texts: Parallel circuit with LED on one path and resistor on the other

texts:
I'm a beginner to circuits. Unlike many other questions, my circuit involves a parallel circuit with a LED on one path but a resistor on the other, as shown in the picture.

Q1: assuming the LED has a 3V voltage drop, does this mean R1 will have to drop 6V even if the LED is on parallel?

Q2: If I know the voltage drop of R1, just how can I compute the CURRENT that will go through each path? Since the LED has a constant voltage drop but R2 has a constant resistance I don't think I can use any laws I know so far — LED's and resistors are not the same things. I only know how to compute the current if both were LED's or resistors.

P.S. This sort of looks like a voltage divider, but the problem is that the LED does not have a separate ground but is connected back to the same battery, which then makes the circuit parallel and I'm assuming thing work differently. (And it did in my simulator)

simulate this circuit – Schematic created using CircuitLab


texts: how to build a high-power (4kW) switched-mode DC-DC converter?

texts:
I would like to build a switched-mode DC-to-DC converter which should support up to 4000 W of power. It should be able to act as a CCCV power-supply, so supply a constant current Imax up to the point where voltage Vmax is required to have that current, and then supply a constant voltage Vmax with a diminishing current.

I would like it to be modular, to be able to swap-out a few components to change the Imax and Vmax. I do not want to have knobs to change the Imax and Vmax like on a general-purpose lab power supply, as these parameters will be changed very rarely, when I change the battery configurations, maybe every few months, and I do not want the risk of me or someone else accidentally turning the knobs, and then connecting it to the batteries with wrong parameters which could kill very costly batteries - as I want this to support up to 4kW, you can imagine the batteries will be large. No, I don't have batteries supporting such current yet, but within years I could have, so I want this device to be easily expandable as my battery park grows.

EDIT - I modified my expectations, which I hope will make it easier to build:

The configuration I would like to have:

Input: rectified 230VAC mains (that will be something around 325VDC?)
Output: CCCV with exactly Imax=15.0A, Vmax=230.4VDC

Parameters:

input and output electrically isolated
low ripple (1% is OK, 2.5% is too much)
efficiency at least 90%, I am willing to spend up to 10% more for every extra 1% efficiency that I gain over 90%.

In the future I would like to be able to install modules to be able to accept a different voltage input, for example from solar panels, so a design that will accept a wide voltage input range (say 100-400VDC) would be a plus.

I would be grateful for some basic pointers into how to build such a beast, possibly using some ready-made blocks, but I don't want to buy the whole device, as I want it to be modular and expandable (unless some DIY kit is available).

I could take four Chinese 48V (adjustable to 58.8V) 15A CCCV supplies for less then 200$ each and connect them in series to do the job, but then I have "black boxes" which if a single component inside brakes, not having the schematic will be difficult to fix. So I would prefer to spend even twice as much for a modular, self-made design, so if something breaks I can easily exchange the faulty element, and if my desired voltages change I can just rebuild part of the device without buying a whole new one.


texts: Need a circuit to find Pulsers per revolution for a rotory Encoder

texts:
Need to find Pulses per revolution for a Renco rotary encoder P/N 77822-224 (No longer manufacture by Renco).

Supply voltage: 5.0v
Current: 70ma
Code: Incremental and once around Pulse Marker
Output format:     Logic Levels: Logic "1" 2.5 Vdc min.  Logic "0"
.5Vdc  max.
Output type: LM2901 (Quad Comparator).

I have tried using a PIC micro to count the # of pulse for one revolution by using a stepper motor and the once around Pulse Marker (using the interrupt pin for the pic. micro).
But the pulse count is different each time. Is there a circuit than I can use to clean up the pulse single, or maybe some one has a DIY circuit that they could share to accomplish this task in counting revolutions for this type of Encoder?


texts: PCB Power Pad destroyed for TPS51125. Fixable?

texts:
While trying to fix a laptop, I was de-soldering a TPS51125. I added a bit too much solder to the power pad while wicking so I had the "smart" idea to use a solder pump to remove it... but the pad came with it!

I've learnt a lesson but I'm wondering if this pad is really necessary for normal functioning? Can I go without it or does it need to be connected for electronic and/or thermal reasons?

If I just stick the pad back on the pcb and solder the IC back, will it not being connected do anything to affect it's ability to function?

EDIT: here's an image of the problem for interest sake


texts: What's the reason for this unusual transmission tower (pylon) design?

texts:
I saw this unusual transmission tower (pylon) while cycling recently:

This is in the UK. Specifically, it's just off the A6, between Preston and Lancaster.

The simple hanging attachments are very common, and the ones with a loop of wire are common too. But I've never seen one that is a mix before. There must be some specific reason it was constructed this way - any idea why?


texts: What is the intended use of the 400 Hz-rated power supply on osciloscopes?

texts:
The power supply of many oscilloscopes and other test equipment from different manufactures are commonly rated for 400 Hz operation. For example, Tektronics MDO3000 is rated to work at 400 Hz at 115 VAC. Rigol MSO7000 is rated at 100-240 VAC, 45 Hz-440 Hz.

I'm aware that 400 Hz power supply is widely-used in aerospace, and I heard some military and industrial installations also use 400 Hz, mainly to reduce the weight of the transformer. But I didn't find any specific case online.

What are some specific scenarios when users are expected to connect the oscilloscope to a 400 Hz power supply? Using an oscilloscope on a flying aircraft sounds unplausible. Most laboratories, industrial or otherwise are likely supplied with 50/60 Hz AC to power all equipment. The only possibly I can think of is field-engineers doing tech support. But even then, I believe it's more common to use a portable, battery-powered oscilloscope.

Does anyone who has an industrial background can explain: Is that really difficult or inconvenient to find a standard mains-frequency power in some factories to make it justified for most oscilloscope manufacturers to rate their scope for 400 Hz operation?


texts: Chaining multi-socket extention cords, can it be done safely?

texts:
I've always read that extention cords should not be chained. Also one should not build a tree of multi-socket cords. My background is physics, and I cannot see a problem with it, as long as one keeps in mind the current that flows. I might be neglecting something, that's why I want to make sure that I did not miss anything.
In Germany the electrical power is at 230 V, and fuses have current ratings of 10 A or 16 A. On many power strips I've seen that they have a maximum rating of 3500 W. The cable of the extension cord should be specified in a way that it can stand the current of around 16 A.
When using multiple extension cords, there are two fallacies that I can see:

People just see more sockets and connect more and more devices, going over the 3500 W of allowed current. The fuse might not trigger, but the cable will become hot and unsafe. This is something that I can easily avoid as in my use case would only have two nightstand lights and a phone charger at 100 W maximum.

The resistance of the total construction becomes so large that it will become a problem. Especially the DIN VDE 0100-600 seems to say that the resistance of the protective conductor must not be over 0.3 Ω for a cord up to 5 m length. For every additional 7.5 m of length, the resistance may go up by 0.1 Ω. The maximum may be 1 Ω. Assuming that individual cords are according to standard, I could hook up three of them; but that would totally ignore the resistance of the plug-socket-connection.

Where does the problem really come in? Is it that the protective conductor becomes useless if its effective resistance is too large? Or can I indeed chain power strips as long as I keep the total power consumption of that system well below the 3500 W threshold?


texts: Fine-tuning/calibrating DS18b20 thermometer via 1-wire

texts:
I am trying to enable remote reading of the temperature gauges in my furnace room by adding DS18B20 thermometers.
Since I had some Raspberry Pis and DS18B20s, and some networking equipment on hand, I decided to crimp on a couple of RJ45 jacks and chain some RJ45 sockets together, with a final network cable with a 1kΩ resistor between the data and 3v wires. This works fine, except for the fact that the temperatures diverge more than I'd like...
Executing cat /sys/bus/w1/devices/28*/w1_slave returns the temperature, but even with the sensors lying next to each other, they diverge by more than 1.5°C I have monitored them over a longer period of time, even covering them with my hand, and keeping them right next to each other.
Sample output
ad 01 55 05 7f 7e 81 66 16 : crc=16 YES
ad 01 55 05 7f 7e 81 66 16 t=26812
b4 01 55 05 7f 7e 81 66 2b : crc=2b YES
b4 01 55 05 7f 7e 81 66 2b t=27250

My setup

Is there a way to calibrate them to the same temperature? I would hate to have to take individual quirks into account, as even if I was to round to nearest 2°C there is no real way to be sure they would be in the same increment. And replacing sensors would mean recalibrating values in my code.
The reason for wanting this is that I want to detect whether the furnace is heating the water at the moment, or the water is at target temperature, or (hopefully not) that the incoming water is warmer than the outgoing water, meaning that my hot water tank is heating the house. If I cannot trust the readings, I may get too many false positives.
I have read guides like this instructable, but as far as I can see, this is gathering the calibration data, and not calibrating the actual sensor...


texts: Purpose of Charge Pump in Motor Driver IC

texts: I have seen and understood the purpose of charge pumps. Used for pumping voltage levels in case of RS232 transceiver IC's. But most of the motor driver IC's also includes a internal charge pump circuitry. What is the exact purpose of this? As voltage required for the motor is already been given through external source.


texts: Why don't we use GaN transistors everywhere?

texts:
There has been a lot of research around GaN transistors, proving that they have a very low on-resistance, low gate-charge and are very effective at high temperatures.

So why are we still mostly producing Si transistors? Even if the GaN transistor is more expensive in production, it surely must compensate if it's used in IC's?


texts: Triac Driver Datasheet - LED Trigger Current

texts:
Looking at the datasheet for MOC30xx (here: http://www.farnell.com/datasheets/1806097.pdf) I see the following note on p4 under the table outlining the respective LED Trigger Currents of the various models (my emphasis):

  All devices are guaranteed to trigger at an IF value less than or equal to max IFT. Therefore, recommended operating IF lies between max IFT (30 mA for MOC3020M, 15 mA for MOC3010M and MOC3021M, 10 mA for MOC3011M and MOC3022M, 5 mA for MOC3012M and MOC3023M) and absolute maximum IF (60 mA).

I can't get my head around why the IF has to be less than or equal
than Max IFT. Is this a typo? "Should it be All devices are
guaranteed to trigger at an IF value greater than or equal to max
IFT"?
If so, does that imply the units with lower trigger currents are the
more flexible and generic?
The prices for the components in this series are as similar, why
not just produce the MOC3023 (which has the highest Off State
Output Terminal Voltage and lowest LED Trigger current) and be done
with it?


texts: Easily controlled color LCD for hobby projects?

texts: I'm looking for some not too expensive, easy to control color graphics LCD I can use for various hobby projects, along with an AVR microcontroller or maybe an ARM in the future. The cheaper the better, but I want to be able to either control it with a serial connection, or a low-speed parallel connection. Some LCDs require multiple MHz parallel control signals to drive each pixel individually, I probably can't manage that with a single AVR. This unfortunately rules out super cheap LCDs like replacement Nintendo DS LCDs or whatever. Recommendations on LCDs that you've personally used & liked will be especially appreciated. Thanks.


texts: How do I load the Demo temperature program on an MSP 430 access point and end point?

texts:
I have successfully downloaded Code Composer Studio v5 on linux under evaluation license and I also have two devices: .

MSP430 2.4-GHz Wireless Target Board (end point)
MSP430 Wireless Development Tool (access point)

My understanding is there is a temperature sensor on one of the devices and it wirelessley sends a signal to the other device indicating the temperature.

My question is: how do I download, install, compile, and execute this temperature demo on Code Composer Studio v5?

I would appreciate all / any guidance regarding this.  A tutorial that has step by step instructions would be perfect.

CCS is complaning that "TIMSP430-USB.xml" does not exist.  What should I do?

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<configurations XML_version="1.2" id="configurations_0">
<configuration XML_version="1.2" id="configuration_0">
    <instance XML_version="1.2" desc="TI MSP430 USB1" href="connections\TIMSP430-USB.xml" id="TI MSP430 USB1" xml="TIMSP430-USB.xml" xmlpath="connections"/>
    <connection XML_version="1.2" id="TI MSP430 USB1">
        <instance XML_version="1.2" href="drivers\msp430_emu.xml" id="drivers" xml="msp430_emu.xml" xmlpath="drivers"/>
        <platform XML_version="1.2" id="platform_0">
            <instance XML_version="1.2" desc="MSP430F2274" href="devices\MSP430F2274.xml" id="MSP430F2274" xml="MSP430F2274.xml" xmlpath="devices"/>
        </platform>
    </connection>
</configuration>


texts: How does a constant current (CC) power supply regulate voltage (V) in parallel circuits?

texts:
I see that some power supplies provide a wide range of output voltages meanwhile maintaining the current.

For example: 2.7 A, 20-36 V output.

I understand that the voltage rate will depend on the end-unit consuming the power (eg., an LED chip).

What happens if the output from the PSU is divided into two parallel connections, one lead connected to an end-unit needing to use 27v, and another using 30v?

What happens internally? What's the reason why for the end result?

Example:

[[80W 2.7 A PSU with 18-30 V]] |--> (21-24) V, 1 A Diode
                               |--> (27-31) V, 2 A Diode

How would it regulate the voltage in each case?


texts:
I'm looking for a embedded controller for a project. I don't really know what's out there so I don't know where to start looking.

My requirements are:

Support for significant amounts of I/O

~150 GPIO (directly or via expanders)
Several SPI (or  I2C) interfaces

Reasonably powerful, able to simultaneously do

~3MIPS
~1MB/s I/O (via SPI/I2C)
<1MB/s of eathernet traffic
And enough room left over for the parts I'm forgetting

Can be used from a standard environment (c, gcc, etc. Not a custom language and IDE)
Simple to use (one, maybe two chips, etc.)

My wants are:

A "standard" architecture that has many implementations (to minimize the effort if I need to switch chips, for some reason I'm leaning towards ARM)
Available on low cost dev boards.
Available as chips (mounting a board on a custom PCB seems silly to me)


texts: 16 Segment LED, 4 Digit, Common Anode (4 sets)

texts:
I'm trying to make an F/A-18C UFC like this:

Now a while ago I bought 6 x "4 digit 16 segment" LED, which happen to be common anode (DataSheet)
What i am looking for is a way to drive all 4 using the minimum of wires - I guess I prefer I²C (IIC) but will work with what ever I can use

Note: I tried something with a HT16K33 IC, but apparently that will only work with Common Cathode, so this HT16K33 but its Common Anode version would work perhaps?

Thank you, and please let me know if you need more info, or suggestions to clarify my question


texts: I am building a circuit from a 4.2 volt battery and I cannot use resistors to lower the current, and I cannot calculate the load resistance but I want to protect the switch from over current, and short circuit. I was thinking of using a diode. To the order of positive terminal, load, diode, switch, negative terminal. I need max amps to pass through the load, and minimum amps to pass through the switch. Will that work?


texts: Displaying 4 different characters on a seven segment display with Verilog?

texts:
I'm programming a blackboard using Verilog. The hardware information is provided in the link above.
My goal is to light up the seven seg. display such that I can see characters on the seg. display after programming. I would like to add the option of turning the display off at the push of a button, but I need to overcome the issue of lighting up the display with different characters first.
I'm a student learning to program and I thought of achieving my goal by studying the schematic. I found that if I could manage to do the following:

b0001000 (turn "off" D, should display A)

b0100100 (turn "off" B and E, should display S)

b0110000 (turn "off" all except B and C, should display I)

The problem I saw was that all 4 segments displayed the same items. I found this forum to be very helpful as far as providing information but I have trouble understanding because I'm still learning all the terms. One of the post mentioned multiplexing and charlieplexing, and I understand the concept just not how to implement said idea into the device. I feel like the answer is staring me in the face, but IDK. Additionally, in the 3rd link from the top it seems that I may be able to control the displays using the following: SVN_SEG_DATA (0x43C10004 - 0x43C10010) but that's as far as my brain got.
Any help would be greatly appreciated, thank you!
https://www.realdigital.org/hardware/blackboard
https://www.realdigital.org/doc/586fb4c3326dcd493a5774b2a6050f41
https://www.realdigital.org/doc/ad0c5fbdaddde0e930abbd9eda84f88b
How to display character on multiplexed seven segment?
`timescale 1ns / 1ps

module Seven_segment_LED_Display_Controller(

output [3:0]seg_an,
output [7:0] seg_cat
//input  btn
);

//assign seg_an = btn;
//assign seg_an[1] = seg_an[0];
//assign seg_an[2] = seg_an[0];
//assign seg_an[3] = seg_an[0];

assign seg_an[0] = ~seg_cat[0] & ~seg_cat[1] & ~seg_cat[2] & seg_cat[3] & ~seg_cat[4] & ~seg_cat[5] & ~seg_cat[6] & seg_cat[7];
assign seg_an[1] = ~seg_cat[0] & seg_cat[1] & ~seg_cat[2] & ~seg_cat[3] & seg_cat[4] & ~seg_cat[5] & ~seg_cat[6] & seg_cat[7];
assign seg_an[2] = ~seg_cat[0] & seg_cat[1] & seg_cat[2] & ~seg_cat[3] & ~seg_cat[4] & ~seg_cat[5] & ~seg_cat[6] & seg_cat[7];
assign seg_an[3] = seg_an[0];

endmodule


texts: How to track the 3d movement of a small animal in a 4x4x8 meter cage?

texts:
I need to track the movement of a small animal (60 grams) in a cage which contains plants, shelter, branches and so on. I need all three coordinates in real time.

Spatial resolution should should not exceed 10 cm.
Temporal resolution shouldn't be less than 3Hz.
Recording time would be as long as possible but not shorter than 3 hours.
Ideal solution would be unintrusive to the animal.

So far I have considered these options and their drawbacks:

Cameras: There would be at least three cameras and the position would be obtained by image analysis of the resulting frames. This would be very difficult if the animal is out of sight (in shelter or behind leaves).
IMU: I have no experience with IMU and the animal cannot carry more than a few grams.
GPS-like methods: The animal would carry a small passive RFID chip, there would be several sensors outside, and the position would be computed based on trilateration. However I have no experience here either and I do not know if this is possible for such a small space.

I have an unlimited budget even for high end devices.


texts:
I am designing a universal shift register of 4 bits in VHDL.

I am also using Xilinx software to simulate the VHDL code.

I have managed to write the code which from reviewing it a couple of times, seems without errors (I understand sometimes the code can compile successfully but in fact there would be a few problems in there which aren't so obvious).

the code:

entity USR is
Port ( clk : in  STD_LOGIC;
       rst : in  STD_LOGIC;
       sir : in  STD_LOGIC;
       sil : in  STD_LOGIC;
       d : in  STD_LOGIC_VECTOR (3 downto 0);
       q : out  STD_LOGIC_VECTOR (3 downto 0);
       s : in  STD_LOGIC_VECTOR (1 downto 0));
end USR;

architecture Behavioral of USR is
signal temp: std_logic_vector(3 downto 0);

begin
process(rst,clk,s,d,sir,sil)

    begin

    if rst='1' then
    temp<= "0000";
    q<= "0000";

    elsif (clk='1' and clk'event) then

        case s is
        -- PARALLEL LOAD
        when "11" =>
        temp <= d;
        q <= temp;

        -- SHIFT LEFT       [0] [0] [0] [0]
        --                  [0] [0] [0] [sil]
        when "01" =>
        temp <= d;
        temp(3 downto 1) <= temp(2 downto 0);
        temp(0) <= sil;
        q <= temp;

        -- SHIFT RIGHT      [0] [0] [0] [0]
        --                [sir] [0] [0] [0]
        when "10" =>
        temp <= d;
        temp(2 downto 0) <= temp(3 downto 1);
        temp(3) <= sir;
        q <= temp;

        -- HOLD
        when "00" =>
        temp <= temp;
        q <= temp;

        when others => null;

        end case;
    end if;
end process;

end Behavioral;

I tried running this on Xilinx ISE simulator but when I simulate the waveform, there seems to be no changes to the outputs.

As the image above shows, when s = "11", the outputs q should be the same as the inputs d as

when "11" =>
temp <= d;
q <= temp;

Therefore the signal temp is assigned with input d and then the output q is assigned the signal temp.

Theoretically something like this should show the outputs q to be the same as input d

I cannot find a fix for this or infact all the modes (s= 00, 01, 10, 11) show no changes in the output.

Is there something that I missed?


texts: What does "Wait State" access mean on a MCU's datasheet and how does it affect me?

texts:
I'm considering using an AT32UC3B in my project (the Super OSD Pro version.) However, something about the datasheet has me worried.

Page 31

0 Wait State Access at up to 30 MHz in Worst Case Conditions
1 Wait State Access at up to 60 MHz in Worst Case Conditions

What is a "worst case condition"? The output stage for my OSD needs to be able run at 60 MIPS (the processor's maximum operating frequency), and I presume a "wait state" means it has to wait to load data from the memory... which would limit me to <60 MIPS.

I suppose, worst case, I could load the code into RAM and execute it from there (I presume this is possible with AVR32s?), but it still has me confused.


texts:
I have read that the power radiated by an antenna is equal to the flux of the Poynting vector through any closed surface that includes the antenna.

This fact is for instance exploited to calculate the radiated power in the Fraunhofer Region, in which the Poynting vector has a radial direction: if we choose a sphere as our closed surface, we get:

I do not understand why we may calculate the flux by choosing any closed surface: why is the radiated power independent from the choice of the surface?


texts:
I'm not very good at this but my question is: why does the output waveform get offset by ~0.4V when passed through the op-amp (LM386)? It is initially a sine wave with no DC offset, 1Hz frequency, and 0.1V amplitude.

After adding the load resistor as Andy said, I get the graph I want. However, now I want to pass that output signal through a diode bridge to rectify it. Am I doing something wrong? How come it gets offset again and the rectified graph isn't actually rectified?


texts:
I want to regulate a voltage suppose 60 V, but I only have an LM317 (or any similar voltage regulator IC) with voltage regulation range of 30 V max.
Is there any way I can use a combination of two or more LM317s to make a voltage regulator that can regulate 60 V (or more)?
Can I feed the positive output of one LM317 as ground in the 2nd LM317, and measure the voltage between the output of the 2nd LM317 and ground of the 1st LM317?
I do not have any particular use or reason to ask this question. I am just curious if I can do that. This is just a hypothetical situation.


texts:
How exactly are you supposed to run the ATtiny13 at 16MHz or higher if you really have to?

What is the method and what external circuitry do you need to add?

Is it altogether more hassle than using an ATtiny25/85?


texts: I'd like to replace NPN transistors with NMOS in this simple circuit

texts:
I'd like to replace a pair of NPN transistors and their associated base resistor with two small N-channel MOSFETs, such as the ESD protected 2N7002K.

I've drawn the two versions of the circuit (left side is known good, right side is what I'd like to do) but I have no idea if it's going to work. PCB fabrication takes time and I don't have the parts on hand to prototype...

Should my replacement circuit work like the original, or am I misunderstanding something important?

Thanks!

See also:

Work in progress: the project this is going to be used in,

Networked Thermocouple Reader with Integrated Display

Okay, it took a while for me to receive the 2N7002K, but now I can confirm this modification actually works! All seems good on my modified WeMos D1. Now I'm waiting for my own circuit to come back from the PCB fab, and I'll test the modified circuit again and report on the results.

Replacement solder is Sn42Bi57Ag1 and it looks a lot shinier than the original lead-free alloy.


texts:
I'm struggling to understand couple of basic points regarding MOSFETs.
Below is an output characteristics of an N-channel MOSFET:

And below are definitions of \$ R_{DS(On)} \$ from two different sources:

Is the power equation \$ P = I_{D}^2 * R_{DS(On)} \$ only valid for the linear region?
I can see that the resistance is almost constant in linear region so it makes sense to use \$ P = I_{D}^2 * R_{DS(On)} \$ formula to calculate the power.

But what if the MOSFET is in the saturation region? \$ V_{DS} \over I_{DS} \$ is not constant with increasing \$ V_{DS} \$ since Id almost saturates.
It seems \$ R_{DS(On)} \$ is meaningless in saturation region. Which formula should be used for calculating the power in saturation region? \$ P = I_{D}^2 * R_{DS(On)} \$ or \$ P = V_{DS} * I_{DS} \$ ? If power for both regions are calculated different ways, should we each time check the saturation condition \$ V_{GS} > V_{Th} \$ and \$ V_{DS} > V_{GS} - V_{Th} \$ and depending on that decide which formula to be used?

Secondly how does the current flow after pinch off point since the depletion layer blocks/closes the inverison layer as in the below illustration:


texts:
I've a problem with the definition of an entity. I'm writing a wrapper that accepts several generic. Among these generic there are some boolean values that have the function to enable or disable the transmission of some input signal to the output of the entity. I'd like to have the width of the output signal related to the boolean values. This is what I want to do :

entity of DUT is
   generic(
     DATA_1_WIDTH : natural := 16;
     DATA_2_WIDTH : natural := 16;
     SWITCH_1 : boolean := FALSE;
     SWITCH_2 : boolean := FALSE;
     ....
     );
   port (
     clk : in std_logic;
     rst : in std_logic;
     DATA_1 : in std_logic_vector(DATA_1_WIDTH - 1 downto 0);
     DATA_2 : in std_logic_vector(DATA_2_WIDTH - 1 downto 0);
     ....
     DATA_OUT : out std_logic_vector);

Where the width of "DATA_OUT" change with the values of the switches :

When SWITCH_1 = TRUE and SWITCH_2 = TRUE => width of DATA_OUT = DATA_1_WIDTH + DATA_2_WIDTH + constant;
When SWITCH_1 = TRUE and SWITCH_2 = FALSE => width of DATA_OUT = DATA_1_WIDTH + constant;

And so on.

Can someone tell me a way to do this ?


texts:
Does it exist a shielded version of 2.54mm pitch breadboard jumper cable wires?
Thin flexible wires, Gauge AWG 24-28. I want use shielded wires for JTAG cable, to reduce electrical noise from affecting the signals, minimize capacitively coupled noise from other electrical sources, the shield act as screening only.

EDIT: I find the suitable cable, from TE Connectivity / Raychem. P/N 55A1114-26-9-9CS2275 Unfortunately, it's non-stocked, very difficult to obtain.


texts: USB2512 - Too low input voltage in datasheet

texts:
I have two USB2512BI-AEZG(datasheet) ICs and would like to drive them using only one external crystal for well known reasons.

What is misleading me is ultra low input low voltage specified in the datasheet

Driving second USB_HUB_IC XTAL_IN input pin from XTAL_OUT pin of first USB hub IC is not an option due to power management (there will be situations where only one USB hub will be working).

I simply cannot find any clock buffer with such low output level(this is not even LVCMOS) - even with 1.8V supply Output Voltage High of clock buffer will be 0.35V max.

Is this a glitch in the datasheet? Does clock buffer which I need even exist?


texts: Changing the power factor of a circuit when connected to transformer

texts:
There is a step-down transformer with a primary voltage rating of 120 volts, a secondary voltage rating of 48 volts, and a VA rating of 1 kVA (1000 VA).
The maximum secondary winding currents can be determined as such: 1000VA / 48V = 20.83A.

So if I connect a pure resisitive circuit/load to the secondary which is 3 Ohm, the current through the secondary winding will be 48/3 = 16A rms which is smaller than 20.83A rms.
I think it means this situation is acceptable.

Now when this 3 Ohm is connected to the secondary and if I play with the circuit adding a series inductor ect.(keeping 3 Ohm and without adding any extra resistor) and make the load's power factor 0.5 instead of 1(pure resistive) what would happen? Would the current increase? How can this situation be analyzed?


texts: Are benchtop lab power supplies usually isolated?

texts: I want to avoid ground loops in a PCB which has several supplies, but I would like to know in general if benchtop lab power supplies are supposed to be isolated - there is not really much point in measuring that on mines, since I would like to know in general for future projects.


texts: Reading a MD25Q128SIG SPI flash memory with raspberry pi

texts:
I'm trying to read a MD25Q128SIG SPI flash memory with my raspberry pi, you can find its datasheet here: http://www.firstjit.com/Uploadfiles/20160121152131319.pdf

Here are raspberry pi pinouts:

Here are the pinouts of my chip:

and its descriptions:

I've connected like this in my raspberry pi:

FLASH / RPI

1 - 24

2 - 21

3 - ?

4 - 9 (GND)

5 - 19

6 - 23

7 - ?

8 - 1 (3.3v)

My question is: where do I connect pins 3 and 7 of my flash memory? Pin 3 is write protection. Something should be done to prevent writing, I guess. And 7, which is hold/reset, what do I do? Are the other pins correct?
Also, how can I read my memory with this pinout using python and save it to the disk?


texts:
Ok, I understand similar questions have been asked in the past, please bear with me. Here is my problem, I have 2 I2C devices to be connected to a single I2C bus. They happen to be the same component and have the same hardware address. The address cannot be changed. My application requires the minimum possible latency. My plan is to use MOSFETs on the SDA line so that I can control when each of those devices is active. For each device there will be a MOSFET and by switching that on and off, I should be able to enable and disable them.

Would this work? If not, what would?

UPDATE: Ok, so I got my hands on MOSFETs (IRF520). I hooked up a digital pin on my arduino to the gate and the SDA lines to the source and drain (Arduino end to drain and device end to source). The thing didnt seem to be working, it gave me wrong values and would just stop entirely on bigger values. So I decreased the I2C frequency to 100kHz from 400kHz and it worked. I know the problem is in the FET because it works fine at 400kHz when the sensor is connected directly. Trouble is, I need it to work at 400kHz. What causes this issue and how can I rectify it? I was considering switching to the IRL540, would this help?

My messy diagram is as follows (I plan to repeat it for each sensor):


texts: Currently I have a serial number hard-coded in my firmware for a design I'm working with.  The firmware can read and report back the serial number.  That works fine for what I need.  The trouble is that each new serial number requires me to change my code and recompile.  This is cumbersome when there are a lot of units to be built, has the possibly to introduce errors, and is all-around bad practice.  The serial numbers are given to me and the hardware design is set in stone, so I can't add any features in hardware to serialize the units (EEPROM/Silicon ID Chip/Pull-Ups).  What I would like to do is locate the serial number at a fixed address, compile the code once, then edit that address in the compiled HEX file for each new serial number.  The number is referenced in several places, so ideally, I want to define & locate it once, then reference that "variable" everywhere else in my code.  Does anyone know how to locate constant data at a specific addressable memory location of my choosing, using the C18 Compiler?  Is there a better way anyone can suggest?


texts: What is the most straight-forward way to simulate this circuit?

texts:
I would like to verify the function of this circuit, as well as determine the power usage and heat generated by each component. (I need the latter for doing a thermal analysis)

The circuit has been designed in EasyEDA, and I've tried simulating with same SW (it uses NGspice), but I get the "unknown subcircuit" error for every component but the resistors.

What is the most straightforward, but acceptable, way to simulate/test this? For the calculations of power, I can accept up to 50% error. I'm considering the following options:

Making the missing Spice models, based on the models of similar components and then changing the key values based on datasheet.
Using another simulation SW
Replacing the components with ones that have spice models, for the simulation and possibly also for the final design.
Order a pre-assembled test PCB where I can isolate parts of the circuit with jumpers, for example, and test with this. (The components are all SMD so breadboarding is no option)
Order the equivalent THT components and test on breadboard.
Doing calculations.

And combinations of the above.


texts: How to communicate with ESP32-WROOM-32E and program it using the same pins

texts:
I'm designing a product that will have an optional add-on board that contains a ESP32-WROOM-32E which will be used to add wifi functionality.
Communicating between the ESP32 and my primary MCU a STM32H7 isn't too hard. But I would like the STM32H7 to be able to write the firmware of the ESP32. The purpose being that I don't have to worry about firmware version mismatch between the 2 boards. The main board will simply reflash the add-on board if it's the wrong version.
I'm new to the ESP32, and it's not totally clear to me how it's programmed. It looks like most dev boards use USART0, but that presumably uses a bootloader (and therefore another piece of firmware to track for compatibility).
What are the minimum pins I can connect between the ESP32-WROOM-32E and my main MCU, that will allow me to talk to it, and also flash the firmware? It could use the following configurations, in order of desirability:

Without using a bootloader

Using a standard bootloader

Using a custom bootloader


texts: What's the reason to make power supplies external?

texts:
Many years ago most electronic devices had internal power supplies only - there was a mains voltage cable running into the unit where mains AC would be converted and distributed for consumption. That was typical for shavers, TV sets, monitors, printers, other stuff.

Now I see more and more devices that have external powers supplies. Either it's a box with two prongs that is plugged right into the outlet or it's a separate box with a mains cable running into it. Either way it has some 12V to 36V DC output cable that is then plugged into the device.

I could see the following reasons for such design:

easier to suite for different voltages and outlets - one single model of device can be equipped with an adapter suitable for the market it targets
less wire with mains voltage - less metal and insulation
less wire with direct mains connection - lower risk of electric shock.

What are actual reasons for making power supplies external?


texts: What is the correct wire size to run to a 12V 1.5 amp window blinds motor that is 47 feet from the DC transformer?

texts: I read somewhere that an 18/2 wire could be used to connect a transformer to my window blinds motor (12V 1.5 amps).  However, it didn't say anything about the distance. Since I am running it inside the wall, I was looking at getting "UL and cUL Listed SPT-2 Wire" 18/2 electrical wire.  Will the distance cause a problem?


texts:
Our company is exporting our product to European market. To sell it to Europe we need CE mark. so we let the test lab test only EMC(EMI+EMS) because our products usually don't equip any RF nor AC power.

Now, we are developing a board type product without housing. The board type product's purpose is very same to the Arduino. So the board can be used in lab. But it can be an IoT Gateway product when the end user implement a product by using our board. And the board doesn't include any RF part and it is powered by DC an adapter.

I think that we need to the EMC test as same to the products which have enclosures.

I have some questions at this point.

When we do the electrostatic contact discharge, contact point should be all point where our fingers could be contacted. If we do the contact discharge test to the very important point, for example: MCU lead, it might be failed.

Our partner test lab says we need an enclosure for the test of the non-housing board.

Is it correct?
How do you test for the board type products?

cf. I have tried to find Arduino test report for reference but I have failed.

Thank you very much.


texts:
I have found that a commonly mentioned definition for the resonance frequency in an RLC circuit is defined as the condition where the capacitive and inductive reactances cancel each other, resulting in a purely resistive impedance.
However, though the simplest RLC circuits (e.g RLC all in series or parallel) show maximum/minimum current at the resonance frequency defined above, this is not generally the case.
For example, the RL-C series-parallel circuit

has a resonance frequency at
$$\omega_0 = \frac{1}{\sqrt{LC}}\sqrt{1-\frac{R^2C}{L}}\tag{1}$$
by the above definition, but shows a minimum current at
$$\omega_m = \sqrt{\sqrt{\frac{1}{L^2C^2}+\frac{2R^2}{L^3C}}-\frac{R^2}{L^2}}\tag{2}$$
My question is why is it defined this way? Would it not be more practical to define it as being at the maximum/minimum magnitude of impedance so that the observables (current and voltage) are also at extrema?


texts: Can i use a SSR for switching a fluorescent light?

texts: Can I use a SSR for switching a fluorescent light on or off? Specifically, can the SSR last for a long time, and can it withstand a very large number of on/off switchings? I would also appreciate a sample circuit related to this, or references.


texts:
I've found this Function Generator in the deep of school's Lab:

I wasn't able to find an user guide or any similar document. I'm not sure on how to correctly use it.
For example, I don't know:

Which output to use: Hi, Lo, Gnd ?
What are and how may I use Auxiliary Output?

Any idea? Thanks in advance.


texts: I am in a little trouble and seeking some help. I got a bunch of mixed up diodes from an old collection. I know there are few diodes which are Germanium Diodes. But they look so similar to 1N4148 and similar transparent case diodes. The problem is, the diodes are old (but working) and it's very difficult to read the numbers printed on them. How can I identify and distinguish Germanium diodes? Can I measure something with a multimeter, or create a simple circuit to identify the Germanium diodes. I am looking for identifying diodes like 1N60 and 1N34A. I would highly appreciate your help!


texts: How to solve a specific circuit with dependent sources

texts:
I am trying to solve this circuit:

V1 is the positive side of Vonc and V2 is the positive side of Vint

My advisor has us modeling this circuit with respects to some biomedical applications. The dependent sources are actually dependent on things that are static in our test case. Since Vonc and Vint aren't referenced to ground. I also need the current through Rint. V1 and V2 are also needed for this, but I'm not exactly sure how to solve it with all these sources.

This is my advisor's equation:

V1 = Vpre*(Rpre + Rint + Rpost)/Rpre + (V1_initial + Vonc - Vint) * (Rpre + Rint + Rpost)/Rint + Ppost * (Rpre + Rint + Rpost)/Rpost

However, I don't really know if this is correct because of his multiplication of the whole circuit by those 3 resistors. If this is correct, could someone explain it to me? Thanks!


texts: how to understand grating lobe problem in broadside array

texts:
In a broad side array we have a radiation pattern for which the Array factor development is shown bellow.
I can understand what is the problem that is called "grating lobe".
Below we have the array pattern expression. How can I see the grating lobe problem from it?
In the last photo we have an expression but I cant see the intuition of how to get it?
Thanks.


texts: Designing a battery capacity monitoring system for AGM lead acid battery

texts:
I would like to design a battery capacity system for my AGM lead acid battery (12v, 40Ah). My idea is that I have values of the battery voltage and its corresponding capacity, which I will use to plot a curve which I can then interpolate with the current voltage reading. I will be measuring the voltage of the battery with a INA219 chip.

I contacted the company that manufactures the battery and was told that designing such a battery capacity monitoring system is not useful as an aging battery would eventually have reduced capacity despite an unchanged full charged voltage reading. They gave an example where the battery might start of with say 13.2V but may have reduced capacity (by 10Ah) in a few years while still retaining its maximum voltage reading (13.2V). Hence, plotting such a curve may not be useful. Also, I would not want to fully discharge the battery with the intention to regularly update changes to this voltage-capacity curve, since doing so would significantly impair the lifespan of my battery.

Does anyone have any thoughts on alternative methods that I can monitor the capacity of the battery while taking into account capacity changes caused by an aging battery? Otherwise how can I continue using the voltage-capacity plot method while taking into account the changes caused by aging?


texts: Grounding paths of a capacitor discharge circuit

texts:
I would like to know how to properly ground the following circuit with 12V input and 390V output.
Do I attach all the ground symbols to negative side of my 12V dc supply near input and all high voltage ground symbols to  ground on output side of dc boost converter?
I was wondering would the feed capacitor close to input (220uF, 25v) blow since it’s positive side is connecting to anode on SCR and cathode would connect to the capacitor.
!


texts: How to write a linear interpolator in VHDL?

texts:
I have to create a linear interpolator in VHDL.My interpolator has to take 2 known values and using a factory level of 2 in interpolation return the interpolated value.Our signal is campionated with a period of T

This is the architecture that I should design.U can have a value of 0 0,25 0,5 0,75.The user puts an input of Y((n+u)T) and I should return the sum of [Y(n+1)-Y(n)]u +Y(n).What I have difficult finding is how to go to lut memory and how to perform calculations of multiplication in VHDL.Sorry for my english


texts:
I have been designing RF PCBs for a year for an RF front-end system.

One of my PCBs has very strict constraints about its size measurements.
So, I should design it very densely.

The problem with this PCB is that there is a microstrip line so close to a GND mounting via as can be seen from the figure.

Also, I should use the copper zone due to GNDs of capacitors, inductors, ICs etc. So I cannot delete the GND copper zone around there.

I used Rogers4350B with the thickness of 30MIL. So, microstrip line's width was calculated as 1.65mm. This line comes from a coupler topology, so I cannot change the line from microstrip to coplanar line.

My question is:
How far the copper zone can get closer to microstrip line without deteriorating the microstrip line topology?

Is there a rule of thumb about these kinds of problems?


texts: Why does current flow through 1M resistor in this case?

texts:
I asked a question about protecting a circuit from current spikes from a piezo electric device: Protecting circuit from piezoelectric disc voltage spike. Someone graciously provided me with a solution in the image below. I have a follow-on question.
Assuming that the piezoelectric device is struck very hard, it's voltage can spike to 30v. That's going to generate current that splits and some goes through the 1M resistor, some goes through the zener diode, and some goes out as signal to an IC (an ATTiny85 in my case). It's my understanding that electricity tries to follow the path of least resistance. If the voltage/current is high enough it will overcome the zener diode and flow through that path. Why would any electricity ever take the 1Mohm path if that path provides such high resistance? Also, doesn't the chip provide for an "easier" path for the electricity to flow through as well so wouldn't it just want to flow through there and fry the chip?


texts: Why do people state their circuit uses  transistors?

texts:
I'm pretty new to circuits, and still don't know exactly how transistors work, but when I search up a tutorial for circuits that include Transistors, they all have in the title, "One Transistor This", "One Transistor That".

Is there any specific reasoning behind that?
What is so special about Transistors?
Why not include "2 Capacitors"?

Example, I searched up "One Transistor FM Receiver", I know that's a little cheaty, but WHY do all these video's have it in the titles?


texts: Remainder of a 16-bit number divided by 3

texts:
I have to design a combinational logic circuit which accepts a 16-bit number as input and then calculates the remainder of the number divided by 3 as its output.

I originally had no idea how to proceed and if there is any convenient algorithm for finding the remainder.

Based on the link provided by @RJR I learned that the following recursive algorithm might be a possibility:

x mod 3 = ((x >> 2) + (x & 3)) mod 3

Can this be implemented with combinatorial logic?  What sort of approach would be taken to break down the problem into functional blocks which can then be reduced to gates?

Is there a better solution?

UPDATE:
If I separate the bits 2 by 2 and add them, and do the same with the result, then the remaining number would be between 00 to 11. For 00 and 11 the remainder is 0, for 01 the remainder is 1 and for 10 the remainder is 2. How can I add 8 2-bit numbers and get a (let's say) 6-bit answer? The answer to this can solve my problem.


texts: How do I draw the truth table of an adder/subtractor that sets flags, and those flags are the inputs of a comparator?

texts:
How do I draw a truth table of a circuit that :

starts off with a full adder/subtractor
outputs the result F based on the two inputs (add if opcode is 0, subtract if opcode is 1)
then output three flags:

N (0 if F is positive or 0, 1 if F is negative)
V (0 if no overflow, 1 if there is overflow)
Z (0 if F is non-zero, 1 if F is zero)

then i want to input N, V, and Z into a comparator which also has two other inputs:

OP1 (0 if not checking for A=B, 1 if checking for A=B)
OP2 (0 if not checking for A
finally I want to output X (0 if comparison is false, 1 if comparison is true)

i don't know if this is vague but i've been searching for resources online and i can't find or figure out the logic behind determining N, V, Z :(
any help even just a small hint would be appreciated

UPDATE

to get from N,Z,V,OP1,OP2 to X, I think i have to

((N xor V) and OP2) or (Z and OP2) = X
my main problem is now just how to modify the full adder in order for it to output the three flags


texts: I've managed to break off a smd ceramic 1206 capacitor of a motherboard I am working on, I'm am new to electronics, so be gentle! Anyway this damn capacitor has vanished into the place where all missing tiny components seem to go! I cannot find any schematics for the board to see what I need to replace. Good news is I have two boards, I need both, so no I cannot swap it out. So how do I test the capacitor to replace the missing one as there's no markings at all? I have a Multimeter only and it's basic AstroAI AM33D. Any advice would be very helpful! I've attached a photo sorry about the quality the parts are small.


texts: I need help finding out how to prevent my components from exploding (TinkerCad)

texts:
Basically, I'm making a logic circuit on TinkerCad and I need to turn on a seven-segment display but some of my components explode and I've got no idea how  to solve this.
The components I'm using are:

74HC04 NOT
74HC11 AND
74HC32 OR

Any help will be greatly appreciated!


texts: Atmel SAM E70 SPI Chip-Select (SPCS) lines

texts:
I deliberate the datasheet of Atmel's SAM E70 Cortex-M7 and i have a confusion about SPI.
When SPI is in master mode, it uses NPCS lines for Chip Select (Slave Select). But i can't find a report which explain that those lines used all of them (as outputs) by the peripheral, or there's able to using one of them.
Therefore, it is forced by hardware to make all SPCS lines as outputs in master mode? Or it is possibility to get only one SPCS line, as chip-select, only SPCS0 for example?

By the datasheet:

The SPI operates in Master mode or in Slave mode. The SPI operates in Master mode by writing a 1 to the MSTR bit in the SPI Mode Register (SPI_MR).

Pins NPCS0 to NPCS3 are all configured as outputs.
The SPCK pin is driven.
The MISO line is wired on the receiver input.
The MOSI line is driven as an output by the transmitter.


texts: If I keep the shaft of a DC motor in place while it is running does this harm it in any way?  Is it bad for it at all?


texts: Tools and libraries to use with J-Link OB and CoreSight

texts:
I have a system with including a Beagle Bone Green board, a J-Link OB module and a Cortex-M4 microcontroller (see figure).

I would like to use the DWT and ITM features but don't quite understand how I can configure and access those register for tracing an application.

Is is possible to use the CSAL library for that or does it not work with J-Link? Or is there another c or python library so that I don't have to program the register accesses in my c files?

Thanks you for any hints


texts: Is there a conductive spray (not paint, ink and tape, only spray)?

texts:
I heard that there is a conductive spray.
So I'm looking for a conductive spray (not paint,ink and tape).
But I could not find sites for selling conductive sprays.

I bought a silver zinc coat spray. I sprayed on the paper and tested for conductivity. Unfortunately, the electricity did not flow.

Does anyone know sites for selling conductive sprays?

Please, let me know sites for selling conductive sprays.


texts: Loss due to impedance matching in a filter

texts: I have a quite basic question, after starting to re-read some RF theory. If a voltage source has a resistance of 50 ohms, and the equivalent impedance of a connected bandpass filter and its load are 50 ohms for a perfect match, won't there be significant loss - so much so that the passband will disappear entirely? If the bandwidth of a filter is defined as the portion where the gain is above 1/sqrt2 ~ 0.707 V, and the highest the output can ever get is 0.5 V due to the voltage divider rule, is it impossible to have an impedance matched band pass filter? Why would someone want to have a matched preselection filter between an antenna and an LNA if matching losses might cause the weak signal to be out of amplification range?


texts: I2C only works when probed or loaded with 1Mohm

texts:
I am trying to troubleshoot communications between an msp430fr5847 (master) and a slave sensor with unknown I2C chip (part of an industrial sensor)

I am having issues with a new batch of sensors where my data is being returned with all zeros, however when trying to troubleshoot with my Saleae logic pro (2Mohm, 10pf), or my oscilloscope (10Mohm, 50pf) the system works perfectly when probing the SDA pin.

Troubleshooting further the circuit works correctly if I add a 1Mohm resistor between SDA and ground, but does not work if only adding a 10pf or 100pf capacitor.

I am using 4.7k pull up resistors to my 3.3v rail.

What could be causing this issue, and what can be done to troubleshoot without unintentionally fixing the problem.

EDIT: 19/07/2017
Here is a quick scope trace of my signals.

Something else I forgot to mention is that only probing SDA causes the board to work, probing SCL or my interrupt line does not get it to work properly.

EDIT: 21/07/2017

The plot thickens, it appears that connecting a different oscilloscope does not get the circuit to work correctly, and it can be seen that the only difference is that an ACK is not being transmitted.

In the above picture, the blue and green traces are the SCL and SDA when the circuit is not operating correctly. The yellow and pink traces are from when I also connect my Saleae logic to the SDA Pin and ground but without plugging in USB (trying to avoid ground loops).

To add a bit more background on the sensor it is an industrial pressure sensor we buy in from the manufacturer. We have previously designed and tested these PCBs with our first batch of sensors. We have recently received a new batch and are now encountering these issues. I have done a bit of investigation and I strongly suspect (after googling unique looking sentences from the datasheet) that internally the sensor uses a ZSC31014 or similar, PDF datasheet HERE

EDIT: 26/07/2017

So hopefully the last installment in solving this issue, as per SamGibson's detailed answer I have implemented the fix of setting the high bit of the address to mask the glitching at the end of the start bit.

This has worked mostly with data coming through as expected, however now it appears that in in the first read command after a write (if that is the correct term for a group of i2c bits), the slave attempts to ACK one bit early (in the position of the write bit). I can tell that it is the slave pulling the line down through adding a small (47 ohm) resistor in series with the SDA Line.

I would usually start this as a new question but when I attach the same scope that had no effect in the above troubleshooting, this issue seems to go away, this really does seem to be a borderline issue as even if I attach the scope probe, without connecting it to the scope the issue is solved so I am assuming it is a capacitance issue.

Plot of issue with no scope attached

Plot of issue with scope probe attached, but not attached to scope, noting the slightly higher voltage when the slave pulls down the write bit instead of the ACK bit.


texts: PWM rise and fall time, frequency and duty cycle setting to control voltage using a MOSFET

texts:
I'm designing a circuit to control voltage between 2.8 and 4.0 volts using a PWM and 3 DMN1019USN-13 MOSFETs in parallel (to handle the load current), the PWM square wave will be low level 0v and height level 3.0v..

The load is a resistive heater (0.2 Ohms) between the positive pole of Li-ion battery (4.2v - 40 amp nominal current) and the drain pin of the MOSFETS.

A shunt resistor of 0.01 Ohms attached between source pin of MOSFETS and the negative pole of the battery to estimate the current.

Question How much rise and fall time, frequency, duty cycle setting to be used with this MOSFET, the idea is that I cannot determine these factors from datasheet and need help to get a full knowledge in this field..

Below is the datasheet for reference.

DMN1019USN-13


texts: Bidirectional connection between a device and a webserver

texts:
I'm a software developer, I'm in no way familiar with electronic devices but I'm working with people who are familiar with them. Our problem is: We need to design a small device able to communicate with a webserver.

We have covered the device-to-server using http requests, but how can we talk to the device from the server?

Requirements:

Must be wireless

Range: I believe it will be via GSM, so I understand it'll require to be within signal radius.

Size: 4cm width, 2cm height, 2cm wide aprox.

Power consumption: I couldn't say, it'll probably need to work with less than 600mAh as battery source.

Thanks in advance for any tips, guidance you can give us.


texts:
About a week ago I have taken my phone (s7 edge) off the charger, used it for about a minute, the phone turned itself off and the screen went black. I have tried turning it on, nudging the battery by holding volume down and power, yet nothing works except a solid blue led light.

I want to discharge the battery since that is what a bunch of sources suggested. Can I just put a resistor over the 5v line of the usb or can I do something that doesn't involve cutting a usb cable?


texts: Purpose of an input resistor to a signal transformer?

texts:
Jensen's datasheet for their "Direct Box" transformer has this recommended schematic for general use:

simulate this circuit – Schematic created using CircuitLab

(shields not shown because CircuitLab doesn't have a shielded transformer symbol)

I'm not sure that I fully understand R1.  They send me a pack of 6.8k 1/4-watt leaded resistors with every order - one for each transformer - and while I use them as recommended, I can't seem to convince myself that they're actually needed.  Especially when their app notes are all over the map concerning its value and even its presence.

I guess I can see some benefit to providing a minimum impedance that is higher than the primary winding resistance, but is there actually another purpose for R1?


texts: What are these female 2.54mm (0.1") crimp terminals?

texts:
So I but some crimping terminals to make my own custom cable connections for the first time today for an Arduino project I'm currently working on.

Comparing to some older ones I have from premade jumper wires I had lying around, I found that they are definitely not the same shape, and I'm unsure they'll even be usable for my goals.

The terminals I'm used to seeing are in the center, the new ones I bought are on the left, and the sockets I have are like that one on the right.

I have tried fitting a new terminal into the socket, but as it was not crimped, It wouldn't fit, though the weird bent part did appear to go in, albeit relunctantly.

Are these usable with this kind of sockets? Did I screw up? Is there a common name for these types of crimp terminals so that I won't mess up while buying them in the future?


texts:
I read AN_201610_PL16_01 (Using the IRS2982S in a PFC Flyback with opto-isolated feedback) from Infineon. I would like to know what the fast lane and slow lane are. The document doesn't explain it in detail.
Can someone explain it?


texts: program resets after ISR for TIMER 2 on pic24F

texts:
I am trying to configure the timer2, but every time that an interrupt occurs, the microcontroller goes to the ISR and then starts the main() function again.
This are the functions:

int main(void)
{

   //Set up I/O Port
   AD1PCFGL  =  0xFFFF;  //set to all digital I/O
   TRISB    =   0x0000;  //configure all PortB as input, RB9 as output
   //Main Program Loop, Loop forever
   Timer2Init();

   while(1)
    {
      //LATBbits.LATB1=0;//process data
    };

   return(0);
}

I have the timer2 functions in a timers.c file

void Timer2Init(void)
{
   TMR2 = 0;// clear the timer
   T2CONbits.T32=0;  //
   T2CONbits.TCKPS = 0b00; // prescaler = 256
   T2CONbits.TGATE = 0; //0 = Gated time accumulation disabled
   T2CONbits.TCS = 0; //Internal clock (FOSC/2)
   PR2 = 0x50; // preset
   IEC0bits.T2IE = 1;
   IPC1bits.IC2IP = 0b111;//set interrupt priority
   T2CONbits.TON =1;
   IFS0bits.T2IF = 0;
}

void __attribute__((interrupt, no_auto_psv)) _T2Interrupt(void)
{

    LATBbits.LATB9 = ~LATBbits.LATB9;   //Toggle output to LED
    IFS0bits.T2IF = 0; //_T1IF = 0;
    return;
}


texts: Killed a component on Single Board Computer, SBC still functions

texts:
Primary question upfront: what is the general purpose of this IC, labeled "D820460". I found what appears to be the component HERE on digikey.
Background: I have an SBC controlling tons of peripheral devices, all via USB. I'm powering these devices with my own custom power harness. I managed to swap POS/NEG power (backwards) on an externally powered USB Hub (the hub is connected to the SBC via USB). Amazingly, the hub appears unhurt, but it was connected to the SBC (via USB) and when the whole system was powered the smoke came out of the above-mentioned D820460. I fixed the harness, and the entire system, including peripherals, are all functioning normally. The component is labeled a "USB switch", so I'm beyond confident the failure was based on my power error. But why are all USB ports on the SBC still functioning? My main concern is that the blown component may be used to limit current, and that I may now have a situation where I can draw too much via USB in a high-load situation and have a safety hazard. The second concern is the system will fail prematurely. I'm strongly considering buying a new component and replacing it myself, but it still leaves me wondering, why it's there to begin with.
I apologize for the somewhat general question, I wish I could provide a schematic of the SBC.


texts: How to calculate gate capacitances (Cgs,Cgd) of a GaN HEMT?

texts:
I have calculated Cgd and Cgs using an analytical model, And I found that the second one is negative for Vgs < Vth, where Vth is threshold voltage and Vgs is the applied voltage. could this be possible and why ?

Thank you for your help


texts: I am using an Arduino UNO R3 to generate a PWM signal, the user sets the duty cycle using the serial monitor. The Arduino output signal is correct, but when the signal is connected to the input of the gate driver IC (IR2104) the low side driver output shows the signal with the compliment of the duty cycle (1-D)? why? I am using this IC to drive an IRFZ44N MOSFET.


texts: What are the brass contacts inside domestic AC power plugs and sockets called?

texts:
I've been hunting high and low across the internet, but I haven't had any luck so far.

What I need:

Brass terminals/contacts that can be soldered on a PCB and will receive electrical plugs. I want it to be able to receive plugs of all standards. What I'm looking for are terminals like these, but PCB mounted:

I can't find them anywhere, and I don't even know what to search for.

Edit:

I am looking for contacts that can be soldered onto PCBs, not complete housings. I need to produce a couple hundred of these PCBs, and the PCB must interface with the electrical plug directly.


texts:
How do i combine 3 × 3.7V Nokia BL5c batteries to make 11.1 volts and 3060 mAh?

I was thinking to use the above configuration to power up a laptop. Also, is it feasible to use a higher 3060 mAh battery at 11.1 volts, where the original battery is 11.1 volts 1500 mAh?


texts:
I have 2 slave devices connected to my dali bus. I can set their short address using the below steps:

Terminate
Initialise
Randomise
Set B1, B3 and B5 search addresses
Compare
Go back to step4 until there is only one luminaire
Program the short address
Withdraw
Go back to step4 until there is no luminaire left

Q1. When there is only one slave device in the dali bus, I can assign short addresses using above steps, one by one. But when there are 2 slave devices in the dali bus, I can only assign short address to one of them, the next luminaire does not respond to compare commands. Is there any chance it might be related to an electrical issue?

Q2. As I understood, if we have only one slave device in the dali bus, we can assign it a short address without using randomise. I'm following the below steps to achieve this:

Broadcast A3 command with the desired address. e.g. for the short address of 05, send: 0xA305
Broadcast CMD128 to make the luminaire use 05 as the short address, send: 0x8180

But I couldn't set short address using this method. I also tried Terminate-Initialise before this process but it didn't work either. Am I misunderstanding the DTR commands?


texts:
why we need waveguide to move microwave power from magnetron to microwave cavity ?

can't we just push magnetron antenna inside the cavity ?

why it has to go through waveguide ?


texts: Power supply from PCI connector pin B25 or B5

texts:
Can I use pin B25 on PCI connector on my motherboard as a power supply or
I need to use pin B5 and B6 (5V) from PCI connector on motherboard and regulate it with AM1117 3.3V for my PCI board ?
I need the power supply for Cyclone II on my PCI board.

Thank you


texts:
I need to connect UART devices in a master to multiple slaves configuration.

I need to isolate the desired slave while I'm transmitting, so others will not receive, non-selected slaves must have its RX line High. These devices only answer when asked, no transmission without a request.

I cannot change the slave devices, this is how they operate, I cannot create slave addresses or something to address this "isolation" in software.

Another issue is that they are isolated by an Optocoupler, PC817, so I cannot create some kind of resistor network to keep the RX line of the slave High while not selected.

This is the slave RX equivalent of the slaves:

This is what I came up with:

The BAT43 is to isolate the TX from slaves. I already used this kind of solution, works great when the slaves don't write to line simultaneously, the pull-up keeps line High if nothing is transmitted, If a slave transmits, only the Low pass through the BAT43.

The doubt is with the TX from the master. In this schematic, I used a 74HC32(OR gates) to keep TX line high(This is a must), even if the slave is not selected, to select a slave, TXx_EN goes Low, others goes High. I don't know if the 74HC32 can drive the PC817 high, in the datasheet it says max 25ma, so I believe it could.

I need to keep RX from slaves high while not selected because otherwise, it would see a "start bit" when de-selected.

Would this solution be a good one? I could use a dual transistor solution(One from TX and another from VCC), but too cumbersome.

EDIT: I'm using STM32F103 as Micro, 3.3v. The R2 resistor is a 470ohms.


texts:
I'm using an ACS712 +-5A to measure DC current, but my current never goes above 1A.
This causes lost resolution in the sensor, since it never measures above 1A.

What are some options for me to measure low values of current at a higher resolution (~1 mA)?  1A or 2A version of the ACS712 would have been ideal, but unfortunately they don't exist. It should be isolated.


texts: How do I calculate the voltage in this circuit?

texts:
I have the following circuit:

I am a beginner at this stuff, so... ;)

Ok, the question is to calculate the voltage across the terminals A and B? I have no clue how to do that? You can't just take together some of the resistors. The Node method seems a little overkill (only based on the small amount of elements).

Question: What is the voltage across the terminals A and B?

P.S. The weird box (for some) in the top is a current source.


texts: How to properly check/evaluate Multiplexer design implementation?

texts:
I am not electrical engineer at all. I am just participating in this course.

I have been struggling for 2 days to implement Mux8Way16 - a multiplexer which has 8 different 16-bit inputs.

How can I design and implement digital logic to do this? Is this some mathematical tool or methodology used to design/implement this type of digital logic?


texts:
Today I wanted o repair my door's buzzer system. After removing the front, there were a number of cables protruding from the wall. Pretty old building, so there was no clear color coding of the cables. Not even knowing whether dealing with AC or DC cables, I measured both possibilities. Strangely, some cables exhibited 4.3 V both for DC and AC option...

So I connected an LED to see if it lights up regardless of how it is installed. If this is the case, I thought, it must be AC. If it's lit only one-way, it must be DC. HOWEVER, it lighted up for one direction, and for the other direction it lighted up, too, only way dimmer, which I can't explain at all!

So am I dealing with AC or DC?


texts: What exactly limits the signal frequency on transmission lines?

texts:
In practice, the frequency of a signal seems to have a significant impact on whether or not it can reasonable be transmitted over a line. As an example, consider the IEEE 802.3ab standard on Gigabit Ethernet (1000BASE-T), which deliberately employs a symbol rate of just \$125\text{ MBaud}\$.
Intuitively, I understand that you cannot use a conventional twisted pair cable to transmit a \$100\text{ GHz}\$ signal. But what exactly is it that keeps us from doing so? In real-world scenarios, what are the equations that when being populated with these frequencies would yield infeasible results?
Here are my thoughts so far:

With increasing signal frequency, the parasitic inductance as well as the parasitic capacitance will probably lead to a significant damping. Is this effect captured by the real part of the characteristic impedance
$$\sqrt{\frac{R'+j\omega L'}{G'+j\omega C'}}$$ in sufficient detail? And if this is the case: Wouldn't this mean that lossless transmission lines (with \$R'=G'=0\$) are unaffected by this frequency-dependent effect?
According to these slides, higher signal frequencies "tend to radiate better." What exactly does this mean? Is this related to the damping that the resulting EM wave experiences during its propagation?


texts: Why is S=1, R=1 state forbidden in RS flip flop?

texts:
I have come across the RS flip flop & I have tried implementing that on a simulator & using actual logic gates. But I'm still not sure whether I have correctly understood the unstable or the forbidden case S=1, R=1 in the flip flop. Can anyone tell me what exactly is that?

By the way I have used 2-input NAND Gates to implement the flip flop. What is the difference between the NAND gate flip flop & NOR gate flip flop?


texts: How to calculate temperature rise of PCB polygon?

texts:
I'm designing a PCB where I have a polygon that carries current from one terminal to two pads, each pad should pull 33 Amperes, so a total of 66 Amperes running through that polygon.
How can I calculate the temperature rise of that polygon?
What software can be of help?
I have the currents and polygon shape, dimensions & copper weight.
It's on an FR4 PCB, it's an external layer, the ambient temperature should be 25C.


texts: Is V/F maintained constant even in field oriented control or vector control drive of PMSM motors?

texts:
I understand that in scalar control V/F is maintained constant below rated speed, as Vector control drive is also a variable frequency drive, I would like to know whether V/F is maintained constant below rated speed in field oriented control of PMSM motors as well, as I don't see it from the equations.
Could anyone show me through the vector control equations?


texts: How to change Voltage Reference in STM32 NUCLEO-F103RB board Analog Input from 3.3V to 5V?

texts:
I have a joystick module for Arduino connected to my PA0 pin (that pin is set as ADC1_IN0). I would like to read the voltage from that pin but there is a problem. The voltage on which the joy-stick module operates is 5V and HAL functions I'm using to read Analog values are referencing it against 3.3V, which renders part of the module (which is essentially a potentiometer) useless and nonfunctional as the value given measured is gonna be simply 4095. Here is the code that I have in the while(1) function in main():

      HAL_ADC_Start(&hadc1);
      HAL_ADC_PollForConversion(&hadc1, HAL_MAX_DELAY);
      raw = HAL_ADC_GetValue(&hadc1);

How can I make it reference this voltage against 5V so I can get the full reading?


texts: How can I rotate a small 240VAC induction motor with 12VDC?

texts:
I have an induction(?) motor that might be 30 years old.  It's principal dimension is ~50mm so fairly small.  It's actually the fan motor from a fan heater. It has one winding and runs off 240VAC with a DC resistance of 375Ω.  There is just one simple stator winding.  It's just like:-

I also have a 12VDC source of sufficient capacity.  How can I get the motor to rotate using the 12V direct source?  All I want is rotation.  It doesn't have to do any useful work just go round.  And the speed is irrelevant, any constant rate is fine.  Beyond any rhyme or reason I'm assessing the feasibility of using it as an on /off indicator in a Steampunk project.  Steampunk gives us licence to do stupid stuff.

Initial thoughts:  some form of siney wavey generator + 12V audio amplifier chip like a LM384 (5 Watts)?  Horrible impedance mismatch but might it rotate? Or is this just too stupid?  Can feasibility be assessed without building it?

I though that running AC synchronous motor with DC might help but that motor is properly voltage matched and seems to be performing work.


texts: Voltage drop on string of constant-power loads: Simulation issue?

texts:
I've noticed something that seems odd to me in an LTspice simulation (see below).

I'm trying to model a system with a number of identical devices which each draw ~11W (with negligible variation over different input voltages) and are separated by long cable runs.

When the input voltage is 47.1V or higher then there is 'normal' voltage drop over the run and the last device (B17) would theoretically work happily.

When the input voltage is 47.0V or lower, the simulation shows huge voltage drops resulting very low voltage at the last device.

If anyone could point me in the right direction it would be much appreciated! It could be a quirk of the simulation, a case of garbage-in=garbage-out or a fundamental misunderstanding on my part :-)


texts: In VHDL, does having large bus input to component take extra resources?

texts:
I have a component that has a very large array signal in it (a couple kilobits) and I currently write and read to it in only one component. I have checked in Vivado if this uses too much resources, and it doesn't. My question is I want to have a sub-component that can access this array (only read from it). If I merely set the array as an input to the sub-component, will it take any more resources that if I implemented the array in the same component? I know the optimizing compiler is pretty powerful, but I don't know what goes on when you interface between VHDL components.

Thanks


texts: How to redirect electric field lines with a copper plane

texts:
I have been testing a capacitive sensing circuit in which an electric field is projected vertically to sense a finger (a grounded conductive object). On the PCB, a tx and an rx are 2 copper structures that act as the 2 plates of a variable capacitor. The nearby grounded finger redirects some of the EF to ground and lowers the capacitance between tx and rx like so:

Now, I have been testing this same circuit with a floating copper plane (notice the difference as this plane is floating, whereas the finger acts as a virtual ground) and I have been explained that doing so will ease the flow of the electric field lines between tx an rx and increase the capacitance (again, notice the difference as the grounded finger reduces the capacitance by redirecting some field lines to ground)
I have been able to get results that match with this explanation. on the image below, the sensor "raw counts", which are inverse of capacity, lower when I lay a floating copper layer on top of the PCB:

The theoretical explanation I was given implies that the floating copper plane pressed against the pcb increases the capacitance between rx and tx as we just seen by (acting as a mirror maybe?) compressing the electric field lines and thus sort of reducing the distance between the capacitor plates (correct me if this is wrong).

My question is: Which laws of physics explain this electric field line "reflecting" phenomenon? Why am I able to reflect and condense the electric field with a copper plane?


texts:
I was going through this lecture pdf.
If I want to have maximum output resistance which cascode configuration I should use. BJT cascode or Mosfet cascode?


texts: Is there a DIP style chip I can use for a 74x245 and a 573 or 373?

texts: I'm looking into using a W65C816S chip but to have full access to the address lines I need a 74x245 and a 573 or 373 chip. The only ones I've been able to find are SMD/SMT and not through hole. I'd like a DIP package so I can breadboard them. Are there DIP packaged chips around that I can use?


texts: How to find I-V characteristics of motor?

texts: I have a motor that I'm turning with another motor. I can determine the speed of rotation with a tachometer. One motor is powered with a power supply and it is coupled with another motor. I need to find the I-V characteristics of the second motor but I'm not sure how to test for it? I put a resistor across the terminals of the second motor and tried measuring the current through it, but I'm not sure if this is the  right way to do it?


texts: Reason of high packing density in integrated injection logic family

texts: I have read that in Integrated Circuit manufacturing , resistors are made of either diffusion or metal/poly deposit. In diffused resistors we use the bulk resistance of diffused regions. But why do people say that  the integrated injection    logic family had high packing density due to complete absence of diffused resistors,when it had few diffusion regions ?  I hope my question is    clear.


texts: Powerbank instead of Alkaline D batteries

texts:
I am an avid fan of charcoal bbq and love fire starters/blowers like these.
They require type D 1.5 V alkaline batteries which are increasingly harder to get and  usually run out in the most inconvenient moment.
Instead of buying a bunch of these batteries I was wondering if I could use a simple 5V power bank with some module to get it down to 1.5 and power up the blower, ideally without soldering.


texts: an LM13700 can be configured as a "floating" voltage controlled resistor ; How resistor-like is it?

texts:
I want to use an LM13700 as a voltage controlled resistor, and I want it to act like a rheostat. When will it act non-linearly?

The description of this circuit is on page 15 of the datasheet, and the circuit diagram is on page 16, figure 28.

I intend to use two of them to produce a variable voltage divider for an audio signal. I am worried that the resistance might vary with regards to frequency, temperature etc.


texts: Can I use this 1.8" TFT LCD to make it show graphic? Or all the TFT LCD can display graphic?


texts: Iam using Tip 31C as a switch, but it always on

texts:
the question in brief is:

does tip31c transistor stay turned on when it is broken ??

I have a circuit with tip31c transistor

the board consists of sensor and RTC with Arduino.

I need to read heat every ten minutes and log them.

for low power consumption, I used the tip31c transistor in order to turn off everything (RTC and the sensor) and just turn them on when I want to read the temperature.

so every 10 minutes the Arduino will send a signal to the transistor to turn everything ON and do the job, then turn it off again ...

everything was OK..

I connected the Arduino to 5v DC source, it works properly, but I found that the RTC and a led are not being turned off !!

they always ON.

they were working well before I connect them to an external power source.

everything was turned off until I turn the transistor ON

but now they are always ON, I didn't change anything with the circuit...

I afraid that the transistor is broke

so my question is

does the tip31c stay turned ON when it is broken??

or I am missing something

this is a diagram of mi circuit:


texts:
I saw a couple of PCB tutorials on youtube in which they are changing the grid size (mm or mil) before placing components and again before placing traces.

I want to know why and is there any rule (i.e. any predefined value to keep) to change grid size

Can you provide default grid size used before placing components and traces


texts: Referring to this post, is it possible to float power supplies by simply not connecting the ground wire?


texts:
I am trying to toggle the GPIO port 8 with:

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);
HAL_Delay(1000);
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);

When I debug the application I can see, that the HAL_Delay does not work. I'm not sure if I missed a configuration option in the STM32CubeIDE to enable the SysTick.

Does anyone use STM32CubeIDE and can give me a hint?


texts:
What is the minimum frequency that can be transmitted by a PCB?

Of course this question is size and shape dependent. So I read somewhere that the antenna lenght must be about λ/4 to transmit those frequencies.

So I was not sure if you take the longest or the shortest side, I believe you take the longest one. So in the case of a rectangular PCB, say 10cm x 5 cm, I took 10 cm for example.

Near Field

Now we need to define the near field of the antenna, so one precise way, described by ednmag.com, is:

r = (2* l^2 ) / λ   , where l is the longest size of the antenna

another general definition is (by Ott & White):

r = λ / (2 * π )

In fact the Ott & White definition, can actually be applied to PCB's too.

So going with the first formula, in case of our example (10x5 cm PCB),

Calculation

At 500 meters, using the first formula for the fraunhofer boundary definition, using the path loss equations (Friis , Schantz) :

The first formula tells us that the minimum frequency that can be transmitted by this PCB is roughly 47713 Hz, since the path loss is positive before this, so this is our minimum reference distance I believe.

Also using the general formula λ / (2 * π ), the min frequency is 72273 Hz Electric and 76303 Hz Magnetic field, roughly.

So there is some discrepancy between the two formulas, but it's roughly in the same range.

However the first formula already puts the limit in the far field where we have planewaves with 377 Ω impedance, while the second one is still in the range where the magnetic and electric field has discrepancies between their impedance.

So I assume the first formula is more accurate in our case since I'd expect the impedance to be 377Ω.

The question is as, stated in the beginning, whether my thoughtprocess is correct, and given that the first formula is more accurate, is the minimum frequency in this case roughly 47713 Hz?

I have read that you need a λ/4 length antenna to transmit those waves. So in our case that would be 12km long antenna, which is obviously larger than 10cm.


texts: Dual integrating ADC to interface with micro-controller?

texts: I would like to measure voltage with an IC similar to the 7106 but I don't want all of the 7 segment display circuitry that it comes with. I just want to interface it to a micro so I can perform other operations beyond just measuring voltage. Does anyone know of an IC that can do this?


texts: Is it common for such basic TTL gate chips as 74LS32, '08, and '86 to be broken?

texts:
I have too many failures with very basic gate chips, while the more complex chips seem to keep working fine. And I find that very puzzling. These aren't even CMOS where I know that a static discharge can cause damage. But have just again determined a 74LS32 quad 2-input OR gate, one of the more basic chips, started to behave like an AND gate. I also threw away a '08 AND chip the other day. And now I'm having an '86 XOR with clearly one input high the other input low and still gives me a low output. And now I plugged in another one from that batch, says "Indonesia" and it too seems a failure. I don't understand how I have so many bad chips, and all those common simple ones, while counters, and muxes and RAM and tri-state buffers, and other stuff is all working.
What is your experience with TTL chip failures? Did you also find that when an OR chip fails it seems to behave like an AND?


texts: P-Channel Depletion Mode MOSFET for Negative Pulses

texts:
Would a p-channel depletion mode MOSFET make the most sense if the goal is to produce a high-voltage negative square pulse?

My reasoning:

MOSFET, because we're talking about a kV square pulse with fast transition times,
p-channel, because that puts the source at/near ground, so the gate can be ground referenced (and not floating on -1000 V, as would be the case in an n-channel circuit),
depletion mode, because the load resistor must always be on the drain side, which would be -1000 V, so we'd like the MOSFET to be "on" most of the time to keep the output at 0 V, and then turn "off" briefly to take us to -1000 V and back.

The problem is that "p-channel depletion mode" MOSFETs seem to be scarce, which leads me to assume either I'm doing something wrong, or my application is unusual.  Is my analysis of these types of MOSFETs incorrect, or are there really just not many manufacturers? Or is there a much better way of doing this that I'm missing?

(More details...) I need to produce a negative pulse with the following specifications:

amplitude:  -1000 V (ref to gnd)
width:  100 microseconds
period:  20 Hz
risetime (leading edge, 10% to 90%):  1-2 microseconds or less

I'm just switching the potential difference (ref to gnd) on a chunk of stainless steel metal between 0 V and -1000 V quickly.  I'm not driving a motor, or some huge inductive/capacitive load.

The circuit I'm thinking of is this:


texts: Mechanical button presser for tactile switch

texts:
I'm trying to create a small Arduino project where I have to attach it on an appliance that has a tactile switch. I want this to be detachable/modular solution that way I can re-use it on other appliances with little or no modification needed. But i'm not sure what component do I use that will do the pressing to those switches.

Is there a pre-made component that can do a push function or do I use servos to mechanically do that? Is there a similar projects on the internet that is similar to my problem?


texts: Driving three LEDs in series with different Vf at 700mA

texts:
Given LED1: Vf = 3VDC for 700mA ---- and ---- LED2: Vf = 4VDC for 700mA

If I put LED1 + LED1 + LED2 (in series) and apply 10VDC across them, will I have 700mA flowing through them?


texts: Did the cold front cause usability issues with the batteries in electric cars?

texts:
This may be more of a motor vehicle question, but since I'm asking about batteries, I think it may be more suited here.

As we know, electronics don't like the cold.

As we also know, last week was real cold.

Now, I've had my fair share of phone troubles in the cold before. For a short while, I lived in the north, and in extreme cold my phone would arbitrarily turn off if I held it out too long. I was wondering if electric cars suffered the same effect at all.

As I understand it Teslas use (in part) Li-ion batteries, like my phone does, and these are the kinds I've heard have the most problems in extreme temperatures. Assuming they follow the same principles as my phone, then driving out of a warm garage may mean your car will arbitrarily turn off on the road. I imagine that's undesirable behavior for a car.

Did this front affect electric cars at all? If not, what measures have the manufactures taken to protect their electrics against this?

Note: I'm not asking about these cars having trouble starting; that's an issue in all cars. But where gas-powered cars primarily rely on batteries to start, electric cars rely on them to keep moving. I am asking if the cold affected the batteries of already-running electric cars.


texts:
I have a headset (HyperX Cloud II), the speaker of the right cup lost sound, after diagnostics, one of the wires that runs between the two cups was faulty (two wires run in the same cord) so I replaced that cord (that runs between the cups), but now the sound is louder in the right cup, would this occur because wire resistance, wire material, or bad soldering?
The cord that I used to replace it was from another headset so it might have a different properties, so would the strand count of the wires effect this, or even strand thickness?
I should also clarify that the original cord had two wires with each several strands coated with enamel then surrounded by insulators surrounded by a fabric on the outside.
The new cord had 5 wires each with several strands with an insulator surrounded by rubber on the outside.
I removed the 3 extra wires within the cord.
I then solder the wires to the correct tabs within the internals of the headset, easy part done, then had to put it back together (a nightmare).
If the issue is resistance could I just figure out a resistor with a certain value, to place in series with the cord, so it lowers the loudness to the correct value? Is that how speakers work with resistors?
Or should I attempt source wires with similar properties to the original, what matters and what does not? (strand count, material, strand thickness, other?)
Thanks for reading and helping.


texts: How does this MOSFET based motor driver designed work

texts:
I have designed a motor driver using a MOSFET that takes a PWM signal from an Arduino and boosts it to operate the motor, but I'm not sure why it works.

I placed the capacitor in parallel to block noise created by the motor and the diode to prevent back EMF, but I'm not sure how the MOSFET operates to boost the PWM signal or what the purpose of the resistors is.

Any help is greatly appreciated, thank you!


texts:
first apologize for wrong wording/idioms.

Found an old washing machine motor. It has six terminals, labeled U, V, W, Z, X, Y

Attached to the motor is a capacitor with two terminals, no more wires attached.

Now my questions would be (living in Europe with 230V mains / 400V):

Can this motor be operated using 230V and what would be the wiring including the capacitor?

Can this motor be operated using 400V and what would be the wiring including the capacitor?  (In this case I guess I would use L1, L2 and L3)

Edit: I checked the resistance between all terminals. There is no electrical connection  between the upper and lower set of terminals. One set of terminals (Z X Y) has a resistance of ~35 Ohms between any other two terminal (thick wire going into the motor) and the other set of terminals (U, V, W) has a resistance of ~ 7 Ohms (thin wire going into the motor)


texts: How to test if my program for SPI communication is working correctly?

texts:
I have developed a simple code for learning about SPI in Arduino Due. The code is compiling properly and now I would like to learn the next step on how to test the code with the board and get the master to communicate with the slave. Here is the code:

#include"SPI.h"
 int mosi = 75;          //assigning variables to pins
 int sck = 76;
 int ss = 10;
 int miso = 74;

void setup()
 {
   pinMode(mosi,OUTPUT);     //Configuring pins as input and output
   pinMode(sck,OUTPUT);
   pinMode(ss,OUTPUT);
   pinMode(miso,INPUT);
   SPI.begin(10);                   // waking up SPI bus
   SPI.setDataMode(10,SPI_MODE_0);  //setting mode for clk phase & pol
   SPI.setBitOrder(10, MSBFIRST);   // setting bit order for transfer
   SPI.setClockDivider(10,42);     //setting clock to 2 MHz
   digitalWrite(10,HIGH);     //keeping slave device unactive
 }
void set_value(int value);
 {
   digitalWrite(10,LOW);      //activate slave select line
   SPI.transfer(0);
   SPI.transfer(value);    // transfer values from 0 to 255
   digitalWrite(10,HIGH);   //deactivate slave line after transfer
 }
void loop()
 {
   for(int i=0 ; i<256 ;i++)     //values to transfer
    {
      set_value(i);             //call function to transfer values
      delay(100);
    }
  }

IDE used : Arduino,
Board used : Arduino Due

I have some doubts regarding this code:

1) How to test this code with my borad to check if its working correctly?

2) Why isn't the mosi, sck and ss pins used anywhere in the code, while all operations/functions are being done with respect to the slave line ss = 10?. Does the SPI module automatically take care of the data transmission and reception through MOSI and MISO?

3) What are the possible hardware connections if I am using one due board as my master and another due board as my slave?.

4) Should I dump this code into the master as well as slave for it work? Or Since master has to transmit and receive data from the slave board, I need to do some changes in this code?

5) If I am missing out anything or any directions regarding this would be helpful. I am newbie to embedded systems and totally confused & full of stupid doubts. PLz dont mind. Thanks!


texts: How do I work out the Inductor value on my a digitally controlled conventional boost converter

texts:
I’m  trying to build a digitally controlled conventional boost converter and implementing a basic Maximum Power Point Tracking (MPPT) algorithm to extract the maximum possible power from the panel under various lighting and shading conditions.
Part of the circuit as you know, involves a Boost converter. Due to me not having a lab available due to the pandemic, I therefore need some theoretical guidance in trying to figure this out. The completed circuit looks like this. Which includes a Voltage and current measuring circuit due to the ARM board.

But for the mean time, I’m trying to build my boost converter shown here;

I’m using a 220uF capacitor, 470ohm ceramic load resistor, MOSFET(datasheet), a Diode 1A 40V(Datasheet) and the 10W solar panel (Datasheet)

Therefore, my question is, how would I be able to work out the inductor value and some kind of rationalle for the PWM frequency?


texts: Is the scalar wave phenomenon real, and if so, why is it not much in practical use?

texts:
There are a bunch of videos on YouTube describing something called scalar waves (sometimes referred to as "superluminal").

Two examples are this one:

Superluminal Scalar Waves for Communications (15m 8sec):

and this one:

Meyl shows Tesla longitudinal waves for wireless energy transmission (17m 48sec)

This latter is by a Prof. K. Meyl who also has a book about the subject on Amazon (there used to be 3 books by him but 2 have been withdrawn).

I remember seeing some university experiment where it was shown how a scalar wave, sent from inside a Faraday's cage, went through the cage and (well, supposedly) lit a light bulb.

Besides above there are also university professors giving lectures on scalar waves.

Here is a video of Gregory Durgin at Georgia Tech giving a lecture on scalar waves:

WAV02: The Scalar Wave Equation (48min 54sec)

And here is a video of Jamesina Simpson at University of Utah:

FDTD Lecture 1a: Scalar Wave Equation (Setting up the Problem) (10min 39 sec)

But because the equations do not make much sense to me currently, and there seems to be a lot of gunk on YouTube around this subject matter (relating scalar waves to UFOs, and other such stuff), I thought I ask about them here.

Update: admittedly the "superluminal" claim can be just that persons unfortunate interpretation. But that does not mean that phenomenon is non-existent, considering that it seems to be taught in some universities.

Is the scalar wave phenomenon real, and if it is, why does there not seem to be much practical use for it?


texts:
I am building a system which will measure and record the voltage of batteries. There are 8 channels in the system with each channel being capable of measuring 0-35V. The accuracy we have decided upon is +/- 0.02V. The LMV324 Opamp was chosen as it has a Input offset voltage of max 6mV specified. A 12bit ADC is being used with a 1.8V reference voltage.

I have built the circuit, and found that even with no input voltage applied, the output of the Opamp is 0.04V. I have two of these Opamps on the same PCB, and all output voltages between 0.038 and 0.04V with no input. At first I thought that noise/ripple from my DC-DC converter, which powers the Opamps may have been the problem. But then I switched over to a linear regulator and the exact same thing happens.

Could someone please explain why this may be happening?

Opamp data sheet: https://www.st.com/resource/en/datasheet/lmv324.pdf


texts: Creepage between Phase/Neutral and Earth (PCB Design)

texts:
The smallest distance between line and neutral on my PCB is 4mm, which ought to be enough for 240V mains. I had a copper pour connected to earth around every trace with a clearance of 1mm. Someone told me I should get rid of it.

I thought creepage could only occur between phase and neutral, but perhaps it applies also to earth? What should I do?


texts: Why might the collector-emitter voltage for this transistor be so high?

texts:
I'm attempting to use an NPN transistor as a switch, to drive an LED load. So I am only interested in the off and saturated states.

My understanding is that when the base-emitter junction is saturated (in my case due to the emitter being tied to ground and the base voltage being high enough), the collector-emitter voltage is close to zero. Multiple places on the web (e.g. here and here) say the same thing, that the collector-emitter voltage should be at most a few tenths of a volt.

However I'm looking at the ULN2003A, which appears to be a very common IC for arrays of NPN transistors, and the electrical characteristics table in its data sheet says that the collector-emitter saturation voltage is typically 1.1 V, and can be up to 1.3 V. Why is this so high? Am I misunderstanding something?