texts:
I am trying to model a very lossy coax transmission line. As shown in the circuit, the top TL model includes the shield line; the bottom lumps the shield terms into the center conductor and looks more like the traditional model.

My error is in wave propagation. (Ignoring the ringing from using a segmentation of 8)

Notice that the complex model single ended signal (top plane) is shown to have instantaneous conduction across the network, as indicated by the three red arrows. Not shown is that the shield path also has this compliment, which makes the differential signal look correct (bottom plane).

Can anyone help shed light on this error? Obviously in real life this would be breaking the laws of physics.

Edit for clarity
The exact problem I am trying to indicate is the short ~200mV step that appears to propagate instantly from one side to the other (in the single ended plot).

Edit for Clarity, Attempt 2
New figure added at the bottom, demonstrating more clearly the error of instantaneous end to end response time across the transmission line simulation. The section indicated by pink annotations should remain identical in all three plots, regardless of what happens after this window.


texts: Boiler feedpump energy consumption and safety

texts: Is it advisable to use VFD on a boiler feed pump ?


texts: Brightness of three parallel light bulbs

texts:
Three lights are connected in parallel across a 120V source. If one of the light burns out, then remaining two will light,

a. will not light

b. with the same brightness

c. brighter

d. dimmer

If one light burns out , overall load R will increase(since three light were in parallel) which should lead decrease in current & hence other two lights will be dimmed but the ans is 'same brightness'. What's wrong with my logic & why exactly we can't apply this logic?

OR

this is completely related to Electromagnetic theory for light where brightness is related to applied voltage to accelerate electrons which emits light when falls from Higher energy level to lower level?


texts: Calculate input resistance of power amplifier

texts:
how can I calculate the input resistance of this circuit?

Thank you!


texts: Using alligator leads as heat sink for soldering/desoldering PCBs

texts:
This is my first question, and I'm pretty new to the world of electronics, although I'm attending an Australian college course called "certificate 3 in electrotechnology".

My guitar tuner seems to have a ground problem. I think it's from the battery terminal, as it was fine but then 9V got stuck in the clips and had to be taken out with pliers. Ever since, it's been unreliable unless i put a bare foot on it. I've bought a new connector and plan on replacing the old one. One thing I am reasonably confident in is soldering, as I've wired my guitars myself for a while now. I understand that PCBs are pretty sensitive and that extra precautions should be taken when working on them. I read somewhere that alligator clips/leads should be used to dissipate the heat from the iron. If this is the case (there's a chance that some wise guy has just said it on the internet without qualification), would I connect these to the leads of the terminal or the board itself?

Also, in the past I have only used desolder wick. Should I go and get a pump for this sort of thing?


texts:
I've build this circuit :

The diode is actually a LED.

With this code on MPLAB x,XC8 :

#include <xc.h>
#define _XTAL_FREQ 20000000
#pragma config WDTE=OFF , BOREN=OFF , PWRTE=ON , MCLRE=OFF , FOSC=INTRCIO

void main(){
TRISIO = 0x001000;
GPIO = 0b000000;
    while(GPIO = 0b001000){
        GPIO = 0b110111;
    }

}

But the GP0(pin7) doesn't react on GP3(pin7) pressed button, why?


texts: Why do I get clear FM signals on my AM crystal radio?

texts: I made a rudimentary radio:  long antenna out the window, coil and capacitor (both home-made) in parallel, diode to guitar amp in parallel to LC circuit.  It works!  Even my calculated L and C correspond to a few AM stations I can get.  BUT almost at all L and C combinations, two local FM stations are annoyingly strong!  I can imagine they put out enough power, and close enough, to flood my system, but why can I hear them well rather than static?? Nothing in my system should demodulate FM.  They are there with or without antenna, with or without ground, etc.!


texts: Why do capacitors across my FETs minimize ringing/distortion?

texts:
I'm designing a 24V to 350V DC-DC Converter based on a H-Bridge. The power requirement is 500W and the circuit operates at 20KHz. The design works fairly well and I've achieved about 90% efficiency at 200W load. The main issue with the circuit is ringing. The waveforms distort/ring when the transformer is connected to the H-Bridge. Without the transformer the waveforms are extremely clean, even under load. Picture below shows waveforms with the transformer connected but without any load.

I found that adding a capacitor across all my FETs helped minimize the distortion severely. Here's a picture from my o-scope demonstrating this (left is without load, right is with 200W resistive load). Note that the output from the transformer is rectified with a full-bridge rectifier and smoothed by a capacitor:

So my question is: why are capacitors across my FETs minimizing the distortion? What is taking place in the circuit? I initially added a RC snubber across the FETs but the circuit works much better without the resistors and just the capacitor!

Here's a picture of the schematic and the layout:


texts:
I have to measure the current of a battery of 3.7 volt(used in HP IPAQ VM) and I am connection a resistor of 10 ohms in series with multimeter and the battery. Since the actual current of battery is 1.26 amps (1260 mA) but the meter shows only 0.37 amps.

How to measure actual current of source using multimeter?


texts: VHDL port map: connect only some bits of a vector

texts:
My design has a entity for configuration which returns std_logic_vectors (length defined by generic - normally 32 bit)

entity CenterConfig is
generic (
    -- Width of S_AXI data bus
    C_S_AXI_DATA_WIDTH  : integer   := 32;
    -- Width of S_AXI address bus
    C_S_AXI_ADDR_WIDTH  : integer   := 4
);
port (
    ...
    ...
    center_height: out std_logic_vector(C_S_AXI_DATA_WIDTH-1 downto 0);
    center_width: out std_logic_vector(C_S_AXI_DATA_WIDTH-1 downto 0)
);
end CenterConfig;

During instantiation I want to connect only the used pins and declare the others as OPEN.

Config: CenterConfig
generic map(
    C_S_AXI_DATA_WIDTH => C_S_AXI_DATA_WIDTH,
    C_S_AXI_ADDR_WIDTH => C_S_AXI_ADDR_WIDTH
)
port map(
    ...
    ...
    center_height(std_center_height'range) => std_center_height,
    center_height(C_S_AXI_DATA_WIDTH-1 downto std_center_height'length) => open,
    -- not working, not elegant

    center_width(std_center_width'range) => std_center_width
);

  ERROR: [VRFC 10-1225] partially associated formal center_height cannot have actual OPEN [/home/mir3/Compute/ip_repo/Starburst/src/Starburst.vhd:306]

The length of std_center_height is also define by generics.
How can I declare the others a OPEN in an elegant way?

Is there something like (others => open)?


texts:
My front dual USB port is broken on my old PC, ie it consists of a gaping hole with distorted pins inside (on the inside, it's still plugged on the motherboard, in fact, it's welded on it).
I have kids, and in order to avoid short circuit problems, I want to fill it up with a glue gun. Could it cause any electronical trouble?


texts: PIR motion sensor. How to drive 5 V IC from 3.3v input

texts:
I'm trying to get a circuit for PIR motion sensor**.  I'll need to use 2 sensor's - first in a single trigger mode and the second one is continuous trigger mode.

** HC-SR501 (datasheet, link goes to PDF)

First sensor will trigger the light and will remain on until the (less)delay set for the first PIR. If any motion detected on second PIR again the high input goes to OR gate and will keep the lamp on (doesn't matter if the delay expired for the first one lamp will be on).

If there is any motion detected on first again it will trigger and switch off the light. (Counter is meant for deactivating the connection ) - while leaving the restroom

I'm looking to have it in rest room. First one is right under the rest room door and the second one will be just before the shower area.

3.3 V battery in diagram represent the out put from PIR sensor

PDF version of this schematic can be found here


texts:
I'm trying to reverse engineer an aging datalogger.
Before building my schematic, I would like to identify all the components. There is one component that I can't seem to identify after many hours searching the web. (T1). Can someone identify what it is please?

Thanks in advance.

P.s How do you post a picture, sorry I'm new to the site.

Please find link below to the picture on Imgur.

Data Logger T1 component verification http://imgur.com/gallery/9RIDXmV


texts: 1V to 5V dc-dc step-up circuit @ Iout = 1A

texts:
I am trying to convert unregulated 1V input to 5V, 1A output within a project I am working on. I have tried working with MAX757 but could not get it to work. It takes a couple of weeks for maxim ICs to be delivered to my country. I need this voltage regulator right away.

It would be great if you could share a circuit that I can simulate on PSpice and then build/print on a PCB that gets the job done.


texts: Primary diff between EEPROM and Flash mem, in terms of code memory

texts:
In terms of storing program commands, what is the definable difference between EEPROM and Flash memory?

Also, in this particular context -
For a personal project developing audio codec using TI AIC3254, a developer zeroed in on Microchips PIC32MX220F032B. Its a 32bit MCU with 32kB EEPROM. It also has 3kB aux Flash with 8kB RAM.

Due to complexity, we are now deciding to use Arduino Mega 2560 based on ATMega 2560, which is 8-bit but 256kB Flash, 4Kb EEPROM and 8kB RAM.

What is the difference here? Flash and EEPROM what diff does it make when storing code?


texts: What's the purpose of having two of the same value caps in parallel?

texts:
Why does this 5V circuit use two of the EXACT same value capacitors?

It's not needing a larger capacitance issue considering 100nF is relatively small.

Here is the full schematic: Arduino Leonardo


texts: Increase the capacity of a 12v battery bank by adding new batteries

texts:
We have two 12v marine batteries connected in parallel – they power some LED lights and a small inverter used to charge a laptop and the odd camera battery. The marine starter batteries are about 2 months old and are charged from a couple of solar panels.

If we purchase a new deep cycle battery (or two new ones) what is the recommended way of connecting these to the existing batteries? Is there a name of a device that handles the different batteries (ie: charge / discharge separately)?

Is it possible to use the new and old battery bank at the same time (charge one, use the other, auto switch between)?

My understanding is connecting new different batteries in parallel would not be efficient (crappy ones drain from better ones).

Currently travelling and coming up to a bigger town and looking to buy something there – need to know what I'm asking for :)

Thanks !
Dave


texts:
I'm working with a position sensor (Correvit Aqua L-350 by the manufacturer Corrsys-Datron) that gives me 0 to 5 V pulses everytime a distance (which I can choose on its software) is swept.

User manual says nothing but "Digital output: pulses - TTL".

How can I know a safe amount of current to draw out of it? I'd like to use these pulses to drive an optocoupler, so I need something around 10 mA.


texts: Turn a METAL HALIDE BULB On/Off in 1 minute Intervals?

texts:
OK, let me 1st give you some background information.

I need to generate 40,000 lux of light in an indoor environment (in a area of around 5 feet by 3 feet) and I need the ability to turn the light on/off in 1 minute intervals for around 10 hours straight (about 600 off/on events in the span of 10 hours).

So far I've come up with two options. I can buy several high-watt compact fluorescent lamp (bulbs) and use a timer than can turn it off/on in 1 minute increments. I already have a timer than can do this so I have no problem with this point. However, I would need around 30-50 105 watt bulbs to generate this kind of light. The benefit of using CFL is that it can be turned on/off in a relatively short time (many are instant on but even if not it won't take more than 20-30 seconds). However, I'd need a ton of such bulbs.

My other option is to use a METAL HALIDE BULB. 1 such bulb can easily generate 40,000 lumens using only 400 watt (compared to 1500+ watt for the CFL bulbs). However, the main issue with these are that it takes anywhere between 3-5 minutes (sometimes more) for the bulb to reach full luminosity - and I need it to reach full   luminosity within a minute or less (instant is ideal).

Furthermore (as Wesley Lee pointed out) I would need to wait several minutes to turn it back on after turning it off (I accidentally omitted this from my OP).

One solution I thought of was keeping the bulb  on indefinitely and placing it in a box. The box will then open and close in 1 minute increments. Thereby allowing the light to illuminate the area for 1 minute and then when the box is closed no light will be emitted.

My question is how to make an apparatus that opens and closes in 1 minute increments? Or is there another simpler solution to my problem?

The solution needs to be automated (not manual).

Thanks


texts: How to calculate cutoff frequency for this filter?

texts:
I want to know what the cutoff frequency is when I change C6 and C11 to 100pF (I don't have 82p/150p)

I'm not even sure what kind of a filter it is.. it says it's an elliptic Cauer, but I can't find anything on how to design it or calculate L/C.

I need the cutoff to be anywhere between 30 and 50 MHz


texts: Controlling MOSFET and LED from same PWM output

texts:
I am controlling a MOSFET and LED from the same PWM output from a PIC.  The MOSFET is driving a fan, while the LED is used as rough visual indicator of the speed.  The circuit is below and it seems to work and I have not experienced any problems yet.  But, I am unsure if this is recommended.

Edit1:

Looking at the suggestions, I made the following changes.

added diode to fan
replaced R21 and with R22 and LED1


texts:
I am having trouble using an comparator, the LM319N.
I am trying to get a 0.5V to -0.5V signal to raise to a 3.3V - 0V signal so i can read it using gpio pins on my micro controller. I tried a few setups
 using various input voltages (3.3V 5.0V and 13.5V) and all it does is setting the vcc value on the output. I put all my images in an imgur album because i cant put more than 2 links. schematics

first i tried picture one.
Put the negative input to ground an the positive to the signal. I tried many different voltages for the vcc+ and ground for the negative. But the out just gives the same as the vcc+ minus a bit. (+- 0.3-0.5 V).

After that i tried picture two.
I put the negitive lead to the negative signal. The signal has a positive and a negative. It comes from an xlr plug. I hoped that with the crossing of the two signals that the "bits" would come out at a more specific spot (or just come out at all). But same as last time just get the value of vcc+.

After that i tried picture three.
I read somewhere that the output was an open drain collector. As far as i am aware is that that means that it pretty much becomes a ground lead when it is active. So i added a pull-up. But again vcc+ was the output. I tried multiple values for R1. (10k, 1k and 500r).

after that i tried picture 4.
I thought an op-amp and an smitt trigger would do the trick to. Op-amp to elevate the signal to [3.3  -3.3] V and than cut it of to [3.3   0] V. with the smitt trigger. But even here the op-amp only outputs the vcc value. I am really at a loss. I appearantly dont get how i use an opamp. (explains why i keep failing my test on the subject). I really hope someone can enlightnen me with what i am doing wrong.

Also the signal in question is a Linear time code. which is usually transmitted over audio. And i tried multiple IC's so the case that it is just a bust ic is pretty much out of the question.


texts: Is it better to combine logic for two flip flops in a single always block?

texts:
I have always used separate always block for infering different flip flops when they dont have much in common.

always_ff@(posedge clk) begin
    if(rst) q1<='0;
    else if(en1) begin
    ......
    end
end

always_ff@(posedge clk) begin
    if(rst) q2<='0;
    else begin
        case(sel)
        ......
        endcase
    end
end

I find it easier to add/modify logic if they are coded in separate always blocks.

I recently read a paper that said :

  Each inferred flip-flop should not be independently modeled in its own
  procedural block/process. As a matter of style, all inferred
  flip-flops of a given function or even groups of functions should be
  described using a single procedural block/process. Multiple procedural
  blocks/processes should be used to model larger partitioned blocks
  within a given module/architecture. The exception to this guideline is
  that of follower flip-flops as discussed in section 3.1 where multiple procedural blocks/processes are required to efficiently model the function itself.

Is there a benefit for using single always block or a hazard if we use separate blocks? The only reason I could think of for not using multiple always blocks is(that I have read elsewhere) is it degrades simulator performance.


texts: How to allow input on bits of Microcontroller port

texts:
I'm trying to figure out this question:

  Write a line of code in C to allow input on bits 2 through 4 of port A.

I am familiar with writing code, I just don't understand the question. Can someone help me understand this?

This is for a 16-bit Thunderbird12 Microcontroller.


texts: Buffering/matching large signal to drive 5 ohm capacitive load at 13MHz (RF)

texts:
I built a Pierce oscillator that generates 13.5MHz @ 7Vpp signal from a V_cc=12V. But I need to drive a capacitive load of 5 ohms @ 6Vpp. I'm not sure how to do this.

First I need a buffer to prevent loading of the signal source. FETs have a large input impedance so I think it's appropriate, so I used a source-follower with a large \$R_S\$. However 7Vpp swing seems too large and leads to distortions, is there any way around this?
Using a resistor ladder to scale down the voltage first, then connecting it to the gate  seems stupid.

I also tried to use a 2n3904 emitter follower, but I noticed that the emitter voltage rises fast but falls slowly and cannot keep up with the signal, therefore I got reduced and distorted output. The falling waveform looks like the RC voltage decay, to make it fall faster I have to substitute a smaller emitter resistor, therefore increasing the loading of the source.

So the first question is how to buffer the signal without significant distortions.

The next problem is how to match the impedance. If I got 7Vpp and 50 ohm of output impedance, using a transformer to match 50 to 5 ohm would require a 3:1 turns ratio. That is, my 7Vpp would become 2.3Vpp, which is too low. Even if I somehow managed to get 12Vpp (Vcc=12V), output would only become 4 Vpp, still not enough.

Is there any way around this?


texts:
I have a sine to pulse converter box(LM2903 is used), it works very well and I also have the circuit schematics. The converter converts the mV level sinusoidal signals to pulses.

I want to rebuild it so first I drew it in LTSPICE but it doesn't work. It outputs constant negative voltage not pulse for given sinusoidal input signals.

What is wrong?


texts: Do full charges and deep discharges wear the battery because of terminal voltage?

texts:
A mobile phone battery charged to indicated 100%, which is not being charged at the moment, might have the same terminal voltage as if it is being charged at 2A while being at an indicated capacity of 70%.

A deep discharge (terminal voltage below 2.5V) is said to cause a harmful chemical reaction in a lithium-ion battery.

If a battery is shorted out in a way the voltage drops below 2.5V, does that have the same harmful effect?

And does a battery wear out because of terminal voltage or capacity if fully charged?

If it is because of terminal voltage, fast charging stresses the battery in the same way an ordinary full charge does.


texts: Esp 8266 - 01 module unable to flash or communicate

texts:
I have an ESP8266 module which is not communicating with the Arduino IDE serial monitor unless I press the rest button on the ESP setup. I tried erasing and reflashing the ESP8266 several times, but it doesn't work or respond to my AT commands from the Serial monitor. At 74880 baud rate it does show something everytime I reset the ESP manually, I want to know step by step how to properly flash the firmware, at get the AT commands to work.

I am using the ESP8266-01 model with 26MHz clock and 8Mbit flash,
I have connected Arduino Tx to ESP Tx
I have connected Arduino Rx to ESP Rx
I have connected GPIO-0 to Gnd while programming.
I have supplied power from the Arduino 3.3v
Also I have connected CH_PD to 3.3v

Sometimes at 115200 baud I get fatal exception(0) and some errors, but that was before I erased the flash.


texts:
I was hoping to get some help understanding a state space model that I have found in time and frequency literature. The literature pertains to a discrete-time model of a steered clock. A phase measurement is available, and the control input is via a frequency control element (e.g. a VCO).
Here is the two-state clock model:
$$x_{k+1} = \Phi x_k + w_{k+1}$$
$$\vec{x} =\begin{bmatrix} x_1 \\ x_2\end{bmatrix}$$, where x1 refers to a phase offset and x2 refers to a frequency offset between two oscillators. The state transition matrix is:
$$\Phi = \begin{bmatrix} 1 & T_s \\ 0 & 1 \end{bmatrix} $$
Which I believe originates from a continuous state matrix $$A = \begin{bmatrix} 0 & 1 \\ 0 & 0 \end{bmatrix}$$. Phase is the integral of frequency, so this makes sense.
The output equation for the phase measurement is: $$z_{k+1} = Hx_k + v_k$$ where $$H=[1,0]$$.
My confusion is related to the model of the input/control matrix B whether in discrete or continuous time.
In core literature, the ideal discrete matrix for a frequency-steering element is described as
$$B = \begin{bmatrix} T_s \\ 1 \end{bmatrix}$$
This comes from: $$B=\Phi \begin{bmatrix} 0 \\ 1 \end{bmatrix}$$ which is described as the "propagation forward of the steer input."
Just looking at the equation, the form of discrete B proposed as such makes intuitive sense-- if we can apply a delta to the frequency of an oscillator, that will be integrated into the phase variable and so on. Also I like this model because it is controllable.
I would be fine with working in the discrete domain, but I am quite confused how this model was derived from a continuous model. What would the continuous version of B be, and how is this justified?
The paper uses the phrase "fractional frequency" to describe the frequency steering mechanism. Perhaps this suggests that $$\ddot \phi = k u(t)$$.
then $$x_1 = \phi, x_2 = \dot\phi, \dot x_1 = x_2, \dot x_2 = \ddot\phi = k u(t)$$.
Then,
$$\begin{bmatrix} \dot{x_1} \\ \dot x_2 \end{bmatrix} = \begin{bmatrix} 0 & 1 \\ 0 & 0 \end{bmatrix}\begin{bmatrix}{x_1} \\  x_2 \end{bmatrix} + \begin{bmatrix} 0 \\ k \end{bmatrix}u(t).$$
This seems to match what is in the paper, because $$B_{discrete} = \Phi B_{continuous} = \begin{bmatrix} Ts \\ 1 \end{bmatrix}$$, which is the computation the authors of [2] use for deriving B in the paper. However, I thought the expression for computing discrete control was:
$$B_{discrete}= \int_0^{T}e^{A\tau}\vec{u}(\tau)d\tau B$$
When I do this integration for constant u, I don't get the same answer for discrete B, but I am probably doing it wrong (u isn't constant, error in doing the integration, etc). In any case I'm not sure how to fix it. But, nevertheless, I feel like I am on the right track for understanding some of the author's assumptions. Any pointers or insights would be appreciated.
By contrast, an alternate form of modeling a frequency steer assuming a voltage-controlled frequency synthesizer obey the following relationship (the assumption that the transfer function of the steering mechanism is linear when the system is operating in closed loop).
$$\dot \phi = f(t) + k u(t)$$
$$\implies $$
$$A = \begin{bmatrix} 0 & 1 \\ 0 & 0 \end{bmatrix}, B = \begin{bmatrix} k \\ 0 \end{bmatrix}$$
This model is not controllable (though it is potentially stabilizable).
Key references:
Reference 1: Koppang. State space control of frequency standards  https://iopscience.iop.org/article/10.1088/0026-1394/53/3/R60/pdf
Reference 2: Matsakis 2019 The effects of proportional steering strategies onthe behavior of controlled cloc https://iopscience.iop.org/article/10.1088/1681-7575/ab0614/pdf
Older refs:
Reference 3:  Koppang & Matsakis, New Steering Strategies for the USNO master clocks https://apps.dtic.mil/dtic/tr/fulltext/u2/a496156.pdf
Reference 4: Koppang and Leland, Steering of frequency standards by the use of linear quadratic gaussian control theory https://ntrs.nasa.gov/api/citations/19960042633/downloads/19960042633.pdf
$$\Phi = exp(A \tau)$$


texts:
I am looking for a way to link a RF433 emitter

to a RF433 antenna

Since there is an "ANT" pin on the emitter I assume I can connect an antenna to it.

However, I do not know how to do this kind of link. I had a look on the Internet, and I saw that some people recommend using coaxial links. Do you have any explanation to share with me?


texts: Are there any pci-e controllers that take like a SPI signal, or USB and then lets me hookup a pci-e x1 card to it?

texts:
I am wondering if such a thing exists, as I could really use one to hookup to a SoC I am designing a board around, as it would allow me to take like a pci-e tv controller, pci-e ethernet card, pci-e GPU.
It should take in some signal a mobile SoC can provide, like SPI, USB, or straight driving it from gpios(probably slow) and then outpu a pci-e x1 lane(s) or more.
Does somebody know of such a thing, that is reasonably priced = < $12?

Thanks


texts: Can there be "too much" capacitance on a buck regulator output?

texts:
I've an MPM3610 buck regulator module with an integrated inductor of 0.47 µH and a fixed internal compensation. It employs constant-on-time regulation. The datasheet gives some application circuits with a ceramic input and output capacitors of only 10 µF.

According to common knowledge (which may be misleading..) more capacitance on the output will reduce output voltage ripple. However, I've no idea how the stability will be affected.

Since I've got quite some space left on my PCB I wonder how much extra capacitance I should reasonably add, taking into account the reduction of effective capacitance due to DC bias effects.


texts: Low-Pass and High-Pass Filters Outputs of Summing Amplifier

texts:
Consider the following figure and questions.

Using KCL, I found vsum(t) = −v1(t) − v2(t). The transfer functions are TLPF(jw) = vo1(t)/vsum(t) and THPF(jw) = vo2(t)/vsum(t). However, I am stuck while finding vo1(t) and vo2(t). I am not sure how to apply KCL at the common filter node (since the output current of the amplifier is unknown) and I don't think I can apply KVL to the right LPF + HPF loop since it's open (or is it? What do the ground symbols indicate?)


texts: Can Proteus Isis open Eagle's schematic?

texts:
I had some years working with Proteus PCB design. A few years then, I did not do the same work.

Now, from Googling, electronics community seem to place Eagle in a dominating position. Sparkfun, Arduino open-source projects are released in Eagle.

Should I switch to use Eagle? or Proteus Isis has some function to import Eagle schematic?


texts:
While reading about the SIM in 8085 i came upon the accumulator state at the data pin 5 where when SIM instruction is executed we have to consider pin 5 of the accumulator to be don't care.
So I am not able to understand why do we need to define or mention about a don't care bit while processing the SIM instruction execution?


texts:
I am routing a development board for STM32F030R8T6 which can use external 8 MHz crystal. Here are the schematics and board for the crystal part:

Crystal traces are routed on bottom layer (blue color).

Initially I have worked with atmega and I never saw a resistor in a crystal circuit. What's the role of R5 (390 ohms) in this crystal circuit?

I have tried to keep other gpio traces away from crystal traces but a few of them are going over them on the top layer. Should I be concerned?

Also, the traces originating from pin 17-30 have too many twists and turns. Will it create any issues during the fabrication process? I am using 10 mil traces.


texts: More specific name for p/s terminal ground-link part?

texts:
Anyone know if there is a more specific name for this kind of ground link, with a vaguely forked shape,  used on the terminal of a power supply? Bought some ebay goodies missing this.
Other p/s seem to have roughly similar dimensions across mfg's.
Was considering something more user friendly than a wire / more finished than a sheetmetal hack.
Already checked manual, it just says "ground link" which seemed too generic.
TIA


texts: In automobiles, are we using the car chassis as a ground terminal of battery? Then why we don't get shocked while touching it?

texts:
My concern is to know if we can use the metallic chassis for a replacement of ground wire.

In automobiles, the positive wire is taken to the headlamps and ground is provided by connecting the neutral wire to chassis of car.


texts: Can this Boolean expression be simplified?

texts:
I have the Boolean expression

!B((!A.!C) + (!C.D) + (A.C.!D))

Can this be simplified using factorization or race hazard and redundancy, or is it in its simplest form?


texts: Represent the given signal in mathematical form

texts:
Is this the mathematical form? I highy doubt myself

$$
-2r(t+3)+2r(t)+16u(t)-r(t)-2u(t-3)+5/2r(t-3)-5/2r(t-5)
$$


texts: I am little confused over what the signal to noise ratio refer to and what is it actually used for. Is higher SNR better or Lower SNR better for your circuitry? Does infinite signal to noise ratio mean that you have no noise in the signal?


texts: What causes the difference in tPLH and tPHL?

texts: What causes the difference in propagation delays, for example on the SN7404N inverter, \$ t_{PLH} = 12-22 \$ ns, and \$ t_{PHL} = 8-15 \$ ns. Why is one longer than the other? Does it have to do with the functionality of the BJTs, or the architecture of the device itself?


texts:
I am trying to verify voltage drop across a resistor as seen on my multimeter with basic ohms law calculations.

As shown in below circuit (from Electronics for DUMMIES). The multimeter shows a voltage drop of 6V at 1M ohm resistor. However that is not what my math shows and I think something is wrong with my maths. Here is how I am doing it

Vb=9V
First Find total Resistance of circuit
R1=1 M ohms= 1000000 ohms
R2=10 k ohms = 10000ohms
R3=470 ohms

R1 and R2 are in series with each other but both combined are in parallel to R3, so
Rtotal = (R1+R2)||R3 = (1000000+10000)||470
= 1010000 || 470
= (1010000 x 470)/(1010000 + 470)
=474700000/1010470
=469.7813888586499=469.7

Now to find Total Current
I=9V/469.7ohms
= 0.019 Amps

Voltage drop across  R1(1 M ohms)
V1=0.019 x 1000000 = 19000(This cant be right)

Did I miss anything?

The NPN transistor is BC546B, which is acting as an amplifier


texts: How should I connect multiple Lithium Polymer battery packs in parallel?

texts:
I have an application for which I need a relatively high amount of current @5V. I was thinking of connecting four external USB battery packs like these in parallel, as they output a nice regulated 5V and are easy to charge. But I know lithium chemistries are sensitive souls and having "unbalanced" cells connected together is a no-no.

How can I avoid any individual pack with a higher charge accidentally trying to charge another? Is it as simple as putting a Schottky diode in series with the positive lead out of each battery? Do Schottky diodes have an intrinsic voltage drop (like LEDs) which will waste a significant amount of power and/or cause my circuit to see less than 5V? Is there a better approach?


texts:
I want to calculate time period by using Verilog code. Is this the correct way to get time period of clock of a particular frequency? Please suggest to me some better Verilog code. The code is not working.

I have written this sample code:

module clk(reg gsclk, output reg time1,output time2,output gs_clk_period)

    always@(posedge gsclk)time1=$current_time;

    always@(negedge gsclk)time2=$current_time;

    always@(posedge gsclk)gs_clk_period = (time2 - time1)*2;

    $display("%clock %b",gs_clk_period);

endmodule

I have to use time period for synthesize and want to run in real device.


texts:
I have built the blue circuit above for my microphone but the one of the problems I'm facing is that when I connect it to my laptop's audio input, it creates a humming sound. My assumption is there is a lot of noise whenever I pug it into my laptop.

Does anyone know why this is happening? Thank you for your help in advance.


texts: A conflicting result in the diode and capacitor circuit

texts:
Consider following circuit:

simulate this circuit – Schematic created using CircuitLab

The question is determining output voltage.
D1 is an ideal diode with zero threshold voltage.

Certainly when input goes from zero to peak voltage the diode is off but the problem is after that time. Both on and off assumptions for the diode is valid when  $$T/4\le t\le T/2$$ If we assume diode is off then $$V_D = 0 - V_{out} = -V_1\lt 0$$ because $$T/4\le t\le T/2 \implies 0\le V_1\le V_{peak}$$
On the other hand assuming diode is on leads to $$ i_D = -C_1V_1' \gt 0 \implies V_1'\lt 0$$ which is true because $$V_1' = V_p\omega \cos{\omega t} \ \ \ \ and \ \ \ T/4\le t\le T/2$$
What is my mistake here? According to my book during entire positive half cycle diode is off but I don't know what's the problem with on state.


texts: Is it possible to construct a NOT gate if given only OR gates and XOR gates?

texts: I was given this problem and I don't think it is possible since if both inputs are zero on a OR gate or a XOR gate, all outputs will be zero.  Or am I wrong here?


texts: ESP32 with external power supply and serial communication between ESP32 and PC

texts:
I would like ESP32 with +3v3 external power supply.
I don't want to use PC-USB's power supply through +3V3 voltage regulator.
Is it possible to make serial communication between ESP32 and PC using usb-uart serial converter(CH340G specifically)?


texts:
I'm getting some really weird effects on my Gerber File outputs from Altium

Altium 18.1.9, using OutJob Files, here are my settings

My layers look completely normal with a copper pour for the ground plane like shown here

However, when I export Gerber files, I get these bizarre lines through everything that seem like they would cause everything to be connected to ground,

I have no idea what is causing this, have any of you seen this before or have any suggestions for things to try? I'd appreciate any help!


texts: How to find the system response given the transfer function without using Laplace transforms?

texts:
The given transfer function is:

$$\frac{6p+100}{p^2+12p+100}$$

and inputted into the system is a unit step response:

$$r(t) = \left\{\begin{array} f0 & t < 0\\1 & t > 0 \end{array}\right.$$

However I'm not supposed to use Laplace transforms to solve this. I believe it has something to do with finding the poles but I'm not exactly sure how to accomplish this.


texts: Quick Disconnects / Connectors for 24VAC Power - Project Box

texts:
I have a small project in which I will be using 24VAC power that runs through float switches to operate relays (listed below).  The 24VAC will also be used to control a small motorized ball valve (listed below).  I'd like to have panel mounted power connectors on the project box (which will house the relays and the transformer) so that I am able to easily plug and unplug the float switches and ball valve.
A DC connector like this seems like it would work well functionally, but not sure if this should be used with low voltage AC??  Are there any connectors out there that are made to be used with 24VAC and are easily connected/unconnected?

Relays to be used:
https://www.grainger.com/product/HONEYWELL-HOME-Magnetic-Relay-2E682
Motorized ball valve to be used:
Electrical Rating: 24 VAC, 60 HZ, 0.48 Amps
https://www.pexuniverse.com/taco-z075t2-sentry-zone-valve
Wiring Diagram:


texts: Can anybody identify this component (SPRAGUE 663044-4) on this vintage electronic?

texts:
I am repairing a vintage Seeburg/Gulbransen 'Select-a-Rhythm' drum machine from 1967, the kind you would sit on top of your organ and play along with.

I am trying to distinguish what this component could be, it basically looks like an old capacitor but it has 7 legs. I've attached a photo below to identify it (highlighted in yellow circle):

The item states SPRAGUE 663044-4, it has 7 feet and there are 6 of them. could these be the pulse generators(for the rhythms) or some kind of logic circuit? The schematic diagram states them as PC001, PC002, etc. The circuit diagram is attached below also. Could PC stand for Pulse Circuit?

Also, if anyone can identify the mysterious transistors which all say '4000' on them and nothing else. the schematic states them as 'q2001, q2002, etc)

The machine didn't turn on when I first bought it and now I have it lighting up, I've attached a foot switch to start/stop the rhythms which is working perfectly with the tempo light, but still no sound!

I've re-capped all the old paper and film capacitors so I'm hoping it could be a few resistors somewhere because these mysterious 7 legged creatures look like they could be difficult to find replacements.

Thank you for your help, I'd love to hear this thing working once again! This is just a hobby for me so I'm in no rush, looking forward to your reply.

Here is a link to the full service manual if needed.


texts: When an isolation transformer is not enough?

texts: I work for a fairly large church and we have powered line array speakers that do not have attenuators in them.  Over time a ground loop occurred from the stage lighting causing a very distracting hiss/buzz noise.  I installed a great isolation transformer from Jensen and it's much better.  However there is still a slight white noise whether the lights are on or off.  The ground wire from the transformer is touching the metal plate on the speaker so buzzing shouldn't be from that.  Any advice?  Thanks a lot - Ben


texts: Am I drawing more current if I'm giving multiple paths from supply to ground?

texts:
Illustrated as such:

Am I drawing more current in the first case than the second case? Would this drain the 9V battery faster?


texts: Why does an analog chip have two ground connections but not two vcc connections?

texts: I'll be using an TLC7528 dual DAC IC in my circuit, and it has two pins for ground named AGND and DGND (which to me means analog and digital ground). It only has one pin VDD for power. Why would it only have one pin for power and two for ground? Why don't they make them so I get the AVDD and DVDD and GND pins instead?


texts: Measuring tiny voltage variation with Arduino ADC handing the rapid changes in control algo

texts:
I'm hoping I can get some advice, I have an industrial laser position sensor from SICK that outputs 0 to 10 volts. I used a voltage divider to scale it down to 0 to 5 volt range, and feeding that into an analog input of an Arduino.

The sensor is very accurate, but it moves about 0.1 (tenth of a volt per inch), and the setpoint of my control system needs to maintain a sensor reading of 2.03 volts (hundrends).

I closed the system loop and it maintains the object at the position but varies from 1.99V to 2.09 volts which is actually a couple inches in each direction.

I found the Arduino can actually read the correct voltage from the sensor but using a laboratory voltmeter the arduino will be off in the hundrends digit sometimes by a few, but I need this to be accurate...

Any suggestions? Can the 10bit ADC even measure the voltage accurately? Also I thought of using a moving exponential average filter to kinda get 10 samples and read the average voltage since it changes so fast...

By the way I'm using the position sensor to measure height of a ping pong ball in a tube, so the ball wobbles a bit, even with PID, so the sensor readings will change like:
2.01
2.03
2.04
2.05

fairly rapidly..

Any help is greatly appreciated!!!!!


texts: Digital circuit for adding multiple frequencies

texts:
The goal is to implement a kind of a digital piano on an FPGA.

Until now, I managed to produce individual notes using counters. Basically, I generate a square wave of a certain frequency, that corresponds to a musical note (of course, in order to do that, I rely on the frequency of the clock, but that's not an issue).

How can I design a circuit that can produce the overlapping of multiple notes? Basically, I want to be able to produce 2 sounds of different frequencies at the same time.


texts: Why do the voltage measured across a DC motor drop when its turned on

texts:
In my experiences with DC motors there is thing that i have noticed where in the voltage measured across the motor when it is off is higher compared to when it is on. Why is that?

I have always paid no attention to it since the motor still spins. Is this a bad indication that supplementary components are needed.

Let us say i have a 6v volt motor and i apply a six volt to it via a driver upon turning it on it will be just 5.3v. I do not believe that the driver is the blame since i know my drivers are using mosfets and the voltage drop should be very minimal.

Should i adjust my input voltage so that upon measuring the motor voltage it goes back up to 6v?


texts: Creating a new library: Pin association to footprints [Kicad 4.0.2]

texts:
I'm trying to create a library for Lipo battery connectors. I started with the most common connector XT60. I drew the schematic, and then drew the footprints. On Eeschema, I can connect my XT60 to other components without a problem, even I can assign XT60 footprint to it on CvPCB. However, on PCB, no connection is created.

What exactly do I miss? Apparently it's a very essential part, but I couldn't just extract the necessary source from the internet. Thank you for your help in advance.


texts: Verify changed analog reference voltage on Arduino

texts:
I want a reference analog voltage of 2.0 volts on a 3.3 V Arduino.

Since there is an internal resistance of 32k on the Arduino, I hooked up a 21k resistor to Vcc.

How can I confirm that I now have an analog voltage range from 0 to 2.0 V? Can I do this via code? Or just use a voltmeter?


texts: How to ontrol a 12v dc water valve with battery powered Arduino?

texts:
I just want to open/close a valve when the soil moisture sensor reports a pre-determined moisture level, using an Arduino.

The main issue I'm facing is that most valves operate at 12/24 VDC and I'm using 5v to power the Arduino. Those 5v come from a Step-Up MT3608 which is drawing voltage from an 18650 Li-Ion battery.

Is there any way to power a 12v valve without adding a second MT3608? Doing this would make the whole thing electrically inefficient (I need to keep the power consumption low).


texts:
I am wondering if it is possible to execute a function or a certain logic automatically without any impulse once the FPGA image is loaded on the the bit file. Something like an initialization sequence without any input from the user on any of the pins. It just needs to run once when the FPGA image is loaded.

Is it even possible ?


texts: Could the W65C02S drive a LED on its databus?

texts:
I am (trying to ;)) building a W65C02S based hobby computer and I am having some trouble now finding a bug where the W65C02S doesn't seem to be driving the databus at all when doing a WRITE (the voltage level hovers around 1.8V or so instead of a steady 0 or 5, even when all loads removed).
So my incling now is that I somehow fried the output of the databus of the W65C02S, so I dove into the datasheet. In my surprise, I can find a output high current and output low current being spec'd as min 700uA/1.6mA, but no maximum.
So, does this mean the output could drive something like a LED?


texts: Source voltage driving a series LED strip seems below combined forward voltage

texts:
I am currently working on a project to build a digital clock. The digits of the clock are to be made from custom-built seven-segment displays.

Each segment of a digit will be made up of a couple of LED strings (more than one LED in series per string) all hooked to the same switch. The LEDs are to be connected to a constant voltage source (NOT current controlled).

Poking around an old product (not mine), I noticed a design with the following characteristics of an LED string.

LED COLOR  =   White
No. of LED's per string  =  5
String series resistance = ~67 ohms
Source Voltage  =  12 V

This has got me a bit confused because the forward voltage of a white LED is almost always specified at about 3 V. This means for a 12 V system, you can have at most 4 LEDs per string (without the current limiting resistor).

Unfortunately for me, the product I plan on sourcing does not come with a detailed datasheet.

So I would like to ask the community if I am missing something here, i.e.:

Are there white LEDs (regular price) with far lower rated forward voltage?
Can a 3 V rated LED be driven at lower voltages and not loose too much brightness?
Any recommended solutions for my project?


texts: No output or invalid output on a 74HC595 shift register

texts:
I have a PIC18F2550 microcontroller on one board with three daisy chained 74HC595 chips. These are driving 7-segment displays and everything is working fine. 7-segment displays are connected with a cable. The thing is connected to my computer with USB. This is where it draws it power.

Then I added an another 74HC595 on a separate board to drive LEDs. It's not daisy chained with the other chips, but connected to separate pins on the microcontroller. These LEDs are sometimes on and sometimes off, might change state once when I try set them in different states from software, or not. Usually all of those LEDs end up being all on or all off. 7-segment displays continue to work as expected.

Then I added yet another 74HC595 on yet another board to drive a separate 7-segment display and connected it to separate set of pins on the micro. It functions the same way as the other separate board.

Schematic shows the "main board". These 74HC595's are working correctly. The other two are connected the same way via pin strips (shown in the schematic as SV5 and SV6) and jumper cables.

Oh, and all the LEDs (including 7-segment display segments) have 1k resistors connected in series for current limiting. Here is a schematic of one of the other boards connected via
SV5 and/or SV6 connectors. These are the ones which are not working correctly.

I have tried slowing down the software side of sending bits to these shift registers with no luck. Everywhere it says that I shouldn't use long wires between chips. Is 10cm long? Should I add some decoupling capacitors or something to next to those non-working shift registers? Should I rather redo everything on one board? Is there an error in the design? Or what?


texts:
I started working on a single series lithium to 15V / 2A Boost converter based on this design: https://www.ti.com/tool/PMP8921.
I got this PSpice simulation model from TI themselves here: https://www.ti.com/lit/zip/slvm706.
After changing the file so that it works like described here: Issue using pspice .lib in ltspice - Unknown Parameter,
I then got a simulation working:

Then, after saving everything and doing something else on my computer I returned to the project and now the results make no sense anymore:

(output of the converter)

(switching node of the converter)

(EN node of the TPS43061 (has to stay over 1.14V ?!)
Why doesn't the output smoothly increase to 16V?
Where do these weird transients come from? I don't remember changing any simulation parameters, so they must be the standard ones.
Are there some parameters I could change to omit these strange errors?
The design has been proven to work before.
Files: https://1drv.ms/u/s!Ai1WNGQ9wFb7g5hYmVUygiMGqTib5w?e=Ww1wg7
Schematic of working circuit:

Cheers


texts:
What does the Holding Current characteristic mean on a triac?

What does this mean for switching loads less than the Holding Current?

For example the Sharp S108T02 has a max 50 mA Holding Current.


texts: Simple and safe solution to control a power plug with Arduino or PC

texts:
What solutions are available to control a power plug (or even if possible a light socket), i.e. turning it On and Off?

I have looked for xbee/zigbee solutions but there doesn't seem to be a solution available for European power sockets (and so few solutions even for US sockets).

A wired solution including an Arduino is OK for me. I want it to be easy to use (as for zigbee I'm ok to learn how to use it), and safe (I don't want to connect or solder things because it's 240V, I don't want any risk  with the electrical installation).


texts: Extension cord from grid through GFCI outlet to off grid inverter. Does the extension cord ground need connected?

texts:
I have an off grid system: PV, charge controllers, inverters, and batteries. I want to add a 120V grid input from a GFCI outlet through an extension cord directly into the inverter AC input. However, the GFCI trips when the AC input connects. But only if the ground from the extension cord is connected. Is it necessary to have the ground of the extension cord connected??

I could see an issue where the hot could touch the case of the inverter but the case would have no path back to trip the outlet's breaker. But wouldn't the GFCI protect it?


texts:
I'm having trouble understanding what the serial number or type of these LED's are so I can look up the datasheet. The packager didn't label them at all. I've searched and searched and I don't know if I'm getting the right specified datasheet that coordinates with each item. I've listed my invoice and then following that I listed some numbers that are printed real small on all the 1"Tall LED's. Could you guys explain to me how to read these things. I'm confused on what I'm looking at and I need to match them up somehow so I know which one is which.

MY INVOICE:

(1)    COM-09481    7-SegmentDisplay    4-Digit(Blue)

(2)    COM-09482    7-SegmentDisplay    4-Digit(KellyGreen)

(1)    COM-11407    7-SegmentDisplay    1"Tall(Green)            "This is a 4-Digit also"

(2)    COM-11408    7-SegmentDisplay    1"Tall(Blue)             "This is a 4-Digit also"

(1)    COM-11409    7-SegmentDisplay    1"Tall(White)            "This is a 4-Digit also"

(1)    COM-11442    7-SegmentSerialDisplay    (Blue)             "This is a 4-Digit also"

There is a number printed on the side of all the 1" Tall LED's. These numbers are listed below.

ATA804.1AW

ATA804.1AG

ATA804.1AB

ATA804.1AB

Also the other 4 LED's (NOT the 1" LED's) are mixed up also because the packager didn't label which one is which. However the only one that is easy to separate out is the Serial Display so I'm good on that one. But the other three has this printed on the side of them.

YS

YS

YS

Thanks for any help you guys have. I'm just confused on how to read these things and what the numbers mean. I have no idea what COM means or what ATA8041 means which appears on all the 1" LED's or what AW, AG and AB mean. I'm guessing the last letter indicates the color. But still, I need some help in how to read and understand these things correctly and how to type them in when I'm searching for the Datasheet.

I believe these two are the same as AB would most likely mean BLUE.


texts: How to make an ideal diode model in LTspice

texts: I would like to make an ideal diode model and have tried to achieve this using different settings in the .model statement, but there is always a voltage drop. I would like to make an ideal diode with no voltage drop even at mV values.


texts:
Before learning the internal semiconductor structure of a transistor, I understood that the value of alpha(Common base current gain) being close to one makes Common Emitter current amplification factor (beta) larger and increases amplification capability.

Now I am studying the internals of transistor currents from Neamen's book on Semiconductor physics. It shows that the emitter current has two major components, one is electrons diffusing from Emitter to Base and the second one is holes diffusing from Base to Emitter(NPN transistor). It says, because the latter contributor does not really contribute to the Collector current, it is not a part of basic transistor action. Hence we would like it to be as small as possible. Making this component small leads to alpha to be close to the value of 1. Hence it is desirable to make the value of alpha close to 1.

Later on from the circuit calculation point of view, it seems clear and makes sense that larger alpha can be helpful in more amplification but it doesn't make sense to me from semiconductor point of view as to what would we really gain by making alpha close to one, equivalent to saying, what would we really gain by making holes diffusion from base to Emitter very small?


texts:
I intend to use these TI CC1101 433 MHz RF modules in one of my project:

Wavelength of 433 MHz will be 69 cm. Half wavelength will be 34.5 cm. Vendor is selling two antenna options with the product. Both are spring coil type. One has length of 25 cm and the other has a length of 30 cm when the coil is straightened out. In one other product, I have seen an antenna which is a straight wire and of length 24 cm.

Q-1) Since all of these antenna are deviating from half wavelength, what's the reason behind making these antenna shorter than half wavelength? What length should give me the best range theoretically?

Q-2) If I want an omni-directional behavior, is it going to matter if I keep the antenna coiled or straight wire? If yes, which type will give better omni-directional performance?

Antenna like this are also available and being used in official launchpads of texas instruments:

Example:

Q-3) How do these compare to coil, wire antenna?


texts: Is the NE555 the IC I need, and if not, what do I replace it with?

texts:
I've noticed that whilst I have a well-known solution using an NE555, that IC doesn't fulfill my needs perfectly. Others have told me that the NE555 is very rarely an appropriate solution to one of the problems it's being used for.

What are the systematic problems with the NE555?

More specifically, I'd like to have a better (lower part count / complexity, better stability, lower power consumption) solution for the following typical applications:

One-off timer (Monostable Multivibrator)
Ramp generator
Dear versed reader: please extend this list with typical applications!


texts: hardware implementation of division algorithm

texts:
I have tried hard but I don't understand how this algorithm is working.Please explain the flow chart.
\$DVF\$ is the divide overflow flip flop.
\$A_s\$ is the sign bit of \$A\$
\$B_s\$ is the sign bit of \$B\$
\$E\$ is the register that has a carry bit
Initially the XOR operation is carried out to check if the sign bits of two numbers is equal.
The dividend is \$A\$ and \$Q\$ and the divisor in \$B\$.
The sign of the result is transferred into \$Q_s\$ to be part of quotient. \$SC\$ is the sequence counter.
I am unable to understand the sequence of operations . What happens after the carry bit is checked for 1 or 0 ?


texts:
I've just found this sensor on Aliexpress, but the vendor says that he provides more information after the device is bought. There is no information on what sensors does this device feature. I can't even find a manufacturer of this device.

Can anybody provide a datasheet or something?


texts: What’s the max instant current draw from a Li-Ion protected pack?

texts:
I’ve been looking for this and couldn’t find the answer so far.

What’s the max current that those Li-Ion video camera protected battery packs, as the Sony NFP-550, NFP-970 can handle? I know for instance that the NFP-F550 has usually 2600mAh capacity and 7.4V, but has an internal protection circuit that handles short circuit, over and under voltages and also overcurrent.

Is there a limit in current they can supply, even if it discharges faster?

Thanks!

Edited for correction of decimal points!


texts:
I am trying to develop a non-contact whole-house power usage monitor.

I have reviewed jasonT's project, which uses AC clamps to measure current usage.

However, from reading this post on how meters measure power, and this post on apparent vs. real power, it seems I need to be able to measure the instantaneous voltage as well as the instantaneous current, in order to calculate an accurate "real" power usage. From the first referenced post:

  Real power is calculated by multiplying the voltage and current at any instant (one pair of samples). Apparent power can be calculated by measuring the amplitudes of the voltage and current over the course of one or more cycles and multiplying the two results together.

(I'm wondering if they got it backward! Real power = requires measurements over multiple cycles, but Apparent power = one instantaneous VA measurement?)

My question is this: how can I measure the instantaneous voltage in a non-contact manner?  I understand that current can be measured inductively with a clamp, which is just a simple transformer which outputs a voltage proportional to the current flowing through the conductor.

If I'm not mistaken, it seems that using a capacitive measurement technique would be correct (like in an electrician's voltage detector probe), but I can't fully wrap my head around what such a circuit would look like.  Would it be just a simple wire placed near the mains conductor, at a fixed distance, with only one end connected to an amplifier (for example, similar to this circuit)? If so, how would such a circuit be tuned to the correct proportional output?

If anyone could point me to any resources or suggestions I would be grateful.


texts: Reverse polarity and reverse current protection for battery charger

texts:
I am using a buck converter with output commanded by a micontroncontroller to charge a lithium ion battery from one to three cells (3.0 to 4.2V, 6.0 to 8.4V or 9.0 to 12.6V)
I would like to protect the out from reverse polarity conection of battery and reverse current.

I could use a simple diode but I want to avoid the voltage drop and  loss of energy, so I am trying a solution with MOSFET.

I think this MOSFET works as protection when battery is connected wrongly with reverse polarity.
But what happens when polarity is correct, but the battery voltage is upper than voltage generated by the buck converter?

For example, just at the beguining when battery is plugged the out of buck converter is zero volts until the battery is correctly identified.

This P-MOSFET would protect for reverse current?

Thanks


texts: connecting solar panels cells with copper adhesive foil

texts: i have purchased some cheap solar panel cells , as am bad it soldering , so i was wondering that Is it good practice to connect solar panels with copper adhesive foil or bad , because with copper adhesive foil its easy to connect solar panels rather using soldering gun and bus wire.


texts: There is ribbon cable which is connected with a locking mechanism as in the picture below. The brown plastic locker is not locking properly, is there a way to get another locker and lock it in place with something else, for example glue?


texts: EN 50121-3-2:2016 radiated immunity frequency range gap

texts:
I was just reading EN 50121-3-2 (Railway Applications – Electromagnetic compatibility – Part 3-2: Rolling stock – Apparatus) and noticed in Table 5 that there is a gap in the test frequency between 2.7 GHz and 5.1 GHz.

In the remarks for the test it states that the tests are intended to simulate disturbances from digital communication devices, which made me think maybe the frequency range is unallocated. But I checked the ACMA spectrum allocation chart, and there are a lot of different uses allocated between 2.7 and 5.1 GHZ, so I don’t think that is the reason.

https://www.acma.gov.au/-/media/Spectrum-Transformation-and-Government/Publication/pdf/spectrum_chart2013-pdf.pdf

The test reference EN61000-4-3 as the basic standard. I checked EN 61000-4-3 (EMC Part 4.3: Testing and measurement techniques – Radiated, radio-frequency, electromagnetic field immunity test) and was unable to find any information that may explain the frequency gap.

Why did they choose to not conduct a radiated immunity test between 2.7 GHz and 5.1 GHz?

Cheers
Phil


texts: How do you determine voltage output with time graphically?

texts:
simulate this circuit – Schematic created using CircuitLab

If the step input is to 2V (0 to 2V at t=0, step function) what will be the plot of output voltage be?

I'm not able to proceed because of the Capacitor in series with the input.


texts:
I'm working on a radio receiver project based on using a Uniden BC125AT, which will be controlled by an external microcontroller.

The original plan was to tap into the BC125AT keypad to issue keypresses etc, an ugly solution, but it works.

But the BC125AT has a USB port for programming and control, and of course this is a USB-serial interface.  When I pulled the BC125AT apart I was hoping to find an FTDI so I could tap into the serial and and use our microcontroller to issue commands.  Unfortunately they're using a Renesas V850ES/JG3-L 32-bit micro with on-chip USB controller:
http://www.farnell.com/datasheets/1581873.pdf

So now I'm left wondering if there's anything I can realistically do to interface with it?  Of course I could use a single board computer... but that's overkill just to achieve comms and I think we'd just go back to hacking the keypad.  I really just want to see if I've missed any options?

Cheers,


texts: 3.3V TTL to other formats and impedance matching

texts:
I am trying to convert a 3.3V 50 Ohm Impedance TTL Pulse-per-second into other formats (GPIB, USB, RS-232, etc.). I've found some format adapters/convertors like the MAX232, but I am either misunderstanding something or missing something.
So I know the TTL line has a 50 Ohm impedance, and from looking at the RS-232 standards, the impedance is 3k-7k (?). I imagine the MAX 232 doesn't convert/impedance match. So, do I have to do my own impedance matching from 50 --> MAX 232 --> Whatever the RS-232 is (any idea how I can find out from the spec since if it is indeed 3k-7k, thats pretty much pure reflection if im not mistaken).


texts: Why we need non-blocking assignments in Verilog?

texts:
I understand the basics of blocking and non-blocking assignments in verilog.
I understand that blocking assignments execute in a sequential manner,whereas it is possible to assign values concurrently using non-blocking statements.

My question is, why was non-blocking assignments included in Verilog. I can think of the following example to give weight to my statement.

Using blocking assignment:

always@(posedge)
   a = b;

always@(posedge)
   c = d;

Using non-blocking assignments:

always@(posedge)
   a <= b;
   c <= d;

So the two pieces of code above carry out the same process (parallel assignment of b to a and d to c, ignoring the race condition in case of blocking assignment). Similarly, if we take the case of swapping two variables in verilog, it is possible to do it with both non-blocking and blocking assignments.

But I am not able to find some example which will showcase that it is not possible to do it with non-blocking assignment and can only be done with blocking assignments.

I hope somebody can throw some light on the same.


texts: Why does a two-port network have two degrees of freedom?

texts:
According to the following lecture https://www.youtube.com/watch?v=1dgdiws3Kl8&t=817s. A two-port network such as the following

can be expressed as the following simultaneous equation
$$a_{1}V_{1} + a_{2}V_{2} + b_{1}I_{1} + b_{2}I_{2} = 0 $$
$$a_{3}V_{1} + a_{4}V_{2} + b_{3}I_{1} + b_{4}I_{2} = 0 $$

However, this implies two degrees of freedom so two independent variables but I struggle to understand why, given when I apply an input voltage it is the only independent factor and all else is dependent on the input voltage?


texts:
I have an EEPROM (AT28C64B) multiplexed and connected to 3 seven segment displays,

I did so using a tutorial online from ben eater https://www.youtube.com/watch?v=dLh1n2dErzE&t=300s

Sorry for the bad quality photo

Here's my setup, from left to right, the ICs I'm using, 555 timer connecting in Astable mode, SN74LS112 Dual JK flip flop, SN74LS139 Demultiplexer and the 7 segment display I'm using is called a SC05-11EWA (I only have two but a third is in the post)

I've had a problem with ghosting on the 7 segment displays and I'm not quite sure how to fix it, I have exhausted google, to no avail so I hope someone can help.

If you need further info feel free to comment.

Thanks, Patrick

(edit)

Here's a schematic I made using EasyEDA, sorry about the cluster it's my second time making a schematic.


texts: Are Wi-Fi 'transparent' buildings superior to antennas mounted on the exterior?

texts:
Looking in particular at wireless mesh networks in cities - is it advantageous to design a building that does not interfere with Wi-Fi (e.g. out of wood instead of steel and concrete), or would placing an antenna on the roof/facade resolve the problem?

I appreciate this is quite open ended, I'm an architect running a design project looking at hertzian space, (the spatial quality of e.m. waves) and without sufficient technical knowledge I'm struggling to progress beyond this question.


texts:
I have an RS422 interface set up between an Arduino and a custom-built device. The device is set to transmit a 16-bit header, followed by 66 bytes of data, at a baudrate of 460,800 and at 200Hz. This cannot be changed.

I have read online that the Arduino serial can handle 460,800 bps without a problem. In fact, I have successfully communicated between MatLab and Arduino at that baudrate without problems. I have also confirmed that the device works, as when it is connected directly to the computer, it is read fine.

When I try to read the data using the Arduino, I don't get what is expected. The header I'm supposed to be getting is 0x55AA. I am, however, getting 0xD56A most of the time, but sometimes I get values like 0xB5CA. It seems the second half of each byte is correct, but not the first, and I have some bits going high and some going low when they shouldn't. Because of this, I question the validity of the data being transmitted.

Can someone explain to me why this is happening, and what solutions I can try to remedy this, please?

Thanks

UPDATE:
I have looked through with an oscilloscope and I can see the waveform coming out as 0x55AA, as it should be. I have increased the Arduino serial buffer, and changed boards, but the problem persists.

I managed to get it working at a lower baudrate (115,200), but I need to have it set at 460,800. At this lower baudrate, I would get 0x55AA, but as sson as I ramp it up to 460,800, I lose this data and it becomes as mentioned above.


texts: How to connect 5X7 LED dot matrix which has 7X7 pin both side.

texts: I have 5X7 led dot matrix. But I am confused, how to connect it. Because it has 7 pin both the side. So, I am not going to differentiate that which is Row and column pin.


texts: Arduino: IR receiver, current draw and resistor

texts:
I was looking for an IR receiver example using an Arduino and I found this site (https://arduino-info.wikispaces.com/IR-RemoteControl) which contains this image of how to wire the IR receiver...

I don't understand why this circuit does not contain a resistor. Surely without a resistor this circuit would cause a large amount of current to flow, potentially damaging components?


texts: What is the RS-485 line wire series resistance limitations?

texts:
Just tried to simulate the communication line with the series resistance in it:

As you can see even at 1 MBPS the signal at the "receiver" is fairly good. I'm pretty sure that this will be OK to receive the signal.

The reason I tried to think about the series resistance is an intention to put the resistors at the reseiver with a parallel TVS (or Zener) diodes to protect the receiver (I will need to have a long transmition line). After I put the zeners the falls and rises become much slower (I beleive that it was due to diodes parasitic capacitance):

I think it would be a bad idea to put TVS without a resistors.

15 pF capacity I took from some RS-485 transceivers datasheet. Actually I was able to find the receiver input capacitance only in the TI's AM26C31ID datasheet (it was 6 pF). Probably there are other devices with this parameter specified but many from MAXIM and Analog Devices was not :(

So it looks that the wire series resistance is not an issue for communication under real circumstances. Are there any other points I am not aware of?

UPDATE:

I made a simulation with lossy transmition line (LTRA) and came to the conclusion that the series resistance is not influence much to the signal (it is 1 MBps, at 200 meters, which is pretty long for this speed):

However this resistance CAN influence the signal in some cases:

if the termination resistor placed AFTER there resistance
if the series resistance become close to the input impedance of the receiver which leads to significant amplitude reduction.


texts:
I'm using DIY pwm-generator based on attiny13 to control servo. Pulse cycle is 37 Hz, pulse width is ~540us - ~2400us. Servo rotates correctly but on stationary positions it's vibrates (gears try to move). It's connected to noise on top of the pulses. Noise has random period.

So, am i doing right that i'm always sending pwm signal to servo? Should i turn off signal after reaching necessary angle? Or it's just wrong pulse width?


texts:
I'm trying to take the first step to establish a connection with an iPhone using the Lightning port. I'm using the Lightning A male connector body, which I believe should set the iPhone to be a USB host. I'm hoping that the iPhone will start to enumerate my USB device, but I'm receiving practically nothing from the phone.

Twice I've seen a short invalid packet of about 16 bits, but that's very rare. What's the first step to take? Do I need some magic pull-up or pull-down somewhere or am I using the wrong connector body? Should I use some other Lightning connector body? I have samples of the four basic types. And yes, I'm an MFi member, hopefully not the only one here.


texts: What do you call a transformer separated from a wall plug?

texts:
I got a hold of (from a friend) a AC->DC 5v 2a power transformer - it connects to the wall with lamp cord/ figure-8 connector, and has a USB plug on the other side.

I can't for the life of me find this (or anything like it) anywhere to purchase.

I don't even know how to search for it.  I've searched by its Samsung model number, Amazon & Ebay for "power adapters", "travel adapters", etc. with no luck.  Everything has the 2 prong wall plug connected to the actual adapter (trying to avoid the wall wart).

Does anyone have suggestions, or know how to find these? Do I need to make one from scratch?


texts:
I would like to calculate the response time of the PMOS cicruit in this ciruit.

But I have some troubles about the gate charging.
I'm trying to use this:
https://www.vishay.com/docs/73217/an608a.pdf

With the IRF6215
https://www.infineon.com/dgdl/irf6215pbf.pdf?fileId=5546d462533600a4015355e44ca219d0

I don't know "which" time should I use in the application note. And how do I do if i don't have Vgp?

Thanks

edit: This question is different from my previous one. Because this new question is focused on how I can applied the application whereas the previous one deals on how to calculate the transient voltage on the load

edit2: Vin1 = 28V and VCMD1 is a pulse in the range of [0;28V]
To be more clear, I'm looking into how to do the calculation, instead of how to understand


texts: Two input nand gates and inverters to sum three products

texts: I am trying to draw the logic gate of the following function using only two input nand gates and inverters A'C'D+AC'D'+AB'. So far I am stuck on trying create the AC'D' part. What I have drawn below would give me the some I think and not the product I am looking for.


texts: i have 2 servos 7.2 volts,the rated current is 0.35 ampere and 3.5 ampere stall.i want to convert it to be continuous,so i will remove the potentiometer and put two resistors equal in value instead of it, the question is ,what is the value of the suitable resistors to put


texts: How to create a linear current response from a passive pot circuit?

texts:
I am wanting to linearise the current response of a circuit which currently has the resistance change from a linear pot.

I have a current input that I want to test using a test jig/simulator.
The limits of the current inputs are 4mA and 20mA. I want to be able to drive the current above and below these limits to ensure appropriate warnings are being triggered. The voltage output is supplied from the control as well as the return reference.

The existing test jig is shown below. A linear 10K pot was used with a 470ohm resistor too.

simulate this circuit – Schematic created using CircuitLab

The current response of this circuit is in orange, while the ideal linear is in blue (point 1 is 0% twist while point 21 is 100% twisted):

This obviously does not have a linear current response to the twisting of the pot knob, only utilising around half/third of the pots range in the desired current range.
I have attempted a few different layouts to try and linearise the response slightly, but none were significantly better than simply choosing a 4k pot and 750ohm (E24) resistor.

Was there a resistor layout to linearise this response so it was closer to the ideal?


texts: What do "S" and "F" markings on this transformer mean?

texts:
I previously wrote this post on identifying a transformer with P241-5-36 inscribed on the top.  I now understand which coil is primary and which is secondary.  Looking at the datasheet for this transformer, the schematic indicates "S" and "F" on the primary coil.

Question: What is the relationship between "S" and "F" and hot/neutral of the house mains?  Should I connect "S" to Hot and "F" to Neutral?


texts:
My EE skills are pretty limited, but gradually improving. I am trying to increase the current capability of an analog output device by introducing the signal to an op-amp (LF 356N) circuit. My current configuration is as shown in the image -- however, I am seeing a steadily decreasing negative voltage on the output side.

For example, I activate my 12V and 24V power supplies, and the output signal will start around -1V and in the span of nearly a minute, it will decrease and plateau around -9.5 V.

Can someone please suggest what I may be doing wrong?


texts: I have a raspberry 3 which can transmit 150mW max. I would like to connect it to my oscilloscope. Is it necessary to use RF sampler?


texts:
Here is shown the design of simple multi-staged amplifier.

simulate this circuit – Schematic created using CircuitLab

I tried to put together all three NPN transistor configurations and this is what I got - just redrawn schematic of each individual configuration connected together.

First I was hoping for optimal power transition between stages and that was meant to be achieved by proper impedance matching between the output and input of each individual stage. Then I tried to achieve desired voltage gain of each stage (with formulas shown later). When I was calculating voltage gain of each stage individually I did consider the ohmic resistance of next stage that was "loading" the first stage (or the stage for which voltage gain was to be calculated).

I set the amplitude of function generator on the value of only 10mVpp, so the output voltage wouldn't be clipped at the first place. The power supply DC voltage was high enough too, so the clipping could be avoided. Maybe you will be wondering why are values of last stage voltage divider so low (which is not usual for a voltage divider) - as I have said, certain input/output impedance formulas needed to be matched for optimal power transition + 14.4V drop across R1''' and 15.6V drop across R2''' (which is also not usual for voltage divider).

Circuit was observed by oscilloscope (analog) and the resulting amplitude of loaded amplifier was a disaster - output was greatly distorted; not clipped but distorted in many different ways. So my question is: Where did I went wrong on this one?

I should also note that calculated loaded voltage gain calculus of each individual stage had very unrealistic values - voltage gain of whole circuit was somewhere about 80k...

This was also my first multi-staged amplifier ever made, so I must admit I was very disappointed upon the results.

Here are listed formulas used in this "amplifier" design process:


texts: What should I use from given options to power a raspberry pi?

texts:
I have a system which consists of 2 12V DC motors(0.65 A on max load) and 1 RPi 2 model B. I want this system to be plug free. I have Li-Ion batteries to power up motors. I use a L298N module to drive motors. This module also can give a 5V output. Here is where the problem appears.

If I use this output for my RPi, RPi shows lightning symbol time to time and shuts itself down if I open things like chromium on it.

I have these options.

I can use this cable to increase cable quality, since I am using a random cable atm. But I don't know if it will really help.
Use a step down module to directly feed RPi from Li-Ion batteries.
Using a powerbank to directly feed RPi.

Which options is better?

(Batteries - 5x Li-Ion 3.7-4.2 V - 2100 mAh each. I use 3x atm)


texts: How can we use a usb(in a laptop) for general purpose input/output operations, such as robotics control

texts:
How can we use a usb port (in a laptop) for general purpose input/output operations, such as robotics control??

I want to control an external hardware such as a robot or say simply an array of LEDs using my laptop's USB port. Is there a way to do so. If not can we use some other ports like Serial port or RS-232 cable?


texts: Dynamically setting address of HT12E with Raspberry Pi

texts:
I have a project where I need to send a wireless signal to one of several receivers to turn on an LED.

One transmitter, several (many) receivers, each with an LED.
The receivers need to have low power consumption.

Transmitter side:

Raspberry pi
HT12E encoder
433 mhz transmitter

Receiver side:

433 mhz receiver
HT12D decoder

Each individual receiver would have a unique, fixed address.

I was hoping I could use the raspberry pi to dynamically set the address of the encoder to match the relevant receiver, but I cannot figure out if this is possible. The address of the HT12 is adjusted by connecting Ax pins to ground. Can I do this with

Is there a better alternative to this? Can I use the Raspberry to simulate the signal from the encoder?
The system must be possible because it is similar to restaurant pagers

This is how I am envisioning it now. Is my understanding correct? Does the address on the transmitter side match with the address on the receiver side?


texts: How to measure the coil voltage in this circuit?

texts:
I want to measure the coil voltage (coil+ to coil-) of the following circuit with my microcontroller, but I don't know how. Do you have some hints or suggestions for me?

Thanks!


texts: I am trying to simulate the Buck Converter LM22676 from TI for a 5V output. But LTSpice shows an error saying that the time step is too small when I try to run a transient analysis. Can someone please help me understand what I am doing wrong?


texts: Isolation Amplifier? Reading differential voltage on 600 V lines

texts:
I need to measure the voltage across the leads of a thermocouple, the thermocouple being physically connected to a 600 Vdc terminal.

The instrument which measures the thermal couple (thermometer) will not withstand a 600 Vdc input.

How can I read the differential voltage across the leads of the thermocouple? I am considering an isolation amplifier, but the problem I have at the moment is I do not know how to power the high voltage side as most are limited to ~20 Vdc.


texts: What happens when the direction of initial current through an inductor is opposite of the direction of applied current?

texts: I am having trouble understanding the behavior of current through an inductor when the direction of applied current is the opposite of what is initially flowing through it. An example is that when an inductor is initially connected to a current source that drives the current clockwise, and then at time t=0, the switch flips such that it is now connected to a current source that drives the current counter-clockwise. I know that the current cannot instantaneously switch directions and I think this is where my confusion stems.


texts:
I'm building a device that drives a motor shaft with the possibility of injury or discomfort if the motor receives too much current. The motor will be driven at 48V with max current around 5.2A. It seems like most fuses have a broad range in which they trip or a somewhat lengthy response time, which I think makes them a poor choice for this project.

I'm not looking to clamp the current, just to cap it at a value deemed unsafe. Is there any way to do this without substantial voltage drop? Is there any such circuit that is reliable enough to not allow the current through above a certain value?

The circuit would not act as the sole safety stop, but it would be an important element. Can someone point me in the right direction?

Thanks in advance.


texts:
I have designed a board that uses the ATSAMA5D225C-D1M (Cortex A5).  I have mostly copied the schematic from the ATSAMA5D27-SOM1.

I am using a J-LINK PRO adapter.

I am using the atmel software framework and GCC to test my new board.

I can single step the debugger until I get to pmc_switch_mck_to_slck()

void pmc_switch_mck_to_slck(void)
{
    /* Select Slow Clock as input clock for PCK and MCK */
    PMC->PMC_MCKR = (PMC->PMC_MCKR & ~PMC_MCKR_CSS_Msk) | PMC_MCKR_CSS_SLOW_CLK;
    while (!(PMC->PMC_SR & PMC_SR_MCKRDY));

    _pmc_mck = 0;
}

after which the debugger tells me

pmc_switch_mck_to_slck () at ../../drivers/peripherals/pmc.c:973
973             PMC->PMC_MCKR = (PMC->PMC_MCKR & ~PMC_MCKR_CSS_Msk) | PMC_MCKR_CSS_SLOW_CLK;
(gdb)
0xdeadbeee in ?? ()
(gdb) s
Cannot find bounds of current function

So what is the meaning of all registers returning 0xdeadbeee or 0xdeadbeef?  Am I missing some trap definition?

What types of causes should I look for on the clock switching issue?  Debugger setting or hardware issue?


texts: Is there a pulse shaping after OFDM modulation in NB-IoT?

texts:
Just as the title says. I have searched for a whole day and haven't found any confidential materials to verify whether there is a pulse shaping after OFDM modulation in NB-IoT?

For example, in https://www.nxp.com/docs/en/white-paper/3GPPEVOLUTIONWP.pdf
in page 15, it mentioned that there is a procedure named, Cyclic prefix and pulse shaping. And the purpose is desripted as "pulse shaping is employed to prevent spectral regrowth.", However, which kind of pulse shaping is unclear.

Besides, I have browsed the referred materials listed in the end of the paper,
for most likely references:

3GPP TS 36.201 – v1.0.0, LTE Physical Layer – General Description,
http://www.3gpp.org/ftp/Specs/archive/36%5Fseries/36.201/
3GPP TS 36.211 – v1.0.0, Physical Channels and Modulation,
http://www.3gpp.org/ftp/Specs/archive/36%5Fseries/36.211/
3GPP TS 36.212 – Multiplexing and Channel Coding,
http://www.3gpp.org/ftp/Specs/archive/36%5Fseries/36.212/
3GPP TS 36.213 – v1.0.0, Physical Layer Procedures,
http://www.3gpp.org/ftp/Specs/archive/36%5Fseries/36.213/

However, there is still no description about the kind of pulse shaping after OFDM modulation.
In other words, if I want to send out the NB-IoT signal (which is much similar with LTE) after OFDM modulated, how can I implement it before DAC?
Any help would be appreciated!


texts: I have no UART on my microcontroller so how can I add one?

texts: I am using a ATMEGA32HVB microcontroller which has a facility for cell balancing by which we can connnect 4 batteries in series and use one at a time. That is  very useful for power management so I can't use a different microcontroller. Please suggest some methods to add a UART to it so I can easily interface to serial devices.


texts: Why do more phase shifts cause the need for higher bandwidth when Frequency Shift Keying (FSK) is used?

texts: What I don't get is why a phase shift "decreases" the data rate and thus the need for more bandwidth to get the same throughput as without the phase shift.


texts: Frequency response of amplifier intuition understanding

texts:
I am facing problem in basic understanding of frequency response of amplifier.
According to this here(my textbook):

"Each capacitor has a region of activity in the frequency domain, which starts from “where it comes out of the open circuit state” to “where it enters the short circuit state.” It is obvious that the open circuit and short circuit concepts discussed here are relative and are determined in a compar- ison with the adjacent impedances."

and it also says:

"Each capacitor, including both the internal and the external ones, contrib- utes to the amplifier’s transfer function by introducing a zero and a pole. At low frequencies, each capacitor’s region of activity starts with a zero and ends with a pole."

and for high frequency:

"The frequency at which an internal capacitor comes out of the open-circuit state is indeed its pole, and its zero is where it enters the short circuit state."

What I dont understand is how does the author says that say for high frequency the open circuit state is a pole and not a zero??
How does he intuitively says that??

If I try to think I see the A(s) function and see that at poles A(s) becomes infinite and at at zeros A(s) becomes zero, How do you associate the open circuit and short circuit thing with either a pole and zero??
Also he defines the transfer function as(please see image below)

I dont get it, Isn't pole and zero -pi and -zi and not +pi and +zi. It's the same case for most of the books(they also define it that way)?? Am i missing something here??

I am posting image of my textbook page here:


texts: Can I edit an incremental resistance of zener diode in PSPICE?

texts:
It seems like breakdown voltage and current of zener diode model in PSPICE can be edited like the screenshot I've uploaded(BV, IBV).
But I want to change the incremental resistance of diode(Rz).
Is that possible on the PSPICE?


texts: "Phantom" touches on appliance's capacitive buttons. A serious problem?

texts:
We have two electronic devices that operate well by themselves.

Device 1 has touch (I assume capacitive) buttons.

If device 1 and 2 are turned on they are fine. But if device 2's motor is engaged, device 1 will start registering touches on its buttons.

We would like to know if this is a harmless problem, or if it indicates a more serious issue with either device, or with our electrical wiring.

Devices:

Pressure cooker

Exercise machine

I should mention that we had another odd problem in the past whereby our washing machine's metal drum would become energized if its plug was inserted upside-down, flipping the poles of the plug (with an accidentally flipped plug adapter).


texts:
A smart device board shown various issues and stopped to power on. I have opened it to determine the cause of the problem and I have seen it has multiple corrosion signs.

The board wasn't exposed to water or humidity by myself, and it is an item produced around a year ago, I'm surprised to see it in such conditions, probably these damages have been caused by some problem in the production or distribution chain.

In what way I could recover it from corrosion damages?


texts: printer for mass-production of pcb masks

texts:
I'm trying to find the best way to make a solid photo mask so that I can finally make some excellent PCB's without spending hundreds of dollars.

When I bought a lazer printer, the first few prints (for PCB masks) were perfect. After several prints, the quality starts to slowly degrade to the point where some tracks appear cut. I used translucent paper (105 gsm) because I was told the toner adheres to it better in comparison to transparencies.

Here's the killer. If I go to an office store and have them print my PCB on a transparency, it comes out perfectly twice in a row with some spots with lighter toner application but at least all spots are filled in.

I have used the darkest settings on my printer and I print at 1200 dpi and currently I use translucent paper when trying to print PCB masks at home.

What would be the best course of action for a quick mass-production of different PCB's when printers designed for home-use start to degrade after the first set of prints?

Am I better just to rely on the office store to print? They charge about $1 a page, but I'm unable to get to the store some days as it closes early, so this is the long method.

Or should I ditch all my printers and buy one specifically for PCB artwork (which I currently don't know who makes it)

Or should I buy toner and pray the artwork will print correctly? (When I tried replacing toner in my old printer, the results did not improve, plus I replaced the drum unit).

Any suggestions would help. and hopefully I won't have to resort to depending on the office store for quality prints.


texts: Energy Transformation in Flyback Transformers

texts: I am trying to understand how is energy transferred as a current to secondary of flyback transformer. First due to the dot convention and secondary side diode, current will not flow in secondary and energy is going to be stored in the core. But after opening the switch, how polarity changes? I mean the current in the primary wont change suddenly and will try to flow in the same direction, as well as the flux in the core. The created flux is going to force secondary current to flow in the same direction as it was closed. What causes the change in the secondary polarity? Can someone explain it?


texts: GSM ZTE MG2639 module freezes after checking SIM

texts:
I'm communicating with my ZTE MG2639 module through UART.
Few seconds after powering it and getting +CPIN and +STKPCI it just turns off (goes to stand by mode)

It only happens with SIM card, and after sending PIN.

What's wrong? I have tried on few different SIM cards and antennas.


texts: What is this capacitor in this TSOP/voltage comparator circuit for?

texts:
In this schematic, we see a 10μF cap (C1).
What is its purpose, wired like that?

Source: https://www.electroschematics.com/9023/infrared-beam-break-detector/

I duplicated this schematic with two TSOP1236 devices, connected to a LM393.

The TSOP1236 datasheet tells me that, in its typical application, I need a cap between pin 1 GND and pin 2 VS. However, here the cap is inserted between pin 1 GND and pin 3 OUT.

So I thought it must be for protecting the LM311. And since I use a LM393, I now have one cap on each side. However, I would think one cap would be sufficient as connected between LM393 pin 4 GND and pin 8 VCC.

Can someone help me understand?

Would it be better to remove the two caps, one on each side of my LM393, and

put one 10μF between LM393 pins 4 and 8, and
put a 4.7μF between TSOP1236 pins 1 and 2?

EDIT: The TSOP1236 tries to detect a 36kHz signal and is connected to an Arduino, via the LM393 voltage comparator. The attachInterrupt() is triggering unexpectedly and I think using caps correctly across my receiver set-up could solve that.


texts: How to convert dBm to V/m, A/m^2 and W/m^2

texts:
Currently I am using a spectrum analyser(SA), Keysight N9020, with an antenna to get readings off the air.
The reading on the SA gives a reading of a unit, dBm.
However, I need to convert dBm to V/m, A/m^2 and W/m^2.
What are the formulae?


texts: Do the existing/defined DALI protocol commands include color temp adjustment?

texts:
I want to know if the officially defined DALI commands entail anything related to adjusting color temperature.

I understand that it specified quite a few commands in adjusting brightness, but I failed to find anything linked to color temp.

Am I correct in assuming it is entirely manufacture-specific?

I've spent quite a lot of time searching, but I can only land search hits with product pamphlets, and nothing remotely related to DALI packets sent and received over the DALI network.

Can someone give me a confirmation? Thanks in advance.


texts: What happens if we connect a led to a monopole antenna?(on a transmitting antenna)

texts:
To my understanding, electrons flows towards a lower potential
so if current(oscillating) flows through a monopole antenna does it mean we can connect a led anywhere on the antenna and get it to blink ?

my question is about a transmitting monopole antenna, since i find it difficult to understand how current can flow when nothing is connected at the end of the antenna.


texts: How does avrdude with AVR-ISP-MKII respond when no target board is connected?

texts:
How does avrdude with AVR-ISP-MK2 respond when no target board is connected?

I'm trying to troubleshoot my set-up, and would like to know if the problem lies between the laptop and programmer or between the programmer and target board.

For me, this avrdude command gives the same result regardless of whether the target board is connected or not. It doesn't matter if the file exists or not.

# avrdude -c avrispmkII -p m328 -U flash:w:flashled.hex
avrdude: usbdev_open(): Found AVRISP mkII, serno: 000200012345
avrdude: Sent: . [01]
avrdude: usbdev_recv_frame(): usb_bulk_read(): Input/output error
avrdude: stk500v2_recv_mk2: error in USB receive
avrdude: Sent: . [01]
avrdude: usbdev_recv_frame(): usb_bulk_read(): Input/output error
avrdude: stk500v2_recv_mk2: error in USB receive
avrdude: Sent: . [01]
avrdude: usbdev_recv_frame(): usb_bulk_read(): Input/output error
avrdude: stk500v2_recv_mk2: error in USB receive


texts: Example circuit with an F12C20C dual rectifier?

texts:
I've salvaged a MOSPEC F12C20C Dual Power Rectifier from an old PSU. I've been looking for example circuits that would use this component, and an explanation of how it works but I've only found its datasheet and not much more.

If I understand correctly, its function is to rectify an AC current to make it DC, is that correct? How is this different from the typical diode bridge? (power dissipation capabilities maybe?)

According to the datasheet, this component is the equivalent of two diodes package together, is that so? If that's the case, how is it that it can achieve rectification with only two diodes and not the usual four?

Do you know of any example circuits I could build on a breadboard to test this component and play with it so I can better understand how it works?

Bonus: mine has the letters MNB next to the diodes schematic it has on it. Is it part of the name or is it just a serial number or something?

Thanks!


texts:
I'm getting very confused about drain source voltages and drain current in a simple common-source amplifier.

Consider the following common-source amplifier:

My understanding is that:

The output voltage is Vout = Vdd - Rd*Id.
If the input voltage increases by a small-signal step, then M1 will have a higher gate-source voltage, thus will increase the drain current and according the Vout equation above, the output voltage will decrease. The output voltage is the drain of M1, and so we can also say that the drain of M1 decreases.

All good so far. Here comes my confusion. If I think back to the Id/Vds plot as shown below:

Notice that in the saturation region, as drain-source voltage increasees, the drain current increases slightly too, due to channel-length modulation. In our common-source amplifier, the drain current increased, yet the drain-source voltage (output voltage) decreased. According to this plot, how is that possible?

I would appreciate it if someone could provide a simple explanation. Where is the flaw in my understanding?


texts: Determine the values and power rating of the resistors to bias the transistor

texts:
I'm in an assembly language programming course and our professor casually dropped a homework assignment in electrical engineering topics. (I'm a software engineering student, so I've not had any training on this.)

I'm given this problem:

Determine the values and power ratings of the resistors R_b and R_c to bias the transistor. The LED requires 100 mA of current and has a voltage drop of 0.7V. The 2N2222 transistor has a maximum current of 1 amp (I_CE less than or equal to 1 A), a Beta of 100, and can burn 1W of power. The output pin of the microcontroller provides 3.3V and up to 20 mA maximum. The power rating is the amount of power that the device needs to be able to dissipate.

I have the following schematic:

I know I need to use Ohm's law and the equation for power, but I'm not sure how to go about solving the problem. How do I tackle this?

I think I can get as far as saying that the diode's 0.7 V in the transistor subtracts from the 3.3 V in the pin to give 2.6 V, and I think I could calculate the current in the wire connected to the pin as a result, but I'm not sure how to proceed.


texts: What are the prerequisites to make a PCB design with processor and other ICs interfaced?

texts: What all is needed (in knowledge and software) to make a small pcb design interfacing processor and external memory and other ICs? Is it possible to make such a thing virtually and give it to a manufacturing company for making it? Are there any open source customizable hardware models which can help?


texts: Raspberry Pi Relay only working tapping it

texts:
I have connected a 2 channel 12 v relay like this to the GPIO of my Raspberry pi. The relay is used to switch on and off an AC lightbulb.

I am using this code to turn on/off the relay:

import RPi.GPIO as io
import time

io.setmode(io.BOARD)
io.setup(5,io.OUT)

io.output(5, not io.input(5))

Connected like this:

simulate this circuit – Schematic created using CircuitLab

The light instantly turns off when it is already on, but not the other way.

The problem:
I have to tap the relay in order for the light to turn on after running the code. The amount of time after running the code does not matter.