texts: Floating electrolytic capacitor with cathode connected

texts:
I have a board where I have some electrolytic capacitors on the input side of a voltage regulator. Under normal operation everything is ok. But the board can also during programming of the MCU be fed from the outputside of the regulator. This would leave the cathode (-) of the electrolytes (that might hold charge from previous operation) connected to ground and the anode (+) would be floating.

Please see the following conceptual circuit (not actual circuit!):

simulate this circuit – Schematic created using CircuitLab

During normal operation V1 is connected and supplying 12V and charging C1. During programming, V1 is disconnected and V2 is connected. The ground level may have shifted and C1 could possibly contain charge.

Do I risk damaging C1 when connecting V2 as the other terminal is floating and one is grounded to a new ground level?

Should I add a diode from OUT to IN to make the positive terminal of C1 not float when the device is being programmed?


texts: Designing a filter by setting an objective

texts:
In my case I am working on passive analog filters, but I think the question applies to any other type of analog filter design.  Typically I think the process for designing analog filters is to calculate the desired components using equations, or perhaps if we're with a large company we might use filtershop.  We will then plot the frequency response to make sure we did the calculations correctly and that's the end of it.

That process is usually fine, but I wonder if it is possible to do this like excel solver does with the objective cell function.  For example, if I wanted to find the values for a circuit that has a certain gain at a certain frequency, is it possible to run through the infinite number of possible component values to achieve this objective?  It could be in spice, matlab, whatever.


texts: Arduino: Generating time critical signals with interrupts

texts:
I have some problems to fully understand how interrupts on e.g. Arduinos/AVR are used in practice. Lets assume I want to generate a time-critical signal like PWM and at the same time be able to respond to inputs from buttons. Both should be implemented with interrupts.

How can I assure that the PWM signal doesn't get messed up when the button is triggered and therefore another (not signal related) interrupt-routine is running? Similar to this, how can interrupt-based libraries like 'wire' assure that no requests are lost while other (maybe also interrupt-based) code (implemented by me or other libs) is running?


texts:
I have to make LDR based light switch that turn on lights in per-defined light condition. To  do this I have to use atmega32 Micro controller. I follow some tutorials and write some codes. the code compile in Atmel studio without any issues but when I run the code using Proteaus simulator code doesn't work
This is the code
#include <avr/io.h>
#include <util/delay.h>

#define LTHRES 500

// initialize adc
void adc_init()
{
    // AREF = AVcc
    ADMUX = (1<<REFS0);

    // ADC Enable and prescaler of 128
    // 16000000/128 = 125000
    ADCSRA = (1<<ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
}

// read adc value
uint16_t adc_read(uint8_t ch)
{
    // select the corresponding channel 0~7
    // ANDing with '7' will always keep the value
    // of 'ch' between 0 and 7
    ch &= 0b00000111;  // AND operation with 7
    ADMUX = (ADMUX & 0xF8)|ch;     // clears the bottom 3 bits before ORing

    // start single conversion
    // write '1' to ADSC
    ADCSRA |= (1<<ADSC);

    // wait for conversion to complete
    // ADSC becomes '0' again
    // till then, run loop continuously
    while(ADCSRA & (1<<ADSC));

    return (ADC);
}

int main()
{
    uint16_t adc_result0, adc_result1;
    char int_buffer[10];
    DDRC = 0x01;           // to connect led to PC0

    // initialize adc and lcd
    adc_init();

    _delay_ms(50);

    while(1)
    {
        adc_result0 = adc_read(0);      // read adc value at PA0

        // condition for led to glow
        if (adc_result0 < LTHRES)
        PORTC = 0x01;
        else
        PORTC = 0x00;

    }
}

And this is a screenshot of proteaus simulation.

I got this error

[AVR AD CONVERTER] Referance value = 0

I only have basic knowledge of programming micro-controllers and simulation using proteaus. can someone please help me how should I configure this ?


texts: Sprinkle switching circuits liberally with small capacitors?

texts:
I have now read enough applied circuit diagrams that I believe I'm missing something that is obvious to those skilled in the art: Where an abstract diagram has a few components, a complete wiring diagram of the same circuit is absolutely littered with capacitors in the microfarad range.

(To do: Find and insert some example images here.)

I can sort of understand how these capacitors would smooth out voltage drops, (and I guess there are usually a few diodes to deal with voltage spikes)?

But how do engineers come up with these applied circuits?  Are there unwritten rules they just know, like, "Yep, gotta put a microfarad on this side of a diode, that side of a transistor, and three of them in parallel by this sort of switch..."?  Or do they wire up a prototype, start scoping every junction, and add them based on actual signal noise they observe?  Or is more prophylactic, e.g., "I wouldn't want a lot of voltage noise here, so why not add some capacitance just to be sure?"


texts: Controlling temperature of soldering iron

texts:
I have those cheap 60w chinese soldering iron that runs on 220/240v ac here. Any time I try to solder some ICs it burns them. I know that there are temperature controlled irons in the market but those are too expensive here.
My objective is to lower its temperature just for soldering  and I dont need much of display or any such complexities. I know there are some Arduino based ones and some triac based once but I thought of doing it using dc.
I plan to rectify the mains with rectifiers and then feed it into pwm circuit (I plan in using 555 circuit to make it simple ) and mosfet . I plan to lower the voltage for the pwm cicuit and use the power mosfet in series with soldering iron . Should I go for it ? Will it work ?


texts: If we have a signal of 1 or 2Hz, can our skin receptors feel that sinewave, if that sinewave has aproppriate voltage level?


texts: Help with interpreting this manual using hexadecimal message

texts:
There's a device which I want to control by sending telegram and it has no online manual:
--to be updated the whole manual file here--
The physical layer defined with no parity at the first page. But there is parity defined as "add all data bytes together" which I don't understand.
According to the above manual what telegram turns on the laser and what telegram set the temperature of the laser to 30C?
(I thought these two examples would show me how to interpret it)


texts: I want to run two component one is 6v and another is 3.7v. I have a 7.4v battery. How can I convert 7.4v to 6v and 3.7v. I see some tutorials. here use different process. (1) using two diode can get 5.8v and and using 5 diode in series can get 3.9v. (2) using Zener di0de can get desire voltage. (3) using voltage regulator ic (7805,1117 etc). I want to know Which will be best. and if any problem or limitation of these process


texts: Removing spikes from multiple onboard power supplies

texts:
I have a board that is based around an STM32F303 and am using the onboard ADC/DAC, fed by a 3V power supply derived from a USB 5V input. The 5V also feeds a module, RD0515, which creates +/- 15V for opamps on the board. My problem is that the RD0515 also creates quite substantial spikes of about 2uS width and repetition rate of 20uS.

These are finding their way through to the analog supply pins on the STM32 at around 100mV amplitude and screwing up measurements. The board is 4 layer (GND and 3V internal planes) and has plenty of capacitor decoupling.

Is there a better way of getting the +/- 15V that will not cause such problems?


texts:
I need to read data from a SRAM in one step (something like READ_RAM(addr) that returns the value stored in the SRAM at the "addr" address).
Is it possible create a function/procedure that integrates a Finite State Machine?


texts: I do not understand what power actually is

texts:
I realize this is probably a super common question, but I have to put it in my own words.

I try to understand ohm's law with the water analogy. Two tanks with water, one with a higher level than the other, and a  pipe connecting the two of them. Water wants to flow. There is a valve which represents a resistor.

The thing that begins my confusion is when I start thinking about heat dissipation in an electrical circuit. Where does this heat actually come from?

It can't come from the pressure, the voltage, because if it did, the valve should be extremely hot if there is simply enough water in the higher of the two tanks, thus exerting a lot of pressure on the valve.

I've read that the heat comes from the actual flow of electricity, the current. At first this seems intuitive. But then I progress on to consider what power is. This is where the confusion sets in. Because if I double the pressure and double the resistance, the current stays the same. I would think this would mean that the heat dissipation would stay the same.

But the power doubles. So what does that actually mean then?

Has my tank drained into the other tank at a different rate because of the higher power, even though the actual flow of current has stayed constant?

What is power?


texts: I want to learn a real microcontroller with STM32F4. Which library should I use (HAL, SPL, or CMSIS)?

texts: From what I know, ST will stop to develop Standard Peripheral Libraries (SPL) for the next generations of STM32. And HAL is not ideal for people who want to understand well about STM32 and microcontrollers. Can you suggest me which one is the best to use (for learning and working in the future)?


texts: Using a thermal fuse in a PCB terminal block?

texts:
(This is related to question How to solder a 70 °C (158 °F) thermofuse).

Would it be a good idea to use a temperature/thermal fuse inside a terminal block like the picture below.

I see only benefits:

No problem destroying the fuse because of excessive heat (no soldering needed)
Solid tight to the PCB
When the fuse blows, it is very easy to exchange it.

Are there reasons why not to do this?

(and what about doing the same for VST diodes?)


texts: BCD4511 Seven Segment Display Decoder + Diode Matrix

texts:
i'm having some issues trying to get a circuit to work that i have found on, yes, the infamous instructables. It consists of a diode matrix that goes to the inputs of a BCD4511 decoder IC. It's literally the only article on the subject I can find and i would like to use this concept in a rotary switch indicator. I'll be brutally honest the instructable is half ass at best and it's missing key information. I have replicated his overall design twice and it cooks the SSD and the 4511 chip gets extremely hot. i'll include a link to it at the bottom. If someone can clear up the holes in the design it would be very much appreciated.

https://www.instructables.com/id/Motorbike-Gear-Position-With-Seven-Segment-Display/

p.s. My comments are at the bottom of the instructable with a schematic that i had copied and completed from the original author.


texts: Safe way connect a 3.3V output to an input with weak pullup to 5V

texts:
I plan to connect a 5V IC to a beaglebone black(explicitly not  5V tolerant 3.3V IOs). For signals going to the beaglebone black I need a level shifter.

But the input of the 5V IC has a weak pullup to 5V. Datasheet says the pullup is 25kOhm nominal. Can I just connect an output pin from the beaglebone black to this input? I measured the current when shorting the pin to 3.3V as 53µA (Which seems plausible given the 25kOhm nominal)

For my application it's required in case the input is not driven by the beaglebone black it is still pulled up.


texts: Can I simply the circuit in this way? If not, how then?


texts: Capacitor values for non-Inverting op-amp circuit

texts:
I found the following schematic here and built it to test it . . .

I think all the capacitors are there to just block DC, but how important are the capacitance values and how does one determine the value of Co? The source webpage only discusses gain characteristics of the circuit.


texts: Ramp compensation for UC1843 and UCC38C44

texts:
When we pick up the datasheets of UC1843B-SP and UCC38C44, we notice that they have the same functional block diagram, specially the PWM generator circuit (Error amplifier, current sensing PIN and the comparotor), the error amplifier of both devices goes through a divider by 3. But when we come the "slope compensation design", we notice that there is a diffence in the design process between the two devices.

*In UC1843B-SP, in page 18/27 of the datasheet, a gain "Gcs=3" is incorporated in the slope compensation design (See equations 46 to 51).

*In UCC38C44, in page 30/50 of the datasheet, we do not see any gain in the design of slope compensation(See equations 31 to 38).

Why there is a difference in the design of current sensing and slope compensation between these devices eventhough they have the same functional block diagrame?

What is the effect of the divider on the output of "Error Amplifier" to the current sensing and slope compensation PIN ?

datasheet of uc1843B-SP: http://www.ti.com/lit/gpn/UC1843B-SP
Datasheet of UC38C44   : http://www.ti.com/lit/ds/symlink/ucc38c44.pdf


texts: Basic questions regarding Push Pull stage

texts:
I am confused as to how the following circuit will work(????)

Lets assume that there is no AC signal and only a DC signal is applied.

According to the books this is a voltage follower stage i.e Vo will be equal to Vi. But how is that possible? Both the transistors are always in cut off because Vgs of NMOS and PMOS should be zero and hence Vo should be floating. But if I sweep Vi from 0 to Vdd then I also see Vo following Vi. How is the output voltage Vo so well defined?
Intuitively this circuit makes no sense to me at all. It would be really nice if someone could explain me in simple words!

EDIT: I will try to explain what i think should happen. For the circuit exactly as described in the picture (no load condition and only DC condition)

When Vi is open or gate terminals are floating, with Vdd applied, Vo is floating.
When the gate terminals are connected to Vi, and Vi = 0 volts, Vo is still floating (considering Vo_floating > 0 volts is most likely, than Vo = 0 volts), VgsPMOS = negative voltage, hence PMOS will pull Vo to ground.
2.1: If Vo_floating = exactly 0 Volts (Vo=Vi) then it is the same case as 2.
When Vi > 0 but less than Vth(PMOS and NMOS) VgsNMOS = +ve and VgsPMOS = -ve (since Vo >=0), Vo = 0 volts
Vi > Vth but Vi << Vdd imples, VgsNMOS > VthNMOS and -VgsPMOS < -VthPMOS, hence both the transistors are conducting. VgsNMOS = Vi-Vo, hence Vo=Vi-VgsNMOS. However at this stage Vo = IdRdsPMOS, where Id is the drain current that will be defined by VgsNMOS (Id = gmVgsNMOS).If RdsPMOS is very high then Vo will increase reducing VgsNMOS. But what if VgsNMOS drop below Vth? Why cant this happen? What will define Vo (is it Vo=Vi-VgsNMOS? or Vo = Id*RdsPMOS?) here and why?


texts:
I am using EasyEDA to design some PCBs, and I am trying to figure out what package to use for your basic 1/4w resistor. The options are-

R-Alial-0.3
R-Alial-0.4
R-Alial-0.5
R-Alial-0.6
R-Alial-0.8
R-Alial-1.0
R-Alial-1.2
Which one is correct? Thanks!


texts: BeagleBone Black won't power up from USB

texts:
I have been successfully using BBB powered from the USB adapter until now.

I had to do some restart, and then the board won't power up (the PWR led blinks once when I press the POWER button, then it stays like that, off).

Now I can only start the board using an external power supply (5.0V), and it seems that the board uses around ~0.8A and up to ~1.1A.

What can be wrong?

Why it isn't working now?

L.E. Also, I have noticed that the main chip (AM355) gets very hot, I can't put my finger more than one second on it.

L.E.2. I don't have attached any relevant power-consuming devices to it, only a USB WiFi dongle.

L.E.3. Before restarting the board, I was trying to get a GPIO pin working, the problem was that from the library I've used (BlackLib) when I set one GPIO pin to high, it would only stay high for around 10ms, and then go low again. So for solving what, I have used this tutorial. I only got to the part where I exported some pins to the /sys/class/gpio/export file, and then echoing 1s and 0s to the associated pin (with a LED connected it didn't work), then I rebooted the board and this problem started.

I don't see any hardware mistakes that I may have done, is it possible that this fault is software-related?


texts: Why not all the diodes are in "on state" in the given picture?

texts:
Given:"all the diodes are ideal",in figure (e), only D3 is on and rest of the two diodes are given off in the solution. Similarly for (f) only D1 is on. I don't understand the logic behind this. Please help in understanding this thing.

Update: Showing my work for (f)

Assuming only D3(diode with 3V) is present and is in "on" condition.I end up getting same situation if I begin with D1 or D2, which gives all diodes are off.


texts: Please clarify something about electrical transformers

texts:
Please have a look at the following picture and tell me what I am not seeing properly.

This is a core type transformer. However, I don't quite understand "One-half low voltage winding and one-half high voltage winding". Does this simply mean primary and secondary windings? Which means that there is one primary and secondary winding on left leg of the core and one primary and secondary on right limb?
Thank you very much for assistance.


texts: What is the connection pattern for multi-pole push button switches like this one?

texts:
It does not appear to be one of the two obvious choices - one side common or button down connects terminals across from each other.

Used on an HVAC unit.

It is busted so I can not probe it out.

Any ideas?


texts: How to apply Kirchoff laws to form differential equation for RC circuit with a variable applied 2nd voltage?

texts:
I'm trying to create a model for how a capacitor charges and discharges in an RC circuit in response to an applied "control voltage" V2. For this, I want to form the differential equation for time-dependent capacitor voltage for the below circuit:

simulate this circuit – Schematic created using CircuitLab
(my interest stems from being able to simulate this circuit, e.g. used practically here: https://pimylifeup.com/raspberry-pi-light-sensor/)

I recall learning Kirchoff's voltage/current laws to analyze such circuits, but am having difficulty applying it to this circuit because of the added V2 voltage (which in practice is used for switching whether the capacitor is charging or discharging).

For example, if we consider the left-hand side 'loop', wouldn't Kirchoff's voltage law give us:

V2 = voltage across capacitor

thus eliminating all time dependence?

I feel I'm missing something simple?


texts: Writing to XTARGET resets TMC 5130 stepper driver

texts:
I am interfacing TMC 5130 stepper driver via spi. I loaded initialization example form 25.1 page 109 of the datasheet. Everything goes well until I command the driver to move the motor by writing to XTARGET register, then the driver just resets. Here is my debugging steps.
PS: My spi communication is fine, I am able to read/write registers and confirm on the scope.
Initialization sequence:
        read(TMC5130_DRVSTATUS, debug_data); // Read Status registers.
        read(TMC5130_GSTAT, debug_data); // Read Status registers.
        write(TMC5130_CHOPCONF, 0x000100C3); // CHOPCONF: TOFF=3, HSTRT=4, HEND=1, TBL=2, CHM=0 (spreadCycle)
        write(TMC5130_IHOLD_IRUN, 0x00060F05); // IHOLD_IRUN: IHOLD=5, IRUN=16 (max. current), IHOLDDELAY=6
        write(TMC5130_TPOWERDOWN, 0xA); // TPOWERDOWN=10: Delay before power down in stand still
        write(TMC5130_GCONF, 0x4);// EN_PWM_MODE=1 enables stealthChop (with default PWM_CONF)
        write(TMC5130_TPWMTHRS, 0x1F4); // TPWM_THRS=500 yields a switching velocity about 35000 = ca. 30RPM
        write(TMC5130_PWMCONF, 0x401C8);// PWM_CONF: AUTO=1, 2/1024 Fclk, Switch amplitude limit=200, Grad=1

        write(TMC5130_A1, 0x3E8); // A1 = 1 000 First acceleration
        write(TMC5130_V1, 0xC350); // V1 = 50 000 Acceleration threshold velocity V1
        write(TMC5130_AMAX, 0x1F4); // AMAX = 500 Acceleration above V1
        write(TMC5130_VMAX, 0x30D40); // VMAX = 200 000
        write(TMC5130_DMAX, 0x2BC); // DMAX = 700 Deceleration above V1
        write(TMC5130_D1, 0x578); // D1 = 1400 Deceleration below V1
        write(TMC5130_VSTOP, 0xA); // VSTOP = 10 Stop velocity (Near to zero)
        write(TMC5130_RAMPMODE, 0x0); // RAMPMODE = 0 (Target position move)

        read(TMC5130_DRVSTATUS, debug_data);
        // Ready to move!
        write(TMC5130_XTARGET, 0xFFFF3800); // XTARGET = -51200 (Move one rotation left (200*256 microsteps)
        read(TMC5130_GSTAT, debug_data);
        read(TMC5130_DRVSTATUS, debug_data);
        read(TMC5130_GSTAT, debug_data);
        read(TMC5130_DRVSTATUS, debug_data);

After issuing write(TMC5130_XTARGET, 0xFFFF3800); the driver resets. During the consecutive transaction read(TMC5130_GSTAT, debug_data) driver returns no data (supposed to mirror 0xFFFF3800 form the previous write) and then reset flag in GSTAT is being raised. Both GSTAT and DRVSTATUS indicate no error flags.
Interestingly after writing to IHOLD_IRUN driver successfully holds the motor in place. What could go wrong?


texts: How to reverse polarity on only one device?

texts:
I have a temperature controller with two SPST relay contacts, one each for heating and cooling, and I want to use them to control a Peltier thermoelectric cooler (TEC), plus a fan and pump and potentially a few other widgets.

When either the heating or cooling activates, the auxiliary devices (fan, pump, etc) need to all turn on, with a fixed polarity. However, the TEC needs to have its polarity reversed between heating and cooling, so it can pump the heat in the correct direction.

I have a circuit with the intended behavior, using a series of SPDT relays to handle the 'logic' of reversing the polarity, however there are some issues with it:

simulate this circuit – Schematic created using CircuitLab

The temperature controller is an ITC-1000F, and the cooler is a TEC1-12706.

I want to be able to run multiple coolers in parallel or perhaps just a single more powerful cooler, but the controller is only rated for 10A, so even two 6A TECs would be too much for this design.

If possible I'd also like to be able to simplify the logic and generally reduce the number of relays I need to use.

I came up with another design that solves some of the issues:

simulate this circuit

It still draws the current for the auxiliary equipment through the temperature controller's contacts, although in my case that's not an issue since the current is low enough.

In any case though, it feels like there ought to be a simpler way of going about this. How can I simplify or otherwise improve this design?


texts: STM32F4 :USB Mass Storage Write Low Speed Using FATFS Library

texts:
I am using fatfs library developed by http://elm-chan.org/ for reading/writing file system in usb mass storage using stm32f4.As I know, for improving speed throughput one should write data buffer in a multiple of sector size (512B).
As stated in  http://elm-chan.org/fsw/ff/doc/appnote.html:

  “The write throughput of the flash memory media becomes the worst at
  single sector write transaction. The write throughput increases as the
  number of sectors per a write transaction …. This effect more appears
  at faster interface speed and the performance ratio often becomes
  greater than ten…Therefore the application program should write the
  data in large block as possible. The ideal write chunk size and
  alighment is size of sector, and size of cluster is the best. Of
  course all layers between the application and the storage device must
  have consideration on multiple sector write, however most of
  open-source memory card drivers lack it. Do not split a multiple
  sector write request into single sector write transactions or the
  write throughput gets poor. Note that FatFs module and its sample disk
  drivers supprt multiple sector read/write operation.”.

I searched in the web and found that the maximum speed that one can reach for writing in a usb mass storage (usb full speed), is about 800kB/s. But even when I increase buffer size to 32kB (64 sector) I can reach 460kB/s. I tested for 4,8,16,32KB buffer size and the maximum speed has not exceeded 500kB/s.

Another thing that I found during test is that the allocation uint size (cluster size) of mass storage (USB flash drive in this case) can affect the speed but I cannot find any clear relation between that and speed. It depends somewhat on flash drive manufacturer. I don’t know if there is any specific configuration option in fatfs library that I missed to set correctly or any point that can increase the speed at least to 800kB/s or even more to rated speed (1.5MB/s).


texts: Compile error in testbench with UVM (mtiRnm library)

texts:
I'm trying to compile a very basic testbench (that actually does nothing) with Modelsim 10.3b. However, I'm facing the error: Error: (vlog-19) Failed to access library 'mtiRnm' at "mtiRnm".

What I'm trying to compile is basically just a package similar to:

`ifndef __MY_PKG
`define __MY_PKG

package my_pkt;

    import uvm_pkg::*;
    `include "uvm_macros.svh"

endpackage : my_pkg

`endif

The error seems related to UVM because of, by commenting out the two uvm related lines, the error goes away. However, Modelsim is able to locate UVM because of the include line generates the warning Note: (vlog-2286) Using implicit +incdir+/tools/MGS/modelsim_SE10.3b/modeltech/uvm-1.1d/../verilog_src/uvm-1.1d/src from import uvm_pkg, so something is happening.

What can be the cause of the problem?

Thanks in advance.


texts:
I'm trying to design  a circuit in GEDA/Gschem in Ubuntu. I could insert new components in the circuit but I cannot in the name change or add values. For instance when opening the window for attributes of a resistor, I cannot see 'value' on the list. I tried to add 'value' but the field for adding the actual numeric value is not a textfield and cannot enter anything. When I click on Add, I always get this message:

The input attribute "netname=" is invalid
Please correct in order to continue

The name and value must be non-empty.
The name cannot end with a space.
The value cannot start with a space.

Utterly confusing. Any ideas what am I doing wrong?


texts: Is it safe to apply higher voltage to the output of a MIC2920A voltage regulator?

texts:
I made a mistake on a board recently when adding an optional PIC12F615 processor to supervise my ARM processor.

I didn't realize the PIC needed >4.5V to erase.

So, I've got this MIC2920A 3.3V regulator feeding the PIC (and only the PIC) and I need to let the programmer pod apply 4.5V to it.

Will it work?  I don't see anything in the regulator datasheet that says it will or won't. The datasheet discusses how "bulletproof" this thing is, capable of handling -20 to 60V on the input pin. I don't see anything about high voltage on the output pin.

I've got 100 fairly expensive PCBs like this (20 stuffed). I can modify one board for development with a diode or reverse-power-protecting mosfet, but I'd like to be able to easily reprogram these boards later on.  I'd planned on simply leaving the PIC off entirely if it didn't work...  but it almost works.

EDIT

The regulator's input is a regulated 5V, so I wouldn't be going over that.

EDIT 2

It works!

I hooked up a bench supply, set it to 4.5V with a 30mA current limit, and then tried connecting it to the VDD pin of the ISP header (which is wired to the regulator's output pin). I didn't see any measurable current.

I was unable to force the programming pod (PICkit3) to supply 4.5V when there was already 3.3V present, though.  The regulator had to be unpowered to program the PIC.

However, this regulator seems fine with it... the GND and VIN pins are 0V, and it draws no current or at least no measurable current.

I was able to erase and reprogram the PIC.  Thanks!


texts:
Testing and integration engineers on electronics.stackexchange

How do you quality check if a GPS module and its subsystems are up to the mark during manufacturing? My company recently had issues with few of its devices. Some weren't having a GPS lock (ever) and the issue was found to be the antenna (once replaced it worked fine).

But we can't test every device (over 5000) for a GPS lock during manufacturing (or is that the only way?). Is there a standard way to check to make sure the hardware won't let us down?

Edit: Can I assume the hardware is fine if I receive a valid data time (a data time other than the default one send by the hardware)?


texts: Is there a need for buffering in this case?

texts:
.. will be updated soon (in construction with a more accurate information)

If the ADC (or the data.acq device) have 100 kohm input impedance, how much accuracy would I lose?

Do I need to buffer this for a better accuracy?

I'm kind of confused to relate the accuracy g and the output voltage here. I would be glad if someone may explain it for a novice.

Setup will be as shown:

..will be updated

There is an interface box for connector input outputs and a dual power supply for the transducers. Number of transducers will be much more but for simplicity I drew two of them. The interface box and the data-acq. board can be very close to each other no prob.

But the transducers (floating wrt the earth) will be around 400 meter away from the box and daq as you see above. A CAT6 twisted shielded cable will be used for each transducer. In the diagram I named the letters for the transducers which corresponds their pins from the datasheet I linked.

The manufacturer states the output impedance as 1 kohm and says load can be 100 kohm.
But isn't that a huge problem for accuracy?

I need an accuracy of 0.4 mV.

I'm kind of ignorant about how to interpret the datasheet to the accuracy and impedance of the transducer and ADC. Does this device need calibration or everything is already in datasheet? Is it possible to achieve around 0.4 mV accuracy?

*power ground and signal ground of the transducers (B and F) are internally connected I checked with a multi meter test.


texts: How much current can a MAX II I/O pin safely sink? 16 or 55mA?

texts:
This question is quite similar to this one.
As far as I understood, an I/O pin configured as LVTTL output can be programmed to source/sink up to 16mA. This is what the MAX II handbook says in Table 2.6:

But the same handbook has this graph about IOH, in Figure 5.1, saying that the maximum strength is around 55mA:

So which value should I take into account if I want an LVTTL pin sink the current required to drive a LED with forward current of 20mA (given I'll add a current limiting resistor)? Is it safe to operate in these conditions?


texts:
Any idea who makes the following connector or what a compatible connector would be called?

I need both male and female but that company only sells female.


texts: In this circuit what is that transformer's rating. I am making this circuit So I need help on this topic.


texts: How does the Nintendo 64 detect a controller is connected?

texts:
To give some context, I am trying to emulate controller input to the N64 via a GPIO pin on the Raspberry PI.

In an attempt to accomplish this, I have one of the PI's GPIO's in a pull-up configuration connected to the data line of the N64 controller input on the front of the system. Here's what that looks like:

In this configuration, I see the N64 system pull the line high when it's turned on, but there is no data request or any further change.

However, when I additionally attach a controller to all three inputs (data, ground, vcc) like this:

I am able to monitor data flowing between the system and the controller with the PI.

So, finally, the question: how is the N64 detecting the controller is connected, and how might I go about emulating that?  Is it the resistance between the 3.3v and GND line? Something else entirely?

This is my first post, so let me know if I've betrayed any stack exchange policies, or if you need any additional information.

Thanks for your help!


texts:
I have an old laptop which I no longer have the charger for. I ordered a new charger for the same laptop series, but the plug is too large, and it is unlikely that I will find the same adapter (Acer is difficult with their proprietary plugs).

I have an idea to connect the power supply directly to the laptop. 15.2V is the battery voltage. The charger provides an output of 19V at 3.42A.

Is it possible to do something like this?


texts: How does design compiler constrain combinational paths?

texts: This is with reference to the question asked here: Finding Critical Path of Combinational Logic. When design compiler command report_timing is run, it appears the timing requirement for the combinational multiplier doesn't get reported (I say this because I expect the multiplication to be the critical path). Will the circuit still be able to run at the given frequency even though it appears that the timing requirement for the multiplier circuit was ignored? From the answer in the link provided, I understand report_timing only reports timing for register-register paths, in general, should registers be applied to all combinational paths in a digital circuit in order to get a correct functionality/ timing report?


texts: What does "a 40 kHz wave modulate with a 1 kHz sound" mean?

texts:
what is mean when say "a 40 kHz wave modulate with a 1 kHz sound"?
which of AM or FM Modulation means?


texts: Wireless Channel Modeling and Channel Estimation

texts:
If a channel model can describe the behavior of a wireless channel (in terms of frequency and distance), then what is the exact purpose of channel estimation? Why does one need to estimate the channel coefficients if the channel behavior is already described by the channel model?

Is it to counter dynamic fluctuations or imperfections in the channel model?


texts: Benchmarking C++ functions' execution speed with GPIO and oscilloscope

texts:
For a research project, I'm trying to determine the execution time of various C++ functions on a Raspberry Pi and an STM32 microcontroller.
To do so, I plan on triggering GPIO pulses before and after each function's execution like so:
void a() {}
void b() {}
void c() {}

constexpr int REPS = 1000;

int main() {
    // GOAL: get execution times of `a`, `b`, and `c`

    // set GPIO signal
    for (int i = 0; i < REPS; ++i) {
        a();
    }
    // clear GPIO signal

    // set GPIO signal
    for (int i = 0; i < REPS; ++i) {
        b();
    }
    // clear GPIO signal

    // set GPIO signal
    for (int i = 0; i < REPS; ++i) {
        c();
    }
    // clear GPIO signal

    return 0;
}

However, I'm not really sure how to do this hardware-wise. I've used an oscilloscope before, but only for basic features, and I don't know how to use the triggering feature that well.
I have the Rigol DS1000E oscilloscope if that matters. Any ideas for a workflow would be appreciated. Thanks!


texts:
So, I can get these batteries very cheap - less than $2 a piece.  However, I have no real idea how to use them.  (I intend to power a robot with them if I can.)  So this begs the question: what kind of batteries are they?  Are there commercially available chargers, or is this some kind of specialty unit?

Is it possible to (safely) build your own circuit around these?  I feel almost like this is a little off topic, but honestly I don't know where else to ask this question, as I don't know where to start.

Thank you kindly.

Edit: I don't know how much it means, but the were dumped en mass and they have a self-test function on them... some of them are even full (varies quite a bit.)


texts:
I am having a little trouble knowing what theorem to use to solve the following problem.

Express the given equation without using OR gates. Hint: the expression two NANDed literals looks like this: (X+Y)'

Y=(A*B)+(A'*B)+(A'*B')

Any help is much appreciated.


texts: AD620 voltage noise and ADC SNR calculation

texts:
I want to calculate theoretically my effective resolution from C8051F350 in-built sigma delta ADC with different interface options like ISL28134, ADA4528, ADA4898, OPA211, mcp6v07.
I want to know their noise in 0.1 to 10 Hz range.
Shown below is my ADC interface.(it will be different if I use ad620)

Actually its a old schematic My LPF before ADC will have cutoff of 10Hz.

So when I look at datasheet of ad620 it gives Noise peak to peak at different gains RTI, my question is why did noise reduce at higher gains.?
My second question is, I know my ADCs rms noise at different PGA gains so how should I combine that noise with the noise of interface circuit to find effective resolution?
Also is it possible to get differential o/p from AD620, and will it be beneficial to reduce noise?

Can someone give me math to find ADC ENOB with above interface circuits.


texts:
Probably not the best place to ask this question, I'll remove it if not received well.
I am trying to perform EMI/EMC analysis of my resonant buck converter PCB. I tried to use ANSYS SIwave for this, but I'm not able to find much documentation on it to clarify my specific doubts, I even tried asking it here before. Does anyone have any suggestions as to what software I could use for this? I'm nor currently in a position to perform hardware tests due to the pandemic.


texts: PID measurement and control different scales

texts:
I am trying to apply PID theory to a real-world case. I understand that the following represents a typical PID method:

error = target_value – actual_value

integral += error

derivative = error – last_error

output = KPerror + KIintegral + KD*derivative

last_error = error

My question is how to handle the measurement data (actual_value) versus the control (target_value). For example, say my feedback is measured with a 10-bit ADC. My control is a PWM with a valid duty cycle range for my application of 55-172.

Do I scale linearly between the two ranges? Say my target is 756 ADC. I would set my PWM to 86 initially?

Should the error calculation take place in the ADC range or PWM range?

What if the PWM control was not linear?


texts:
I have two different embedded devices with ethernet connection. One is based on Texas Intruments DM648 DSP chip and the internals of the other are unknown to me.

When I connect each one of them sperately to a PC, there is a connection.

When I connect them together, no connection is made. I have put a breakpoint into an emac link callback function, and the program did not stop there.

Could this behaviour be caused by incompatiable physical protocol? By incompatiale baud rate? Full duplex/half duplex incompatiabilty?

Can these things be software configured?


texts: I need to calculate the Applied power on a TVS Diode, what I know is P=U*I, I am applying 5v voltage on the TVS Diode but I am wondering what should be the Current value? Should I use the Leakage current as it is reverse Biased? also can this be applied on any type of reverse biased diode?


texts: Is it acceptable to use USB connectors in non-USB applications?

texts:
In my project I need fairly long (up to 5 meters) shielded cabling that has compact 4 pin connectors (will be used in a noisy environment). As I understand the shield of the cable should connect to the connector, which connects the shielding to the header, which is grounded on the PCB. I believe that a good choice here would be RJ45, but the size of the connectors is excessive.

From an electrical engineer's point of view, would it be acceptable to implement USB or microUSB ports for an application which has nothing to do with the actual USB protocol? Would this decision cause problems if it would become a commercial product? The cables are for connecting digital sensors to a controller.

Suggestions for alternatives to USB connectors are also welcome.


texts: How do we reduce or nullify the back current from the wheel motors of the modern electric vehicles?

texts:
As expected, this EMF opposes the voltage of the source that created it; that
is, the motor becomes a generator as soon as it is turned on, and the
opposing (or counter, or back) EMF will increase with increasing frequency.However, the applied EMF overcomes this "reverse emf" and makes the
current flow in the direction suggested by the applied EMF; in effect, the
reverse EMF acts as a brake on incoming current and limits it.Won't it affect it affect the efficiency of the EV's.More over won't these back emf badly affect the electronic circuit system.


texts:
I am trying to replicate http://www.instructables.com/id/Music-LED-Light-Box/ .  But instead of using 6 LEDs, I want to go with >150 LEDs (also, using a LED strip instead of the individual LEDs), how can I make this circuit scale? Do I just append more LEDs or does it get waaaay more complicated? Is it different to add the LED strip rather than soldering LED by LED, manually?

The best thing about this circuit was its simplicity, and I'm trying to keep it.

edit: the initial circuit diagram is in the step 6 of the original instructable


texts: Does circled transistor or capacitor value cause buffer stage to stop transmitter from working?

texts:
I built myself an FM transmitter with an enable option so I can interface it with a micro controller. The Enable line is set through the micro via a 1K resistor (not shown). Once set to enable, the FM transmitter starts sending whatever sound is injected to the input on the left (in this case sound from the computer earphone terminal via earphone extension plug).

With this design (excluding the circled parts and using test point 1 as a 6-inch wire antenna) I'm able to achieve a transmission of up to about 50 meters.

I then researched buffer stages and adopted an idea from http://talkingelectronics.com/projects/Spy%20Circuits/SpyCircuits-2.html by adding the circled components and using TP2 as an antenna instead of TP1. After testing again with the parts added, I get no audio signal at all, even if I have the transmitter and receiver within 10 centimeters of each other.

I'm trying to run this transmitter with a carrier between 300 and 500Mhz and I'd like to achieve a few hundred feet distance.

Rather than place an order for trimmer capacitors and waiting weeks for them to come in so I can ultra-fine-tune the band (which I didn't have to do when testing with the red components excluded from my design), is there anything else I can do to increase the range of my transmitter and still receive an audio signal?

Is capacitor or transistor wrong?

Two things that no one pointed out yet were the 10pF capacitor value (capacitor circled in red) and the add-on transistor (also circled in red).

I'm just wondering if a certain reactance amount in ohms between the first and second amplifier stage needs to be met for both stages to function.

Also, could I get away with a Pn2222 instead of a Pn3563, or maybe even use a set of diodes instead? I'm asking because 99% of the time when I make a circuit with Pn3563, the transistor internally blows up and I have to replace it (no I didn't short the circuit board). Also the maximum current limit for Pn3563 is 50mA and I think with the part values I use and the frequency of interest, I'm approaching and/or exceeding that limit.


texts:
I'm having a very hard time trying to read and keep a low current draw from my sensor which is FSR-402: https://www.adafruit.com/product/166, but to help others, this can also be a problem with photo resistors and other such low resistance sensors.

Basically, the problem boils down to the low resistance of the sensor when reading (Ordinarily 1k ohms, when event occurs it jumps to 4k ohms with a variance of a few hundred ohms).  This is a significant problem since I need the reading to only draw 1 - 9 micro amps.

To further complicate things, I wanted to read this as a digital value to tell when an event occurs, so that the microcontroller can go to sleep and wake on an event.

I'm open to any type of circuit design.


texts: What does Vivado HLS do and how is it different to what SDSoC does?

texts: I am a newbie to design of digital systems. I understand that Vivado HLS is a tool that accelerates the design productivity by allowing to check designs by checking them through an HDL. What does Vivado HLS to achieve this? What is the process that it goes through? What does it do in comparison to SDSoc?


texts:
As a software engineer I apologize in advance, I'm definitely an amateur in the field of electronics.

Problem

I'm looking to gauge distance from an ultrasonic emitter to a mobile device. To test this idea, I've built a proof-of-concept app that takes microphone input, runs it through a Fast Fourier Transform, and using the inverse square law of the frequencies' amplitude to guage distance

Now I'm looking to build a reproducible speaker (that is, not my laptop's) that has high output (dbA) at ultrasonic frequencies (20khz-22khz). note: the frequency can be constant if it makes things easier to build.

Where I'm At

To start I looked up speakers that were designed to produce ultrasonic frequency,  I've found this speaker which generates frequencies from 2.1khz-45khz at 118dB (which seems significant)

Rat. Impedance: <1200 Ohm
Rat. Noise Voltage: 14V
Crossover Fraq. Range (fc): 10000 +_ 25% Hz
Rat. Fraq. Range: 2500 - 45000 Hz
Sound Pressure Level: max. 118dB +_15%

Reading the specifications I see the rated voltage is 14v. So knowing I'm probably going to need to want the final current to be an AC, I looked up 120V to 14V, AC to AC transformers. These seem pretty easy to find. I found this.

Input Voltage: 120VAC @ 60Hz
Output Rating: 14VAC @ 850mA
Size: 2.5"H x 2.0"W x 1.7"D

Now here is where I'm stuck. I have the desired 14V output, but the current as far as I know is still alternating  60HZ (standard American wall-out).

I'm unaware of any off the shelf methods to convert a 60HZ AC current to the static 20khz-22khz signal that I need. Is there an easy/cheap way? What parts should I be looking at? It seems that any signal generators that I find are super expensive and very general-purpose.

Thanks!


texts: Two input voltages to buck voltage regulator, using diodes to protect the sources

texts:
I have a buck regulator that takes 4.4-36V input voltage, and gives 3,3V 1A output. It will have two voltage sources, one potentially 25V and one 5V. Do I need a mosfet circuit to make only one source active at a time?
OR
Can I use two diodes in this way to protect the sources? The buck regulator should be able to handle the total voltage of the two sources put together so I don't think that is a problem.

simulate this circuit – Schematic created using CircuitLab


texts:
I have that project, where I have as an input voltage 12 V (lead acid battery) and would like to have 4 output of 5 V 1 A that would be switched on and off with a mosfet.
I'm thinking which way you would recommend me to proceed.

Option 1 : Use a single voltage converter 12 V to 5 V with 4 A( for the 4 outputs) and then have the 4 mosfets connected to the 5 V line of the output.
Option 2 : Use 4 voltage converters 12 V to 5 V with 1 A for each outputs connected to the battery and connect each output to a mosfet.

Thanks in advance!


texts:
I made the below discrete two transistor buck converter. When NO load the output shows 5V nicely. Even a small 100mA load, the output voltage drops down.

How to overcome the issue?

Actually I need to convert 12V to 5V with a 600mA load current.

Thanks

Here is the Q2 collector voltage when no load.


texts: What are the Weller "Steckverbinder für Ablage" used for?

texts:
I just bought a Weller WXMP Soldering Iron and got these two plastic things (pictures) in the package.
I have searched the web but can't find any instructions on what to use them for.
What are they used for?


texts: Why does multipath impulse response contains a complex phase shift?

texts:
The multipath impulse response is defined as

$$h(t) = \sum_{n=0}^{N-1} A_n e^{j\phi_n}\delta(t-\tau_n)$$
My qustion is, from intuitive point of view, why is there a complex phase change of the signal? Isn't the delta pulse time delay enough to describe this process? Convolution by a real signal would result in complex one. How does that work?


texts: Can I use the circuit from an electric mosquito bat in a homemade 3'x3' panel?

texts:
SUMMARY:  I'd like to take the control circuit out of four electronic mosquito bats and use them on a homemade panel version of the same thing.  I know little about electronics, so my question is, will it work, or will I need a different circuit (and/or maybe larger batteries) to power something that large?  I know that DC loses voltage over distance.  FWIW, the well-reviewed mosquito bats output 3000-4000V, and discharge is limited to 9 mA, well below the danger threshold for human contact.

GOAL:  I want to reduce the local mosquito population because they terrorize my wife and she can't enjoy the yard with the dogs.  She has a sensitive allergy and gets 1.5" dark blue bruises when they bite her, plus itching.

PLAN:

Construct a four-wall, open-top cage, 3'x3'x3', with window screening
on the inside.
Attach an electrified panel on the outside of each wall (i.e.,
1.5" from the inside screening).  The spacing prevents accidental nuisance shocks from inside the cage.  The panels will be 2x2 wood
framing, with horizontal wires (alternating positive/negative), 6.1
wires per inch, using 16-gauge galvanized wire, with as many extra
vertical 1x2 as necessary to keep the wires straight.
Attach 2" wooden spacers onto the outside of the panels, then
install 1/2"-hole hardware cloth (wire mesh) to the spacers, to
prevent accidental nuisance shocks from outside.
Connect each panel to a circuit removed from an electric mosquito bat.  Connect all four
circuits to a momentary switch, so the panel can't accidentally be left on.  All panels will be activated simultaneously by the switch.

NO ALTERNATIVES:  Whenever someone posts a problem on the Internet, everyone always suggests going with some other plan rather than solving the actual problem posted, so let me try to pre-empt that:  I don't have a porch I can screen and that's irrelevant anyway because we want to enjoy the yard.  None of the mosquito repellant products available works very well (we've tried several) or is toxic.  Electric bats have several downsides, the biggest being that it's easy for mosquitos to bite her before she notices them.  You've also got to go at them one at a time, so it's inefficient.  Fans with screening to catch them are okay but the CO2 has to constantly be replaced and there's no audible feedback of mosquitos being eliminated, so it's less than ideal.

PRE-EMPTING OTHER OBJECTIONS:  We don't have to hope that mosquitos will fly into it; they always make a beeline straight for her.  Mosquitos never bite her above the waist so 3' high, with no roof, should be fine.  If it doesn't work I'll build a taller cage with a roof.

Panel with alternating wires (6.1 wires per inch):

+|-------------------
 | -------------------|-
 |------------------- |
 | -------------------|
 |------------------- |
 | -------------------|
 |------------------- |
 | -------------------|
 |                    |
 +                    -


texts:
i got an old PC fan which according to its label runs at 12V drawing 0.14Amps.

I would like to run this with a 9V Battery so that it doesnt go too fast.
Does this make sense?

How long would the fan run approximately with a typical 9V PP3 sized battery?

edit: another question is, how much amp will the fan draw when powered with 9V ?


texts: How to determine a system is stable without knowing the input?

texts:
I was doing some exercises for an upcoming exam and ran into this. I am not sure how to find if the system is stable without knowing the actual input (since Routh array is the only method I'm familiar with.) (The answer provided is a)

Can someone explain briefly what needs to be done?
Thank you in advance!


texts: Name for genderless/male-and-female-all-in-one connectors for chaining PCBs?

texts:
I'm looking to make a modular system which can be expanded left or right, as well as fed from either left or right side, depending on customer location and available space.
Having a standard outlet in a female connector and input in a male counterpart will make it less flexible since it has a given direction and/or you need to flip the board upside down. One can cheat using two connectors like this simplified example (pardon my MS paint skills):

But is there no magic search term for a connector which has one male and one female part in the same connector to achive the same thing? My google-fu is failing me here.


texts: Name of circuits with parallel branches starting and ending at different points

texts:
Is there a name for, and where can I find info on, the study of voltage drops, currents and resistances in circuits where 2 parallel branches off a main trunk line might not start and end at the same point?

E.g. below.

Wasn't sure what to search for on google or stack exchange.

simulate this circuit – Schematic created using CircuitLab


texts:
This is a conceptual question. What I understand is that runt pulse is like a glitch but its amplitude is less than the main pulse's amplitude.
If Im not wrong on this definition, below illustartes the difference:

Since I observe all of these kind of outputs time to time; can a very low hysteresis be the source of the problem by cosnidering the shapes of the pulse outputs? I can understand a Schmitt trigger with very low hysteresis can cause a glitch but I dont get if it can cause a runt pulse or other type of noisy outputs above. Is that possible? Or runt pulse's source should be searched some where else?


texts: What is the cause for a 180 phase shift between current and voltage in LT-spice simulation

texts: Just by clicking on the resistor, I got a display of the plot of current passing through it, marked with I(R3). In my opinion it must be in phase with the voltage across the resistor, but on the screenshot it seems to be different, could anyone help me to understand it?


texts: Is it possible to change a USB's enumerated descriptors (from the OS side) after plugging it in?

texts:
I don't mean as in change the descriptors built into the device, but the descriptors that the OS has enumerated. Can this be done from the OS side without touching the USB device?

For example, can I plug in a default Arduino UNO scripted to send keyboard keystroke signals, then in the OS side of things (Linux in my specific case, but I'd like to know about Windows and OS X too) change the descriptors so that the OS can interpret the device as (for example) a keyboard without ever having to modify the DFU firmware of the Arduino directly?


texts:
This question generally applies to many situations, but in this case I am trying to figure out the best choice (no limit to the perfection).

I am stuck at both input coupling capacitor and output coupling capacitor.

Input coupling.

Datasheet states that 0.1 uF capacitor is recommended. It shows non-polarized capacitor (but that does not 100% guarantee it may not be polarized). People just copy the reference circuit from the datasheet putting caps they have or are easily obtainable - X7R of 0.1 uF.

However reference design uses 1000 pF caps, with this unconfirmed brief info on the AD forum that AD must have used X7R caps. I am skeptical about it, and given tons of documents and opinions read last days I suspect that AD actually uses NP0/G0G 1000pF capacitors (no BOM for the device is available, and I suspect asking AD will not give any outcome). This nominal exists and is available in 0805 package. I did not find direct mentions that X7R are bad to use on the video path, but there're numerous mentions that it is not so good for audio paths, however minding voltage rating of cap (bigger is better).

Am I correct in my conclusions, and it is much better using NP0/C0G as input coupling caps? Or even electrolytics?
Output coupling.

I bought EEU-EB1E221SB, which is 220uF/25V rating. Now I am not that sure that I have chosen correct cap. Forums and publications mention that lower ESR is better, but I can not find ESR informaton for EB family of caps. This information is only available for F* families. Looking through forums  found out that F* must be "audio-grade" caps. Panasonic does not state the target usage for the families at all, it would be much convenient if they list typical applications for the families.

Do "audio-grade" electrolytic caps apply to the video transmission bandwidth and minimally impede video signal transmission? How to choose this cap type for the video application?

I want to hear your experiences, supported by the proven theory. Please refrain from statements that something will work just OK in generic cases. Please note I do not ask about nominals of the caps, I am asking about technologies of the caps.


texts:
I'm a mechanical engineer with very few knowledge in electrical so your help is very appreciated.

I'm doing a small project which require to automatically the fill and empty a sink.

How can I automate the filling of the sink, make it stop (so the sink don't overflow) over a long period of time.

I've experimented a little bit with solenoid valves, but they get very hot (and I fear that they melt) if powered more than a few hours.

Here is the valve I used. I know I should probably use a Normally Open one.

Once again, your help is very appreciated.

EDIT:

I will ask my question differently.
How can I have a Normally open solenoid valve closed indefinitely?


texts:
I need to find vo / vi and I need to find differential gain.
What kind of path should I follow? Can I help you?


texts: What make TEA18362T by NXP to work upto 75W?

texts:
I am planning to develop SMPS for 24V-4A using TEA18362T, but according to datasheet it useful up to 75W output power. Even online design tool by NXP works up to 75W.

Is it possible to design and get work from such controller beyond its rated capacity ?
Which constrain make it to ideally work for < 75W ?
Can we mask this limit ?

Other company like ON Semiconductor have such controllers but they don't mention such power limit for controller.


texts:
I want to run a single phase motor with a single phase VFD.

I don't believe that the motor is rated to run with a VFD. To compensate for the issue I would like to use a sine wave filter. Unfortunately finding a single phase sine wave filter has been problematic.

I'm wondering if using a 3 phase sine wave filter and only using 2 phases is feasible?

Additional information:

Link to proposed VFD.

I'm between a rock and a hard place. I have a piece of equipment that was moved from the UK to the US. The equipment itself is north of 500k. It has one small 130W 230V 50Hz motor. The manufacturer of a small subsystem does not offer a US version of the motor. I'm trying to retrofit something to get it working.

Here is a picture of the motor.


texts: Choosing values of resistive divider, versus pullup resistor value

texts:
I have a slight Catch-22 with my circuit portion shown below.

The ADM6320 is, among other things, an undervoltage detector with factory threshold of 2.93 V (thus Reset output pin toggles when VCC < 2.93V).

I wanted to alter the threshold to be 3.45 V, so I inserted a resistive divider of ratio 0.85 as seen below.

Only one problem: The values of the divider resistors are of a similar order of magnitude to the pullup resistor on the Reset output pin of the IC. I'm concerned that there will be problematic interplay at certain values of VCC. (For reference, I have also included the Internal block diagram of the ADM6320, see further below.)

Of course I could choose resistor values that are significantly different, but I am concerned about unnecessary current draw.

What values would you optimally set for the divider on VCC input pin, and for the pullup on the Reset output pin? I am having a bit of trouble imagining what behavior might result at various values of VCC, and how to ensure all cases are considered.

My circuit:

Internal block diagram of ADM6320:


texts:
I have circuit where I am using transisitor 2N3904 and Mosfet IRF9540. Following is the schematic:

In the above circuit, chargePin is the digital pin of Atmega328p(arduino uno). Solar+ is the pin where solar voltage is coming. Battery+ is the battery voltage pin. So depending upon the few conditions, MCU will enable the chargePin which will enable the transistor and then Mosfet will connect the solar voltage to battery voltage to start charging. But what's happening is, chargePin is disabled but still the solar+ is connected to battery+.

Is there any error in the above circuit.


texts:
So two resistors in series can be a voltage divider. So say I have the following circuit -

From what I have read the voltage gets split across the resistors based on their resistance. So there will be 2V across R1 and 8V across R2. Now I have also read that Vout takes the value of the voltage across R1, in this case, 2V. What I am not sure of is why it takes the value of  the voltage across R1 and not R2?


texts: How do I identify the SMD component marked as !3S 4?

texts:
I have a SOT-23 SMD component marked \$\underset{\bullet}{\vert}3\bar{\textrm{S}}\;\bar{4}\$ as shown in the following images

I managed to find out that \$\textrm{3S}\$ stands for MMBT5551 NPN transistor. But I couldn't find the meaning of the prefix \$\underset{\bullet}{\vert}\$ and of the \$\bar{4}\$. I appreciate any help you can give me with it.


texts: Gain vs ADC performance vs ADC settling time

texts:
I have some basic doubts in ADC conversion. I am using AD7798 ADC. I am reading ADC values using AT90USB1287 micro controller using SPI communication. I am able to read ADC values perfectly but i have some doubts.

I had gone through the datasheet several times. I am setting Configuration register as "0x0230" and mode register as "0x0009". It means update rate as 16.7Hz and gain from "4 to 128".

When i try to read ADC value with 16.7Hz update rate it is taking more time but accurate values.

I would like to get values more fast than present time so i changed update rate from 16.7 Hz to 232Hz. Now ADC reading values more faster but not accurate.

How can i read ADC values more accurate and faster? Changing gain will effect ADC update rate?

Could anyone give me some explanation regarding Gain Vs Update rate vs accuracy?

From the datasheet i see that gain will effect on resolution and update rate will effect on signal to noise ration.

AD7798datasheet


texts:
I've designed a dice circuit, simulated it in Proteus (which worked) and got the PCBs manufactured. A problem I'm facing on the real thing is that if the button is pressed normally (e.g. for as long as you'd press a key on your keyboard), the "roll time" is always the same, resulting in the same number showing at the end of the roll. Holding the button for longer than what I assume is the C6 charge time results in the expected randmomness.
Is there a way to randomise the "time on" of the 555 latch without having to get new boards manufactured?
Ideas I've had are using an LDR or thermistor to somewhat randomise the time.
Here is the circuit diagram in question:


texts: How can I determine the the Wiring Configuration of an LVDT sensor?

texts:
I have an LVDT Sensor for measuring linear displacement similar to the one on the picture. The problem is that I don't have the manufacturer's wiring diagram and they don't provide it, because originally it has a six pin connector. It's a 6 wire LVDT:
Pin 1 - Orange
Pin 2 - Black
Pin 3 - Yellow
Pin 4 - Blue
Pin 5 - Red
Pin 6 - Gray

How can I determine which cables correspond to each of the LVDT's Primary and Secondary Coils?


texts:
In PIC12C5XX programming guide I found a requirement:

  1.1 Hardware Requirements

  The PIC12C5XX requires two programmable power
  supplies, one for V_DD (2.0V to 6.5V recommended) and
  one for V_PP (12V to 14V). Both supplies should have a
  minimum resolution of 0.25V.

What does it mean?

I found an article on power supply resolution versus accuracy, and it boils down to:

  Our power supplies use Digital to Analog Converters (DACs) to take the user inputted settings and convert them to analog signals that set a programming voltage that will interact with the control loop of the power supply to set the output.  The resolution supplemental characteristic represents one single count of the DAC.

Which means it applies to power supplies where the user sets the voltage; minimum step by which the voltage can be changed. Now in the guide we have a pretty loose requirements for preset voltages, no requirement for them to be changeable by the user. I really don't see any application of supply resolution as explained by the article. The basic requirements look like if I apply 5V and 13V with accuracy +-1V I should be set. So what does the resolution mean in this context?


texts:
Repairing the Audio Oscillator section in my B&K Mod. 970 Radio Analyst, which has a bad 16L64 NPN transistor. I'm not able to find a replacement.
Any help is more than appreciated.

Note:
Revised and corrected. The Transistor number is 16L64 NOT 16L46 and it is a NPN NOT a PNP.
I'd like to apologize to every one for my mistake.
I found the schematic and will using the instrument for repair.


texts: Does anyone remember this article about the Euclidean Algorithm?

texts: In the 70's I had a stack of old Amateur Radio magazines (50s-60s), and for a long time I saved an article about using the Euclidian Algorithm to combine a number of resistors to achieve a specific value. Does anyone recall and have a copy of this article, or know how the Euclidean algorithm is applied to solve this problem?


texts: What would be the correct amount of voltage to power an Arduino UNO, XBEE shield (with XBEE module), and five Tower Pro SG90 Servo motors?

texts:
I am designing a glove-controlled robotic hand using Arduino UNO and XBEE. For the hand itself I am using the adafruit 16 channel PWM Servo Shield and using 5 SG90 servos for each finger.
My problem is that the USB ports of a computer will simply not provide enough power so I'm wanting to use alkaline batteries.
Would 4x AA provide enough power for the entire system, or should I use a 9V or even 12V battery?


texts: How can I run my e-bike wheel on AC power?

texts:
I have an electric wheel designed for an electric bicycle conversion. By my understanding, the wheel is essentially a 48V, 1000w rated brushless DC motor. It comes with a thumb throttle and kill switch built into a break lever.

I am looking to set it up as part of a stationary rig to do some testing and want to run the wheel on AC power. The wheel has no regenerative breaking so only draws power from a battery (not included in the kit).

Instead of wiring the positive and negative terminals of the motor to a battery, can I wire them to the appropriate terminals of an AC-DC transformer adapter such as this one and plug this directly into mains?

If not, what extra components do I need to include?


texts: Dependence of wireless channel capacity on the system operating temperature

texts: Does system temperature have any effect on the achievable channel capacity (channel capacity modelled using Shannon's theorem)? If the temperature is tripled or doubled, will it affect the channel capacity?


texts: How can microinverters be as efficient, or more, than power optimizers of solar arrays?

texts:
According to Wikipedia:

  solar panels produce voltages around 30 V. This is too low to be effectively converted into AC to feed to the power grid. To address this, panels are strung together in series to increase the voltage to something more appropriate for the inverter being used, typically about 600 V.

A power optimizer on each panel would then ensure the failure of one panel won't ruin the overall production of the serial circuit of panels, and roughly 600V would be delivered off of the roof to a single inverter.

Microinverters, on the other hand, do not spit out 600V from a serially connected loop. They convert to 120VAC directly at each panel from the ~30VDC output at the panel. These microinverters are more expensive than power optimizers, for obvious reasons, but are touted as being more efficient.

So:

The wikipedia article says it's more efficient to convert to residential AC from 600VDC than from 30VDC
Industry says the most efficient system is micro inverters, which converts to 120VAC from 30VDC

How can microinverters be more efficient than power optimizers if the most efficient way to convert to residential AC is from 600VDC?


texts:
I have made a quick search but couldn't find anything specific around.

I need to design a rudimentary circuit for a photodiode in conductive mode.  I am interested in high speed rather than sensitivity, a wavelength around 550nm.

I have a notional idea of a battery connected across the legs as a voltage bias, but how do calculate what resistor to use to avoid overloading the diode...

Sorry for being vague, I'm struggling to find out where to begin!

(nb. I have a background in physics so have a basic knowledge of electronics.)


texts: PCB with no analog and ac current and capacitor question

texts:
I'm a beginner in EE. Lastly I read a lot about this field and I want to jump in.

I think of a toy PCB design, to experiment essentially.
I picked the different hardware so that all the components have digital outputs, which is what I want to stick with (less complex, no type mixing, less costly). As well, the power source is an AC to DC adapter. So no AC in the circuit, apparently.

I get that current is not perfect in the real world. So a capacitor near a Vcc pin of an IC is needed to smooth input current and limit its own impedance.

Given these elements:

Is it still needed to put a decoupling capacitor to each ground on this DC circuit? Isn't it useful to filter high frequencies (AC) only? Do we really care about the noise a ground may have?
would an ethernet PHY really need a decoupling capacitor in this circuit? Do they generate so much spikes by themselves?

I keep seeing decoupling capacitors in the schematics I read (Raspberry Pi, Arduino, and others). But their constraints are different, I guess.


texts: Question about Intermittent Torque Zone and Rated Voltage

texts:
In the below two diagrams, the Intermittent Torque Zones are different, figure 1 is triangle and figure 2 is rectangle. I don't know which one is correct, is there something related to motor's rated voltage?

Here is my analyze:

τ = kt * I; I is phase current, τ is torque, kt is constant
Pin = U * I; Pin is input power, U is phase voltage
Pin = τ * ω + Ploss(I); ω is speed, assumming power loss is proportional to I(only heat loss)

Let's analyse the Intermittent Torque Zone in figure 2: Pin = τ * ω + Ploss(I), When "ω" increases toward rated speed, "τ" keeps constant and "I" keeps constant due to "τ", so Pin increases; Pin = U * I, because "Pin" increases and "I" keeps constant, so "U" increases. Now the question is changed to, if "I(phase current)" keeps constant and "U(phase voltage)" increases, will it burn the motor with a short time peak torque in figure 2 ?

To answer this question, let's look at the motor coil's equivalent circuit, U = I * R + L(ω) + E(ω), "I" is constant so it can not burn "R", but "U" increases as "ω" increases toward rated speed in figure 2. Is there a limit for the voltages on "L(ω)" or "E(ω)(Back EMF)" in case it might degrade the motor?

Should they be under motor's rated voltage?
Which figure is correct for Intermittent Torque Zone?

Thank you.


texts: Communication between micro controllers - I2C, SPI, UART?

texts:
Basically I have two microcontrollers that I need to communicate with each other.

Both controllers send and receive data.

Basic idea that I have:

I2C, SPI - What I think we can NOT use these protocols in this case. Because both are master slave based protocols. So if one controller is configured as master and other as slave, then in that case if the slave uC wants to transmit data then it can not initiate the transmission and it is also not allowed to generate the clock.
UART -  I guess this should work as it's asynchronous. So nobody is bound to be slave or master.

My question is, if the above made assumptions are right? If no then please correct me.


texts:
What's the maximum dotclk frequency for a typical OLED display with serial input?
I've looked through some driver specs, example: SEPS525 but its not clear to me.
I'm looking to update a small resolution RGB oled (64x64) display at several hundred Hz for a perception/display experiment.

I think my best bet is to drive the dotclk and sync signals, while delivering the data 18 bits wide in serial format.


texts: Width/Length of a Mosfet in LTSpice on Macbook

texts: In order to change the width and length of a mosfet gate in LTSpice on Windows you just right click on the device, but how do you accomplish this on a Macbook?


texts:
I'm currently designing a bus-powered usb 3.1 hub. It will use a USB-C for UFP and 3 USB-A downstream. The hub will only be acting as a sink.

As of my understanding, since it may be connected to USB 1 (low speed), I need to limit the possible current drain to 100mA before negotiations, and only after negotiations, set the maximum current drain that can be provided upstream?

I have been looking at two reference designs from TI that specifically states "USB 3.0 compliant hub". Is that really correct?

TIDA-00287: http://www.ti.com/tool/TIDA-00287
TIDA-00288: http://www.ti.com/tool/TIDA-00288

Neither of these reference designs have implemented current limiting upstream, only downstream.

I have been looking for IC's that specifically manage current limiting upstream, but so far I have only found down-stream limiting.

Do I need to limit the hub's power drain?

Do anyone know of a chips that manage this or reference design which have implemented power limiting upstream based on the current negotiation?

Thanks!


texts:
This is from the Datasheet for Texas Instrument's NE5532:

Does this mean I can safely supply Vcc- = 0V, Vcc+ = 30V, and let all other voltages swing within that range?
If that's the case, then that would be one of the ways I've been reading these datasheets the wrong way. Values would usually show up like this:

I used to think that that meant the absolute maximum potential difference between the supply pins should be 22V.
Why is it expressed as ±22V when they could just say 44V?
Why use the ± symbol at all?
Why say 'absolute' then present a negative value?


texts:
I am trying to simulate the following Lithium Ion Battery Charger circuit in LTSPice:

I have looked online for the DW01A chip but can't find it. Can anyone please provide a model for this chip? If not, can anyone provide a protection circuit (overvoltage) that can be simulated in LTSpice? Thanks.


texts:
I have an Ampire AM800480STMQWT00 touchscreen display. In the course of testing the device, the cable for the touchscreen proper got ripped by accident.

Is it possible at all to repair the cable itself, or would I be forced to simply acquire a brand new touchscreen to mount on the display? I tried searching around for the touchscreen display I have but there's not a lot of information available on it.

The actual rip is towards the end of the cable that would be plugged into a device.


texts: How do the parasitic elements behave in a bidirectional power switch made from back-to-back MOSFETs?

texts:
I would like to know how to determine the value of the total internal gate mesh resistor (Rg) and different parasitic capacitors especially Cgs and feedback capacitor Cds of a bidirectional power switch build by two back-to-back MOSFETs (with common source). What about the Miller plateau? I am interested in the switching behavior of such kind of power switch in order to define a proper dead time of a multilevel power inverter.
thanks


texts: Making a DC motor turn in saturation and cutoff modes of an NPN transistor

texts:
simulate this circuit – Schematic created using CircuitLab

So I have a DC motor that should turn with light on LDR and should stop when I cover LDR or turn off the lights.

Basically the transistor should work in saturation and cutoff modes.

Transistor will operate in cutoff mode when no current goes through the base, that means I have to put a resistor  with high resistance in series with my photoresistor. This high resistance plus the high resistance of LDR due to darkness will make transistor to work in cutoff mode.

Transistor will operate in saturation mode when the base voltage is at its highest that means low resistance at the base.

This is my dilemma, so if I put a high resistance in series with my LDR that will help my resistor to operate in cut off mode but will prevent my transistor to achieve its max current in saturation mode because of the voltage drop across the large resistor at the base. So what should I do?


texts: Best practice in transmitting sensor analog signal over longer distances (approx. 100') -- in cost sensitive products for microcontrollers

texts:
I'm looking for best practices for transmitting an analog sensor signal over long distances to a microcontroller such as the Arduino running at 3.3v or 5v. Keeping costs low is imperative.

SPI and I2C is very common in Arduino land, but it seems there just isn't much of a solution when sensors need to be more than several feet away from the microcontroller. But perhaps I2C or SPI will work with the right components and wiring. Any ideas?

4-20 mA current loops seems like a solid solution since current doesn't drop along distances as long as the supplied power stays consistently above the demand. But 4-20 mA systems of sensors, transmitters and receivers seem to be mainstays in the industrial world and virtually absent in low cost embedded systems.

A classic need is detecting temperature through a resistive based thermistor. Are their inexpensive transmitters that can be coupled with a thermistor to transmit a 4-20 mA current loop signal? And then an inexpensive receiver on the microcontroller side? I would think something like a MOSFET on the transmitter side would work, coupled with a resister on the embedded side.

Alas, being a software engineer, electronics is still a bit fuzzy to me.

UPDATE:
Should have specified more. 30' - 150' distances through potentially electrically noisy environments. I can go VERY low on bit rate: 10Khz. Even 1Khz if such a thing is viable. Putting in a low pass filter and/or software filters is not a big deal. I would like to be less than $10 per sensor (not including housing). But I would also like to stay away from a custom PCB board at the sensor if possible.


texts:
Suppose, I have 10 pieces of PVC squares. Each PVC square has a number printed on it.

I want to create a robot who identifies the number printed on a square. Can anybody give any ideas? I mean is there any pre-built device or something that I can use?

What I have tried?

I have thought of sticking barcodes. But these squares will be used by human beings, so that these barcode stickers might come off due to wet hands or something ike that. So, I think its a bad idea.

Another Idea is to cut out the numbers from each square. Now, put the square between two circuits. 1st cuircuit will have LED's and the 2nd circuit will have Photo diodes to detect from where the light has passed and thus detect numbers. But this idea will be much expensive if I will have 10000 such squares as I have to cut numbers on each square. And my real project has 10000 squares.

If you have any ideas then please share.....


texts:
I am having trouble getting my N-channel MOSFET to work. I am using the MOSFET to control a DC motor. I have the the positive end of 5V power supply going to my motor and from the motor to the drain. I then have the drain grounded to the negative end of the 5V power supply. I believe that this part is set up correctly. I'm really confused about how to get the gate to complete the circuit between the drain and source. I tried just touching the positive end of a 3V power supply to the gate and sometimes the motor turns on and sometimes it doesn't. When it does turn on, it seems to stay on... I'm not sure that I'm even using the gate correctly because I'm not grounding it in any way. To apply a voltage to the gate do I have to have a ground involved?

Also, sometimes, when the motor does turn on, the speed of the motor varies quite a bit. It goes fast and then slows down and then goes fast again. What is happening?


texts: Boosting load current of voltage regulator

texts:
I'm trying to connect little 3v LEDs to a motorcycle's alternator and i want to regulate the voltage of it to 3 volts so the LEDs don't burn up
the alternator gives off 2.5 volts and over with 3 amps and over
i can't get my hands on a better regulator, and i have LF33CVs
how can i boost the possible current load? i know i can't connect them in parallel but the datasheet doesn't give a sample circuit
thanks


texts: Making a battery pack out of 8 cells in 4S2P configuration

texts: I want to make a battery pack of 4S2P using 8cells. Is it better to first make 2 sets of 4 cells each (4 cells joined in series to each other) and then join these 2 sets in parallel or first making 4 sets of 2 cells each (2 cells joined in parallel with each other) and then join the 4 sets in series? And Why?


texts:
Here is the circuit I am trying to analyse.

simulate this circuit – Schematic created using CircuitLab

Now I know generally how to do this.

Loop 1 we can call the RIGHT one and Loop 2 we will call the LEFT one.

Loop 2 is clearly 2A because it has a current source.

Loop 1 is 30/10 = 3A

and the voltage at A is clearly 12V because V = 3A*4

But how in the world do I find the Node voltage at B?


texts:
I took apart a asus eee pc remote control and borrowed it's ir sensor to implement the remote using my arduino. I have a sketch I borrowed from ladyada so I can look at the raw ir signal.
Since she has a professional scope and I have a cheapo one who doesn't trigger properly.
But I don't get the same results each time. I tested the sensor using the asus board without it's case and it works fine.

I noticed on the asus board it has some fitlering caps,100 ohm resistor and what looks like an inductor/fuse. Am assuming I shouldn't just wire the vcc = 5v gnd=gnd ouput = digital 2? How should I be wiring this up


texts: Saturation current of my inductor not agreeing with formulas

texts:
I have wound my first inductor and I have verified the inductance with 2 methods.

However, when I test its saturation current, its much lower than the formula gave me:

\$B_{peak} = \dfrac{V\cdot T_{on}}{A_e\cdot N}\$ (units: volts, microseconds, mm2, turns)

I set \$B_{peak}\$ at 0.2 Tesla and I'm using N87 material in my core.

I admit my windings were sloppy, but other than that I'm not sure what could cause such low saturation current.  This has been causing my boost converter to blow up every time.

Here is my test circuit for measuring both the saturation current, where I increase pulse width til it saturates and also use for method 2 inductance measurement.

simulate this circuit – Schematic created using CircuitLab


texts: Reference circuit design for UART on GSM module

texts:
I'm designing a small development board (from schematic design to PCB), centered around an ATmega32U4 MCU, and a Quectel M95 GSM module. I'm using the M95 Hardware Design Manual (http://www.quectel.com/UploadImage/Downlad/M95_Hardware_Design_V1.3.pdf) and there's a part that I don't understand for the UART reference design, to connect the M95 to the ATmega32U4 MCU.

It firstly shows this simple connection:

Then it's got this one:

And the DC characteristics for the UART port on the M95:

Where VDD_EXT is 2.8V.

I don't particularly understand which reference design to go with? The first one makes sense, you just connect the UART pins from the MCU to the GSM module. The second one also makes sense: if your MCU is based on 3.3V (which mine is), then this is the reference design to follow in order to have a voltage drop of 2.8V, in order to satisfy the DC characteristics listed above (?). I'm unsure which one to go with? Does it matter?


texts:
I'm putting together a bank of 3 batteries, connected in parallel for use in a solar PV system. The primary load will come from a 1000W inverter (2000w surge). The inverter manual recommends using a 3ft. run of 25mm^2 cable to connect to the batteries.

Is the size of the interconnects dependent on the maximum load the batteries can be expected to deliver or is there another factor which needs to be considered?

Edit: The battery bank consists of 3x 12V AGM batteries. The inverter draws 1000W @ 13V under normal operation but will pull 2000W @ 13V for brief periods when necessary. This means I should use wire that can carry 154 amps (2000W / 13V = 153.8 amps) from the battery bank to the inverter. Should the size of wires used to connect the batteries together be calculated using the same amount of current (154 amps, which is the largest load that will be connected to them)?


texts:
Are there any circuits than can remove DC bias of an input signal without inducing a phase shift?
I'm thinking for the input of an amplifier but whatever will work.


texts:
I’m charging a high voltage capacitor to 200v. I’m looking for a way to turn on an LED when the cap isn’t taking any more power or when it has reached the full 200v. This will serve as a visual indicator. Similar to the way a disposable camera has an LED that comes on when the flash is ready.

Would it be possible to use an op-amp comparator to compare the input voltage (200v) against the charging voltage of the capacitor? It seems logical but voltages are somewhat high.


texts:
I created my own clock since I need a 2Mhz clock and the clock generator IP wont let me go bellow 6Mhz.  I created a clock divider module.

module clock_divider#(parameter HALF_CYCLE_COUNT = 128, COUNT_BITS = 8)
(
    input clk_in,
    output reg clk_out = 1'b0
);

    reg [COUNT_BITS - 1:0] counter = 1'b0;
    always @(posedge clk_in) begin
        if(counter == HALF_CYCLE_COUNT - 1) begin
            counter <= 0;
            clk_out = ~clk_out;
        end else counter <= counter + 1;
    end
endmodule

Here is my top level module.

module audio_visualizer
(
    input clk,
    input m_data,
    output m_clk,
    output reg m_lr = 1'b1
);

    wire pdm_clk;
    clock_divider#(.HALF_CYCLE_COUNT(100), .COUNT_BITS(7)) pdm_clk_div(clk, pdm_clk);
    assign m_clk = pdm_clk;

    wire [7:0] sample;
    wire sample_changed;
    sampler s(pdm_clk, m_data, 1'b0, sample, sample_changed);

    ila_0 i(clk, sample, sample_changed, pdm_clk);
endmodule

I want to declare a constraint so that vivado knows the frequency of pdm_clk.  Here is what I have right now for clocking constraints.

set_property -dict { PACKAGE_PIN E3    IOSTANDARD LVCMOS33 } [get_ports { clk }]; #IO_L12P_T1_MRCC_35 Sch=clk100mhz
create_clock -add -name clk -period 10.00 -waveform {0 5} [get_ports {clk}];
create_generated_clock -name pdm_clk -source [get_ports clk] -divide_by 50 [get_ports pdm_clk]

I keep getting this error.

[Vivado 12-1387] No valid object(s) found for create_generated_clock constraint with option '-objects [get_ports pdm_clk]'. ["/home/chase/vivado-workspace/Sound/Sound.srcs/constrs_1/imports/Desktop/Nexys4DDR_Master.xdc":9]

I am not sure how to tell vivado what the output of the generated clock is.  I have also tried [get_pins audio_visualizer/pdm_clk].


texts: Does this headphone jack-type component exist?

texts:
For a personal project, I'm looking for kind of equipment that acts like headphone jack and plug, where the plug can be easily pulled out after applying some force on the wire.

However, the problem with using a headphone jack is that the plug can't be pulled from the wire when is pulled at an angle (unless you pull very hard). Is there any component that can do this? Or is it possible to modify an ordinary headphone jack to do this?
Please comment if you'd like for me to elaborate. Thanks! :)

EDIT: It doesn't have to be a headphone jack styled component. All I'm trying to do is create a wire that can be disconnected (by being pulled) from a circuit, which would result in electricity flowing through a different path.
However, now that I think about it, a headphone jack is probably not the best way to do this because the jack doesn't necessarily complete a circuit only when the plug is plugged in. So, if there's a better way to do this, please share!


texts: Normally open capacitive sensor with MOSFET is closing relay, how can I make it open?

texts:
Would love some help here, I know next to nothing about electronics.
I've been asked to fit a normally open (NO) capacitive sensor to a MOSFET to operate a relay.
My problem is it is working backwards to the way I need it to.
I have a 24V supply to the relay +ve, the mosfet source is connected to the relay -ve.
Drain is connected to ground.
Gate is connected to the sensor, and I have a resistor from the sensor/gate to ground.
When the sensor detects an object it goes to 24V, and the MOSFET is then closing the relay which is activating a pump.  But I need the opposite result, when it detects an object it needs to open the relay and turn off the pump.
The task was to replace a NPN-NC sensor with a PNP-NO sensor.  Knowing nothing about MOSFETs I read that this would require switching from an n-channel one to a p-channel one.  I guess I didn't understand that p-channel MOSFETs can be enhancement or depletion.  So I think I've got a MOSFET that does the same as the previous one did, hence the logic is now backwards from what I wanted as the sensor is switched.
Unfortunately I do not have time to find another MOSFET, order and test it.  This has to be operational today.  Is there anything I can do with what I have?


texts: I'm designing a preamp to connect 10K load. I need 2vptp at output from an 200mVptp input. but I want these bias conditions

texts: Need gain 0f 10. without changing dc bias conditions. what will be best solution?


texts: 12 V LED used with 12 V, 6A power supply

texts: There is some unknown factor here. I need to use an LED to light an area of a device. The device has a 12V, 6A power supply. I was expecting to have to reduce the current from 6A in order to use the 12V LED but the LED is working as -is, connected directly to the 12V, 6A supply. How can this be? I expected the LED to get hot or to burn out. It isn't even getting warm. I'd like to know why.


texts: Programming Custom STM32F446RE Board With STM32F446ZE Board

texts:
Hi I made a custom board by following the NUCLEO F446RE schematic from ST microelectronics website.
Here's a picture of the board:
As you can see on the bottom left of the picture SWD connections are present.

And here's the picture of the STLINK-V2 board i ripped from a STM32F446ZE board.
I tried to connect GND, TMS and TCK pins between the board and fed the main board with an external supply (I'm sure the MCU is powered.) but I couldn't program the board.
I need help programming my custom RE board with a ZE programmer board.
And one last thing to mention I can control the BOOT0 pin. I can connect it to  ground via pulldown resistor or VCC via pullup resistor. This is done via jumper header.


texts: How to stop/reset the watchdog timer from low-power sleep mode on an STM32L0C8?

texts:
On an STM32L0C8 MCU, I have the watchdog enabled while executing. At certain points in execution, I would like the chip to go into low power sleep mode. When it goes into low-power sleep mode though, the watchdog timer remains activated and will reset the entire MCU after the timer goes to 0, making it seemingly impossible to use both the watchdog and low-power sleep mode at the same time.

My question is, how do I refresh the countdown timer while in low-power sleep mode or how do I disable the WDT to stop it from resetting the MCU?

I looked all around the reference manual linked below to figure out how to disable / refresh the timer but it seems like this isn't possible. On page 514 it says:

  20.3.4 Behavior in Stop and Standby modes
  Once running, the IWDG cannot be stopped

(IWDG being the Independent Watchdog) but it doesn't say anything about low-power sleep mode. In multiple other areas it suggests the same thing, that the IWDG can't be stopped. Am I missing something? Are we not supposed to use the watchdog if we want to go into sleep mode? Is it possible to modify the watchdog countdown timers code to stop decrementing before entering sleep mode? Please let me know!

Reference Manual:
http://www.st.com/content/ccc/resource/technical/document/reference_manual/21/bd/0f/bd/1c/88/40/f0/DM00108282.pdf/files/DM00108282.pdf/jcr:content/translations/en.DM00108282.pdf


texts: Heating wire filament with low voltage high current?

texts:
Is it possible to heat  nichrome  wire  with 0.5V 20A?

what is the different between heat produced by 0.5v 20A (10watt) and 10v 1a (10watt) ?


texts: Stable power for LED from 5.5 to 7.5V AC

texts:
About a year ago I posed the question "Making 12V DC from 6V AC".  Since the conversion from AC was going to be problematic (for me), I tackled the tail/brake light first, because working with the 6V DC side of the wiring circuit was much easier for me to grasp.  Now I'm ready to create an LED headlight.  The source is the AC leg of my Honda's generator which produces 5.5V AC at idle and about 7.5V AC at high rpm.  Instead of my original desire to double the 6V to 12V, I'd like to simply rectify the AC to DC and build an LED headlight from there.

I believe that a full bridge rectifier with a capacitor is my best option for producing clean DC for the LEDs, but I think I'll also need a regulator.  Would I regulate before or after I rectify?  I'm confident that I can develop the proper LED array, once I decide on which LEDs I'll use and what output of my conversion yields.  I didn't have to figure all that out for the tail light, since it pulled from the 6V battery.

Thanks for the assistance and remember, I'm just good enough to install lights and stereos.  I don't have any formal education on electricity... I just know it hurts sometimes.


texts: LED circiuit for a current limited circuit

texts:
I have the following requirements for a circuit:

The circuit is supplied from a 500mA current limited voltage source
The circuit should indicate the status of the supply, i.e. if it is in current limit or not with an LED, the LED must be lit when current limit is on and be off when current limit is not active

I am testing the current limit with a 20 Ohm resistor that I am able to switch onto the supply. When I switch in the resistor the current limit is impossed and the source voltage drops to approx. 10V to give 500mA thorugh the resistor. When the resistor is switched out of the circuit the source voltage is 24V.
Placing the LED in parallel with the load gives the correct behaviour, but only a few mA flows through the LED and the light can barely be seen. I need full current to flow in the LED. I tried simulating an 18V Zener in series with the LED and resistor, all in parallel with the load and this works fine, with the exception that the LED is lit when the resistor is switched out and off when switched in (opposite of what I want). I have also tried a resistor divider on the supply voltage and the supply voltage voltage directly into a 24V comparator, but this obviously just scales down the input voltage when current limit is impossed, so this is also a bad solution.
I feel like this should be easily fixed, but I just cant seem to find a smart solution.
Only thing that comes to mind is to incorporate a voltage reference IC to have a fixed voltage into the comparator for comparing with the supply voltage.
Any ideas would be greately appreciated.


texts:
I have to write a testbench using "tasks" to verify the functionality of an 8-bit ALU. My tasks are not getting simulated properly in EDA playground. Can anyone please tell me where my mistake is?  In syntax or in logic?
Design of 8-bit ALU
module alu(input [7:0] a,b,
                 input [3:0] alu_select,
                 output reg [7:0] alu_out
                );

  always @(*)
    begin
      case(alu_select)

        4'b0000 : begin alu_out = a + b; $display("Addition operation"); end
        4'b0001 : begin alu_out = a - b; $display("Subtraction operation"); end
        4'b0010 : begin alu_out = a * b; $display("Multiplication operation"); end
        4'b0011 : begin alu_out = a / b; $display("Division operation"); end
        4'b0100 : begin alu_out = a % b; $display("Modulo operation"); end
        4'b0101 : begin alu_out = a & b; $display("Bitwise-AND operation"); end
        4'b0110 : begin alu_out = a | b; $display("Bitwise-OR operation"); end
        4'b0111 : begin alu_out = a && b; $display("Logical-AND operation"); end
        4'b1000 : begin alu_out = a || b; $display("Logical-OR operation"); end
        4'b1001 : begin alu_out = a ^ b; $display("XOR operation"); end
        4'b1010 : begin alu_out = ~ a ; $display("Bitwise-Invert operation"); end
        4'b1011 : begin alu_out = a >> b; $display("Right Shift operation"); end
        4'b1100 : begin alu_out = a << b; $display("Left Shift operation"); end
        4'b1101 : begin alu_out = a + 1; $display("Increment operation"); end
        4'b1110 : begin alu_out = a - 1; $display("Decrement operation"); end
        4'b1111 : begin alu_out = ! a; $display("Logical-Invert operation"); end
        default : alu_out = 8'bXXXXXXXX;
      endcase
    end

endmodule

Testbench
`timescale 1ns/1ps

task addition;
  input [7:0] a,b;
  output reg [7:0] c;
  begin
    c = a + b;
  end
endtask

module alu_tb_task;

  reg [7:0] a,b;
  logic [7:0] alu_out;
  reg [3:0] alu_select;

  alu uut(
    .a(a), .b(b), .alu_out(alu_out), .alu_select(alu_select)
  );

initial begin

    $dumpfile("dump.vcd");
    $dumpvars(1,alu_tb_task);

    a=8'h01;
    b=8'h02;
    alu_select=4'b0000;
    addition(a,b,alu_out);

 end

endmodule