current from the TX/RX pins, as mentioned in another question.
kindly help thanks.