texts:
I'm trying to power a 24V DC motor using 2x 12V batteries, an Arduino and a Cytron MD10C Motor Driver. I followed the description on Cytron's website for how to connect the Arduino and the motor to the driver board. The 2 batteries are plugged in serie to provide 24V, then to the driver board power inputs.

On the first test with this schema, there were several issues, most importantly the GND wire between the Arduino and the driver board burned and some sparks appeared on the driver board when the motor was started using an Arduino signal. The Arduino also had some difficulties and kept rebooting.

I was wondering if this is a case of ground loop? If yes, how should the Arduino/driver board data section be isolated from the high current?

One of the battery is also connected to the Arduino to provide 12V input current (I now know this a bad practice, but left it on the schema in case it might play a role). In the future, the Arduino will be powered with a DC/DC switching regulator from the same 24V cables going to the motor driver.

Oddly enough, the schema works perfectly when the Arduino is powered by USB (from PC) and the driver board by 120V/5V AC wall converter. The motor driver also has test buttons which allow to test the board and power the motor without the need of an external MCU. When using those buttons, there are no sparks, nor burnt wires.

The Cytron datasheet does not indicate if the driver board is isolated, so I thought the motor current might go through it, then to the Arduino, then back to the battery.

The motor is a 24V DC motor (draws under 10Amps), similar to a windshield wiper motor. The batteries are 12V car batteries.

UPDATE:

Thanks for your answers. Below is a suggested schema using a DC/DC Step down regulator to provide the 12V to the Arduino. I also added fuses in series with the battery bank. I assume that the shared ground would remove the possibility of short-circuit?


texts: Splitting a 4-20mA signal to two separate data loggers

texts:
I am wanting to read a single 4-20mA signal from a water meter on two separate data loggers. I need help on the wiring in order to split the signal to the two loggers. The first logger is a Campbell Scientific CR800 data logger https://www.campbellsci.com/cr800 which provides power to the loop. The second is homemade a non powered 4-20mA register connected to a Raspberry pi.

From the water meter which is an Octive Master Meter is outfitted with a 4-20mA output device, there is a + , - , and a ground wire coming from the meter.

Any and all help on this topic will be appreciated and welcomed. I hope this is enough information, please let me know if you need any additional information. Thanks.


texts: Whats the cost to create your own custom ASIC chip?

texts: There are never any bitcoin miners available to purchase and whenever Bitmain (the leading bitcoin mining manufacturer) releases a new batch of miners they all get gobbled up in seconds. For those who don't know Bitcoin mining requires the use of computers to solve complex math problems and the reward for solving the problem is bitcoin. Bitcoin mining evolved from CPU processors to ASIC chips and it seems only a few companies have been able to create their own custom ASIC chip. Is it really that cost prohibitive to manufacturer your own custom ASIC chips for bitcoin mining? The demand is much greater than the supply. How does one create a custom ASIC chip with the sole purpose of mining for bitcoin and how much would it cost? I read some answers that were 10 years old in regards the the cost to creating ASIC chips but I'm hoping costs have come down since then. Hoping someone can shed some light on this subject, thanks in advance!


texts: Error while uploading hex file to AVR uC

texts:
I am trying to upload a hex file to an ATtiny85 from Ubuntu by running these commands:

avr-gcc -mmcu=attiny85 -Wall -Os -o src.elf main.cpp
avr-objcopy -j .text -j .data -O ihex src.elf src.hex
avrdude -p t85 -c avrispmkII -e -U flash:w:src.hex

I get this error:

avrdude: ser_open(): can't set attributes for device "/dev/ttyS0": Inappropriate ioctl for device

I tried to use different USB ports, but that didn't help. How can I resolve this issue?


texts: Why high current MOSFET is driven with another transistor

texts:
As the power rating of the MOSFET is increasing in the case of continuous current and the Max voltage rating, i see people drive the gate of MOSFET with a transistor. Could you explain the reason for.

1)Is it because as the current drawn increases the gate to source voltage increases so a 3.3v logic cannot handle.
2) If so why there is no second transistor at STEVER_A- input.

VCC is LIPO voltage around 10-15Volts**


texts:
I am trying to measure the resistance of a nichrome wire that has a PWM (1000Hz and different duty cycles between 0 and 100%) voltage applied to it from a 5.0V regulator. The setup I have in mind looks like this:

5V PWM ---- Wire (~20 Ohm) ----X---- 1W Resistor (0.5 Ohm) --- Ground

I then measure the voltage at point labeled X with respect to ground, and amplify it using an instrumentation amplifier (TI INA122). As the nichrome wire is heating, I want to obtain its temperature by measuring its change in resistance which would correspond to change in measured voltage given by my amplifier. However, I expect noise so I want to filter it out. I don't know to go about doing this since the signal is PWM. If it was straight up DC then I'd use a low pass filter, but now I am stuck.

Here is a picture of what I'm trying to accomplish. Basically smooth out the noise like shown.

Thank you in advance!


texts: How can I replicate a brownout for the purpose of testing

texts: Is there a device or design in which I can place in between the wall outlet and the powered device itself that will cause the powered device to undergo a brownout condition?


texts:
We have in our company Ni-Cd batteries; in each bank we have 142 cells, Amp/h.We found that 17 cells are defective within same bank, and the life of the battery bank is almost 8 years. Now My questions are:

Shall we go to replace defected batteries with new batteries?

OR

Do we need to replace overall battery bank?


texts: Simulating mouse button click event only works at the first click

texts:
I'm using CH9329, a uart to USB keyboard/mouse simulator chip, to simulate mouse movement, with a moveable signal sender and an esp32-based signal receiver connected to it.
[sender] -> signal
signal -> [receiver->ch9329(simulate mouse)->computer]
Now I can see while I am moving my sender, the simulated cursor correctly moves and it also responses to mouse click (by clicking some desktop buttons). But, the weird thing is, if I open a whiteboard program, and want to draw a line, the cursor clicks at the first point, showing a visiable dot, but then failed to draw other points (moved correctly). However, I'm sure I am sending the right packet to indicate the mouse button is down (through uart tools).
In one sentence, it seems in all my "left-button-down" data packets, only the first packet really clicked, while other packets just let the mouse move.
How can this be possible? Any ideas? I think real mouses also report positions in the form of discrete points to the host, and the host knows how to draw a line. But my case failed.
--Edit--
I assume when using a real mouse to draw a line in a general painting program, you press the left button and then holding the button to keep it down, when you finish drawing you let the button up, right? That's what I did.
The chip protocol uses a byte to indicate the mouse state in every mouse-host communication packet. A 0x01 means the left button is down and a 0x00 means the left button is up. And when I detected a esp32 button is pressed, I begin sending 0x01 down packet, when I detected that esp32 button is up, I then changed to send 0x00 up packet.
My logs showing the button and packets I send:
.[0;32mI (95069) uart-mouse: sending to host : mouse state: 0
.[0m
.[0;32mI (95089) uart-mouse: sending to host : mouse state: 0
.[0m
.[0;32mI (95089) server-main: btn clicked
.[0m
.[0;32mI (95089) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95109) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95129) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95149) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95169) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95189) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95209) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95229) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95249) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95269) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95289) uart-mouse: sending to host : mouse state: 1
.[0m
.[0;32mI (95299) server-main: btn released
.[0m
.[0;32mI (95299) uart-mouse: sending to host : mouse state: 0
.[0m
.[0;32mI (95309) uart-mouse: sending to host : mouse state: 0
.[0m
.[0;32mI (95329) uart-mouse: sending to host : mouse state: 0
.[0m


texts: USB / Serial converter without FTDI Chip

texts:
First of all I want to mention that this question is related to my last question about USB connection.
( please note that this question is about a specific topic that my last question is not about, but it belongs to it )

I am searching for a way to do a USB / Serial convertion without an FTDI chip or so.

So is it possible to build a simple circuit that does what the FTDI is doing ? And if so, how can I make it and does it pay the work ?
And last but not least, what exactly does the FTDI chip ?

How does it converts the signal from Serial to USB and what are the diferences between those ?

( For more information about the project that is going to use this "selfmade" USB / Serial Converter, please check out my question that is linked abow )

Thanks for all of your answers.


texts: Connection between STM32F446 and CODEC (PCM3060)

texts:
I have decided to connect an external crystal to the MCU (STM32F446RC) and then doing the following routing using STM32cubeMX UI.
MCU to the CODEC using the I2S mode of the SPI peripheral: I am enabling two connections, one for the ADC of the CODEC and the other for the DAC of the CODEC. for the ADC, am I selected the "Master Clock Output" option, however does this mean I do not need the I2S1_CK anymore? For the DAC, I have not selected the "Master Clock Output" option, though I selected the mode as Half-Duplex Master, thus routing the I2S2_CK to the SCKI2 of the CODEC, corresponding to the clock of the DAC, is this correct or should I select the Half-Duplex Slave instead?
So,
I2S1_SD  -> Dout
I2S1_WS  -> LRCK1
I2S1_MCK -> SCKI1
I2S1_CK  -> ?????
I2S2_SD  -> DIN
I2S2_WS  <- LRCK2
I2S2_CK  <- SCKI2
I am confused since the way it is portrayed in the documentation*
Documentation:  Interfacing an STM32L1xx microcontroller with an external I2S audio codec to play audio files. [online] Available at: https://www.st.com/resource/en/application_note/dm00087544-interfacing-an-stm32l1xx-microcontroller-with-an-external-i2s-audio-codec-to-play-audio-files-stmicroelectronics.pdf


texts: Trying to understand practical applications for bonded metal laminations & insulated epoxy coating

texts: I am trying to better understand practical applications for bonded metal laminations and insulated epoxy coating. I started a new job at a company that does this and I am so lost. Any insight would be greatly appreciated, thanks in advance!


texts:
I am using a CP2103 to interface with a simple 74HC4051 MUX. I want to use 3 of the I/O ports on the CP2103 to control the input pins of the MUX. The 4th I/O port is being used for something else. The problem is, when switching the I/O ports, there is a delay which the MUX reacts to far too quickly.
If I went from a 0-0-0 input to a 1-1-1, then during the time it takes for the CP2103 to switch all its outputs, on the output of the MUX, I will also see the outputs for 0-0-1 and 0-1-1 go high for about 10uS each. I know this is due to the I/O ports of the CP2103 switching high one by one, rather than simultaneously.

Unfortunately, I can't go into much more detail about what is on those outputs as it is a work thing, but all I can say is even the small 10uS pulse is having an undesired reaction.

So, my question is, is there a MUX out there that has some sort of built in debounce (5mS or something) so these small delays won't register? I would really like to do this without having to get a microprocessor as it seems a bit unnecessary for something like this.

I did think about using capacitors to delay it, but then realised it would just delay the other outputs as well and not actually fix anything.

I hope I have managed to relay my question properly and you guys understand. Feel free to ask any questions and I will try to answer.


texts:
Here is an example of an op amp used for amplification:

What I understand:

C1 is used as AC coupling to remove any DC bias.
Vref is used to apply a DC voltage to be able to amplify negative voltage values.
R2 and R1 these are used for gain.
C2 is used such that the gain formed by R2 and R1 only apply to AC signals as C2 at low frequencies looks like open circuit for DC

What I think I understand:

Since there is no input current, ideal op amp, R3 has no voltage across it. Hence input voltage is Vs+2.5 .
v+ = v- = Vs+2.5
Since the gain is 1+ R2/R1 then this means that Vout = Vs+2.5 ( 1+ R2/R1)

What I Know I got wrong:

The analysis above is only true for AC signals? But how could I do I arrive at the "general" answer for all types of signals. I am not sure how to approach this.


texts: Op Amps: how do they know whether the supply is split?

texts:
Most op amps can operate in single and split supply configurations. However, I cannot see how this is possible.

If I connect voltages \$V_\text{SY}^+\$ and \$V_\text{SY}^-\$ to the positive and negative supply pins of a op amp, and \$V_+\$ and \$V_-\$ to the non-inverting and inverting inputs, then the output is (if \$A_\text{OL}\$ is the open loop gain of the op amp):
$$V_\text{out}=A_\text{OL}(V_+-V_-)+V_\text{SY}^-\tag{Single-supply}~\text{ }~~\text{ }~~\text{ }~~\text{ }~~\text{ }~~\text{ }$$
The above equation is from personal experience using op amps in single supply (i.e. \$V_\text{SY}^- = \text{GND}, V_\text{SY}^+ > \text{GND}\$).

In split supply, we can use the following diagram from MIT's 6.002 introduction to electronics lecture video:

$$V_\text{out}=A_\text{OL}(V_+-V_-)+(V_\text{SY}^+-V_\text{SY}^-)/2\tag{Split-supply}$$

These two equations, however, are mutually inconsistent: If I take an op amp and hook up a single voltage source between its supply pins, how does the op amp know that the resulting voltage is not split between two sources?

It must know - but how does it know?


texts:
There is an old age board (doubt to be a PLC) which outputs keypad and touch panel data through a single BNC connector. I've managed to capture its output signal using oscope which is available in following address (signal image also attached):

http: //s000.tinyupload.com/index.php?file_id=62566907866564858099

I just want to read touch panel data through the coax cable but I can't decode it's data. Just knowing whatkind of cocommunication protocol it use is enough. Does the pattern of data in excel file familiar to anyone? Any kind of help would be greatly appreciated

Picture of board:


texts: Why is a voltage buffer loading my input signal (Audio)?

texts:
Hi I have this weird thing going on and I have no idea why.

This is my input

And this both my input and output. The voltage is following, but still 10mV off is this normal due to being a real world application and not perfect? But none the less, where did 300mV go?

simulate this circuit – Schematic created using CircuitLab

Is it because I am shorting my signal to "virtual Ground" ?


texts:
Is this a right implementation of an axi stream fifo?

entity PlusOne is
        Port   (        Clk : in  STD_LOGIC;
                Rst : in  STD_LOGIC;

                --AXI_Slave interface
                S_AXI_Data_In       : in    STD_LOGIC_VECTOR (31 downto 0);
                S_AXI_Valid_In          : in    STD_LOGIC;
                S_AXI_Ready_Out     : out   STD_LOGIC;
                S_AXI_TLast         : in    STD_LOGIC;

                --AXI_Master interface
                M_AXI_Data_Out      : out   STD_LOGIC_VECTOR (31 downto 0);
                M_AXI_Valid_Out     : out   STD_LOGIC;
                M_AXI_Ready_In      : in    STD_LOGIC;
                M_AXI_TLast         : out   STD_LOGIC);
    end PlusOne;

(definition of entity)

architecture Behavioral of PlusOne is
-------------------------------------------------------
--
-- Signal
signal I_Out : STD_LOGIC_VECTOR (15 downto 0) := (others => '0');
signal Q_Out : STD_LOGIC_VECTOR (15 downto 0) := (others => '0');
-------------------------------------------------------
---------------------------------------------------
type STATUS is ( S_WAIT_for_VALID,S_Dummy_0 , S_WAIT_for_READY, S_READY);
    signal NextState   : STATUS;
    signal ActualState : STATUS;
    signal Latch_Out   : STD_LOGIC := '0';

begin

STATO: process(Clk,Rst)
begin
 if (rising_edge(Clk))  then
  if Rst='0' then ActualState <=S_WAIT_for_VALID;
  else ActualState <= NextState;
  end if;
 end if;
end process;

(process to change the state)

STATOPROSSIMO: process(ActualState, S_AXI_Valid_In, S_AXI_Data_In, M_AXI_Ready_In, S_AXI_TLast, I_Out, Q_Out)
begin
 Case ActualState is
 when S_WAIT_for_VALID =>
  if (S_AXI_Valid_In='1') then
    NextState<=S_Dummy_0;
  --  NextState<=S_WAIT_for_READY;
  else
    NextState<=S_WAIT_for_VALID;
  end if;
   S_AXI_Ready_Out    <= '0';
   M_AXI_Valid_Out    <= '0';
   --M_AXI_Data_Out     <= I_Out & Q_Out;
   M_AXI_Data_Out     <= (others => '0');
   M_AXI_TLast        <= '0';
   Latch_Out          <= '0';

 when S_Dummy_0 =>
   NextState<=S_WAIT_for_READY;
   S_AXI_Ready_Out    <= '0';
   M_AXI_Valid_Out     <= '0';
   M_AXI_Data_Out     <= I_Out & Q_Out;
   --M_AXI_Data_Out     <= x"0000000F";
   M_AXI_TLast         <= '0';
   Latch_Out            <= '1';

 when S_WAIT_for_READY =>
  if (M_AXI_Ready_In='1') then
    NextState<= S_Ready;
  else
    NextState<=S_WAIT_for_READY;
  end if;
   S_AXI_Ready_Out    <= '0';
   M_AXI_Valid_Out     <= '1';
   M_AXI_Data_Out     <= I_Out & Q_Out ;
   --M_AXI_Data_Out     <= x"0000000F";
   M_AXI_TLast         <= S_AXI_TLast;
   Latch_Out            <= '0';

 when S_READY =>
    NextState<=S_WAIT_for_VALID;
   S_AXI_Ready_Out    <= '1';
   M_AXI_Valid_Out     <= '0';
   M_AXI_Data_Out     <= I_Out & Q_Out;
   --M_AXI_Data_Out     <= x"0000000F";
   M_AXI_TLast         <= S_AXI_TLast;
   Latch_Out            <= '0';

 when others =>
   NextState<=S_WAIT_for_VALID;
  S_AXI_Ready_Out    <= '0';
   M_AXI_Valid_Out     <= '0';
   M_AXI_Data_Out     <= (others => '0');
   M_AXI_TLast         <= '0';
   Latch_Out            <= '0';

end CASE;
end process;

 I_Out <= S_AXI_Data_In (31 downto 16);
 Q_Out <= S_AXI_Data_In (15 downto  0);

end Behavioral;

Because I have some problem when i connect this implemtation to DMA in Vivado. When i try to run the xaxidma_example_sg_poll.c it stops at this point :

while ((ProcessedBdCount = XAxiDma_BdRingFromHw(RxRingPtr,
                               XAXIDMA_ALL_BDS,
                               &BdPtr)) == 0) {
    }

Can you have any information about it?

Thanks in advance


texts: Floating DC power supply (solar panels) - do I need double-pole breakers and why?

texts:
I am in the process of building a small off-grid solar setup.

There will be 4 parallel strings of panels in this setup, and I understand that for 3 or more strings, you need some sort of over-current protection to prevent back-current in the case of a short.

However I've read in several places that it is 'good practice' for floating DC power supplies to have DOUBLE pole breakers (ie on positive AND negative) if they do not have their negative terminal grounded ie they are 'floating'. I  have specifically seen this referenced in discussion and standard about PV panels.

I don't understand why - surely with one breaker on the positive side tripped, there is no circuit and the panel/supply is isolated?

Can someone please explain the specific mechanism, in plain terms, as to why and why a double pole breaker is needed in a PV array? What fault/scenario are double-pole breakers protecting against?


texts: Generate XCF file for Lattice Diamond from command line

texts:
I am writing a Makefile for Lattice Diamond and have come as far as to cover all steps from synthesis to bitfile.

To program the FPGA (a MachXO3L in my case) I looked for a command line tool, and found pgrcmd.exe in the bin folder of Lattice Diamond. However this tool demands a XCF file as input. I cannot figure out how to generate this XCF file from the command line at all.

I was able to create a XCF file from the Lattice Diamond GUI. but can't spot any log message which shows what command was run to achieve this. But I don't want to manually generate that file from the GUI every time I need it.
On a sidenote, the documentation for Lattice Diamond command line tools is just ghastly and full of errors and omissions.

Is there any way to generate the XCF file from the command line at all?


texts:
could you explain what it is that causes harmonics in transformers?
I've read that these are the reasons, but it still doesn't give me a proper explanation.

Saturation of the core
Magnetizing current


texts: Solar Panel Boost converter (40v to 100V)

texts:
My project is to deliver the output of 200w solar panel (40v,1.5A)- very low because I am using lamps instead of the sun- to a load at a voltage level of 100v, after implementing the design of my boost circuit (L of 4.4 mH, C of 220 uF, IRF510 as a switch gate driven by a PWM of 10v amplitude to have the maximum current rating of MOSFET) the output of the boost still at the same level of the input (no stepping up!). I'm not sure what is my mistake,by the way the output of my arduino is only one wire connected directly to the gate of the MOSFET I didn't referance the GND of the arduino to the -ve side of the system main flow. is my calculation to the inductance and the capacitance values correct?

here's a drawing of the system
Please show me what should I correct

Thanks and regards


texts: Leviton GFCIs constantly trip on shaded pole motors

texts:
Update: I consulted with other electrical engineers. Here is a plausible mechanism. Again refer to the circuit diagram of this GFCI:

Look at the board layout. There is a long trace from where C3 is located to the SCR gate. It is suspected that transient capacitive coupling (within the circuit and not from outside) to the SCR gate is the cause.

Suggestion is to try putting C3 directly at the SCR gate, and a 100 ohm carbon comp resistor in place of the trace. This creates a low pass filter at the gate input and also reduces the capacitive coupling to the gate.

The inductive kick at either turn on or off may be the source of the transient.

The series resistor in combination with the shunt capacitor to the gate is to reduce transient voltage at the gate.

Comments??

Original message:

Does anyone own any Leviton GFCIs (those models without any automatic monitoring self test)? I found out the shaded pole motors from Waterpik can constantly trip on them (50% of the time), but not other brands of GFCI (which I just tried). Someone in the following url has similar experiences with his Leviton GFCI and even a second new Leviton he bought.

https://www.justanswer.com/electrical/2g0be-gfci-outlet-trips-even-when-clear.html

So it may not be problems with the normal working of a GFCI but particular implementation of the Leviton GFCI. Anyone got a clue what is that mechanism that can cause shaded pole motors to trip on the Leviton GFCI?

The youtube video describes the shaded pole motor in the Waterpik in details.
https://www.youtube.com/watch?v=PmNcRsxSovs

To recap. Even if the plug is 2-prong (without any grounding and it's put on glass surface). The Waterpik motor can trip any Leviton 5mA GFCI (I tested 4 Leviton GFCI outlets) even when isolated and not wet (even if rotor removed). The trips occur either during startup or turning off. Not when it's already on.

In other motor/GFCI combination. What is the reasons why it could trip during startup or turning off. It's not wiring problem. There are many reports of this everywhere. Have you experienced or read about it? What is the mechanism for the constant tripping? (supposed it's not wiring problem which I'm sure it is not in the waterpik motor and Leviton?

You may have heard of new refrigerators tripping on new GFCI. It could if the GFCI is a Leviton brand.. which may not be compatible with refrigerators. I have new refrigerator that also trips every few hours on the Leviton GFCIs. I'm testing it with other GFCI now. Please share your experiences about this too.

Btw, I use GFCI on all my electronic projects to be on the safe side.


texts: Triple Modular Redundancy w/ Majority Voting when a microcontroller fails

texts:
In a simple majority voting system, the majority input values will be the output, as shown below.

(source: 6502.org)
However, how does one deal with scenarios where one or two microcontroller fails? Also, how do we overcome the problem of having floating inputs when a microcontroller dies?


texts: I see the term "analog switch booster" in the ST reference manual for the stm32g071. However, I do not see anything anywhere that explains what it is or does. What exactly is an analog switch booster?


texts: How to create on-board USB blaster for Intel FPGAs?

texts: Intel/Altera FPGA development boards only require a USB cable to configure the FPGAs. There is no need to buy a byte blaster. How is the USB blaster implemented on these boards, is this method/design open to public?


texts:
Why in the SS relay the connection line 1 and 2 appear a altern symbol, can I use to connect a DC line ?

The symbol above 24~380VAC is a capacitor ?


texts:
I was given a small task (actually it's part of a much larger task) where the requirement is to generate a signal which looks like it came from a microphone. The following requirements needs to be kept:

1.0Vpp
Sine Wave
Differential

Now these are actually two questions:

I understand that the signal needs to be differential, so I need two signals but must these two be symmetrical around 0V? What is the normal output a microphone gives here. Otherwise: Could I just use a single sine wave, multiply it by two and the input to the receiver would look the same?
What is a cheap way I could do this? I understand that I could use a microcontroller and its DAC feature to generate a nice sine wave. Yet, how would I get a differential signal from that. Or is there any IC which already does what I want?


texts: What is this electronic component, in series (I think) with the fuse just on the input of a computer PSU?

texts:
Is similar tu a capacitor but is in series, the neutral cable of the phase is conected direct to this.. or I think is maybe after it passes the fuse...

On the board it is writen THR and on another board it says TH3...

What it is?

Some low voltage power made this to blow

Here ar some pictures:


texts: How could a digital multiplexer transmit at a rate higher than its input?

texts:
From Wikipedia, "a multiplexer, also known as data selector, is a device that selects between several analog or digital inputs and forwards it to a single output line."

https://en.wikipedia.org/wiki/Multiplexer

Each input take turns in connecting to the output line. There is only one input channel transmitting at a time. When an input is selected, it is as if there is a continuous path from that input to the output line.

So therefore, the line rate of the output channel must be the rate of which input it is connected to. For example, consider the figure above. If input B is selected, and its rate is 64 kbps, the output rate should also be 64 kbps.

But we know that in T-carrier system this is not the case. The rate of T1 is 1.544 Mbps because it is 24 channels of 64 kbps each plus 1 framing bit of 8000 samples per second.

Now that's the mathematics. But in terms of electronics, how could the multiplexer transmit at a rate higher than the input rate?


texts:
I'm using a PCB with some nixies on it.

They are driven by the KD155IC, which is a clone of the SN7441.
I run them on 175V with a 10k Resistor, should give them a working voltage of 145V, 3mA.

But a strange effect happens when cycling through numbers:

Some numbers don't even display properly, the just produce some
red-glowing something in the tube
Some numbers display, but with a small or large blue glow behind them
The rest display properly

Not working: 1
With blues-glow:  0,3,4,8,9
Normal: 2,6,7

Here are some images to understand what I talk about:

What I tried so far

Changed tubes to a set of "know-working" which run in another project for a long time  No Effect
Mounted the "not working" tubes into a "know-working" circuit WORK FINE!
Changed several KD155 ICs  No Change!
Tested KD155 IC's on other circuit, WORK FINE!
Changed power supply.  No Change

Does anybody has an idea what could be the problem?


texts: Need help with three-stage transistor amplifier in LTSpice

texts:
I am currently attempting to design an amplifier in LTSpice for an E1 project. My professor tends to emphasize analysis of these circuits, so he hasn't really given us any kind of a design process to follow, and he hasn't really done any example problems of circuit design from the ground up. So needless to say I can use some help with this.

The criteria are as follows:

Needs to operate between 100 and 10000 Hz
Input voltage .02Vpp
Must deliver 2 watts to load
Input impedance of 2200 Ohms, output 32 Ohms

Here is what I have so far:

And right now it does pretty much nothing at all:

Really not sure where to go from here; would greatly appreciate some help. Thanks!


texts: What sensors shall be used to detect if a dustbin is full (light weight material like paper,hair, etc)?

texts:
Considerations:
I am trying to detect if the dustbin is full. The dustbin is a rectangular shoe-box like structure without any lid. The kind of material that will be collected will be mostly hair, paper, carpet etc. I am thinking to use optical sensors. But I do not want to go through the pain of cleaning sensors again and again.

Are there sensors that can be put in a glass case and they can penetrate through the glass? This will protect the sensor from dust/collected material.
Is there a better alternative then optical sensors (IR, depth, laser,weight, acoustic, capacitive, touch, limit switches ).
The system needs to be robust.
Weight sensors: seems to be unreliable because the weight is not consistent.
Touch sensors: The material, say paper, if it touches the sensor then we can think the dustbin is full. But because dustbin is long (not cylindrical), the indication can be false. Also, in case of hair, the weight or touch, neither can help in detection.
Multiple IR sensors: These can be mounted and based on blockage, we can detect if the system is full but again I want to eliminate the need of cleaning sensors again and again.


texts: What type of glass fuse is this and what does the spring do?

texts:
This is a standard sized glass fuse like what cars used before the 80s.  I can faintly make out 20A, but I’m not sure what to call it in order to find a replacement.  The fuse in the picture has not blown, but it is the only one I have. I don’t think it matters, but this happens to protect a transformer for a pool salt generator.

I’m also interested in what purpose the spring serves. I’m sure I can find another 20A fuse, but I’m not sure I can find one exactly like this, so I’d like to know why it is special.


texts: Is a negative resistor a superconductor that does not require being cooled down to get 0 resistance?

texts:
Title explains it, is it possible to create a superconductor using negative resistor oscillator / amplifier? As superconductors are conductors with 0 resistance. Isn't an amplifier a superconductor?

Or is what I am asking for wrong? I just need to learn.


texts: Smallest Capacitor for Flyback AC/DC Converter

texts:
Most of the isolated flyback AC/DC converters I’ve seen place a rather large (>1uF) electrolytic capacitor in parallel with the bridge rectifier that follows the AC voltage source. To provide a specific example, this part from Murata needs a 6.8uF rated at 400V which can make the device rather bulky. If I’m looking to only generate 100mW @5V from a 120VAC supply instead of 1W, can I get away with using a ceramic capacitor with a much lower capacitance value (rated for the same AC voltage)?

My second question would then be: is there a general formula available I could use to determine what size capacitance I need to provide a certain output DC power? (Like 100nF for 50mW, 200nF for 75mW, etc.)
Thanks!


texts: Negative Feedback and life cycle of Vacuum tubes

texts:
There are many guitar tube amplifiers schematics that don't use negative feedback.

I was wondering how the negative feedback can help in the life cycle of the tubes? (If can help)


texts:
Hopefully this is the right sub to ask this question. Anyways, I'm working on a USB Audio device on a microcontroller and I'm having issues with getting a consistent audio input.

Some preface:

As of right now, I have connected the mcu and codec via I2S (codec is slave) with the following configurations:

MCLK = 11.2896 MHz
BCLK = 2.8224 MHz
LRCLK = 44.1 kHz
USB CLK = 12 MHz

When I do a simple DSP bypass (codec input -> mcu -> codec output), the audio is glitch free and awesome. However, when I enable USB, that's when things get weird. I'll get occasional glitches and the signal sometimes repeats itself. I'm not totally sure if this is because I'm not using enough buffers when writing to USB.

Right now my codec reads and USB writes are happening separately:

Codec Flow: Codec Input -> MCU I2S RX -> DMA Interrupt when I2S RX buffer is full
            -> Write this buffer into USB buffers -> Calculate next input frame len

USB: USB initiates input -> Write buffer to USB endpoint -> USB Write Callback
     called when USB transfer is complete -> Start reading next buffer

How I'm calculating my frame lengths:

#define AUDIO_POLL_INT     4
#define FRAME_BYTES        3
#define NUM_CHANNELS       STEREO

// Calculate the frame length
uint16_t frame_len = 44 (44.1kHz/1000 samples) * NUM_CHANNELS * FRAME_BYTES;
// Every 10 ms, calculate frame length with additional frame (only applies to 44.1kHz sample rate)
if (!(frame_pos % 9)) frame_len += (1 * NUM_CHANNELS * FRAME_BYTES)

// Increment frame position per usb call
frame_pos = (((frame_pos + 1) / 8) * (2 << (AUDIO_POLL_INT-1))) % 10;
frame_pos = (frame_pos + 1) % 10;

Actual Question/What I think is going wrong (?)

I'm guessing there is some jitter issues due to the codec MCLK and USB CLK rates being different (11.2896 vs 12). I'm only guessing this because the interruptions/glitches happen pretty periodically. I also have noticed that the codec buffers will "catch" up to the USB buffers every once in a while (codec buffer will overwrite a USB buffer even though the USB buffer is marked "full"). However, I'm not sure how to stop this from happening because the codec would go out of sync and I would lose audio data. I also cannot speed up the USB transfers obviously... I'm transferring a max of 270 bytes per USB write for a sample rate of 44.1 kHz.

If anyone has had experience with USB audio and synchronization, your help would be appreciated! I'm not sure how to approach the problem from here honestly. If you're wondering, USB Audio output is fine though (with the exception of some channels not being synchronized).


texts: Charge Pump PWM to GND connection necessary?

texts:
Hey there,
first post from an avid forum reader:
This is the schematic for a simple Charge Pump circuit from circuitdigest.com* (great website). I am trying to build a charge pump with 12V VCC and 5V PWM, effectively giving ~17V at the output. I understand the working principle discussed on the website, though when building a "single stage" charge pump as shown above, does the PWM input need to be tied to GND? I get what all other components do.
My question is, does anything change when I disconnect PWN from GND? (doesn't otherwise get the pulses discharged directly into ground?)
Im my design the pulse generator with be tied to the same ground as the OUTPUT GND.
Thank you very much!
Sources: *https://circuitdigest.com/electronic-circuits/charge-pump-circuit-design


texts:
De-ionized water is generally regarded as an effective cleaning agent for PCBs, as shown here and here. However, removing that water means compressed air, oven, and/or lengthy drying-time. Even if all these are used, water can still be present under (and inside) some components (i.e. transformer housing), possibly contributing to crevice corrosion and other un-desireables.
Similar to the question regarding Vacuum dessication of MSL components, what would the efficacy be of subjecting a washed PCB to low-pressure conditions for accelerated drying?
Most discrete components are solid and homogenous, so should be unaffected. But what about:

Electrolytic, polymer, polystyrene capacitors
Sealed non-vacuum items (fuses, relays?)
Sealed vacuum items (thermionic tubes, neon lamps, etc)
LCD displays
Battery cells

Can electrolytics survive vacuum, or will they vent? What about a glass fuse? Are Nixie tubes safe in a vacuum? Would an LCD display be altered at all?
Batteries are interesting. One video reports that certain 18650-sized cells may be unaffected by vacuum, while LiPo swells but remains functional. I'd not trust one after this, nor consider coin cells, or vented liquid-electrolyte types. Another video shows a GoPro camera and Fieldpiece temperature probe both operating well under vacuum conditions, however that was of short duration. Real vacuum moisture removal would take an hour or so, depending on ambient temperature.


texts: Scaling Voltage for Arduino Analog In, Beyond Voltage Dividers

texts:
I've recently built some fiber-optic bend sensors and I want to read the values I get from them into a computer via an Arduino. I'm measuring the light with this photodiode from Industrial Fiber Optics. Currently, I'm giving the LED on the other end as well as the photodiode 2.2V. My question has to do with the fact that the voltage fluctuations as measured by a multi-meter on the photodiode are linear, but rather small as the fiber is deformed, even quite radically. With the fiber straight, depending on the fiber (its hard to score them identically), the voltage hovers around 1.92V, for instance, and with bending it will it will go up to, say, 1.93-1.94V. I'm not worried about getting the voltages identical as I can scale in software.

What I am worried about is losing resolution when doing A/D with the Arduino. If my voltage fluctuations are on the order of 10mV, won't the Arduino's 10-bit A/D quantize the hell out of it, even if I step the voltage up to 5V with a voltage divider? What I'm looking for is an analog scaler. How can I stretch out that range between 1.92 and 1.94 to cover the full range, from 0V to 5V so that I can take advantage of the full range of the Arduino A/D?

I feel like this has got to be a common operation in electronics, but I've never studied it formally, so a lot of things are lost on me.

(You may be thinking, as davr was, "why are you using fiber optics for bend sensing? Why would you expect a voltage change when the fiber is bent?" The trick is to remove the cladding on one side of the fiber optic cable. This lets light spill out. When the cable is bent away from the scoring, even more light is let out of the cable, causing a voltage drop in the receiver, and vice versa.)


texts: How to power a device with a LIPO battery correctly

texts:
I have a little device which is normally powered by 5V 2A.
But the manufacturer says it is compatible up to 16V 2A and I tested it with a powerbank which outputs 12V 2A.

Sadly this powerbank is a bit big to carry around, so I thought I could build something with a Lipo 3s Battery.

As far as I know 3S Lipos have around 12V. I asked my electronics teacher, and he said I could simply connect the device to the Lipo battery, but I do not want to kill a 300$ device so I want to have a second person checking it.

Will I be fine with simply connecting the battery to the device and it will self regulate the Ampere?

Thanks


texts:
I need to regulate an incoming DC supply from a wall-wart down to 5 volts. I'm experienced with designing power supplies with ordinary transformers. In this situation, the maximum voltage I can expect would be the transformer AC voltage rating * 1.4 * transformer regulation * mains tolerance (10%). This works nicely all the time I have access to the transformer's datasheet to determine the regulation %. For example, a 9V AC transformer with a 57% regulation could produce a peak voltage of 22V in the worst case. I can then calculate the virtual impedance of the transformer from its regulation and determine what the actual voltage will be at my maximum expected load - and therefore determine regulator dissipation.

Unfortunately though, when specifying a DC wall-wart, I have no control over what type of wall-wart the user will connect. The user might assume that because the input is marked "12V", they can choose any 12V wall-wart. If I'm lucky, the wall-wart chosen will be close to the maximum current drawn by the circuit - in which case the voltage will be close to the nameplate rating. But what if the user connects a wall-wart rated several times higher than the projected current draw? The wall-wart's output voltage will rise dramatically.

Exactly how much will it rise, though? From doing some measurements of a few wall-warts I have laying around, the off-load voltage varies all over the place. For a couple of 12V 1A linear wall-warts, I was seeing about 18-21V off-load. Smaller wall-warts might be worse, but I didn't have any 12V ones to check.

So, is there a rule of thumb for calculating a typical worst-case wall-wart off-load voltage? It will surely depend on the regulation percentage of the transformer used, but what's the worst typical transformer encountered in practice? Also I'm not even sure what transformer voltage a 12V wall-wart uses - since it needs to be large enough to account for transformer droop due to peak rectifier current (which could be quite large with a small, high-resistance cheaply made transformer). I would guess around 10V RMS? Probably the worst chassis-mount transformers I've come across have a regulation of around 60% - but wall-warts are so cheap and nasty I wouldn't be too surprised if it were worse. On the other hand, if the wall-wart is overrated in current, it will probably have a better regulation percentage due to the bigger transformer. So I suppose there will be a sweet spot where the transformer is big enough that it's running partially-loaded, but small enough that it has a poor regulation - giving the worst-case input voltage.

I found one source online claiming they were seeing an off-load output voltage from a switching wall-wart of twice the nameplate voltage. That seems awfully high, and perhaps not typical? But do I need to design my device to tolerate such a high input just in case such a wall-wart does come along? Are there wall-warts that could be even higher than twice?

I don't have any control over whether a switching or linear wall-wart is used - it could be either. But it's probably safe to say it won't be regulated either way.


texts:
Can the TL783 be used to regulate negative voltage by connecting the output to my system ground and using the regulator ground as my negative voltage source? I couldn't find anything in the datasheet pertaining to negative regulation except something like this:

  The device works to keep the voltage at the OUT pin 1.25
  V higher than the voltage at the ADJ pin. Therefore, a resistor divider can be used to set the output voltage.

This would lead me to believe it should work as I described, but I'd like to verify with someone who knows more than me about this.


texts:
This simple 3rd order low-pass circuit

simulate this circuit – Schematic created using CircuitLab

can be described with the following 3 equations:

$$-V_1 = \displaystyle \frac{-1}{sC_1} \left( \displaystyle \frac{V_{in} - V_1}{R_S} - I_2 \right)$$

$$-I_2 = \displaystyle \frac{-1}{sL_2} \left( \displaystyle V_1 - V_3 \right)$$

$$V_3 = \displaystyle \frac{-1}{sC_3} \left( -I_2 + \displaystyle \frac{V_3}{R_L} \right)$$

It can be realized through an active-RC filter using integrators and so opamps. The resulting signal flow graph should be

simulate this circuit

Note that \$ I_2 \$ is a voltage value and not a current. The values or numbers alongside of the branches are their transfer functions.

Suppose that it is possible to realize the negative resistances corresponding to the right-hand side branches. The active RC realization is as follows:

simulate this circuit

Each integrator is realized with an opamp circuit; it is assumed that the input signals of each integrator are currents and the outputs are voltages.

It is explicitly specified in the book that the second stage is a non-inverting integrator (realized through the negative resistances of the right-hand side branches, so that the minus sign in its transfer function is cancelled by the minus sign of these resistances).

So, why is it used the equation

$$-I_2 = \displaystyle \frac{-1}{sL_2} \left( \displaystyle V_1 - V_3 \right)$$

instead of

$$I_2 = \displaystyle \frac{1}{sL_2} \left( \displaystyle V_1 - V_3 \right)$$

?

As stated in the comments, I think there is no correspondance between the equations, the signal flow graph and the realization with opamps:

if the second block is a non-inverting integrator, in the signal flow graph its transfer function should be \$ 1 / sL_2 \$ instead of \$ - 1 / sL_2 \$; the output should be \$ I_2 \$ instead of \$ -I_2 \$ and the resistances on the left-hand braces should both be \$ -1 \$ (so, even if the signal flow graph can perform only summation, it is possible to subtract \$ I_2 \$ in the first and in the third stage);
the active RC circuit doesn't exactly realize the signal flow graph: its second stage is a non-inverting integrator (while in the signal flow graph it appears as inverting) but it realizes the positive left-hand braces resistances.

Did I make some mistakes or is the circuit built in a wrong manner?


texts:
Above is the circuit with my attempt and how I viewed it. I'm wondering if there's anyone that can confirm if I got it right? The middle red line that goes through the Not gate confuses me.

Any help would be very appreciated!


texts: Designing electronics and their enclosures for the outdoors

texts: I think the title captures it, but to expand upon this further.  What are some of the best practices that you use to place electronics outdoors?  Include what you do for the cases and mention issues with temperature, moisture, lightning, shock hazards, UV Damage and if your device generates heat how do you deal with it, how do you get power to it etc.


texts: What is the equation for the 555 timer control voltage?

texts:
I was just wondering what the equation is to find the 555's output frequency is, when a control voltage is applied to pin 5. That would be very useful for me to know!

[Edit By OP]

So based on what Spehro Pefhany said, the equation for the output frequency (Substituting the equations for the high and low times) would be:

Where:

\$V_{Control}\$ is the control voltage

\$C \$ is the timing cap

\$V_{cc}\$ is the supply voltage

\$R_{1}\$ and \$R_{2}\$ are the timing resistors

\$f\$ is the output frequency


texts: Meaning of N parameter in Chan Model LTspice

texts:
I'm trying to model an audio transformer for core saturation simulation but I don't understand what N parameter represents in the Chan model. It should be the number of turns of the windings but if I set it in the model I don't have what I expect from simulation. I see what I expect only if N is equal to one.
Could anyone explain me what N parameter exactly represent?
In the picture below you can see my transformer model.

Thanks a lot


texts: A question about electronic measurement of pulsed laser

texts:
I have read recently somewhere which I cannot find now, that extreme short pulse width lasers cannot be generated electronically.
But if electronic circuitry is not capable to to generate such laser pulses, how is the pulse width of them measured and recorded by a device(which is also made up of electronics)?


texts: Is it possible to enable both UART and PLL at the same time on PIC18F?

texts:
I'm doing an application where I'm turning on some ws2812 LED with my pic microcontroller and I want it to talk with my smartphone via bluetooth. Now, I got the code for the LEDs from

http://mjhdesigns.com/?p=312

and I can light up the LEDs with the colors I want (via hardcoding a RGB value) and separately, I can send a message on my phone (via bluetooth terminal) and my microcontroller does receive the full message (inspected by debugger).

However, the problem is when I put the two together.  The LED code I got require PLL to be enabled, but I am finding out that when I put the line to enable the PLL

OSCTUNEbits.PLLEN=1;

the microcontroller's receive message gets garbled.

I already tried turning the PLL on and off after the microcontroller receives the message ie

//Receives the message from smart phone
for(i=0;i<10;i++){
            while(!RCIF);
            receiveArray[i]=RCREG;
 }
 //Turns on lights
 OSCTUNEbits.PLLEN=1;
 OSCCONbits.IRCF = 0b110;
 SetAllRGB(0,0,100);
 writePinMain(0);
 DelayMs(5000);
 OSCTUNEbits.PLLEN=0;
 OSCCONbits.IRCF = 0b000;

However, this results in the LED colors being inaccurate, which leads me to believe the frequency is off or the PLL is screwed up.

I should also note that the code runs on a XTAL_FREQ of 8MHz configuration bits haven't changed at all when I swapped between LED lighting and UART code (comment one or the other out), so I do not think configuration bits are a problem, but other then that, I'm out of ideas on what could cause this.

Is there something I'm just not seeing?


texts:
Basic idea is to extend existing device with a buzzer: I want to make noise when one of the diodes lights up (DL12 on the attached picture). From the layout of the board I assume that U1 (M74HC595) is driving both rows of LEDs (DL8-12 and DL13-17, only one diode from each row is lit at a time) in turns (fast enough that there is no flicker).
I want to read from U1 which is a tri-state logic IC and detect both QB and QG (Q1 and Q6 below) to make logical AND on them.

I was also to build simple circuit based on transistors but without luck (NE555 circuitry is omitted) :( What have I done wrong?


texts: What is the meaning when we say power of circuit having a clock frequency 100Hz is 2W?

texts: When we say clock frequency is 100Hz, then there are 100 clock pulses in one second. So when we say power is 2W, is it 2W for 100 cycles or one cycle ? Or is it anything else?


texts: I am so sorry,  I have to ask such a stupid question.  I got these stepper motors from a thrift shop, the owner had no idea what these are.  And these have all labels damaged. Can anyone help me figure out the name,  model, or wire codes of this. Thanks in advance It has pink,  yellow,  green,  and blue wires. Here is its image: https://ibb.co/HDm7BKj


texts: Understand an accelerometer data sheet correctly

texts:
I want to use an accelerometer to measure vibrations.
Most important for me is the operating frequency range. Reading a sensor data sheet, section dynamic specifications, there is (mostly) nothing written about this frequency range (like e.g. "the sensor measures vibrations in the range of 5 to 1kHz").
Which are the sensor specs I have to look for in order to know if the sensors fulfills my requirements towards freq. range?
Thanks in advance!


texts: smart thermostat circuit needed some layout tips

texts:
I have smart thermostat project for my graduation and I just wanted to be 100% sure before sending it to China for manufacturing - its my first time with PCBs O_O. It takes 3 weeks to arrive my country therefore I don’t have time to test it, I only got one shot. My prototype works perfectly on breadboard.

This is the dropbox link to my BRD files and some screenshot for you guys to check it real quick: https://www.dropbox.com/sh/05sbwndrdl5tqql/AADXK4_4RyO7QGvu2Xw_t1Hka?dl=0

I have few questions below, and I really do appreciate if you download them and control it.

Transmission traces between FT232 and Atmega328 are not short
traces. Are these traces going to cause any trouble?
Did I place the decoupling capacitors correctly in my layout?
Is 16mil drill size too small for manufacturing?
Do I need to add a diode between LM3940 and ESP8266-1?

Transmitter:

Receiver:


texts: I'm working on an FPGA MAC module and I'm kind of confused with TX_ER signal. A '1' in TX_ER means there's a whatever error in the current packet being sent by MAC. To my understanding, a MAC frame consists of protocol specific header and FCS where I don't expect errors occur, and playload from upper layer which should be transparent to MAC. Then where does this error come from? If MAC is aware of this error, why does it send the frame?


texts: Another way to increase Tungsten filament resistance?

texts: I understand that the thing that allow a lightbulb to glow white high is the fast amount of resistance the electrons face with all the many spiral the filament has. But I need a thicker more resistant filament so is there another way to increase resistance?


texts:
In my textbook , they have given some applications of gray codes.
One main use of gray code is in karnaugh maps.

Here gray codes are used. but why decimal equivalent of binary code is written in that box instead of decimal equivalent of gray code.
That is ,first row third column box should be written as 2 right!! Since 011 is gray code ,its decimal value is 2.
Please clarify this...


texts: How to power on Murata D1U-2000-48-HB4C without plug in

texts:
Hi guys i'm trying to power on murata AC to DC D1U-2000-48-HB4C model.
i have tried connecting PS_On and PS_Kill to ground since in datasheet stated that ps_on and ps_kill need to be pulled out but still failed to power on the psu. please advice..

Datasheet link: https://www.murata.com/-/media/webrenewal/products/power/datasheet/cps_d1u-2000-48-hx.ashx?la=ja-jp

Thank You


texts: PCB design review: Decoupling, bypassing and grounding

texts:
I'm trying to make my own wireless sensor using ATmega microcontroller. I've some basic understanding of electronics but I'm a total amateur when it comes to designing circuits and PCBs.

This is just a hobby project so it's not expected to be of a production quality or anything like that. But still I would like to make it as good as possible just for a good feeling of doing things right.

I've read something about decoupling, bypassing and grounding but not sure if I understand it correctly. So if someone could look at the board and point out things which should be done differently I would be really thankful.

Edit: added schematic of the circuit


texts: In Xilinx ISE, why can't I rename the net of some of my ports?

texts: In Xilinx ISE, most of the time, when I want to rename the net of a certain port, I have no problem. I right-click on the I/O marker, click Rename Port, and I get the window for Rename Net. However, for some reason, when I do the same for some I/O markers, I get the window for Rename Bus. How can I get the window for Rename Net?


texts: Can the NFC antenna of smart phone read signals from (active) RFID tags/transmitters

texts: Can the NFC antenna of mobile phone such as the Galaxy S4 or iPhone in addition to their NFC functionality, also be used to read signals from (active) RFID tags/transmitters e.g. from 20ft away not 20cms?


texts: Voltage Dividers for a beginner (with respect to soil moisture sensors)

texts:
I've just started with electronics and want to make an analogue soil moisture sensor (with Arduino).

When I looked online for an explanation of the working, every site said that it works as a voltage divider.

These are my questions:

What exactly is a voltage divider? How does it work (for a beginner) ?
The tutorial said that a wire has to be connected from the Vcc to an analogue pin on the Arduino for the readings.
But how can a wire from the Vcc send analogue signals about the soil's resistance? Doesn't it just supply power?
The tutorial mentioned a capacitor between the Ground and the signal wire for filtering noise.
What is this noise? How can the capacitor filter it? Why does it need to be filtered?

I've attached an image of a part of the tutorial for reference.

Thanks a lot and apologies for my silly questions (couldn't find a satisfying explanation elsewhere) .


texts: What exactly is primary rated voltage of transformer?

texts:
For example,
we have a 2200/220 V non-ideal transformer.

Is primary rated voltage defined as the supply voltage to get 220 V across the load in this case? Or it is just the 2200 V as mentioned in rating?

More generally, is primary rated voltage defined as the supply voltage we need to have so that the secondary rated voltage is appeared across the load? Or is it just equal to primary induced EMF RMS value?

Model of transformer:

Source: Electrical4U.com.


texts: Does the cost of an ENIG-finished PCB depend on the surface area of the exposed gold at a large scale?

texts: At very large quantities (>100k-1M), does the cost of an ENIG plated PCB increase as the surface area of the part exposed to gold increases? Intuitively it would make sense, as more gold would be consumed in the bath to coat a pcb that is just a large ground plane exposed, as opposed to one with just the component footprints. But any website I looked at for quotes would not show a change in the price depending on the PCB Design.


texts: I am recently using a ADS1278 as the ADC of my system. The configuration is Frame-sync, TDM, Fixed for the 8 channels. The mode is high speed (sampling at 64KSPS). The core clock and the serial clock is the same at 16384000 Hz. The voltages and analog circuits follows the example circuit in the data sheet. So I am reading the data (input is a square wave for now), and all 8 channels seem to give reasonably correct values (at least in estimated voltage), the clock seems not too jittery and I can take the values to re-plot the square wave. However I noticed that all the values I read are repeated twice (always, and very consistently), for example, if I read 5 as my first value, the next value will be 5, and the two afterwards are the same value, and so on. I am not sure why that is the case. I did probe the data line vs the frame sync line which shows that two consecutive frame syncs worth of data gives the exact same value. I don't know why this is the case.


texts:
Can a stranded wire exhibit a capacitive reactance?

I measured the real and imaginary part of a piece stranded wire using an old LRC meter( HP 4284a).
Applied an open loop and a closed loop compensation for the parasitic impedance of the lead wires.
Measured reactance is negative. This left me puzzled, is this phisically possible?

I know that a real conductor will display an inductive behaviour because of self inductance, with positive reactance, increasing with frequency.
Could a stranded geometry cause a negative reactance to be measured?

Or is this more likely a wrong calibration issue?


texts: Large Power System - Separate Earth Grounds?

texts:
I'm a EE working on a scientific instrument that is large in scale, like a building. The structure is all metal and will have many server cabinets and electronics equipment, motors, sensors spread all over it. It is not yet built.

Power is supplied from a local utility feed to the instrument as 3-phase AC power where both 3-phase and single phase can be utilized. The 3-phase includes L1, L2, L3, N, and PE. PE is tied to earth ground and Neutral at the utility feed.

There is a strange requirement to keep the PE from the power source isolated from the structure itself. Equipment with a metal chassis must either have its PE-connected chassis isolated from the structure or the equipment's chassis can be bolted to the structure if PE is disconnected inside. They say this is to reduce noise and ground loops.

For example, if I installed a rack computer, I would need to either isolate the chassis from the structure or remove any PE connection from its power plug to its chassis to isolate it. Then ensure the chassis is bolted to the rack which is bolted to the instrument chassis for safety ground.

I believe that they're confusing PE with an actual current carrying conductor. They keep calling it Ground. I can't make any sense of it. Perhaps I'm misunderstanding the requirement. Have any of you ever heard of something like this?


texts:
I am  using this circuit to amplify a sensor signal (220mV p-p) to about 5Vp-p and measuring by microcontroller ADC:

When I connect the input signal, the input voltage level goes up (changes from 220mV p-p to 600mV p-p) and the output signal is corrupted.

The input signal is 220 mv p-p, 11.5 khz.


texts: Efficient way to selectively unpower USB ports

texts:
(Edited and expanded from original question for clarity)

USB interfaces as a means of controlling external hardware from a desktop or laptop computer are ubiquitous; many thousands of hardware models are available, ranging in price from 10-1 to 106 USD. It is reasonable to require that the +5V DC voltage line be able to be switched off from the host computer, but this is by no means guaranteed across every mainstream PC/laptop running every widespread OS.

I am looking to have a true cross-platform solution to be able to selectively power USB ports down and up from software, for totally arbitrary lengths of time. This is not because I am prototyping or breadboarding, and nor is this my first foray into electronics making an LED blink on and off; I require a long-term reliable solution.

I am looking for an efficient solution which minimizes:

Cost
Implementation time
Other general hassles, such as volume or amount of trailing wires

Based upon comments, I have thusfar ranked my options as follows:

Option 1

Buy a dedicated USB splitter, with fully cross-platform proprietary software, such as the Yepkit YKUSH hub:

$42
Negligble software compilation time + some time to "box up"
Compact and neat

Option 2

Buy a programmable USB hub:

$300
Small amount of time to implement command-line software control
Professionally boxed

At the moment, I would be tempted to get a 4-way USB hub, splice its power lines through a separate arduino-controlled relay (as I have an arduino that need never be unpowered).

Option 3

Buy a fairly off-the shelf hub compatible with uhubctl. Then either run Linux or program a way to make it work in Windows. A VM would also be a headache, because programs in Windows will have trouble interfacing with Linux programs inside the VM.

~$20
Long time to implement cross-platform software
Professional USB hub

Option 4

Buy a USB hub and a Normally Closed 5V relay, controlled by e.g. an arduino to cut power to the USB hub as required:

~$25
Long time to solder and tidy connections + short time to implement switching in arduino code
Fairy ugly due to splicing wires

(Surprisingly not suggested in responses given that this is an Electrical Engineering site)


texts:
Why is AND gate equivalent of positive logic OR gate in negative logic?

I do not get why we express AND operation as OR gate in negative logic.

And what is the advantage of negative logic systems?


texts:
I am studying maximum power point tracking (MPPT), and I have found many setups using buck converter. Since buck converters step down the voltage, how can you have the maximum power at load if you step down the voltage? Do you increase the current so you get maximum power?

I am also confused about what load to use in the output of the buck converter. For example if you step down from a 17V solar panel input to a 5V output, and the maximum power from the solar panel is 10W, you need 2A current at the output (5V*2A = 10W), so your load should always be 2.5 \$\Omega\$? So if one changes the load, then the maximum power cannot be reached?

I hope someone can point me in the right direction, and correct me if my understanding is wrong.


texts: General question about safety-critical use of microcontrollers

texts:
I was wondering if microcontrollers that hobbyists use, such as the 8-bit Atmel AVR ATMega328 which is used in many of my small projects, can be used in sensitive things, for example a life-dependent application such as an aircraft of space shuttle?

I am asking out of curiousity: I am a student in school.


texts:
I'd like to make a small anechoic box for RF measurements.  I need roughly a 30x30x30cm cube of usable space, and I'd like the reflections from the walls to be attenuated by 10dB or more from 100MHz to 1GHz. If this can be made from cheap and readily available materials, that would be ideal.

My current idea about this is to take an old microwave as the shielded box, and use salt water as the absorbing material.  It is a bit hard to get the water to go all the way around the device under test, but perhaps one plastic box nested inside another box with the in-between space filled with water would work to surround it from the sides and bottom; something else would have to be used for the top.

Would salt water work as absorbing material?  What is the best salt concentration that gives a good impedance match to free space?  (And how do I model this?)

Is there some other material that is better than salt water? (Perhaps bits of crushed salvaged ferrite choke cores...)

Even better: is there an instructable / blog post that describes how to DIY this? :)


texts: How are Microchip configuration straps used?

texts:
I'm working with a Microchip USB hub IC (USB2533 to be specific) and can't nail down a straightforward answer on how their configuration straps work through my own research. On this device, many pins perform multiple functions which is done through the use of configuration straps.
Here's what I've found in their documentation, quoting from the datasheet directly:
Note 3-3: Configuration strap values are latched on Power-On Reset (POR) and the rising edge of RESET_N
(external chip reset). Configuration straps are identified by an underlined symbol name. Signals that
function as configuration straps must be augmented with an external resistor when connected to a
load. Refer to Section 6.3, "Device Configuration Straps," on page 23 for additional information.
And Section 6.3 says:
Configuration straps are multi-function pins that are driven as outputs during normal operation. During a Power-On
Reset (POR) or an External Chip Reset (RESET_N), these outputs are tri-stated. The high or low state of the signal is
latched following de-assertion of the reset and is used to determine the default configuration of a particular feature. Configuration straps are latched as a result of a Power-On Reset (POR) or a External Chip Reset (RESET_N). Configuration
strap signals are noted in Section 3.0, "Pin Descriptions," on page 7 and are identified by an underlined symbol name.
The following sub-sections detail the various configuration straps.
Configuration straps include internal resistors in order to prevent the signal from floating when unconnected. If a particular configuration strap is connected to a load, an external pull-up or pull-down should be used to augment the internal
resistor to ensure that it reaches the required voltage level prior to latching. The internal resistor can also be overridden
by the addition of an external resistor.
From this, my takeaway is that weak pullups/pulldowns are to be applied to set the configuration, which is only determined on startup or reset. Afterwards, the pullups/pulldowns are ignored and the pin is driven as an output (hence weak pullups/pulldowns so as not to interfere with normal operation). I believe the timing diagrams (figures 9-2 and 9-3) support this conclusion.
However, I wasn't able to find anything that explicitly states that these weak pullups/pulldowns are the solution. The other scenario I can come up with is that the configuration straps are to be applied for a brief period of time and then removed after a reset or power cycle using an external device (unused pins on a microcontroller, for instance). I'd rather not commit to one design until I'm sure due to the turnaround time and expense of getting it wrong.
Am I interpreting Microchip's datasheet correctly?


texts: Advice on safe discharge circuit for HV Capacitors (400v)

texts:
In designing a relatively high voltage DC-DC converter, my output capacitor happens to be a 100uF electrolytic charged to 400v nominal. Efficiency is a design constraint, so I would like to know of any common design practices that handle the discharging of these capacitors.

This system will be debugged and characterized, so I'd hate for someone to get a nasty shock. Is a resistor the best way? To get quiescent power draw low enough, I have to use ~1M.


texts: i always knew that current will take all paths, even the other post on this forum said so, but i was doing this RC circuit today where the resistor and the capacitor are wired in parallel, i was told that the capacitor charges quickly because the current " will the take the path of least resistance", so now i am confused


texts: How can a resonator do band-pass filtering?

texts:
I've read many times some statements about resonators like this (reference):

Resonant circuits are circuits, which offers a high impedance or low impedance (for parallel and series
resonance respectively) to the source at a particular frequency of operation. The frequency at which the
resonant circuit has a very high or low impedance is called its resonant frequency.The frequency selectivity property of resonant circuits are exploited in building filter circuits

1) It's a basic concept that is written everywhere, but I cannot understand in practice how resonators may filter an input signal. Precisely, let's consider a parallel RLC circuit:

It may represents different kinds of resonators. It's simple to find that the input impedance of the parallel RLC circuit which represents the resonator is the following one (in terms of real and imaginary parts):

If we look at the graph, I understand the initial statement: this graph is very frequency - selective.
But let's look at the RLC circuit: what does it filter? There is an input voltage signal. If I take the voltage across one of RLC components, it will be the same of the source. I'd say that this circuit, given an input voltage signal, gives an output filtered current. So, how should I read this filtered current (from a circuital point of view).
2) What If the parallel RLC circuit is only a model (not a real circuit) of a cavity/waveguide resonator (i.e. a closed tube of metal in which there is my electromagnetic source)? My electromagnetic source (consider a simple antenna) generates an EM field with some frequencies, and the cavity selects only specific frequency. How may I read the filtered signal?


texts: Microcontroller on-chip flash consumption - size matters?

texts:
For a given MCU, all other things being equal, does the memory capacity impact the power consumption ?
A 512kB flash memory would consume more than a 128kB ?


texts: Computer Instruction Format - Calculating the number of Opcodes

texts:
I found the following question on a different site:

A processor has 64 registers and uses 16-bit instruction format. It has two types of instructions: I-type and R-type. Each I-type instruction contains an opcode, a register name, and a 4-bit immediate value. Each R-type instruction contains an opcode and two register names. If there are 8 distinct I-type opcodes, then the maximum number of distinct R-type opcodes is _______ .

Note – This question was Numerical Type.
(A) 14
(B) 15
(C) 16
(D) 12

The author claims the correct answer is 14. I do not understand why. Here is my reasoning. For an I-type instruction, we have 6 bits for the register and 4 bits for the immediate value. That leaves 6 bits left over for the opcode. That means that we should have 2^6 = 64 opcodes which means we have 64 - 8 = 56
R-type opcodes.

Another way to look at this problem is to say that an R-type instruction needs 12 bits for two register specifications. This leaves 4 bits for the opcode. Hence, there are 16 R-type opcodes. I am not sure
about what happens because some of the I-opcodes overlap.

Hence, I am not sure what the right answer is, or how to get it?

Updated Answer:

Now for an R-type Opcode, I see
1-bit for a flag to specify if it is I or R format
12-bits to specify two registers
3-bits for the opcode

Now, I am seeing 8 different R opcodes because 2^3 = 8.


texts: What's the correct term to describe a conductor which doesn't always obey Ohm's law?

texts: Non-ohmic comes to mind, but that gives an impression that the conductor never satisfies Ohm's law. Is there a better term which describes a conductor which might satisfy Ohm's law at certain voltages and temperatures, but not at others.


texts: Non-resettable zener/polyfuse for overvoltage protection

texts:
My setup is two DC-DC converters (hobby BECs) supplies, one acting as a backup for the other. A relay, powered by the primary BEC will automatically switch to the secondary BEC if the output from the primary one goes dead.

Now, I want to protect both BEC's against overvoltage (in case they fail to short the main 18V power supply to my 5V devices). For this I was planning to use a combo zener and polyfuse (or even a polyzen if I can find a suitable one), but I want one that is non-resettable, i.e. when it blows it blows catastrophically. Can I achieve this by replacing the polyfuse with a normal fuse?

The output from the BEC at 5V will be no more than 5A.


texts: Is powering a 12v DC motor with 11.1 volts a bad idea? (3 * 18560 battaries)

texts:
I am working on an Arduino project where I will be controlling 4 individual 12 volt, 0.71 Nominal amp draw DC motors, the arduino will be separately powered with another power supply.
I'm going to use a L298N controller which is known for having a significant voltage drop of 2 volts, so perhaps it's okay to use 4 18560 batteries for the power supply and using only 11.1 bad for the motors?


texts:
I'm attempting to design an H-Bridge which can supply 24V at 60A. As 60A is a lot of current I decided to parallel upto 4 FETs per leg to split the current.

I am using a MIC4102 2A driver to drive the FETs and I understand the important of keeping drive loop of the FETs small. Here's a circuit showing just 2 legs. The layout is also shown for the high-side.

The layout shows the path from pin DH (pin 3) to the FETs' gates to their sources and back to pin HS (pin 4).

Since the high di/dt return current will try to stay close to it's drive path I decided to just pour a polygon beneath the drive traces (and resistors) and let the current flow back to the IC. I also annotated the layout picture above to show where I think the return path will flow (white dotted line in the picture). If it follows this pattern I think the drive loop will be quite small. There is a small error in the annotation - the white dotted line should go to pin 4 of the IC and not pin 3.

Can I count on this return path pour to reduce ringing that my FETs experience? Most datasheets which show a layout only show a single high-side FET and no gate resistor. The inclusion of the gate resistor and multiple FETs made it necessary for me to have polygon.

The H-Bridge (Only Half Bridge shown in schematic. The other half is exactly the same) is intended to drive a transformer at 20kHz and boost 24V upto 350V.


texts: How does an op-amp know where ground is?

texts:
Although I've been working with op-amps for a while, the following question never occurred to me before today.

Consider first the op amp on the left (A). The negative terminal is connected to ground, and a small voltage \$V_d\$ is applied between the positive terminal and ground. If the output voltage is measured with respect to ground, it should read \$A \cdot V_d\$.

Now consider the op-amp on the right (B). This time, \$V_d\$ is applied directly between the negative and the positive terminals, with no reference to ground. If the output voltage is measured with respect to ground, would it still read \$A \cdot V_d\$? How could this be, since this op-amp has no idea where ground is?


texts: In many PCB board, I have seen zero ohm resistor in between the signal lines. What is the reason behind it? Can't we simply connect it through copper trace?


texts:
I have designed a custom PCB with an ESP32 and an OV2640 camera module. The image contains some noise and I don´t understand where the noise is coming from.

My suggestion is that the data lines from the camera module to the ESP32 are too long (shortest 45 and longest 54 mm), but I´m not sure. And I´m unsure how I can solve this issue.


texts: Help me fine what kind of Transformer this is

texts: Can you help me find what kind of transformer this is? I'm having a hard time looking it up based on the numbers. It came off a Kenmore 220V stove


texts: Why don't we think about battery storage for all sources of electricity on a utility scale instead of just renewables?

texts:
One of the repeating solutions that comes up when talking about renewable energy power generation and the intermittency of it is battery power storage.

This has got me thinking, it takes hours or days for gas and coal fire plants (and I assume other fossil fuel options) to fire up and so you essentially have to keep these going as power backups for renewables for when the wind doesn't blow or the sun doesn't shine.

This got me thinking, why isn't anyone talking about using energy storage for all sources? Specifically utility-scale solutions that can hold weeks or months of energy? I would think that such a solution could vastly reduce inefficiencies in all power generation as my understanding our traditional sources are quite wasteful and the energy is use it or lose it.

Maybe my understanding is wrong and quite frankly I am not sure what happens with excess energy that doesn't get used (I assume it is dissipated into the environment in some way).

It just seems to me that we could reduce costs and combine energy generation sources and need less of all sources if we can store all the excess energy we don't immediately use.

Edit (additional info):
There is a lot of confusion about what I mean and intend here. First, the type of battery is not relevant to my thought process here. It could be pumped air/fluid/whatever storage as much as it could be Tesla's utility scale batteries. The point would be to store excess generated and potential energy more readily to reduce raw energy waste throughout the system.

My thought process is that fossil fuel plants don't simply turn it off and on. The oil/gas/coal keeps burning and turning a turbine, whether or not it is connected to a generator at the time or not. It takes time to turn it on and off and thus there is a lot of time that these fuels are burning and generating pollutants when they could just throw that energy that goes to the turbines which goes to the generator (if you let it) into a secondary storage that can be more readily accessible.

As my thinking continues, I suspect there is a ton of potential energy waste throughout our power generation systems. Whether it be those generators that could be generating (but would overload a system that is fully powered) or excess heat not being utilized or electricity that is (I am guessing) somehow dumped and not used.

If I am correct in my thought process then we could be storing that energy in some way, shape, or form instead of losing it. If we can store it and access it readily then we can reduce the need for so much power generation in the first place. I could be totally off base with some or all of my thinking though.


texts: when i connect two alternator together how much is

texts:
I saw in large power plant a lot of huge generators connected together so i wondering

when i connect two generators together in parallel ( both at 120 volts ) at same phase , frequency and speed, how much is the total volts ?( will it be 240 120+120=240?


texts: + 12volt and -12volts from pc psu. Can I get 24 volts?

texts:
I have an unused pc atx psu. I want to make a bench power supply. The usual ebay breakouts give 3v 5v and +12v and -12v. Can I use an LM317 and make a variable output up to 24v?
Any advice gratefully received.


texts:
in fish farming the fish are fed at a percentage of their weight. i measured the weight of the fish that i put into the tank, and i can remove the fish once in a while to reweigh them but that is very stressful to them. i would like to insert a laser into my fish tank, that can count the amount of time that the beam is interrupted by a fish- kind of like the lasers that are at the entrances to stores. i think there should be a strong correlation between the amount of time that the laser beam is covered and the weight of the fish in the tank. can someone help me out of what kind of laser to use? i read in another post (Underwater distance measurement/Sensing) that a 405 nm laser is good for underwater, but i don't need to know distance, just time the beam is interupted. i plan to run the whole thing with arduino
thanks, tom.


texts: What happens to RLC circuits at resonance frequency, conceptually

texts:
What occurs when $$\omega = \omega_r$$
The circuit frequency equals its natural frequency? So what. And why is it important?


texts: Signal clipping in cascade transistor amplifiers

texts:
The two-layer voltage amplifier circuit can transfer a signal of up to Vi = 50 mV to the output without clipping.and 1st stages gain Av1=-6.41             .                               +15 volt is connected to the circuit from above, -15 volt dc source is connected from below. how can i calculate second stages gain ?

@G36


texts:
I've got an emissions source that's designed to generate a peak at a certain frequency that when measured by an antenna 3m away gives a value of X dBuV.

If the emissions source if moved closer to the antenna at 1m away, what should I expect the dBuV reading to be? (ignoring any other effects such as reflections)


texts: Connect lots sensors (more than 10, mostly accelerometers) to Raspberry Pi by using slaved Arduino solution

texts:
I am a programmer but quite new to electronics.
I am trying to connect more than 16 sensors into a RaspberryPi for analysis, because I'm mainly focusing on computing science's machine learning research.
I don't think I want to find a very complex electric configuration, so I decided to use Arduino as slave interface for sensors. I successfully connected one Arduino with my Pi and executed code, now the real problem comes.

In my system, I need more than 10 sensors (10-16) to be connected to the single RaspberryPi.
Since most of them are accelerometers, I think each one produces 3 analog signals as X,Y,Z axis, so it will consume more than 30 inputs!

I realised that multiplexers can help me while searching the web. I have following concern points, since my the requirements for the sensor data are:

They should be practically 'synchronised', which means data from all sensors should arrive in about the 'same time' (I know it's not possible for perfect synchronisation, but extremely low delay)
No error being generated by the complex wiring solution

Is there any solution can solve this issue? I really appreciate your help!


texts: Would analog data loggers record PCB 353b33 accelerometer datapoints for a minute or more?

texts:
I'm currently recording data points from an analog accelerometer (PCB 353B33) using a TDS3014B oscilloscope which has a record length of 10,000 points at a sample rate of 1.25 GSa/s.
Since the oscilloscope is a triggered data logging device, it's not capturing the whole cycle of the experiment.
I'm trying to look into analog data loggers that would help in seamless data logging for a minute or more with a good sampling rate that would help me capture data for at least one cycle. Is analog data logger the only option remaining?
I'm not sure if an analog data logger would be a good solution for my problem, so if anything else would work for my case please suggest that as well.


texts:
Texas Instruments encourages the use of the TPS62730 step-down converter with bypass mode along its RF devices. Does this mean :

its noise is low enough not to affect RF ? Thus being a more efficient solution than an LDO ?
using 3.0-3.6V devices and a 3.0-4.2V battery, the converter could be bypassed when battery hits 3.6V and efficiency would become 100% ?


texts:
I have gotten the task of finding an appropriate connector for our application, but given so much information there is on connectors, I don't even know which information is relevant.

So this is the task;

I have a cable that has a strand of 10 smaller insulated wires inside. I must find an appropriate connector that will guarantee IP 67 protection.

I measured some of the dimensions of my cable and they are;
Cable outer diameter = 6.5 mm
Wire insulation outer diameter = 1.1 mm
Wire copper cross-section = 0.205 mm²

My question is where do I search for the connectors? Is it at the sellers like Mouser and Farnell, or should I try looking straight to the manufacturers?
How do you find the right connector in the vast sea of all the possibilities?

Thank you all.

Additional information:

The connector is going to be used in automotive application. The wires will transmit mostly digital signals for communication and a pair for supply power of 12V no more than 1A. It should be wire-to-wire attachment.


texts: Mathematical therefore symbol (∴) needed for documenting circuit analysis calculations

texts: When doing circuit analysis calculations I use the mathematical therefore symbol in my calculations and need to document my iterations to support my analysis. There is no ASCII code for the "therefore" symbol. There is a UNICODE U+2211 for it that doesn't work. I had to cut and paste the one in the title. Any pointers here?


texts:
I have a trivial question about EM propagation in a microstrip line.

Why do the electric and magnetic fields have the following lines? Which are the physical laws (Maxwell etc) for determining them?

By looking at the image I think that the electric field lines between the 2 planes are due to the voltage applied to the planes (like those inside the dielectric of a capacitor), while the magnetic closed lines are determined by the current flowing inside the upper strip (but why are the lines of the GND plane not present?).


texts:
I want to use both the conventional WDT and deep sleep WDT.

I will be using WDT to prevent any code lock cases if any.
And the other after entering deep sleep mode to wake up periodically in deep sleep mode.

My question is whether the WDT will continue working after entering deep sleep and intervene the DSWDT if not disabled?

I'm using PIC18 controllers.


texts: Utilizing mini-pci bluetooth card from laptop as a transmitter

texts:
Would it be possible (if the traces can be identified) to use a blutooth card from a laptop to transmit data from an arduino to say a phone.

I know the arduino to phone part will work, I am just unsure if I can use a laptop bluetooth card in  such a manner


texts: What is the purpose of a voltage divider in a flex sensor?

texts:
I've been following this flex-sensor-arduino tutorial on setting up a simple flex sensor with Arduino, and I got confused on this part:

  The flex sensor changes its resistance when flexed so we can measure that change using one of the Arduino’s analog pins. But to do that we need a fixed resistor (not changing) that we can use for that comparison (We are using a 22K resistor). This is called a voltage divider and divides the 5v between the flex sensor and the resistor.

Why exactly did I need to add the second resistor? Couldn't the Arduino just get the voltage change from a single variable resistor that is the flex sensor? I'm very new to electronics, so an explanation in simple terms would be great.


texts:
I am trying to make a circuit that slowly discharges a multi cell lithium battery to storage voltage. I already have a comparator circuit that can turn on or off discharging. I want to support 2s to 6s batteries so we are talking about voltages ranging anywhere from 7.6v to 25.2v. I am shooting for 500mw of power dissipation so I can achieve my form factor requirements for the PCB (11mm x 15mm). Ideally, the same circuit can discharge any cell voltage with constant power. So far I have tried/considered:

PTC Thermistor load. This will essentially run the PTC perpetually in its "tripped" state. I have an NTC thermistor in series to handle the inrush current until the PTC heats up and protects the circuit. This best captures what I want. However, I contacted a support engineer and they say the use case is not specified and could negatively impact the life of the device.
https://www.murata.com/en-us/products/thermistor/ptc/prg
BJT with an NTC thermistor switching a resistive load on or off. I would preferentially avoid this due to extra components necessary.
I would like to stay away from MCU controlled constant heaters for simplicity sake.
Buck or Boost converter is not practical for form factor and cost.

Any help will be appreciated.

More context:

I am creating a battery discharge circuit small enough that can be integrated into a battery connector (like an XT60 adaptor).
Users may inadvertently connect a higher cell count than selected or thermally insulate the device so I want overtemperature and overcurrent protection.
Users can choose cell count with a DIP switch so I want a constant power load.
I also want to decrease the BOM cost of course, so one device that does it all would be wonderful :). So far a PTC thermistor fits the bill but I am wary of leaving it in a tripped state for extended periods.

Edit:
One last requirement that I overlooked (I apologize). The device will be "plug in and forget" so it needs to have a very low quiescent current so it can be left on the battery for months or even years without over discharging the battery (which will damage it). The solution I have right now has a leakage current in the microamp range.

Current Schematic:


texts: Parity bit checks using General Hamming Algorithm

texts:
In a logic circuit, I have an 8-bit data vector that is fed into an ECC IC which I am supposed to develop the logic for and that contains a vector of 5 Parity Bits. My first step to develop the logic (with logic gates, XOR), is to figure out which parity bit is going to check for which Data bits (since they are interlaced). I am using even parity, and following general hamming code rules (a parity bit in every 2^n ), I get the following sequence of output:

P1 P2 D1 P3 D2 D3 D4 P4 D5 D6 D7 D8 P5

Following the General Hamming Algorithm:

For each parity bit, Position 1,2,4,8,16 and so on... (Powers of 2), we skip for the first position n (n-1) and we check 1 bit, then we skip another one, the check another one, etc... we repeat the same process for the other bits, but this time checking/skipping every 2^n, where n is the position they occupy in the output array (P1 P2 D1 P3 D2 D3 D4 P4 D5 D6 D7 D8 P5)

Following that convention, I get:

P1 Checks data bits -> XOR(3 5 7 9 10 12)
P2 Checks data bits -> XOR(3 6 7 10 11)
P3 Checks data bits -> XOR(5 6 10 11 12)
P4 Checks data bits -> XOR(9 10 11)

Am I right? The thing that confuses me is that if I should start checking counting the parity bit as one of the 2^n bits that are supposed to be checked, or 1 bit after that specific parity bit. Pretty much sums up to if it is inclusive or not.

Thank you for your help in advance!

Cheers!


texts:
The link http://www.njr.com/semicon/design_support/faq/10088.html do some explanations about the phase-reversal of OpAmp. And give a figure:

And the output when phase-reversal occurred:

It states

  When the base voltage of Q5 falls, the Q5 and Q6 transistor of the next stage cut off. The output stage stays near V+ supply voltage side by connecting a current source to a corrector terminal of Q6.

In what situation will the base of Q5 can fall to make Q5 and Q6 cut off? Assume Q2's emitter is at a fixed voltage, then Vb5 (Q5's base voltage) = Ve2 - Vsat2, will this voltage goes low with the base voltage of Q2?


texts: How to calculate ripple voltage in this bridge-rectified zener-regulated circuit?

texts:
For one of my labs I need to design a power supply with the ripple less than 1% of the nominal 4.7 V value (since Vz = 4.7 V) and calculate its load regulation.

I know that the ripple will most likely be within the required 1%, but I am having problems calculating it's exact value that I will need for load regulation calculation.

Here is the circuit:

The load has to be \$50kΩ\$. R1 and C1 are adjustable. Since I will only have one \$100µF\$ and one \$10µF\$ capacitors in the lab, I am going to shunt them for better filtering.

Attempted solution:

Input:

\$V = 15 V_{p-p}\$  or  \$7.5 V_{p}\$ @ 50 Hz

After passing through bridge rectifier (two diodes - two 0.7 V drops):

\$V = 6.1 V_{p}\$  @ 50 Hz

Here's where my problems start.

After passing through the filter:

I wanted to calculate the amplitude of the ripple using: \$ V_{r} = {{V_{p}} \over {2fCR}}\$, where f = 50 Hz, \${V_{p}} = 6.1 V\$, \$C = 110µF\$ and R is the resistance of the circuit parallel to the capacitor. I have no idea how to get \$R\$, even if I pick any \$R_{1}\$, since I suspect the resistance will vary because of the Zener diode.

So, how can I find the ripple amplitude at the input of the Zener regulator? I need this value for Zener regulator calculations and, consequently, precise output ripple value and load regulation.


texts: I2C on PIC12s using MPLAB x (win7) and XC8

texts:
I am from a programming background, but very new to microcontrollers.  Pardon me if this question is very basic, or doesn't make complete sense.  I'm trying to bootstrap my knowledge, and the learning curve appears to be steep in some areas.

I am trying to get I2C working with a new IC I purchased, the PIC12LF1552.  This IC comes with an I2C module in it, so I shouldn't have to bit-bang.  However, It seems like XC8 doesn't support I2C on the PIC12 series.  MPLAB X can't seem to find the ic2.h include file (this may not actually be a problem, it could be paths are not setup correctly), so I linked the file with a full path.  i2c.h includes pconfig.h on line 32, and pconfig.h includes p18cxxx.h on line 16, which seems like it won't work as it's for a different chip series.

So my question is, what support is there for running native I2C on PIC12 series ICs?


texts: Make a DVD drive turn the other way around

texts:
Lets assume I have a CD/DVD burner, and I'd like to burn the disc in the "wrong" direction, i. e., I want the DVD drive motor to turn the other way around.

Can this be done (with a normal drive) by reversing the polarity of the motor driving the disc? Or would that break the motor / the mechanics of a standard DVD drive because these are not designed to turn the other wa around?

If I can get the drive to turn the other way, can I burn a disc? I've read that blank discs have something like a "blank" data track which contains information about the disc? Would that even work when the disc rotates in the "wrong" direction? Can I get a standard DVD drive to ignore that track and just force write even if it doesn't find that track?

And finally, if I actually managed to burn a disc that way, could that disc even be read in that drive? Or in other drives modified in the same way?


texts: Can my dead Lead Acid batteries be reused?

texts:
I have two 12V 4.5Ah sealed Lead Acid batteries from an old electric scooter.
The scooter is a decade old, and packed up a few months after purchase. The batteries were literally left as is for almost ten years, and I am unsure if they were connected to the circuit or not during that time.

Okay, so the one measures 1.1V, and the other -0.6V! The negative voltage is very odd as the batteries were in series and I can't think how that could be physically possible through (dis)charge..

I do not have any desulphation equipment or similar, all I have is an alarm "UPS box", which slowly charges SLA batteries, although it never gets them above 13.4V as that is what it outputs when no battery is connected, also it's all linear - nothing fancy.

Is there anything I can do to resurrect these batteries with the equipment I have, or should I just have them recycled? I have a fair amount of knowledge in electronics if there's anything I could do. Also, are there any dangers hooking it up to my charger or hooking up one with a voltage too low in general?


texts: Why do RC applications use such a small PWM duty cycle?

texts:
I know that RC applications, such as a drone, use PWM signals to drive the motors. This PWM signal is mostly 50 Hz (0.02 s). The pulse itself varies from 1 ms to 2 ms. So a 1 ms pulse corresponds with a minimum motor rotation and a 2 ms pulse with a maximum motor rotation. So basically the other 18 ms of the period the signal stays idle.

Why does the PWM signal have such a format? Why is the active part of the signal not spread over 1 ms and 10 ms? What is the advantage of using such small pulses?