texts:
Could someone be kind to explain some features inside ST-Link Utility.

What is the unit of measurement for size, how it works?
What does represent data width?
Changing data width presents different view in box 3, how does this display works and what does it show?
How does the memory address scheme works in box 4? (it looks like it increments in value of 16 but why?)

Looking through ST-Link pdf documentation didn't gave much information about it.

Thank for helping out in advance.


texts: Sizing a battery according to an existing solar panel (and not the opposite!)

texts:
I have one 60-cell 260Wc ~30V ~8.5A panel left over after a solar installation.
I did record consistent and factual 1400Wh per day and per panel in winter.

I want to use the energy of this extra panel for a home-made low-voltage ventilation in our house (12V ideally, or 24V more realistically(?)).

In winter I can use the "real time" production and use any surplus to heat the vented air itself.
But in summer, I would like to draw the maximum of daily-stored energy to vent the house with cool air during the night.

I have no need for cycles larger than 24h... but I still need a battery.

So here is the question: I want to store the best of a 1400Wh daily solar production into a battery. Which capacity should I get?

As you see I am not driven by my power requirement, but by what I can already produce with this panel. It stands out from what is usually talked about and what solar calculators do (namely: assessing needs to know the hardware to buy).

Given "rules of thumbs" like "15 watts delivers about 3,600 coulombs per hour of direct sunlight (i.e. 1 Ah)":

1400Wh in a 12V battery = 116Ah
1400Wh in a 24V battery = 60Ah

I was to get a 60Ah, 24V battery setup (e.g. 8 LiFePo cells) but I realized I am probably oversizing it given losses in the changer, BMS (battery management system) and battery charging chemistry itself?

I am unsure that the above "rule of thumb" takes these issues into account. Can someone help me?


texts:
I'm trying to understand how oscillators work and am currently working with an RC phase shift oscillator:

$$R_1, R_2, R_3 = 200 \Omega$$

$$C_1, C_2, C_3 = 4.7\text{nF}$$

one of the issues I'm having is that one source states that \$R_{\text{fb}} = 29R\$ for sustained oscillation yet when I set the resistor to \$5.8\text{k}\Omega\$ I get a flat line in nV.

What am I missing out?


texts:
When looking at the Texas Instruments Webench designer, one of the columns reads

  Vout-pp

What does this mean?


texts: Package Length (mils) and Propagation Delay(ps/Inch) data for DDR3 and FPGA

texts:
I need to provide below data to my software team for DDR testing.
1.Package Length(Mils)
2.Propagation Delay(Ps/inch)
We are using MT41K256M 16HA-125 DDR3 chip with ZYNQ 7045 FFG FPGA.
I am unable to find the above mentioned in the datasheet.
EDIT:-
We are using a custom board of the ZYNQ 7045 FFG package and trying to do an Ethernet throughput test based on xapp1026. We followed all the configuration settings required in ZYNQ and also in PC as mentioned in xapp1026. But our applications in ARM are getting hanged either in pre-fetch abort or data abort and the iperf application in PC is not receiving any further data. But when we try the same on the Xilinx ZC706 evaluation board it is working fine and getting the expected speeds without any interruption. Source files and settings used on both (custom and Xilinx) hardware are the same.
One observation is this problem is coming only when we are trying to do data transfer at a higher data rate. For normal speeds, it is working fine.
The Ethernet IC chipset used in our custom board is Marvell 88E1512. The DDR IC chipset used in our custom board is MT41K256M 16HA-125.
Can we debug anything by observing the XML file (the one in system_hw_platform folder) that is generated when creating the project in the ISE tool? Please throw some light on this issue which will help us in debugging.
They need the above data for Board Delay Calculation Table


texts: How to feed laptop + bulb with solar energy?

texts:
I reside in Kathmandu where the current power supply is so weak one has to face between 8 to 18 h power cut per day. In order to work, I need to have continuous supply of energy for my laptop and a bulb a night.

I have looked into this Q&A already and found some answers, some of which are too broad or assume I know something about electronics. In spite of my interest, I have always been very bad with electronics: I need please a case-specific and for-dummy answer.

I own a Dell Vostro 1510 laptop, which will run all day long (let's assume 24 hours as I need to download data from a slow Internet connection), and I will use an energy saving bulb to light up my desk at night.

From what I understand, I need a solar panel, connecting into a power controller, connecting into a battery, connecting into an inverter.

How do I find out what solar panel I need? (A local store which I don't really trust, proposed I buy their most expensive model, a 60W panel)
I am concerned about the battery too, in term of efficiency and environmental impact. What are my options?


texts: Understanding RLC series circuit fed with a square wave

texts: I'm simulating a RLC series circuit fed with a 60Hz 3.3V square wave coming from a microcontroller. The inductor series resistor is 100 ohms, so the total R= 110 ohms. According to the simulation, the peak current is about 17 mA for those values. I would like to do the proper math to get that result. It looks like the circuit is overdamped, R^2 > 4L/C. But I don't come up with those 17 mA peak. How do I calculate it? If you have any book or resource that helps me understand this better, I will appreciate it. Thanks.


texts:
I currently have am trying to power a 300M 5V WS2812b from only one end from a 5v 20A power switching supply that I got off ebay. There is about 8-10 feet of distance between the two, and I was wondering what guage wire should be used in order for this to be safe.
I have been told by some that use CAT6 cables would be fine, but I have doubts around this. I was thinking more like 16AWG wire.
Not too sure if this length is too long though. I am trying to avoid having a buck converter or power supply near the LEDs for aesthetic reason.
Thanks!


texts: Why are some capacitors bent on old boards?

texts: I've noticed that on older boards some of the electrolytic capacitors don't sit up straight, they're not totally vertical. I wonder why this happens, is it because they were soldered by hand and the person doing it placed them that way? Were they placed vertically and bent over time? Is it bad to the circuit in any way?


texts: How to identify an unknown protocol with a logic analyzer?

texts:
I have this Inbras electrolyte analyzer, a rebranded version of the same device manufactured by Diestro. It uses a PIC18F87K22 (master) which communicates with the sensor using a PIC12F629 (slave) through 4 pins in a custom IDC-DB9 connector with the following connections:

I will be referring to the slave device's pins since it is what I am interested in.
This device is supposed to measure the level of two liquid containers, but actually just counts down from a fixed volume. I want to program a microcontroller to replace it and actually measure the level of these containers, but to do so I need to figure out the communications used without having access to the programs stored in the microcontrollers (I don't have any programmers and it probably also is copy-protected).

The package where the reagent bottles are kept and the "sensor" attached to the green bottle.

There are no sensors at all. It just connects to the analyzer through the IDC connector and these pads do nothing.
I used a generic FX2 based logic analyzer along with Sigrok + PulseView to capture the data. Samples here. All these captures should indicate that the containers are empty and I unfortunatly only have access to these right now.
Here are some of the things I would like to find out:

Which pins are for transmission and reception?
What is the baud rate?
Which protocol is being used?

Some observations:

Sample from the slave-connected-calibrate.sr file.

A bit closer in, with SPI decoder (CLK = GP1, MISO = GP0, MOSI = GP5, CS = GP2 and CS polarity = active-high).

Signal seems to be an asynchronous, since there is no apparent clock signal.
Signal frequency is 7 kHz.
GP2 seems to be some sort of chip enable pin because it stays high during 8 long pulses.
GP1 probably is the transmission pin because there’s so much data in it.
Probably not UART (at least not using with the common baud rates).


texts: Why my transistor switched when base was grounded?

texts:
I am from a programming background, so I dont quite know the theory, But I want to control a motor from a mictrocontroller. So I used a TIP 122 to do it.
My circuit looks a bit like this:

simulate this circuit – Schematic created using CircuitLab

Why did the motor run when I connected the base of the transistor to gnd? also, the motor runs at full speed even if I apply base voltage as low as .2 volts. What is going wrong here ?

I even tried adding a 500ohm resistors to base, but it still doesnt have any change.


texts: LED strip driver using Standalone atmega823 and MOSFETs

texts:
I want to make a LED strip driver, using an atmega328 on a custom PCB.

I was able to get it to work perfectly using an arduino UNO, with the mosfets connected on a breadboard. However, when I just had the atmega328 chip on the breadboard (with crystal and capacitors) it was unable to drive the LEDs.

I had uploaded a sketch to use PWM to fade the LEDs on and off, which works perfectly on the full arduino UNO board, but when using the standalone atmega328 the PWM worked sometimes but then seemed to reset the arduino, and was just generally unstable.

How can I resolve this?

Here is the breadboard:

Thanks for your help


texts:
I'm working on a project where I want to be able to conect 230VAC and power one LED.
The load when measured need to be about 15W.
What would be the best and least heat to disipate?
It's to simulate the load one light in a trafficsignal system.
When done it will be 8 sets of 4 LEDs (white, red, amber and green) so in total 32 LEDs and about 480 watts so there will be a good heatsink for it.
Edit: The traffic light controller is measuring to make sure lights are working so when testing in a lab it needs to appear to have a load that is similar to the real thing.


texts: How long does analog to digital conversion take?

texts:
I am analyzing Voltage signals from many channels which have passed through a multiplexer for analog to digital conversion, before reaching the computer. I am wondering how long the conversion takes, and whether there is a correction applied i.e. interpolation of the digital signal to give exact correspondence in time across signals.

Perhaps the answer is device-specific although I would have thought that someone might know roughly how long it takes per signal...


texts: Which type of sensor for measuring height of horse step?

texts:
Is that possible? I'd like to track the amplitude of a horse leg/foot height for a show.

The many many difficulties:

constantly moving! So ultrasound way too slow
the floor is irregular, made of shavings
seems that an accelerometer isn't reliable for measuring distance, as I read here.

The best would be a sensor I can put on the horse's leg/foot rather than video tracking (i.e. openCV) because the stage is round, and I'd love to keep the process light (not putting cameras all around etc).


texts: Low voltage power lines - formula for spacing between poles?

texts:
What is the distance or separation between pole-pole in a 230 VAC distribution line?

Is there any formula for this, or we can take any distance?


texts:
This is a very newbie question, but i don't understand it well, and i'm studying a lot! =(

I have a Cmos not gate, and I don't understand well how it works.

Dividing in cases:

case X = 0V: the nMos if off and from pMos to Z arrives High Voltage. Ok.

case X = 5V: here is the problem. pMos is off, and nMos is on. If nMos is on, it should arrive to Z high voltage because it is on!

But this is my mistake, i know.
Can someone please, patiently, explain me this?

Thanks a lot.


texts: Difference between the natural response and transient response of an RLC circuit

texts: Some books talk about the natural response of the RLC circuit. This is when the voltage source is taken out from the circuit. Some other books talk about the transient response of an RLC circuit, which is the time it takes the circuit to reach to steady state. The equations seem similar. I googled and some people are saying that natural response and transient response are the same thing. I don't see how, when one depends on the voltage source and the are doesn't. Could anyone shed some light on the two concepts?


texts:
I've been studying NPN's and I'm trying to calculate the voltages and currents.

Consider the following transistor circuit

simulate this circuit – Schematic created using CircuitLab

with Vb, Vc and Ve the voltage at Q1's base, collecter and emitter respectively.
Assume the sources and resistors are chosen in a way that Q1 is operating in forward active region, so
$$V_C > V_B > V_E$$
In active region the following relation applies
$$I_C = \beta I_B$$ and $$I_E = I_B + I_C$$
With network analysis we can then find
$$I_C = \frac{V_{EQ}-V_{BE}}{\frac{R_B}{\beta} + R_E\frac{\beta +1}{\beta }}$$
From this point I'm not sure how to proceed; When looking up Beta (or Hfe) in the 2N2222 datasheet

or by graph from this datasheet

we see that Hfe depends on the both Ic and Vce, but in order to calculate Ic we need to know Hfe. So how do I get an exact answer for Ic (and thereby solving Ib, Ie, Vb, Vc and Ve)?


texts:
Since I am having some trouble with a battery pack and a charger I want to use for a home robotics project I got a tip to just use some alternative power source and buy a new battery and charger once my project has proceeded a bit. The alternate power source that was suggested was my PCs PSU. So I unscrewed my computer and got a lot of louse ends.

My question is now: from which ends can I take 12V?


texts:
I've got a simulation that simply takes an address as an input and 64 clock cycles later it simply outputs it on another port. For some reason, when I register the output data, it is not delayed by a clock cycle (see waveform). Is this some crazy part of the standard or did I find a bug in the delta step of my simulator?

Testbench:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity bug_report_tb is
end bug_report_tb;

architecture TB of bug_report_tb is
-- MIG UI signal declarations
signal app_addr                 : std_logic_vector(29 downto 0);
signal app_en                   : std_logic;
signal app_rdy                  : std_logic;
signal app_rd_data              : std_logic_vector(29 downto 0);
signal app_rd_data_r        :   std_logic_vector(app_rd_data'RANGE);

signal ui_rst                   : std_logic;
signal ui_clk                   : std_logic;

begin

process(ui_rst,ui_clk)
begin
    if ui_rst = '1' then
        app_en <= '0';
        app_addr <= (others => '0');
    elsif rising_edge(ui_clk) then
        app_en <= '0';
        if app_rdy = '1' then
            app_en <= '1';
            if app_en = '1' then
                app_addr <= std_logic_vector(unsigned(app_addr)+1);
            end if;
        end if;
    end if;
end process;

process(ui_clk)
begin
    if rising_edge(ui_clk) then
        app_rd_data_r <= app_rd_data;
    end if;
end process;

--*********************************************************
module : entity work.bug_report_mod
    port map
    (
        ui_clk          => ui_clk,
        ui_rst          => ui_rst,

        app_rd_data     => app_rd_data,
        app_rdy         => app_rdy,
        app_en          => app_en,
        app_addr        => app_addr
    );

end TB;

Module:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity bug_report_mod is
    port
    (
        ui_clk          : out   std_logic;
        ui_rst          : out   std_logic;

        app_rd_data     : out   std_logic_vector(29 downto 0);
        app_rdy         : out   std_logic;
        app_en          : in    std_logic;
        app_addr        : in    std_logic_vector(29 downto 0)
    );
end bug_report_mod;

architecture behavioral of bug_report_mod is
signal clk                  :   std_logic;
signal reset                :   std_logic := '1';

signal app_en_sr        :   std_logic_vector(63 downto 0) := (others => '0');
signal dly_counter      :   unsigned(6 downto 0);
signal rdy_counter      :   unsigned(6 downto 0);
signal app_rdy_int      :   std_logic;

type int_array   is array(natural range <>) of integer;
signal addr_array       :   int_array(63 downto 0);

begin

process
begin
    clk <= '1'; wait for 2.5 ns;
    clk <= '0'; wait for 2.5 ns;
end process;
ui_clk <= clk;
ui_rst <= reset;

app_rdy <= app_rdy_int;

process
begin
wait for 50 ns;
wait until clk'event and clk = '1';
reset <= '0';
wait for 2 ms;
end process;

process(clk)
begin
    if rising_edge(clk) then
        if app_en_sr(63) = '1' then
            app_rd_data <= std_logic_vector(to_unsigned(addr_array(63),app_rd_data'LENGTH));
        end if;
    end if;
end process;

process(clk,reset)
begin
    if reset = '1' then
        app_rdy_int <= '0';
        rdy_counter <= (others => '0');
        dly_counter <= (others => '0');
    elsif rising_edge(clk) then
        app_en_sr <= app_en_sr(62 downto 0) & (app_en and app_rdy_int);
        addr_array <= addr_array(62 downto 0) & (to_integer(unsigned(app_addr))*4);
        rdy_counter <= ('0' & rdy_counter(5 downto 0)) + 1;
        app_rdy_int <= not rdy_counter(6) and dly_counter(3);
        if dly_counter(3) = '0' then
            dly_counter <= dly_counter + 1;
        end if;
    end if;
end process;

end behavioral;


texts:
i modified my door bell with a NodeMCU which is now capable of triggering the door opener using a relay. Now I want to add a door bell detection to this system. I figured out two contacts which supply a DC of ~5V for a second while the bell rings.
How can I connect this to the NodeMCU since it has only 3.3v GPIOs as far as I know. Do I need a resistor and if so - how much ohm? Or a step down converter? And what's about the amperage?

Sorry I'm really new to electrical engineering and might need some noob explanations :)

Thank you!


texts:
I have a complementary MOSFET switch that turns ON/OFF a DC voltage offset of 2.25 V that is provided to another circuit. The switch is controlled by a digital signal, Vctrl, from a PIC18.
Simulation in LTSpice shows that the switch works as intended; however, I am concern with protecting the switch when the MOSFETs are switching and the 2.25 V source gets shorted to ground.
What's a good way to prevent the source from momentarily shorting to ground?

Thank you,

Chris.


texts: Motor driver board - wingxine - need help with wiring

texts:
Recently I bought this motor driver but I didn't get wiring diagram for it (it's last time I bought something like this). I would like someone to provide some wiring schematics for this motor driver if it is possible... Great would also be explanation of pins on the board...

Another thing I would like to know is what motor can I drive with it? On the page there are those data:

Voltage: 12V-30V
Current: 5A

So if I understand right I can run the 12V motor that has peak current of 5A? Am I right? Do I need regulated supply for the motor or is it unregulated power supply ok?

EDIT

I attached specs of LD6201P that is on the PCB.


texts: How to wire an entire room / kitchen with LED light strips?

texts:
As the question suggests, I'm looking into adding LED light strips throughout the kitchen (over cabinet, under cabinet, and kick -- I think under the countertop would be neat, but harder to hide). From what I have been reading, I realize that to more accurately determine what is needed that I would need to know specifics about the lights (like wattage, amperage, run lengths, LEDs per foot/meter).

But without knowing those specifics yet, to try to better understand how feasible this is, here is my intended setup. The kitchen has cabinets on opposite walls, with an island in the middle, something like this (where the square brackets represent cabinets and the island):

[]  []  []
[]  []  []
[]  []  []
[]______[]

Is it possible to have everything wired together on one circuit, even though there's about 15' from one side of the kitchen to the other? Am I able to run a wire (maybe 16/5 -- thinking of using RGBW) under the floor/ceiling to get to the other side and then hook up the strips without worrying about voltage drop? I'm sure this is possible, I just don't want to spend a fortune to make it work.

As a side question, if anyone knows, is there such thing as a on/off/motion switch, that also works with wifi (for use with Google Assistant / Alexa)? The thought would be I could turn the lights on or off, or to a motion mode that detects presence in the room.


texts: Where do I find a list of Arduino DIY shields

texts:
I am interested in Arduino shields for fun, so I do not have a specific need. To save money, I would like to build the shields myself. Is there somewhere I can see a list of the most common, simple and useful shields? I am interested in:

Parts cost
Parts availability
Buying pre made print boards with no components
Level of expertise needed to assemble


texts: Battery power supply for Arduino and DC motors with L293D

texts:
I got a 6 AA cell pack. So I can basically get 8.2V.

I need to power an Arduino and 2 DC motors driven by a L293D.

My Arduino can accept 7V to 12V DC input and the L293D between 4.5v to 36V.

Can I simply deviate another line from the cell pack and feed the L293D with it? I want to do that because the load of the two DC motors can quickly be around 200mA/motor, the 5V input is 500mA max, I've got other things to feed with (one servo, an IR sensor, some leds and two other sensors) so I can quickly be higher than 500mA.

Something like this:

simulate this circuit – Schematic created using CircuitLab


texts:
Im new to Verilog, so please just dont blast me.

If in a module i declare as inputs' vector

[0:3]D

or

[3:0]D

What does it change ?


texts: can android phone power a peripheral via usb?

texts:
The 5V micro usb port on the android phone allows the phone to be charged from the mains and programmed.  Is it possible that a usb connection to the phone can power a peripheral?

ie I want to power a PIC microprocessor and want its power to come from the phone rather than a separate power supply


texts: Help to identify unknown Sync Serial Bus

texts:
Has anyone seen a sync serial bus communication like this?

Repeated Pattern :

Detail of beginning :

Personally, I haven't been able to figure it out myself...

It seems like I2C, however:

The clock is running at 2 MHz (as it ought to be in HS-I2C at minimum)
The line seems to be pulled down (I2C is usually pulled up)
I can't seem to set any START conditions: The first piece of data seems to move after 2 clock cycles...

It also seems like SPI, but:

If the data line is MOSI, the pattern repeats after 5 words of 9 bits each (while a normal SPI word is 8 bits). Later, another pattern seems to be repeated: 4 words of 6 bits each... I have never seen a SPI communication where word length changes for the same master/device pair. The smaller word length could be a common denominator, but then this should give me word lengths of 3 bits...
If I disconnect the device from the bus, the master still sends the exact same signals, even though it knows that the device is not present, and there is no other data line, so it look like this data line is bidirectional (as is I2C) and there is some sort of handshake (ACKnowledge) occurring somewhere.

I'm thinking that this might be a standardized bus/protocol that I simply haven't heard of and that perhaps someone here might have seen it somewhere.


texts: What is Maximum Average Forward Rectified Current? (1N4001 Diode)

texts:
I am wondering if someone can explain what Maximum Average Forward Rectified Current means for a diode. I see that this is marked as 1 Amp in the datasheet for the 1N4001. I have not been able to find a clear explanation of what this means online.

This came up when I was doing stress testing on a circuit I am designing. I was driving the circuit under it's maximum conditions for long periods of time. In these tests 1.7 Amps of current passed through a 1N4001 diode for over 10 minutes. The diode did not get hot or show any signs of distress. Someone later pointed out the 1 Amp in the datasheet, but clearly this doesn't mean the maximum current that can pass through the device, or there would have been some sort of negative effect.

Can anyone explain what this attribute means for a diode, and why the circuit operated without any negative effects at the higher current?


texts: Proof of formula to convert from parallel to series impedance

texts:
So, I tried to find a proof to the formulas to convert from parallel to series reactive circuit, which I found in the ARRL Handbook:

\$R_s=\frac{R_pX_p^2}{R_p^2+X_p^2}\$
and \$X_s=\frac{R_p^2X_p}{R_p^2+X_p^2}\$

where \$R_s\$ and \$X_s\$ are the series resistance and reactance to match the impedance of a parallel circuit with \$R_p\$ and \$X_p\$ resistance and reactance.

The resistances are positive and real values and the reactances are signed real values (positive for inductive, and negative for capacitive).

I decided to use the complex representation of impedance (I use j for i because it seems to be the convention in electronics):

\$Z_s=R_s+jX_s\$

and the complex representation of admittance:

\$Y_p=G_p+jB_p\$
which gives:
\$\frac{1}{Z_p}=\frac{1}{R_p}+j\frac{1}{X_p}\$, then, with some algebric manipulation:
\$Z_p=\frac{R_pX_p}{X_p+jR_p}\$

After that, I do \$Z_s=Z_p\$, meaning:

\$R_s+jX_s=\frac{R_pX_p}{X_p+jR_p}\$

To bring the complex term to the numerator, I multiply by the conjugate of the denominator:

\$R_s+jX_s=\frac{R_pX_p}{X_p+jR_p}*\frac{X_p-jR_p}{X_p-jR_p}=\frac{R_pX_p^2-jR_p^2X_p}{R_p^2+X_p^2}=\frac{R_pX_p^2}{R_p^2+X_p^2}+j\frac{-R_p^2X_p}{R_p^2+X_p^2}\$

Now, to set real and imaginary parts equal, we get:

\$R_s=\frac{R_pX_p^2}{R_p^2+X_p^2}\$
and \$X_s=-\frac{R_p^2X_p}{R_p^2+X_p^2}\$

The first formula is fine, but what is wrong with the second formula? Why is there that extra "-" in front?


texts: Smart High-Side Switch - Reverse Battery Protection Feature

texts:
I'm designing a switch for an automotive application and found this IC BTS428 that supposedly solves all my problems. Following the manual, i came with the following circuit (LATCH PUSHBUTTON).

Everything went well at first, the circuit work as intended and the SC/OverTemperature protection features worked fine. The problem happened in the reverse battery protection test. The momment i conected the supply with an inverse polarity (-13.5Vbb) (IN input  in LOW STATE) i noticed a voltage  output of -12.5V. The circuit overheated and stop working(even with the right polarity). After this test, the output was aways OFF (0V) regardless of IN state.

Can you help me find my mistake?


texts:
I am studying a standard flyback converter. For the circuit we are talking about please refer to (I took it from www.power-eetimes.com)
.

Now, I know the law of inductors, so when the switch turns on (it allows current to pass), there is a fixed voltage across the inductor. The current ramps up linearly and the slope is dependent on the value of the voltage source and the inductance.

Now, when the switch turns off and the current is decreasing in a very short amount of time, according to the law of the inductor, the voltages is inverted and therefore the voltage also changes polarity on the secondary side and current can flow on the secondary.

To my question:
What determines the speed that the current is decreasing on the primary? I would suspect that it depends on the value of the impedance of the secondary side. The idea would be that a low impedance can accept (or let's say demand) a bigger amount of current and therefore allow a faster teardown of the field. I would suspect, that on the secondary side, current is the "driving" force and the exact voltage value is a result of impedance and current? So is it correct that the secondary impedance determines how fast the energy of the magnetic field is transferred to the secondary or is it "just" dependent on the output voltage instead?


texts: What are the capacitors between the IN and OUT pins of a TDA7318 mixer chip for?

texts:
Fiddling around with my TDA7318 mixer chip, I've found a strange contradiction between the suggested "test circuit" cited in the manufacturer's datasheet, and the schematic published by someone who made up a complete audio solution by using this chip. It's all about two connections, both directly between two neigboring pins:

Pin #6 (IN (R)) and #7 (OUT (R))
Pin #16 (IN (L)) and #17 (OUT (L))

The manufacturer suggests the use of one 2.2 µF capacitor on each connection, whereas the abovementioned maker simply laid direct connections (just a couple of millimeters of wire) between the respective pins.
Which alternative is better? I've been thinking of coupling capacitors here, but which purpose should they serve when cross-connecting two pins on the same chip?


texts: Why is the 1 mH (inductor) in this design? What happens if I probe at 23/54 to measure CURRENT without having the 1mH?

texts:
I need to MEASURE the CURRENT at 23 and 54.
I don't see the 1 mH in the schematic. Do I need to add that?
What happens if I probe for current without the 1 mH?
What does the 1 mH do to the circuit?
Will I damage the card if the 1 mH is not present while checking for current?

would It be safe to measure -0.4A to +0.4A across pin 23?


texts: RF one-shot circuit capable of producing 5-ns pulse

texts:
I am looking for a one-shot circuit capable of producing a 5-ns output pulse with short switching time. I saw this one (http://www.nxp.com/documents/data_sheet/74LV123.pdf) in a previous question, however the switching time is much too long. We ideally want to run our circuit at 100 MHz, so a rise and fall rate of 50 ns/V is much too slow. I did find one from Dallas semiconductor that would work, however it has been discontinued by maxim integrated and there is no replacement product.

I need something that will produce a 5-ns pulse when triggered in order to switch a bipolar transistor.

Thanks!


texts: Relative positioning system using Electromagnetic field from a wire

texts:
I am quite new to electronics and I'd like to build a really small car (something like Lego scale) that follows a path given by a wire under a thin plastic layer.
I researched a bit, and seems like hall sensors or flux gates are the way to go.
If I understood correctly, using two hall sensor like A3144E on the front left and right of the car I could sense the electromagnetic field and decide if turn left or right to make the car back on track and keep the wire under the plate in between the sensors.
Few question, how much current needs to flow in the wire in order to produce an electromagnetic field big enough to be sensed by the hall effect sensor from 1cm away? Are there more sensible sensor or more ideal ones?


texts: Connecting an IR receiver to Transistor for current control

texts:
I thought I had a simple circuit ready but I need help finishing it off. I’m using an IR receiver, transistor and a matrix of four 3MM LEDs. Want the LEDs  to turn ON only when IR is detected.

Using a VS1838B IR Receiver, BC548 NPN Transistor and the 3mm LEDs powered by a 5V power bus. There are matching IR sources, as well, that are not a direct part of this circuit. The set-up is part of a large scale art installation where each circuit and LEDs will be on PCB “leaves” within a grove of “trees” (lots and lots of these little leaf set-ups). The individual “leaves” light up as someone gets near, triggering the IR receiver, off otherwise.

The main question: Though Ive seen this simple current source transistor circuit everywhere, I’ve not understood exactly how I can wire up the IR receiver to the transistor (especially because the receiver is a LOW when reading IR), and thus turn on/off the LEDs. Maybe wrong connections? Wrong Transistor? More resistance, Vcc?

Some Datasheets:

Transistor
https://www.sparkfun.com/datasheets/Components/BC546.pdf

VS1838 IR Receiver datasheet
https://www.optimusdigital.ro/index.php?controller=attachment&id_attachment=4

3mm LED similar datasheet
http://www.ea1uro.com/ea3gzl/Data%20sheets/Diodo%20Led.pdf


texts: Basic confusion about how transistors work

texts:
I am trying to understand transistors but it doesn't matter what source I find, there is always something that I cant fully grasp.
In Make: Electronics second edition, page 88, it says that
"[a transistor] won't respond unless the voltage at its base is higher than the voltage at its emitter (usually by around 0.7V)"
I have trouble understanding this sentence. Voltage is measured across two points, right? So what is the voltage 'at the base' and 'at the emitter'?
Is it the voltage remaining after all voltage drops?
But them how to change the voltage 'at the emitter'?
I know it's a basic question.


texts: I'm not sure how to search this so hopefully someone will answer. I'm rigging a floundering boat for my son and want to use LED light bars on the front and sides. I want to power then with an inverter generator because they are so much lighter and quieter. The LED light bars are 12 VDC, the invertor generator is 2000 watts and has 2 receptacles for 110 VAC and one for 12 VDC. The LED light bars will total around 1200 watts at 12 VDC. Will the single, 12 VDC receptacle handle that many watts or is there another way I should power the LED light bars?


texts: CAN -> acceptance filter then interrupt or vice versa

texts:
I would like to know which occurs first while using CAN communication.
Based on the answer I would conclude whether an acceptance filter must be used in my project or not.

Scenario: There are three nodes in my project (for example, node A, B, and C). All have unique IDs. All nodes have been configured to interrupt on receiving a message. As of now, an acceptance filter is not configured for the nodes.

When node A sends a message to node B via CAN, both node B and C will trigger an Rx interrupt. In the ISR, I'll filter out the message based on ID in software. Suppose acceptance filters are configured for all the nodes, when node A again sends to node B, will even node C's Rx interrupt trigger?

My question is: Will a receive interrupt be triggered only after a message passes through the acceptance filter or is it triggered when a message is received by the CAN hardware even if an acceptance filter has been configured?

Note: I'm using LPC1778 (if that matters).


texts: Considerations for debounced power switch with Li-ion battery source

texts:
From a battery source, I have connected multiple voltage converters (100V, -1500V etc...).

I wish to turn all of this on with a single switch. First of all, will a simple RC filter with large C be sufficient for debouncing?

It is quite important that the converters actually get the full 5 volt from the battery source. How can this be maintained?

I have no experience with connecting Li-ion batteries to my circuit and so I'm mainly asking for input on what I need to consider when doing so. E.g.  the effect of battery source resistance and internal resistance of the converters.

EDIT: Here is my current switch and debouncing cap:

Max load is ~300 mA. I've understood that I should probably place an efficient voltage converter between the battery and the switch in order to provide a constant 5V.


texts: Capacitor rated voltage vs supply voltage

texts:
I opened an old DC supply. I tried to replace its filter capacitor, which was 47uF/16V, and I plugged 1000uF/25V capacitor and checked its output. Its output was 23v which is strange because I measured the Pulsating DC via a multimeter, it supplies 25v only for just a second and then it drops to ~16v but the capacitor (1000uF/25v) somehow retains that potential and that's strange!.

I didn't get that phenomenon because the cap voltage should also drop to 15v but it doesn't. why ?


texts: Why do they place a high current device in a low current package?

texts:
For instance, it is said that the practical current limit of the TO-220 device is 75A. But I frequently see MOSFET devices for which the specified maximum continuous drain current is above 75A. (Examples)

Is there any practical difference between two TO-220 devices such that, one of them has a maximum continuous current of 75A and the other one has a limit of 150A, and all other specifications are same? If there is no difference, why do they bother producing high current devices in TO-220 package and advertise it with current ratings above the practical limit?


texts: Transistor Power Dissipation / Overheating

texts:
I am working on an audio project in which a voltage controlled square wave oscillator drives a 5W 4Ohm Speaker. I am using a unipolar 12V supply. In order to limit the current going through the speaker I use a TIP31A (NPN power transistor) with a 10k resistor at it's base, which acts to limit the current across the speaker to ~0.4A (12V x 0.4A = 4.8W of power). However, I'm running into a problem where the transistor is getting very hot.

What I'm wondering is this: does the transistor get hot based on the fact that it is limiting current, or does it get hot simply based on the amount of current passing through it? If I reduce the size of the current limiting resistor at the transistor base and added another current limiting method, such as a power resistor in series with the speaker, would that reduce the amount of heat dissipated by the transistor?

Here is the part of the schematic relevant to power consumption, square wave flips 2n3904 on and off (this is to invert the signal, since the oscillator idles high) which controls power on the base of the TIP31A, which in turn drives the speaker:

Here is the full schematic. Keep in mind I am driving the speaker with a square wave (full on / off) so changing the amplifier topology to class B or AB will not help.


texts: Capacitance of parallel wires in checkerboard pattern

texts:
Below is a cross-sectional view of a 4x4 array of inter-meshed cylinders...

$$\begin{matrix}\Huge\circ && \Huge\bullet && \Huge\circ && \Huge\bullet \\\\ \Huge\bullet && \Huge\circ && \Huge\bullet && \Huge\circ \\\\
\Huge\circ && \Huge\bullet && \Huge\circ && \Huge\bullet \\\\
\Huge\bullet && \Huge\circ && \Huge\bullet && \Huge\circ \\\\
\end{matrix}$$

\$\Huge\circ\$ & \$\Huge\bullet\$ are cylinders coming out of & into the screen, resp.
Voltages \$v_o\$ & \$v_i\$ are applied to them, resp.
Rows & columns are equidistant apart \$d\$ (measured centroid to centroid).
All cylinders are same length \$L\$, dia. \$D\$, & overlap \$O\$.
\$O\lt L\$.

How do I find the overall capacitance between them for a generalized nxn array?


texts: Is there a virtual ground in this op-amp?

texts:
Consider an ideal differential operational amplifier whose circuit looks like this,

Now in this circuit diagram it is given that, the negative terminal is at 0v.

But if I give a sine wave as input to this op amp whose frequency is high and capacitance of the capacitor is 1.I think almost can't be such a high voltage drop across the capacitor to make the negative terminal at 0v.

If so, is there a virtual ground in this circuit. If yes, please explain me how??


texts: Digispark Attiny85 dev-board - Program via USB or UART/serial converter?

texts:
How do I program those Chinese ATtiny85 Digispark clones? Are they programmable via USB or do I have to use a USB to serial converter to program them?

For example, this unit.


texts:
Is a simple LM317-based laser diode driver safe for powering a laser diode?
https://www.youtube.com/watch?v=iuMngik0GR8 (the diagram is at 1:37)

I've been told the the proprietary drivers offer some extra protection from very short spikes (on power up and shutdown) in the current which laser diodes are very sensitive to and might be damaged from. But isn't the LM317 regulator taking care of that itself already?

I've been told this from people who actually sell commercial laser diodes so I'm thinking they might be showing some bias.


texts:
I'd like to write a desktop app that would be able to automatically read all measurements off my treadmill, and to fully control the treadmill instead of the native dashboard.

Unfortunately I know next to nothing about electrical engineering, and I was hoping that someone could point me in the right direction as to how to go about building the interface between my computer and the treadmill.

Let me first describe the setup. The treadmill has two major parts -- the dashboard, and the mechanical part with the running surface. They are joined together via 8-pin connector shown here:

The dashboard has various controls that can set the speed and the incline of the running surface. It also has the handles that measure heart rate.

I was hoping to perform an analog of a "man-in-the-middle attack" on the connection between the dashboard and the mechanical part, and insert my own controller between them that would be able to both read the measurements and control the running surface.

I'd imagine that one could buy a some sort of 8-pin splitter and connect it into Arduino that would in turn connect to my desktop. Is that a reasonable approach?

If I can "intercept" the communication between the dashboard and the running surface, I'd probably be able to reverse-engineer the communication protocol, and would then be able to fake the dashboard commands from my app.

At this point I don't know if the communication between the dashboard and the running surface is one-way or not. It might be the case that the speed and the incline that are displayed on the dashboard are the "target" values, rather than the values directly measured on the mechanical part and communicated back to the dashboard. However it might also conceivably be the case that the speed is actually directly measured on the running surface, communicated to the dashboard, the dashboard compares it to the target value and in case of mismatch send a correcting speed-up or the speed-down command to the running surface.

I've found this Youtube video where some guy seems to have been able to connect Arduino to his treadmill, and control the treadmill's speed from his laptop. Unfortunately the video provides no details on how exactly this was accomplished.


texts: Wiring a 2 pole three-phase DB motor to a VFD

texts:
Hello everyone this is my first time posting here so forgive me if my post seems a little choppy. So my dilemma is trying to hook up a 2 pole three-phase DB motor rated at 230 X 3. I did a fair amount of research and thought I had the situation figured out until I got the motor disconnected from the machine and took the plate off of the junction box that is mounted to the motor and come to find 2 sets of wires each one with 1 blue, 1 red and 1 black. And another set that is wired into a brake rectifier.

Now I do have a couple questions. First do I need the brake rectifier wired in if I'm using a VFD or do I need it at all in order for the motor to run?

Also after doing a lot of reading and watching I thought I'd find 9 wires (there are 9 but the brake rectifier is throwing me off) with a diagram (no diagram) telling me which wires are what and then I'd be able to wire it up either y or delta.

Thank you.


texts:
I'm trying to understand if the following debounce circuit works. I want a logical HIGH when the switch is closed and I want to smooth over bounces by means of a low-pass filter.
When the switch is open, C13 charges up in time R23*C13 (1ms). When switch closes C13 discharges through R3 in same time. I now have proper debouncing, right?
Can I omit R23? Or will that momentarily short Vcc to GND?

Edit: updated schematic


texts: How to check beacon's signal strength - nRF52832?

texts:
I want to check beacon's RSSI using my nRF52832 (PCA10040) and if the signal is strong then send beacon's MAC over UART to WiFi module.

I'm having hard time understanding Nordic Semiconductor's documentation. I found sd_ble_gap_scan_start function but can't find any example code on how to use it.

m_scan_param.active       = 0;            // Active scanning set.
m_scan_param.selective    = 0;            // Selective scanning not set.
m_scan_param.interval     = 0x00A0;     // Scan interval.
m_scan_param.window       = 0x00A0;   // Scan window.
m_scan_param.p_whitelist  = NULL;         // No whitelist provided.
m_scan_param.timeout      = 0x0000;       // No timeout.

err_code = sd_ble_gap_scan_start(&m_scan_param);
APP_ERROR_CHECK(err_code);

I'm using Keil uVision.


texts:
I'm building a board with a PIC microcontroller that uses the Microchip bootloader and it's connected to a FT232RL chip (USB to UART) with the RC7 and RC6 lines.

Is it possibile reuse these two I/O lines in the application firmware without problems? Obviously without using jumpers in order to disconnect the FT232RL chip.


texts: Can I meet NEC class 2 or 3 requirements by fusing a 120v circuit at 0.5a?

texts: I am installing a device that operates at 120 VAC, and I wish to use a class 2 wiring method. The device is rated at 0.1 A, and I want to know if I can simply fuse a 120 V circuit to meet class 2 requirements, or if I need a transformer or some other kind of current limiting device?


texts: Identify LED driver IC / manufacturer logo

texts:
I am interested in an LED driver IC. It drives a 40W E27 LED with a 12V fan.
The logo looks kind of like "JD." The IC number is difficult to read: something "960?S" (see picture.)
It seems to drive a buck converter with two outputs: 12V (for the fan) and about 90-100V for the LEDs.
It uses a transformer / inductor combination in the path of the driver.
So there is one driver IC and one "transformer" (this is not an insulated driver!) driving two voltages.


texts: Bode plot of poles that are close to each other

texts:
I have a transfer function of the following form:

\$\ T(jw)= a0 / (1+ s/w1) (1+ s/w2) (1+ s/w3) \$

where a0 = 3600
w1= 1MHz
w2= 4MHz
w3= 40MHz

I drew the the bode plot and double checked with matlab and I found some discrepancy. I found out the problem happens between 1MHz and 4MHz as the poles are close to each other (Less than 1 decade difference).

So since at 0 Hz, the gain is around 71 db, I expected that at 1MHz, the plot will start declining with 20db/dec.
Between 4Mhz and and 1Mhz, there is ( \$\ log(4M/1M) = 0.6 \$ decade (not a full decade), and hence at 4MHz the gain is 71 - log(4M/1M)*20 = 71 - 12 = 59 dB.

However, in MATLAB, at 4MHz the gain is 69 db. Which means the gain dropped by 8dB not 12 dB. Can you please tell me where is the flow in my understanding?

I know that this problem happens because the poles are close to each other with less than 1 decade difference, and I am not sure how such cases are handled.

So the purpose of My main point is what's the gain at 4M (2pi) rad/s? Or in other words, how much the gain will fall between 2pi*1M rad/s and 2pi*4M rad/s and why?

My plot (The x axis is multiplied by 2pi and it is in rad/s):

MATLAB plot:


texts: Mod-3 asynchronous up counter using T flip flop in verilog

texts:
Design:

 module t_ff(q,qbar,t,clk,rst);
 input t,clk,rst;
 output reg q=0,qbar=1;

 always@(posedge clk,posedge rst)
 begin
 if(rst)begin
 q=0;
 qbar=1;
 end

 else begin
 case(t)
 1'b0:begin
      q<=q;
      qbar<=qbar;
      end

 1'b1:begin
      q<=~q;
      qbar<=~qbar;
      end

  endcase
  end
  end
  endmodule

  module mod_3_asynchronous_counter(a,abar,b,bbar,clk);
  input clk;
  output a,b,abar,bbar;
  wire rst;

  assign rst= a & b;

  t_ff one(a,abar,1'b1,clk,rst);
  t_ff two(b,bbar,1'b1,abar,rst);

  endmodule

Test_bench:

       module tb_mod_3_counter;
       reg clk;
       wire a,b,abar,bbar;

       mod_3_asynchronous_counter tb1(a,abar,b,bbar,clk);

       initial begin clk=0; end
       always begin #5 clk=~clk; end
       initial begin
       $display ("\t\ttime\t clk\t\t {b,a}\t");
       $monitor("%d\t %b\t\t %b\t",$time,clk,{b,a});
       end

       initial begin #100 $finish; end
       endmodule

In the above verilog code, I have written module for T flip flop. Using those T FF in toggling mode, I have created asynchronous mod-3 up counter(0,1,2) as mentioned above. while simulating t_ff one is actually toggling with respect to posedge of clk. But t_ff two is not toggling with respect to posedge of abar signal.I have simulated this program in both cadence simvision & icarus verilog.

can anyone see the error in this?

why am I not getting correct output?


texts: How can I remove the label from heat shrink tubing?

texts:
I want to use heat shrink tubing on the jacks of an instrument cable I'm making (like in the photo below). The problem is that the tubing I have has a label printed on the side with the size and such, and I don't think I'd be able to find any that doesn't. I really don't want a label like that on the cable - it looks ugly. I've tried sanding it with 400-grit sandpaper, which is the highest grit I have on hand. The label definitely comes off, but it's fairly easy to see scratches left behind on the tubing. If I were to use finer sandpaper, would I have better luck? If not, is there another solution available?
(Note: Apologies if this question is posted in the wrong place. I wasn't sure exactly where to post it.)


texts: What is the maximum charge current and discharge current of R5460 Series IC?

texts:
I am using "R5460N214AF" IC for 2 cell Li-Ion battery protection. According to datasheet, excess discharge current threshold is 0.2 V and excess charge current threshold is -0.2 V.

I would like to understand these voltage thresholds in terms of currents. Some one please explain how to understand max charge current and discharge current supported by the IC.

I am attaching the datasheet for your reference.

https://www.mouser.in/datasheet/2/792/r5460-e-1085730.pdf

Let me know if I am not clear and please help me in this regard.

Thanks.


texts: How does integral term in PID lead to reduced stability margin?

texts:
Please can someone explain the following statement related to integral term. I read this in a reputed journal paper "From PID to Active Disturbance Rejection Control" by Jingqing Han:

  The integral term (in PID controller), while critical to rid of steady-state error, introduces other problems such as reduced stability margin due to phase lag

How does it lead to reduced stability margin?


texts: How can I toggle a one shot during the timing cycle?

texts: I need a non-retriggerable one shot circuit (monostable) that will turn off during the timing cycle if a second input/trigger pulse is received. I.e. I wish to have a single momentary switch to start the timer, but if I press it again during the timing period, the thing cuts short (output goes low again) and the circuit resets. I don't mind whether this is done with a 555, flip-flops or a dedicated one shot IC, but can't for the life of me work out how to do it. Any pointers appreciated.


texts: Use a steel welding table to ground yourself from electrostatic discharge (ESD)?

texts:
I have a large steel welding table that I have been using as a work station to solder together my own custom PCBs.

I have been using my anti-electrostatic discharge grounding bracelet and connecting the alligator clip on the lead coming from it to my welding table.  I also have my MIG and TIG welders plugged into the wall but turned off, with the ground cables clamped to the welding table.

Am I right to assume that I am electrically effectively connecting my wrist to the ground of the circuit breaker panel in my workshop?

Any thoughts on this technique in general as a way to control ESD?

Any electrical schematics of a typical TIG or MIG welder, showing the grounding clamp connections?


texts: How to open and close PNP transistor with IO pin?

texts:
PNP transistors open when you connect their base to ground. For the use with processors, NPN transistors are recommended because you can open them by emitting high signal through them. However I don't have any of these and I'm in the middle of something right now. I'd like to finish the job with PNP transistor.

What I tried was to connect transistor's base to ground through great resistance. This leaves it open by default, but if you also connect it to VCC, the transistor closes.

simulate this circuit – Schematic created using CircuitLab

The circuit above works, but only if I use actual switch to connect base to VCC. If I use processors LOW signal, it doesn't work - instead the relay that is connected to transistor only opens for a brief moment every time signal changes. Strangest thing is that the same happens when signal goes from LOW to HIGH and vice versa.

The processor I'm using is ATTiny13, IO pin 3 in particular.


texts: Dual power supply with two different amperages

texts:
I'm new at electronics so please bear with me.
I'm trying to build a power supply for an old device that needs +5v at 3a and -5v at 220mA.  Here's my circuit:

What I have is: a center-tap transformer that produces two 12v currents at up to 4a, which feeds into a bridge rectifier (Vishay PB5010), which outputs it as about ±14V DC.  After 1000µF smoothing/decoupling capacitors, the current goes to a pair of voltage regulators, LM1084 (+5v 5a) and LM7905 (-5v 1.5a), then two 10µF decoupling capacitors, an indicator LED, and then to the device.
When I test it with a multimeter, it tells me that the voltage is exactly right from both outputs.  However, when I plug the device in, I get the -5v at 220mA, which is correct, but then only 500mA from the +5v.  I'm able to plug a +5v-only supply to the device and it will draw all 3a that it needs, so the problem must be in my circuit.
My thoughts ahead of time are:
-I probably don't understand the datasheet on the bridge rectifier; the one I got is rated at 4a regulated current, up to 1v at 22.5a, which I assumed meant the maximum amperage would go down proportionally as the voltage increased, to just about 4a at 5v, but it may just not mean what I thought it would.
-My understanding was that using a full-wave rectifier would allow the circuit to use the full 4a that the transformer can output, but that may not be true.

I've looked all over for answers to these questions but they're so specific that I haven't had any luck.
In brief my question is: How do I get 3a from the +5v?


texts: PWM above 16v for speed control? Will it work?

texts:
I have recently ordered 1 x VNH3SP30 Motor Driver Carrier MD01B

I was just reading the charts and found below saying about the pwm,

VNH3SP30 and VNH2SP30 Comparison:   VNH3SP30        VNH2SP30
Operating supply voltage (Vcc)      5.5 - 36 V*     5.5 - 16 V
Maximum current rating              30 A            30 A
MOSFET on-resistance (per leg)      34 mΩ           19 mΩ
Maximum PWM frequency               10 kHz          20 kHz
Current sense                       none            approximately 0.13 V/A
Over-voltage shutoff                36 V*           16 V minimum (19 V typical)
Time to overheat at 20 A**          8 seconds       35 seconds
Time to overheat at 15 A**          30 seconds      150 seconds
Current for infinite run time**     9 A             14 A

* Manufacturer specification. In our experience, shoot-through currents make PWM operation impractical above 16 V.

** Typical results using Pololu motor driver carrier with 100% duty cycle at room temperature.

Does this mean if I want to PWM (vary the speed) of 24v actuators under load, will this work correctly with this VNH3SP30 board? or will it 'jump' voltage and not work
How/What would you recommend please?

Thanks in advance,
Galen


texts: How to choose an alternative for a specific BJT transistor?

texts:
I'm trying to reproduce some circuits with electronic pieces that I've at home. Unfortunately I miss some recommended transistors so I'm trying to understand how to replace them with an alternative transistor and overcome this problem.

How can I choose the right transistor alternative for my circuits. I know that there will be a lot of parameters depending from my circuit but which are the most important parameters that are mandatory? and are there criteria that could be helpful for choosing the right alternative?

My specific case
In my case I don't have a 2N2222 transistor. In alltransistors.com I've found that I can use BFX95, BSW63, ECG123A, MM531 that are different alternatives  that I don't find in other site where it seems that 2N3904 is the right one. I don't know which are the parameters they look at.
For example I'm try to amplify a signal and send it to a loud speaker (with a 100 Ohm resistor) in a circuit with a load lower than 6 V, can I use a C945 that as the same Ueb but uses an hfe of 130 instead of 100 of 2N2222? What will happen?


texts: NGspice 26 returns result that is 6 orders of magnitude too small for simple depletion MOS test jig

texts:
So, I'm trying to diagnose a simulation issue with the IXTT20N50D in CircuitLab, and created a very simple transfer characteristic test jig to do so:

TEST OF IXTT20N50D MODEL

.MODEL IXTT20N50D NMOS
+ LEVEL=3
+ L=2.0000E-6
+ W=5.5000
+ KP=1.0446E-6
+ RS=1.0000E-3
+ RD=.22202
+ VTO=-.89028
+ RDS=20.000E6
+ TOX=2.0000E-6
+ CGSO=3.5684E-9
+ CGDO=37.622E-12
+ CBD=4.8729E-9
+ MJ=1.5000
+ PB=2.6055
+ RG=10.000E-3
+ IS=1.3714E-6
+ N=2.0283
+ RB=1.0000E-9
+ GAMMA=0
+ KAPPA=0

V1 1 0 DC 0
V2 2 0 DC 30
M1 2 1 0 0 IXTT20N50D

.DC V1 -3 4 0.1
.PLOT DC I(V2)

.END

This should replicate the transfer characteristic graph from the datasheet, right?  Well...I 'run' it in ngspice and then plot the current through the drain voltage source (aka i(v2)), and get:

What did I do wrong to get a transfer characteristic plot that is 6 orders of magnitude off from what the datasheet says it should be?  Or am I simply reading the graph wrong?

Also, I get a warning from ngspice even with the simplified form of the model that was suggested in the comments (commenting out all but L W and VTO):

Warning: Model issue on line 3 : .model ixtt20n50d nmos l=2.0000e-6 w=5.5000 vto=-.89028 ...
  unrecognized parameter (l) - ignored
unrecognized parameter (w) - ignored

And the resulting graph (with L and W migrated to the M1 line, and W fixed to be the correct magnitude of 5.5E-6):


texts: Tunnel diodes used for oscillators without loses

texts:
Suppose we have this circuit:

simulate this circuit – Schematic created using CircuitLab
And replace the diode with a tunnel diode. If the voltage stored on the capacitor is close to the voltage  in which the tunnel diode has negative resistance , can't this help oscillators run longer than they do or even never stop?


texts: Xbee receiver producing garbage characters when not transferring data

texts:
We are trying to make two Xbees communicate with each other. One Xbee module (configured as transmitter) is connected to one PC (PC1), and the other Xbee module (configured as receiver) is connected to another PC (PC2). Using HyperTerminal of PC1, we tried sending multiple characters (e.g. my name is myriel kaye torres 1234567890) through the Tx Xbee.

We monitored the serial data received by the Rx Xbee thru HyperTerminal of PC2. On sending the characters, it will be received correctly by the Rx Xbee as shown in the HyperTerminal of PC2, but when we are not transmitting, we still receive garbage characters like in the image below. How can we delete the garbage characters so that the only received data will be the one that we sent?


texts:
I have a window comparator with two outputs (hi-threshold and low-threshold) that would go high sequentially (few examples shown in the attached image). I want to use to combine these two signals into one, which would be used to wake up a MCU. Here's a basic truth table:

Red High then Blue High ---> Output High
Blue High then Red High ---> Output Low
Red Low But Blue High   ---> Output Low
Red High But Blue Low   ---> Output Low
Red Low And Blue Low   ---> Output Low

The time difference between the trailing edge of the Red line and the leading edge of the Blue line is usually <200ms - I am still working on spec'ing it.

I believe a circuit that would be detecting if two pulses are received within a reasonable time frame and in the right order. I am inclining towards solving this on the hardware side to keep my MCU selection and Firmware design simple.

Does you have any suggestions?

EDIT
Clarifications:
1. the truth table captures all the possible use cases. Trigger case is determined by the correct sequence of pulses and presence of both the pulses. All other input cases should result in output being low.
2. For MCU to wake up, I need a minimum pulse width of 10us.
3. Triggers are not expected frequently, may be once every hour.
4. Pulse width is max 1 sec for serviceable requests.
5.  Rule 3, 4, 5 are also intended as sequential events - for example Red goes high but Blue doesnt after the trailing edge of Red; this wouldn't be a valid trigger.


texts: What is Capacitive Loading (Intuitive understanding)

texts:
I have read about capacitive loading. But what does it actually mean like intuitively? Just asked this question so as to get an intuitive answer and also know what should I understand when one says that a load is capacitive.
Question 1 :
When we have a capacitive load, I know that current leads voltage in phase and therefore, we will get the current on the capacitor before the voltage reaches its maximum value.
But what does it mean when one says,"It is a capacitive load" and what should I understand (intuitively) when one says so?
Question 2 :
It would be great if one can also add on "why output impedance should be low for capacitive loads?"


texts: I have made a photodiode circuit and measured using multimeter - still no change in voltage. What to do?

texts:
My photodiode is MTPD1346D-100 (InGaAs PIN photodiode.)

What is the photodiode input voltage?

This is my circuit schematic:


texts: Is there any criteria to call a load inductive for switching applications?

texts:
I was hesitating to ask this but in many applications such as the ones with electrical machines or relays we always read such precautions or considerations: “If the load is inductive do that don’t do this ect.”

I know that some loads are very inductive such as electric motors, transformers, relays, any sort of coil operated stuff. I also know what power factor is and the phasor represation of AC currents and voltages. But in reality is there a way to categorize devices as inductive or not. Because no device is pure resistive or inductive or capacitive.

For example, a triac based SSR is not recommended to use with zero crossing with inductive loads. Alright so if I use a transformer as a load I can understand that zero crossing is no good for that.

I mean there are some loads such as power supplies where I dont know whether they are inductive enough.

As a load take an SMPS and a linear power supply for instance. Imagine you have a zero crossing type SSR. And your load could be one of those power supplies. Would you consider the linear power supply an inductive load? How about if the load were an SMPS?


texts: Send a command in keil as soon as Breakpint is hit

texts:
I want to store a variable every time a breakpoints is hit, while i am running a test. Any idea how can i automate the task??

Or How can we monitor keil via python or any other script language ?


texts: Convert 0 -2.5 V to 0 +2.5V for measure with adc

texts:
I have a negative voltage which I want to measure using an ADS1115, but it can t measure negative voltages.
Can anyone recommend a simple schematic / device etc which is capable to just invert the polarity and not affect the voltage? E.G. If input is -(minus)1.5V I want to transform it into +1.5V
Thank you in advance


texts:
The problem is....Find the Thevenin equivalent looking into terminals a-b of the circuit and the current ix. V=60V and I=7A.

If u look at my work, i got Vth and Rth correct,( i checked) i am just not able to get the value for Ix correct.


texts: Do I need a license to design IP cores with AXI interfaces?

texts:
Many IP cores especially from Xilinx have an AXI interface from ARM. (AXI, AXI-Lite, AXI-Stream, APB, ... are parts of AMBA - ARM's bus architecture).

The AXI interface standard is free for download (after registration), but I don't think it's free for implementation. So I asume Xilinx has bought an AMBA license to eqip its IP cores with AXI interfaces.

I don't have such license.

Can I offer AXI interfaces for my (open source) IP cores written in VHDL or Verilog?

It's a bit off topic, but how expensive could it be? How could I get one? :)

Edit
I don't know of any Xilinx document, stating if it's legal to build AXI components interfacing with Xilinx AXI cores. Xilinx cores are bound to Xilinx FPGAs and tools by the Xilinx license. This does not effect own components.

On the other hand these components need to implement an AXI interface to interact with Xilinx cores. How can I atleast design such components without an AMBA license?


texts: Why does turning a MOSFET ON too fast cause ringing?

texts:
Going though app notes, I can understand that turning it off (i.e. when drain-source voltage is increasing) can cause ringing due to parasitic NPN and also drain-gate capacitor which can charge the gate and turn the MOSFET back on, if the dv/dt is high enough.

But what's the reason behind ringing when turning the MOSFET ON? (i.e. when drain-source voltage is decreasing) How exactly does it happen?

Update:

Could it be that when people refer to ringing when turning on the MOSFET, they refer specifically to half/full bridge, and not a circuit with only a low side MOSFET? (As turning on the high side MOSFET would cause a positive dv/dt on the low side MOSFET.)


texts: Photo Resistor to Complete Circuit in Light

texts:
I am trying to create a very simple circuit using a CDS photo resistor.  The situation is simple, I need a circuit to be connected when its light, disconnected when its dark.  The photocell will sit in complete darkness, when a camera flash is fired, I want the photocell to simply connect a circuit which will then trigger other flashes.  The flash circuit doesn't carry any voltage, it just needs to be completed.  Basically, I need the two photocell to simply connect two wires when its light and disconnect them when its dark.

I am using this CDS photo cell: https://www.creatroninc.com/product/7mm-light-dependent-resistor-photo-resistor/?search_query=light+sensor&results=60

This is my first experience with one of theses Photo Resistors LDR and I thought it would be really simply but I'm striking out this morning.  Thank you!


texts: how to get delays of a circuit under process corner in hspice?

texts:
my circuit is composed of a chain of inverter (delay line), and i want to see how the delay of this chain of inverter behave in process corner? i want to know if the delay line will be still functionnal and the delay will be acceptable in process corner

Thank you


texts:
I'm planning on connecting a MCP2003 to a ESP8266.
The voltage levels of the uart (and any io) on the ESP8266 is 3.3v.
As far as I understand the datasheet, the MCP2003 needs to be powered by 6-30v, and it's io (out) levels on the uart side match the power voltage.
So:

Is it common that the 6v is the absolute minimum for these kind of chips, or do I have a chance that it'll run at 3.3v?
Am I missing or misunderstanding something in the datasheet that could help me do what I want? (For example, is there another way to get a lower output signal? Or is there so little power behind the signals that the ESP would be fine fine with them?)
If neither of the previous questions give me a way to do what I want, what would be the easiest or least component alternative?

Some background information:

What I want to do is to control a AXA Remote 2.0 device with an ESP over wifi. This device uses a LIN bus, and the MCP2003 converts from UART to LIN.
The voltage on the LIN bus is higher as I understand it, but this shouldn't be a problem, as the MCP2003 can handle that (I think). I haven't quite figured out how the LIN 'output' from the MCP2003 works, can't find a easy description of LIN, but I'm guessing it the bus get's pulled down similar to onewire? In which case there's no output voltage to the LIN bus to worry about.
The AXA Remote 2.0 device sadly isn't very well documented, basically this is it: http://files.domoticaforum.eu/uploads/Axa/AXA%20Remote%202%20domotica%20English%202012nov_V2.pdf It shows how to solder a MCP2003 to a 5v TTL USB serial dongle :)

Any helps or insights would be greatly appreciated! :)


texts: Hi. when I make experiment with BJT amplifier. I see the wave of output voltage is clipped at 2 peak. Can you explain me why ? And Does this problem happen with JFET amplifier, when ?


texts:
I've been studying the schematic for this RLC Bridge from Heathkit (IB-5281).  The full pdf can be found here (search for the part number): http://www.vintage-radio.info/heathkit.

The circuit contains an AC source to drive the bridge which is basically a JFET Wien Bridge oscillator with selectable oscillation frequencies.  A spice version of the circuit (for 1KHz) is given below:

I recognize most of the constituent pieces: the band bass filter, the voltage amplifier and push-pull follower, etc.
But I have a few questions:

1) Is the purpose of the feedback through R7 to present a zero phase shifted signal to the source of the jfet to "select" the resonant frequency (similar to how the op amp version works)?  How exactly does this mechanism work?

2) What exactly does the section in the red box do?  My feeling is it acts like a variable resistor (operating the jfet in its linear region) and pulls more current through the J1 source on positive going half-waves thus providing negative feedback to control the gain, but that's just a guess.  I have no clue about D3, C5 and C6.

Thanks.


texts: Modify the AD8232 chip configuration to use only LEFT and RIGHT arm in steel leads configuration

texts:
I am an industrial designer (little experience with electronics) trying to modify one of the AD8232 chip configurations. The AD8232 is a Single-Lead, Heart Rate Monitor Front End. In the datasheet, page 24 there is an exercise to measure heart rate signal at your hands with steel electrodes. This is the one (see image below) I would like to modify to get a good signal from steel electrodes, but without the right leg electrode.

I am working on a breadboard using a breakout for the AD8232. So far I do not get good results, I tried to use a configuration like can be seen below.

I need help with the configuration and setup, perhaps there are better ways to achieve the end result, I am open to ideas. Thanks.


texts: LM2596S-5 Circuit, 7.x V instead of 5V output voltage. What did i do wrong?

texts:
for a little project of mine i need 24 and 5 Volts on my PCB. To do so i want to step down a 24V supply.
I planned to use the LM2596SX-5.0/NOPB for this task and designed it with the TI Webench Power Designer....
The PCB's arrived yesterday and i added the last missing parts. While testing the circuit with 12V i measured 7.4 Volts on the output of the LM2596.
I am a bit confused and i don't get what i did wrong.
I would appreciate it a lot if one of you could look over my circuit !
Thank you very much "


texts:
I have this sample program to blink LED with PIC18F4550 using external oscillator.

I'm using a 20.000 MHz crystal oscillator with 30pF capacitors.

The problem is when I wire the capacitors the the ground the LED doesn't blink (still off), but when I disconnect them from ground (not wired) the LED starts blinking. Blink speed change with _XTAL_FREQ.

Program works well with internal oscillator (just by setting FOSC = INTOSCIO_EC)

Is there direction wiring of capacitor or oscillator?

Ground here is PIC Vss

This is when using PICKIT2 directly. When using the circuit alone like the scheme, nothing happens with FOSC = INTOSCIO_EC configuration (not working), but works well with internal oscillator.

#include<p18f4550.h>
#include "delays.h"

/* COMPILER DIRECTIVES FOR CHIP CONFIGURATION BITS*/

#pragma config FOSC = HS //INTOSCIO_EC    /* Sets the oscillator mode to HS */
#pragma config WDT = OFF   /* Turns the watchdog timer off */
#pragma config LVP = OFF   /* Turns low voltage programming off */
#pragma config DEBUG = OFF /* Compiles without extra debug code */

#define _XTAL_FREQ   12000000  //delay_ms change by changing this

void main(void) {
    TRISD = 0xF0; // PORT B Setting: Set all the pins in port B to Output.
    while (1) {

        LATDbits.LATD0 = 1; // RD-0 to High
        LATDbits.LATD1 = 1; // RD-1 to High

        __delay_ms(50); // Half sec delay

        LATDbits.LATD0 = 0; // RD-0 to LOW
        LATDbits.LATD1 = 0; // RD-1 to LOW

        __delay_ms(50); // Half sec delay
    }
}
/* THE END */


texts: Why do some people use resistors to create a HIGH connection on a chip?

texts:
This is a follow-up question to my previous one, What does Low/High mean on the connections of a chip?.

To create a HIGH connection, you often just connect the pin to VDD, which is often above VIH (and therefore sets it to HIGH). However, some people choose to add resistors to those pins, as shown below:

Credit: Wolfson

In this case, DVDD is 3.3V and the VIH is 0.7×DVDD. Looking at that, it seems that the resistors aren't necessary. What are these resistors for, and do I even need them?


texts: Xilinx equivalent for Lattice's Input DDR generic mode in X2 gearing primitive

texts:
I used to work with Lattice FPGA (Lattice ECP3) and I used to have this primitive: IDDRX2D1

the block internal circuit:

I can't find an equivalent for this kind of input DDR in Xilinx Series 7 libraries,
the closest thing I found is this:

which is similar except that it's not 2x gearing, I need 4 outputs like the primitive from Lattice.
Any ideas if such a thing exists in Xilinx primitives?


texts: Methods for managing loose wires during prototyping

texts:
I have quite a few switches and other somewhat bulky components to fit into a box for a build, which will require some careful management of the free space within to avoid other wires getting pinched, or tugged on.

Is there a material that would reliably hold 18-22awg wire to a plastic chassis semi-permanently? (ABS or PVC, depending on location, in case it makes a difference). Would simple Scotch tape, or typical electrical tape hold up in a bit of heat? LED strips within the chassis can get it pretty warm. Would a tacky putty work, or would the warmth turn it into a gooey mess?


texts:
I am trying to collect data from a circuit and use that data for a regression analysis to get results. For my analysis purpose, one input needs to have different output (as the circuit I am using is the chaotic circuit).
My input is a sinewave with an amplitude of 3V and at 10k frequency. So when I export the data from LTspice, input changes very fast, and even I put very small max step time it doesn't give the same input values like for example for the 1st period of the sine wave the transient analysis collects data when input is at 0.01 then for the other period it's collecting at 0.0139 or something like that.
So, is there a way that I could collect the same input for all the periods of the sinewave?
The circuit I am using:

Thank you in advance, I couldn't get to upload an excel file but I am happy to explain more if needed.


texts:
I have been using an 8-bit AVR MCUs to build line-follower robots with students for a few years now. Now I would like to step up to an ARM Cortex-M3 because I'd like to add some more CPU-intensive features like odometry and sensor fusion.

The requirements are:

8 analog inputs,
4 PWM outputs,
I2C,
2 quadrature encoder inputs,
serial I/O,
Self-programming wirelessly without physical access
to the robot.
Multiplatform toolchain + IDE (OS X, Linux, Windows).

The steps I've taken so far are:

I'm using this STM32F103C8 based board. I believe this MCU has everything I need, including the 2 x QEI which I planned to implement in software but this one happens to have it in hardware, so great:

Board http://eud.dx.com/product/high-quality-cortex-m3-stm32-stm32f103c8t6-development-board-w-swd-interface-844380789
Programmer http://eud.dx.com/product/st-link-v2-programmer-emulator-mini-stlink-downloader-for-stm8-stm32-mcu-development-board-844380733

I've followed this to set up my toolchain + IDE:

http://www.davidrojas.co.uk/stm32f3discovery-on-mac-os-x-using-eclipse-gcc-arm-and-openocd/

I've found that the documentation for this chip is scattered among a number of PDFs, which I downloaded:

STM32F103x8 datasheet http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00161566.pdf
Reference Manual http://www.st.com/st-web-ui/static/active/en/resource/technical/document/reference_manual/CD00171190.pdf
A few other documents like AN2606 (memory boot modes), PM0075 (flash programming manual) and AN3155 (serial bootloader protocol), which I'll probably need in the future.

I also downloaded the STM32F10x standard peripheral library, but that in turn recommended me to get the newer STM32CubeF1, which I believe is just a marketing rename of the above, so I got both:

http://www.st.com/web/catalog/tools/FM147/CL1794/SC961/SS1743/LN1939/PF257890
http://www.st.com/web/en/catalog/tools/PF260820

Finally, I've also got "The Definitive Guide to the ARM Cortex-M3" by Joseph Yiu, which I'm reading as I wait for the boards to arrive.

My questions are:

I'm a bit overwhelmed by documentation, to say the least, and I'm not even sure I got it all. For example, the datasheet and the reference manual state that the chip has 3 timers capable of quadrature encoded inputs. But, I can't find documentation of the registers that control the timers anywhere in the PDFs above. What am I missing?
Should I use the (older?) Standard Peripheral Library, or the (newer?) cube thing? What's the difference? I understand that both libraries save me from manipulating registers directly and are the recommended way to go. Am I right?
Where is the documentation for the libraries (besides the embedded doxygen comments, which are nice and all but I'd rather have a searchable html/pdf)?
I chose Eclipse + GCC ARM + OpenOCD as my toolchain because I consider this is the only option that will run on the 3 main OSes without code size or other limitations. Are there any more options?


texts: Powering a RF circuit with CR2032 along a capacitor, pulse currents of 150mA

texts:
I am designing a battery powered circuit which performs RF communication. The goal is to use a 3V CR2032 battery. The RF circuit consumes 0.2mA as average current and lowest voltage it can work on is 2.8V. This average current is broken into various pulse current draws which are as follows:

WAKES UP
8mA for 2ms
15mA for 1.5ms
[90mA for 0.2ms,15mA for 0.3ms,150mA for 0.2ms] X 4 times
Deep Sleep with current of 20uA

The part in bracket (step 4) happens 4 times as 4 Tx/Rx cycles. The circuit is doing this at every 2 secs. I am trying to put a capacitor so that these pulse currents can be taken care by a supercap. As per my calculations:

For an average current of 0.2mA, assuming we need capacitor to store enough power for 5 secs,
Charge required in capacitor = 0.00028mAh = 1mC

Using C=Q/V at 3.1V,
C = 1mC/3.1V = 0.32mF

I am planning to use a 330ohm resistor so the charging times comes to be:
T=5*R*C = 5*330*0.32mF = 0.53 secs

Questions:

Are the above calculations and assumptions correct?
I tried using a 1.5F capacitor but the performance was dismal, there was a continuous draw which started at 200uA and gradually went upto 1000uA bringing the voltage of battery<2.8V, I am assuming this is because the capacitor wasn't getting enough time to get charged.
Please propose any better alternatives

Battery Datasheet : https://www.alldatasheet.com/datasheet-pdf/pdf/596824/PANASONICBATTERY/CR2032.html

Capacitor Datasheet : https://www.mouser.in/datasheet/2/40/AVX-SCM-1018838.pdf
Version used by me works at Vmax of 5V and has quiescent current of 10uA, to be on safer side of calculations I am assuming 15uA


texts: Adafruit 3G Module sends data but don't accept it

texts:
I'm having trouble sending commands to the GSM/GPS/3G module from Adafruit. It gives me status data at bootup without any issues (takes a few seconds).

The product in use is this: https://learn.adafruit.com/adafruit-fona-3g-cellular-gps-breakout?view=all#pinouts

The guide says (all be it at the very bottom) that a battery is required. And that might be the case. However I've managed to recieve data from the breakout board, but I'm struggling with sending data to the board.

I'm mainly wondering if anyone else has managed to drive this board without a LiPo battery?

I'm planning on putting it in a car where I have a constant power source, with a 5V regulator that can handle a few amps. The board boots, looks to behave normal, except that I can't send anything in on the RX pin.

Pinout:

5V -> 5V regulator (12-18V power supply)
GND -> 5V regulator/Power-supply ground
Vio -> Tried both 3.3V on the Arduino, 5V on the arduino and 5V regulator
RST -> D4 on Arduino
RX -> D2 on Arduino
TX -> D3 on Arduino
Key -> Ground

Two antennas connected, and that's about it.

The code I'm using is this one: https://pastebin.com/N0Yn5udm

And the result looks like this:

Again, when I send the AT command, I get nothing in response. The I know it's been sent because the internal LED flickers pretty quickly.

I've run out of ideas except pulling ~3.7V from a voltage divider or regulator off the 5V supply and plug that into the JST connector. Unfortunately I don't have any JST's at home.

But if a battery is the only way out, I'd like to learn why that is. Because there aren't much information for this module, only a tutorial saying "That's just how it is".


texts:
I've been searching for a set of headers and connectors as defined in the USB 3.0 Internal Connector and Cable Specification document for a casemod project.

Unfortunately, after scouring Digi-Key and a few manufacturer websites I can't seem to find any products actually advertised as suitable for this application.

Every other connector I've found so far is somewhat off in size and keying that I must be missing something in my search.

Is there such a thing as a USB 3.0 header or do I just need to keep comparing datasheets till I find something that makes sense?


texts: Generally 0.1 μF 50 V ceramic capacitors are connected across the motor terminals to reduce noise. How this value is decided? Does it depend on the motor rating?


texts:
What is the name of this 7-pin round data connector? It doesn't seem to be Mini Din 7.

It's on the data cable from a Ohaus Defender 7000 scale indicator to the weighing base.
There are 7 pins, and the diameter of the inner ring is about 13 mm (1/2 inch).
Is this some proprietary Ohaus thing, or is there a chance to buy a matching (female) counterpart in general electronics stores, and what keywords to search for?
It's also not a full-size DIN, although they are about this size (13.2 mm), in my plug this circle is plastic, (not a conductive metal like in a DIN plug for shielding), and the arrangement of pins in a DIN 7-pin is very different:


texts: GMII/RGMII TX_ER signal: guaranteed functionality?

texts:
I have a question seeking to clarify EXACTLY what happens during a GMII exchange between MAC and PHY. Specifically, regarding the TX_ER signal.

IEEE 802.3 Section 3:

  TX_ER is driven by the Reconciliation Sublayer and shall transition synchronously with respect to the GTX_CLK. When TX_ER is asserted for one or more TX_CLK periods while TX_EN is also asserted, the PHY shall emit one or more code-groups that are not part of the valid data or delimiter set somewhere in the frame being transmitted. The relative position of the error within the frame need not be preserved. Figure 35–4 shows
  the behavior of TX_ER during the transmission of a frame propagating an error.

My Question: When TX_ER is asserted by the MAC (while TX_EN remains high), does the frame still leave the PHY with all other frame bytes still intact, and ONLY the bytes transmitted while TX_ER is high get jumbled? Or does the PHY completely stop transmitting the frame once an error signal is detected?

I am working on an FPGA design that should be able to drop or pass a frame based on its contents, and I am wondering if assertion of the GMII TX_ER signal to the PHY would be considered "dropping the frame" or not.

In the case of the bytes still leaving the PHY, it would seem that the packet would only be "dropped" because the Ethernet FCS would not match the contents of the packet. But the frame contents would still be received by the PHY on the other end, and so if the receiver side had access to the physical layer, the data could be potentially recovered (which is not acceptable in my case).

I have tested this using the network utility iperf, and it appears that the application data does not go through if TX_ER is asserted. However wireshark seems to tell me that there are still valid TCP packets being received, and I don't understand how that is possible if the physical layer CRC doesn't match the frame contents.

Any insight much appreciated.

Thanks!


texts: I am using digital IR Receiver Module and digital IR Transmitter Module connected each with different Arduino Uno. How can I transmit data like "1234" to the receiver and display data on LCD? This is because most of the example that I found using IR remote code like Sony and RC4. I just want to send a simple data.


texts: Verilog to spice using v2s- specificing the port order in the command v2s

texts:
I was trying to convert from verilog netlist into a spice netlist using the option v2s. Can I specify the pattern in which the ports will be arranged in my resulting spice netlist?

For example: if my verilog netlist is this:

F10L16B_NOR2X4 nor1 ( .o ( nor1_o ) , .i0 ( cnfg[0] ) , .i1 ( cnfg[1] ) , .VDD ( VDD ) , .VSS ( VSS ) );

and I wanted a corresponding spice netlist in this port order:

Xnor1  VDD VSS cnfg[0] cnfg[1] nor1_o F10L16B_NOR2X4


texts: Possible to tap a PLL signal as a clock for multiple devices

texts:
We have an oscillator providing a clock signal for an MCU.  It has oscillator in and out pins: XTAL-IN and XTAL-OUT.

We'd like to use the same clock signal as a digital clock input to another MCU.  Can I simply tap the XTAL-IN signal and use that directly as the input to the other MCU, or will this interfere with the PLL?


texts:
I need to design frequency divider from 50MHz to 200Hz using FPGA. I'm using Xilinx and the language that I used is VHDL language. I got stuck because I can't get the output. So, anyone can help me? Here I attach my code.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity FreqDivider is
port(
    clock   : in STD_LOGIC; -- 50 Mhz
    clear    : in STD_LOGIC;
      adjclk : out STD_LOGIC
);
end FreqDivider;

architecture Behavioral of FreqDivider is
signal adjfreq: STD_LOGIC_VECTOR(17 downto 0) := "000000000000000000";
signal adjcntr: STD_LOGIC_VECTOR(2 downto 0) := (others => '0');
signal adjclock : std_logic := '0';

begin

adjclk <= adjclock;

countClock: process(clock,clear,adjfreq)
begin
    if (clear = '1') then
            adjfreq <= "000000000000000000";
        elsif(clock'event and clock = '1') then
        if (adjfreq = "111101000010010000") then  --50MHz/250000=200Hz
                adjfreq <= "000000000000000000";
                adjclock <= '1';
            else adjfreq <= adjfreq+1;
                adjclock <= '0';
            end if;
    end if;
end process;

process(adjclock)
    begin
            if (adjclock 'event and adjclock ='1') then
                    if adjcntr = "101" then
                    adjcntr <= "000";
                    else adjcntr <= adjcntr+1;
                    end if;
            end if;
    end process;
end Behavioral;

Below is for testbench,

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.std_logic_unsigned.all;
USE ieee.numeric_std.ALL;

ENTITY FreqDivider_tb IS
END FreqDivider_tb;

ARCHITECTURE behavior OF FreqDivider_tb IS

-- Component Declaration for the Unit Under Test (UUT)

COMPONENT FreqDivider
PORT(
     clock : IN  std_logic;
     clear : IN  std_logic;
     adjclk : OUT  std_logic
    );
END COMPONENT;

--Inputs
signal clock : std_logic := '0';
signal clear : std_logic := '0';

--Outputs
signal adjclk : std_logic;

-- Clock period definitions
constant clock_period : time := 40 ns;  --50MHz
constant adjclk_period : time := 40 ns;

BEGIN

-- Instantiate the Unit Under Test (UUT)
uut: FreqDivider PORT MAP (
      clock => clock,
      clear => clear,
      adjclk => adjclk
    );

-- Clock process definitions
clock_process :process
begin
    clock <= '0';
    wait for clock_period/2;  --for 20ns signal is '0'.
    clock <= '1';
    wait for clock_period/2;  --for 20ns signal is '1'.
end process;

adjclk_process :process
begin
    adjclk <= '0';
    wait for adjclk_period/2;
    adjclk <= '1';
    wait for adjclk_period/2;
end process;

-- Stimulus process
stim_proc: process
begin
  -- hold reset state for 100ms.
  wait for 40 ms;clear <= '1';
    wait for 80 ms;clear <= '0';
  wait for clock_period*10;

  -- insert stimulus here

  wait;
end process;

END;


texts: Mitigating unknown error in power analysis of ATMega328P microcontroller

texts:
Setup:

Arduino Uno (ATMega328P Microcontroller) running inline assembly instructions using asm statements. Global interrupts disabled. Pin 13 (PORTB5), DDRB5 designated as output used for trigger event for oscilloscope. The oscilloscope is measuring voltage drop of resistor soldered to VCC on microcontroller and using pin 13 toggle as trigger event. Clock of microcontroller is 16MHZ and the oscilloscope is sampling at 1.25GHZ.

Issue:

The traces acquired from the setup above are relatively uniform. However, they give some odd behaviour causing some errors in my analysis. Every 8 or 16 clock cycles, the waveform will peak on the trailing edge. Reading documentation of the microcontroller about the fetch-load-execute cycle does not lead to any nice conclusions. Has anyone else encountered this issue?


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I have a push button switch that is single-pole, that I need to independently control two circuits. The button will be connected to a digital pin of two different microcontrollers. So its a low current application. Unfortunately, in this case, a two-pole button cannot be used. Is there a way of doing this?

Obviously the first that springs to mind is opto-coupling, however, there is a chance that one circuit is not powered, which would mean there is a chance the opto-coupler is not powered.

It cannot be guaranteed that these two circuits share the same power supplies, hence the complications. Technically the two circuits should be +5V, however the grounds aren't necessarily common.


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Dark fiber (unused fiberoptic cables) is a confusing term for me. Why would any company build so much excess capacity? Such a business decision seems unwise. There are even companies that brand themselves as 'dark fiber providers' which is even more confusing.
https://www.ufinet.com/services/dark-fiber/
Was the expectation of utilization massively overestimated? Or is switching and multiplexing tech rendering it cheaper to use few fibers?
I realize this is not technically an EE question but am hoping that some real EEs have insight into why this has happened. If the mods feel a different forum is more appropriate I can move this post there.


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I have two circuit board.
1.PCB for battery pack
2.Embedded PC with various modules.

I was wondering if there could be an automated way of measuring current consumption by the embedded module during various operations. I need to automate this measurement as I will more than 200 pair of this boards for testing purpose in the next one month.


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I intend to use an SD card to record the movement (X,Y,C) of an animal for a research purpose.

I am using the Texas Instruments ARM Cortex-M4 TM4C123GH6PM launchpad along with a Sparkfun Micro-SD card adapter. I use SPI protocol to write/read the micro SD card.

Above is a photo of the specific micro SD adapter I use.  Please note this is a type of adapter that has no resistors, capacitors attached to any pin on it.

I want to ensure reliability of my application as it is of imperative importance. If the SD gets corrupted within 14 days after mounting, more funds will have to be spent re-collaring the animal.

I have tried my best to ensure software reliability but I sometimes get errors when I use fprintf, fsync upon which I re-initialize and arrange the file for appending again. At last, if nothing works I RESET the system fully. A reset usually mounts the filesystem again and usually works. But that is something I don't want to do.

I write ten of following strings a second and that is all I write to data.txt

1014067x3.97y-1.82z8.31x-0.02y-0.02z-0.01T5-45-28-900GPGLL,0654.8824,N,07958.3790,E,171619.300,AB88,4030

I have connected this micro SD adapter directly to the MCU SPI pins. There are no resistors, capacitors as support circuity. i had this micro SD adapter with pull-up resistors etc and I have already noted better reliability with that adapter. But I want to know for sure if additional circuitry can help.

Would someone be able to help me know if pull-ups or any additional circuitry would make my SD writes more reliable?

At the moment I have noted I receive about 1-2 errors from one of the Fat-fs functions I use every 3-6 hours. The system must run for 14 days and the data.txt is expected t become as big as 1.5GB after 14 days.


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simulate this circuit – Schematic created using CircuitLab

I have several about this op-amp curcuit:

i1 flows from Node 1. Does it flow into the op-amp? Or Another current will flow from the output of the op-amp? (I don't think i1 will flow into it, because Node 1 where i1 flows from has 0V and V0 is a positive number.)

I am confused with the use of this ground symbol. It is not a physical ground where charge can flow out of. It is just a reference point, so we have one less node to calculate the voltage. Potential doesn't matter, the difference does. But i2 and i3 both flow out of the ground/reference. And nothing flows into it. Should either i2 or i3 flow into the reference to preserve the conservation of charge?


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I am in the middle of a project where i want to use a mcu (ST32F3028U6 with DAC of 2.4V - 3.6V) to control the V_out voltage of a LT8494 SEPIC DC/DC Converter. I understand the basic operation of the converter and the purpose of some of the components in the application example.

I have also included a snippet from the LT8494 datasheet

In my case V_in is from a 1S Li-Po, so approx. 3.0 - 4.2 V

I understand completely the functions of and the external components belonging to pins V_in, SWEN, SS, PG, GND.

What i am having trouble with is the circuitry in the upper area of the picture. Hence, the question  of this post is: What is the purpose of the circuitry in the upper section of the snippet (including components D1-D4 etc), what is the purpose of BIAS and FB pins and how do i choose the correct resistor values R1, R2, R3 (in the picture 1M, 78,7k and 26.7k) to be able to control the output voltage with the DAC of my MCU

My current understanding of the circuit is as follows:
 Please correct me if I am wrong at any of the following aspects/explanations

When the NPN in the SW pin is enabled the current from Vin is stored in L1 and when the NPN is disabled the current is discharged through C3 to the output, generating the desired output voltage using R1, R2, R3. I dont understand the effect of L2 and the rack of diodes and capacitors.

Sorry for the long post, i was trying to be thorough in my explanation of the problem. Any help is greatly appreciated

EDIT: My desired output voltage would be in the range of approx 1.3V - 12V


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I am working on a two-layer PCB with ground pour in both layers. A few of the components recommend using bypass capacitors.

Going off of this guide, I understand that it is important that the current passes through VCC and GND directly through the capacitor.

The route seems to correctly pass through the bypass capacitor before I add the pour.

However, after I add the pour, now the current can circumvent the bypass capacitor. Does this make the bypass capacitor ineffective? Do I have to remove the ground pour from the VCC and GND pins when using bypass capacitors?