texts:
I'm trying to communicate with rc522 chip with the use of this code, I only modified the SPI calls to use the HAL libraries and initialized SPI with HAL libraries. Kept all other functions intact. Now the image below is what I captured with my logic analyzer and I really just have no idea what am I doing wrong. To my newb eye, my SPI communication looks okay. The chip however, is not really returning anything and I am getting 0xFF everytime (I also captured that with my logic analyzer while rc522 was connected to my STM32F7Discovery).

Does anyone have any idea why my chip would not be responding at all?

I am initializing my SPI with:

    /* SPI SCK GPIO pin configuration  */
GPIO_InitStruct.Pin       = SPIx_SCK_PIN;
GPIO_InitStruct.Mode      = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull      = GPIO_PULLUP;
GPIO_InitStruct.Speed     = GPIO_SPEED_HIGH;
GPIO_InitStruct.Alternate = SPIx_SCK_AF;
HAL_GPIO_Init(SPIx_SCK_GPIO_PORT, &GPIO_InitStruct);

/* SPI MISO GPIO pin configuration; MISO line should be floating */
GPIO_InitStruct.Pull      = GPIO_NOPULL;
GPIO_InitStruct.Pin = SPIx_MISO_PIN;
GPIO_InitStruct.Alternate = SPIx_MISO_AF;
HAL_GPIO_Init(SPIx_MISO_GPIO_PORT, &GPIO_InitStruct);

/* SPI MOSI GPIO pin configuration  */
GPIO_InitStruct.Pull      = GPIO_PULLUP;
GPIO_InitStruct.Pin = SPIx_MOSI_PIN;
GPIO_InitStruct.Alternate = SPIx_MOSI_AF;
HAL_GPIO_Init(SPIx_MOSI_GPIO_PORT, &GPIO_InitStruct);

/* SPI CS GPIO pin configuration  */
GPIO_InitStruct1.Pin = SPIx_CS_PIN;
GPIO_InitStruct1.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct1.Speed = GPIO_SPEED_HIGH;
GPIO_InitStruct1.Pull = GPIO_PULLUP;
HAL_GPIO_Init(SPIx_CS_GPIO_PORT, &GPIO_InitStruct1);

SPIx_CLK_ENABLE();

SpiHandle.Instance               = SPIx;
SpiHandle.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32;
SpiHandle.Init.Direction         = SPI_DIRECTION_2LINES;
SpiHandle.Init.CLKPhase          = SPI_PHASE_1EDGE;
SpiHandle.Init.CLKPolarity       = SPI_POLARITY_HIGH;
SpiHandle.Init.DataSize          = SPI_DATASIZE_8BIT;
SpiHandle.Init.FirstBit          = SPI_FIRSTBIT_MSB;
SpiHandle.Init.TIMode            = SPI_TIMODE_DISABLE;
SpiHandle.Init.CRCCalculation    = SPI_CRCCALCULATION_DISABLE;
SpiHandle.Init.NSS               = SPI_NSS_SOFT;
SpiHandle.Init.Mode              = SPI_MODE_MASTER;

I am connecting the reset pin of my board directly to RFID-RC522 reset pin.

I also tried the chip with miguel balboa's library for arduino and it works just fine there.

After I push the reset pushbutton on my board, the first two values aren't even decoded by the analyzer's software. If I look at what the library is supposed to be sending out for reset is 0x01<<1, so 0x02 as the reg_command address, then 0x0f as pcd reset command. Why would it differ?

Here's an image how the communication looks like right after a reset:

As you can see my chip select goes low during reset and it's still low when the communication starts, even though I put a pullup on it.

Also this paragraph from the datasheet makes me think I might have gotten my SPI CPOL/CPHA values wrong, since it seems that the data is stable during the falling clock edge (I thought that's what SPI_PHASE_1EDGE setting was doing):

  Data bytes on both MOSI and MISO lines are sent with the MSB first.
  Data on both MOSI and MISO lines must be stable on the rising edge of
  the clock and can be changed on the falling edge. Data is provided by
  the MFRC522 on the falling clock edge and is stable during the rising
  clock edge.

Also from this paragraph, which is the only one describing these values, I cannot decipher what the base value of the clock should be. High or low?


texts: Is there a standard In Circuit programming connector for LPC chips?

texts: The various LPC microcontroller chips have a boot mode that accepts serial communication and writes the received program to Flash. I want to make a PCB with and LPC1114 that must be programmed in circuit, with only minimal interface circuitry on the PCB. Is there a standard connector for supplying the required signals (GND, RxD, TxD, Reset, BootModeEnable)?


texts: What are the advantages of this gold finger shape?

texts:
Some PCBs, like the PCI card specification have gold fingers which start very narrow near the bottom edge, and gain their usual width much higher, where the actual contact is expected to be made.
What is the advantage of having the narrow part?

Why not make the pad fully wide all the way to bottom, like ISA cards, DDR, etc.? Or simply make the finger shorter, only in the area of contact? What is better in gradually increasing the width?
My speculation:

To connect ground pins first - All the pins have this shape.
Resistance against peeling the pad off - The smaller trace seems much more susceptible to damage
Insertion force - I expect the narrow part to be made of equally thick gold, which would require the same amount of force.
Insertion force - Can it be that some number of the connector contacts (in motherboard) get pushed sideways in each stage as the card goes in, lessening the amount of force needed to insert the board?

Can't seem to find any evidence or description why this is designed this way. Some high frequency high pin count stuff (DDR modules) use rectangular pads.
Note: See page 196 of the linked PCI card specification document.


texts: Measuring voltage across series capacitors... Impossible?

texts:
OK so this might seem like a dumb question, but I have been toying with it for hours.

Suppose you have this circuit...

simulate this circuit – Schematic created using CircuitLab

OK, hopefully we all know how to calculate that, given enough time:

\$V_{c2} = V_{BAT1}/2\$

So I want to measure that to check? How do I do that?

Before you snap-answer the question, remember that any current drawn from the join between \$C_1\$ and \$C_2\$ during that measurement will unbalance the charges on \$C_1\$ and \$C_2\$. When you remove the meter, or circuit, that unbalance will be locked in changing the voltages across \$C_1\$ and \$C_2\$.

Granted, given enough time, leakage current should settle things back to their balanced charge state. But let's assume leakage is very slow compared to your desired measure rate.

The question is, is it possible to repeatedly measure the voltage \$V_{c2}\$ with any real device or circuit? Or is this just one of those weird physics curiosities that has no solution.

EDIT: I realize BIG IMPEDANCES help, and are probable fine for scope/meter measurement, but this is a thought experiment.

EDIT2: I also realize there are electrostatic measuring devices, but I'm more looking for something you can build into a circuit board and monitor it with something.


texts: Why are relatively simpler devices such as microcontrollers so much slower than CPUs?

texts:
Given the same number of pipeline stages and the same manufacturing node (say, 65 nm) and the same voltage, simple devices should run faster than more complicated ones. Also, merging multiple pipeline stages into one should not slow down by a factor grater than the number of stages.

Now take a five-year-old CPU, running 14 pipeline stages at 2.8 GHz. Suppose one merges the stages; that would slow down to below 200 MHz. Now increase voltage and reduce number of bits per word; that would actually speed things up.

That's why I don't understand why many currently manufactured microcontrollers, such as AVL, run at abysmal speed (such as 20 MHz at 5 V), even though far more complicated CPUs manufactured years ago were capable of running 150x faster, or 10x faster if you roll all pipeline stages into one, at 1.2 V-ish. According to the most coarse back-of-the-envelope calculations, microcontrollers—even if manufactured using borderline obsolete technology—should run at least 10x faster at one quarter of the voltage they are supplied with.

Thus the question: What are the reasons for slow microcontroller clock rates?


texts: Is it possible to calculate how much heat dissipation and temperature rise will take place in a resistor

texts:
Suppose I have a 100 mAh battery at 20V. I connect a 1000 kohm resistor across it. How much heat will be generated and how can I find the temperature rise in the resistor? As the battery operates I think that the current flow will reduce over time but am not sure about the voltage for a real battery. Perhaps I am not giving sufficient information here, I am sorry for that.

I just wish to know, what information is needed to make such calculation? Have you ever done it? In the ideal case (taking only the most significant factors into consideration) what factors are considered to make an estimate of the heat dissipation and temperature rise and why would the real heat dissipation and temperature in the actual practical experiment be different?

I know this question looks hard, but I will be very happy if I can finally have this mystery resolved.


texts: Defining contrast ratio and dimming ratio in a LED driver

texts:
I read in this article which analyze the contrast ratio achievable with switched mode LED driver system, that is defined as \$ \frac{1}{t_{on}} : 1 \$.

Intuitively I can get that the minimum time which the driver can be turned properly on, is considered the smaller amount of current that can be delivered. Like a lower bound which defines my SNR, somehow.

My problem here is how to arrive to the fraction \$ \frac{1}{t_{on}} \$. Is it defined as the ratio between the maximum duty cycle (DC) and the minimum? If \$ D_{max} = \frac{(T - t_{sd})}{T} \$ and \$ D_{min} = \frac{(t_d + t_{su})}{T} \$, seems that the Contrast Ration (CR) is defined as \$ \frac{(D_{max} / D_{min})}{D_{max}} = \frac{1}{t_{on}} \$, because \$ \frac{1}{t_{on}} \$ is defined as the minimum DC.

Now I have 2 issues:

is this definition true? The \$ \frac{(D_{max} / D_{min})}{D_{max}} = \frac{1}{t_{on}} \$ comes from my thinking, since I was trying to arrive to such conclusion, because is not intuitive the ratio \$ \frac{1}{t_{on}} \$ without considering the ratio of some full scale, because is a relative unit, so related or divided by something. My thinking is that is supposed to be the duty cycle ratio  related to the maximum duty cycle, but I'm not sure about it.
Is the DC ratio \$ \frac{D_{max}}{D_{min}} \$ the so called Dimming Ratio? Is so, why is not sufficient to use this for measuring the contrast ratio?

EDIT Trying to clear more the issue. The article explains around this image the CR and the various PWM parameters

And defines the CR as \$ \frac{1}{D_{min}\cdot T} : 1 \$, where basically to me seems the minimum DC achievable and make sense because the CR is something that is able to tell how low is possible to go. But looking for CR definition, seems to be a ratio, hence the ":1" term and hence is how low is possible to go compared to, IMHO, some maximum. That is why I put the \$ D_{max} \$ in the question. So, to me the CR is here bad defined or either is derived in a way that I don't get, which seems more probable to me.

From a comment, seems that the question #1 is wrong, so I don't know how to get the ratio, that will be then scaled down to get the "1" on the right side of the comma (CR defines as => left_term : right_term).


texts:
I have a current transformer with following specification:
- LV Current Transformer
- Type : RLC-50
- PT : 1
- Ratio : 400/5 A
- Class : 1.

I want to know the meaning of PT and RLC-50?


texts: Reverse Engineering: TTL/LVTTL signal direction

texts:
I just ordered my first scope (a Rigol DS1054Z) and have been thinking about some interesting experiments/learning projects to perform with it. Thus far most of my experience has been in building circuits/MCU + FPGA programming.

One thing I'd like to try to play around with is signal reverse engineering on a bus between two unknown MCU's. While tapping the signal either with a scope, or with a logic analyzer which I also have is fairly straight forward, the question occurred to me, how might one determine signal 'direction'-- I.e. Assuming it is communication between two MCU's, not just out to a passive peripheral, for any given signal, how might one determine, at any given point in time which chip is actually the one 'doing the talking' ?

My first thought in this regard was to design a simple off board circuit that I could use to tap into the bus that would have scope touch points and two LED's in an opposing parallel configuration with the minimum required resistance to operate them. While of course this may not preserve the complete signal integrity for the duration, at least I might be able to obtain a matching 'time/direction' map on the scope I could use to compare with an unfettered bus signal.

However, reading around a little bit I've seen suggestions that imply in this case 'current flow', is not always equivalent to direction, and so this approach might not work.

Even still, it seems to me that the signal must have some temporal propagation delay, implying direction, however small.

My question then is what might be the most reasonable/logical approach to address such an exploration ?


texts:
I'm trying to design PCB traces for a 27512 EPROM chip. But its pinout for the higher half of the address bus seems completely illogical to me and I cannot imagine how should I lay out my traces for it. Here's how the pinout looks like:

Other components have the data and address bus pins in order, so I need (and I would prefer) to keep it that way.

27512 has it in order, too, but only for the lower half of the address bus (A0..A7) and data bus (D0..D7); although the data bus goes around the bottom of the chip and around the ground pin (so I would need to trace it in some other direction or use a jumper wire to jump over my data bus).

But the upper half of the address bus jumps all around the chip and doesn't seem to follow any particular order: first it goes down (A8,A9), then it goes up starting from a completely different pin (A10,A11), and then jumps to the other side of the chip, then it jumps back to move up again, and then jumps to the other corner :-/

This is really weird to me, and I don't know how to make it in order again (especially to keep up with the order of the lower half of the address bus).

So my question is:

Is there any clever logic behind all this jumping around? I cannot imagine that the designers of the chip just put the pinout randomly (especially when they kept the order of two other buses well enough). I'm more likely to believe that they had some particular sophisticated PCB layout in mind when designing it. But I also cannot see the logic behind it.

I also took a look at other EPROM and SRAM chips and they all seem to have this very same pinout design, so I guess there was some rationale to keep it that way. But the PCB layout for this particular layout isn't very obvious to me. Is there any standard way to lay out the traces for these memory chips I should know of? Because without it, I would have to make a lot of jumpers on my PCB (one-sided) to restore the correct ordering of the bus lines.


texts: Very low network impedance close to 13th harmonic frequency

texts:
I carried out a frequency scan of an electrical network model with a proposed 220kV transmission line. Addition of this line lowered the system impedance to very low value (to 3 Ohms) at 13th harmonic frequency (or 650Hz). Impedance was seen from the 220kV bus where new line proposed to connect.
What kind of impact will be on the electrical network with such low impedance if 13th harmonics presence?
Will it be act as a 13th harmonic filter? If so, where will this 13th harmonic current be flown?


texts: Audio Signal Switching - "DPDT switch vs. 4066"

texts:
I've got a signal coming from an electric guitar and I need to switch it. Basically it's a distortion circuit. I need to switch between the distortion and clean (directly connected to the output)

My first approach was to use a DPDT switch but I have none at home, they are a bit expensive at my local shop and I haven't got a lot of money for the moment (around 8€/10$ for the cheapest one).

Then I took a look at what I have in stock and I found a cheap solution, a simple momentary switch, an ATTiny45, a 4066 quad bilateral switch and some caps and resistance. Basically the ATTiny45 read the switch and control the 4066. Even if I had to buy them, the sum for these components is cheapest than the price of a single DPDT switch. I've tested this solution and it seems to work fine from an ear point of view. And I've got no switching noise, which I suspect I would have with the DPDT solution.

So my question is, do you see any technical advantages for the DPDT or disadvantage for the "logic" solution regarding the application I've described ?

TIA - EIS


texts:
I have a mathematical problem with the following formula.
The goal is to transform this equation to have a seperated real and imaginary part.
I have already done this with several other equasions, but for this particualar one I don't know where to start.

I dont expect you to do the complete work of transforming for me, it would already be very nice if you could give me a hind on how you would start.

Thank you in advance!

C||RLC

This is my current progress:

My question is:

How can I get rid of the imaginary part jωC2*R?

When the denominator is completely real I can just split up the formula and have an imaginary and a real part.


texts: Reading S2P Files - What Does Each Column Represent

texts:
I'm having a hard time reading s2p files.

For an example say that I am measuring the parameters of a 2-port network (port 1 and port 2).
What do each columns represent? I can tell that the first column represents the frequency, but what about the other columns?

Here is an example of one row from the .s2p file:

5.050000000000000E8    -2.558448512169542E1  -1.431102329159351E2  -9.961776146321423  -9.887263195538942E1  -9.965578328110700  -9.877563761786192E1  -2.571534263692556E1  -1.414368175364255E2


texts:
Is there a way to send digital signals over long wires(2-3 m)?
Can I use buffers to do so? Is it efficient enough.


texts: GSM antenna connection from the phone does not make sense

texts:
I recently came across a phone (Samsung Galaxy Grand Prime SM-G530f) with trouble getting any network signal, I did some troubleshooting and ended up finding out that one of the pin(the GSM pin) to the antenna was torn and it ripped two traces connected to it, I have never worked on any antenna related task before therefore this was new to me.

I googled and found the schematics for the phone in order to see where the traces lead to, but I am not able to make sense of how the antenna is connected to the motherboard.

Here is a snippet from the schematics:

Here are the pins that connect to the antenna + the antenna (I don't have the phone right now so I am using the closest images I could get for context)

The pin ANT101 (GND pin) is supposed to be ground which makes sense but what I can't  figure out is the ANT102 pin (GSM pin) , it seems to me that it is also essentially connected to the ground and any circuitry beyond it is useless.

How then is the signal from the antenna received?, is this how all antennas are connected?

The full schematics are available here for anyone interested, page 25 and 27 show the complete Antenna circuitry.


texts: Is it possible to use a DPDT switch to swap 2 inputs and 2 outputs?

texts:
I want to create a passive device with two MIDI inputs and two MIDI outputs, with a switch that has two states. In the first state, input 1 is connected to output 1, and input 2 is connected to output 2. The other state swaps them, with input 1 connected to output 2 and input 2 connected to output 1.

Each input/output has a positive pin, a negative pin, and a ground/shield. I figure I can just wire the grounds together, but I'm trying to figure out if it's possible to shuffle the positive and negative inputs/outputs around with a DPDT switch and some diode trickery, or if I need something less common like a 4PDT switch (or something else entirely).

I would love to figure it out with just a DPDT switch if it's even theoretically possible, but I'm a newbie at electrical engineering, and I don't know very many of the seemingly common tricks to control flow with diodes and such.


texts:
I don't know if this is the most indicated stackexchange site to ask this, but I'll give it a try:

I know 902-928 MHz is part of ISM band, and I know for sure it is a free band to use in Region 2 (USA, Canada...).

I am in Region 1, Europe. I have searched for a while and I haven't found anything clear. It would be so nice to have an intuitive web to look for bands availability by countries, but I only know where to look the ones for my country (Spain), and it's not very clear either.

Anyway, I think GSM-900 is into that band in Europe, so 902-928 would not be usable for other practises. Am I right?

It is intended to be used onto an aircraft, so I don't know if regulations change for that kind of uses.

Any help?


texts: Why sine wave UPS triggering surge protector again and again

texts:
I recently open up brother's APC sine wave UPS to fix and trying to repair some damage that usually happen over time due to age by replacing components I suspect one by one.

When I start doing AC output LC filter, I notice the UPS triggering surge light on surge protectors connected to UPS output again and again but only when switch to battery operation.

Currently, UPS have 6 AC output in parallel and 3 surge protectors from vendor A, B and C hooking to them and 3 directly to other device.

Vendor A very well known in U.S. and B and C only midgrade from Costco.

Previously, before I start fix, only surge protector from vendor A trip some time, but now all  surge protector trip the moment I cut UPS input power making it switch to battery operation!

I not be explain this besides that some change I did is making output sine wave peak perhaps swing above (1.7 * 120)V AC?

But I only change component with expensive high quality parts and as per original datasheet spec, so UPS is actually better than new (but brother not willing to believe as he sees opposite and he paid for all expensive high quality parts himself after I request him with confidence).

Old circuit pics still visible: Old circuit pics


texts: Multiple AC inputs protected by single MOV

texts:
I am interfacing multiple AC wall switches to activate relays that control appliances. For surge protection, instead of connecting a MOV for each switch, thinking of connecting one MOV through diodes from each switch. Pls see the diodes D2 & D4. I have total of 8 switches is each relay controller board.

Is this an efficient way or should connect individual MOVs without diode and across the AC terminals?
Pls see the Zener Diode (ZD1) for constant voltage & the diode (D1) for reverse voltage protection, which are connected parallel. Is this more efficient that having only the Zener diode?

As I felt so and as Andy aka had mentioned, here is the updated circuit. Please advise if any mistakes or anything more to be considered.


texts: switching power loss calculation in sinusoidal pulse width modulation

texts: How do i calculate the switching power loss in sinusoidal pulse width modulation SPWM in a H bridge inverter (4 IGBTs), and precisely is it linearly proportional to the frequency switching or to the number of switching actions ?


texts: Are there reasons *not* to have a copper-pour ground plane on a PCB?

texts:
I am taking a first stab at designing a PCB from scratch. I am considering using a CNC mill fabrication process, and it seems like with this process I would want to remove as little copper as possible. A copper-pour-style ground plane would seem to be a good way to address this constraint.

But I have noticed that relatively few PCB designs have a ground plane, and even those that do often have them only in specific areas of the board. Why is that? Are there reasons not to have a copper-pour ground plane that covers most of a PCB?

In case it's relevant, the circuit I am designing is a 6-bit D/A converter plug. A first cut at my PCB layout (which does not include a ground plane) is shown below.


texts: Oscillator configuration for PIC24F proteus

texts:
I'm trying to simulate a PIC24FJ in proteus for the most realistic way but even tough proteus is running the simulation it doesn't allow me to configure HS or XT oscillator for primary oscillator neither external oscillator , it is giving me the following message:

  [PIC24 SETUP] PC=0x000000. Oscillator selected by POSCMDx (0b01) and FNOSCx (0b100) bits is illegal or reserved. Defaulting to FRC clock. [U1]

which means that it allow me to configure my oscillators as I want.

I can work that way but it'll force me to modify the timer values when I implement the real circuit.

Can someone tell me how to make the simulation works wih HS oscillator?


texts: Full bridge inverter using IR2110 giving output in patches

texts:
I have made a full-bridge inverter using IR2110 IC. The MOSFETs used are IRF540n. The bootstrap capacitor is 4.7uf. The diodes used are 1N5819 high-frequency Schottky diodes. The operating frequency is 50KHz. The input signal is given using an Arduino Uno. 1.5kohm gate to source resistor is also connected. The pictures of the inverter are shown below.

The power to both ICs is given using a single isolated 12V power supply. The 5V signal is also given using the same supply with the help of the LM7805 regulator. The picture is shown below.

The input DC signal is given from the DC supply of 31V. The output is taken across a 5Kohm 10W resistor.
The issue is that the output signal is not consistent. The signal comes for some periods of time. The output signal picture is shown below.
[![enter image description here][6]][6]

The areas in which the output is coming is absolutely correct. But overall it is not coming. The ICs are tested they are working fine.

Can anybody tell what can be the issue. Is the 5v and 12v signal must be given from separate isolated supplies or that is not the problem.
This is the schematic diagram.

Regards


texts: How to convert from "with 'argument' select" to if else statment in VHDL

texts:
Our assignment is to design a 4-bit ALU in VHDL using Xilinx and I'm having problems in the design of the 1 bit ALU. I found an example on Internet which uses with "Argument" select statments, here is the example:

FullAdder: OneBitAdder port map (InputSignal(1),InputSignal(0),CarryIn, ArithmeticModeOutput(1),ArithmeticModeOutput(0));

with Mode select
    UnitOutput <= ('0' & LogicModeOutput) when '0',
                        ArithmeticModeOutput when '1',
                        "00" when others;

with Sel select
    LogicModeOutput <= (J and K) when "00",
                            (J or K) when "01",
                            ( J xor K) when "10",
                            ( J xnor K) when "11",
                            '0' when others;

with Sel select
    InputSignal <= (J & '0') when "00",
                            (J ,K) when "01",
                            ( J, not K) when "10",
                            ( not J, K) when "11",
                            "00" when others;
CarryOut <= UnitOutput(1);
Foutput <= UnitOutput(0);

This code works, it compiles without an error and the simulation works but our assignment wants it to be an if else statment. I tried writing one but it did not work properly:

process (Mode,Sel,J,K)
begin
if(Sel(1) = '0') and (Mode ='0') then --Logic mode combinations
  if(Sel(0) = '0') then
  LogicModeOutput <= (J and K);
  else
  LogicModeOutput <= (J or K);
  end if;

else

  if(Sel(0) = '0') then
  LogicModeOutput <= (J xor K);
  else
  LogicModeOutput <= (J xnor K);
  end if;

end if;
end process;

process (Mode,Sel,J,K)
begin
if(Sel = "00") then --Arithmetic mode combinations

  InputSignal <= (J & '0'); -- since J is 1-bit, we have to add a '0' after.

elsif(Sel = "01") then

  InputSignal <= (J , K); -- J and K are 1-bit, so we concatenate them.

elsif(Sel = "10") then

  InputSignal <= (J, not K);

elsif(Sel = "11") then

  InputSignal <= (not J, K);

else

  InputSignal <= "00";

end if;
end process;

process (Mode)
begin
if(Mode = '0') then --how to select the mode

  UnitOutput <= ('0' & LogicModeOutput); -- since LogicModeOutput is 1-bit, we
have to add a '0' before.

elsif(Mode = '1') then

  UnitOutput <= ArithmeticModeOutput;

else

  UnitOutput <= "00";

end if;
end process;

I'm open to all suggestions with my priority being that it should be an if else statment. Thank you for your contributions.


texts: Eagle Library Missing Micro b Connector?

texts: I'm not sure if this post belongs here or in another community but here we go. I'm working with Eagle cad (pcb) and i'm looking through the libraries and I couldn't find a single MICRO b usb connector. I found a MINI b connector but I truly require a MICRO b connector for my design. Has anybody found one? I need one specifically for this Connector


texts: How can the armature current of a DC shunt motor be zero at no-load?

texts: I have seen the mathematical explanation of this explained using back EMF, where the back EMF would equal the input voltage and hence the armature current would be zero. But I'm unable to understand that if the armature current is zero at no-load for the motor then how can the motor shaft rotate with the maximum speed at this state ? (As there is no current flowing through the armature windings it shouldn't be able to rotate?)


texts:
I set power supply voltage=15v and the input is a sine wave. So, the maximum complete sine wave should swing +/-7.5v. If amplitude large than 7.5v, the waveform will change. For acoustic signal, will its pitch change?
If the pitch will be changed, why we give a limitation to amplifier?
If this as a real amplifier, as volume increase, the sound sounds strange. How to solve it?


texts: How to Calculate the Power Absorbed by Resistor 2

texts: I'm sure I am doing something wrong as I keep getting the wrong answer, but if someone could explain how to solve this question for me that would be great.


texts: Voltage drops when a signal is fed into op-amp comparator

texts:
I have a function generator SFG-2110 from GW Instek. I set it to generate a square wave with max/min of aroudn +- 1 V. And I checked with an oscilloscope.

However, when I connected outputs of the function generator to an op-amp comparator with TL972IP from Texas Instrument, voltage significantly drops, even though I DID NOT make any change on the function generator.

I think there's something wrong with circuit impedance. But I've only heard about that and have no idea how to adjust impedance of a circuit.

Why does an oscilloscope show a different voltage from a signal generator? says some generators have High Z mode. But, I can't find such a thing on my one.

Currently, my circuit looks like:

simulate this circuit – Schematic created using CircuitLab

Will this problem be solved if I put a tiny resistor between (+) and (-) of the function generator?

If I am thinking wrong that impedance is a source of the problem, please point it out.


texts:
I was trying out a sound experiment, starting off with sample code which sent data to the Discovery F4's audio codec using I2S. The sample code used polling in the main loop and sent data when the transmit buffer was empty.

I set up an interupt handler for SPI (in I2S mode) to do the same thing. I set a flag when the interupt was generated and then this flag triggered transmission of data in the main loop. The problem is, the interupts were generated too quickly and the code in the main loop never executed. I had to disable and enable interupts for this to work.

void SPI3_IRQHandler ( void )
 {
    STM_EVAL_LEDToggle(LED3); // NC
    if (SPI_I2S_GetITStatus(SPI3, SPI_I2S_IT_TXE) != RESET) {
        SPI_I2S_ClearITPendingBit(SPI3, SPI_I2S_IT_TXE);

        if (SPI_I2S_GetFlagStatus(CODEC_I2S, SPI_I2S_FLAG_TXE)) {
            STM_EVAL_LEDToggle(LED4);
            transferFlag = true;
            ready = false;
                    __disable_irq();
        }
    }
}

Main loop:

   while(1)
    {
        STM_EVAL_LEDToggle(LED6);
        if (transferFlag){
            STM_EVAL_LEDToggle(LED5);
                //generate the sound
        SPI_I2S_SendData(CODEC_I2S, value);
            transferFlag = false;
            __enable_irq();
        }
    }

I even made the generating sound very simple (like value = 1000), and it still did not work, without enabling and disabling the interupts. In fact, LED5 and LED6 never turned on at all, indicating that the main loop was not entered. Additionally, I placed the "generating sound and transmitting to SPI" code in the interupt handler. This worked, but the sound was softer the current code shown above.

The Cortex M4 on the STM is definitely not that slow, the FPU is also turned on. I plan on making a DMA version of this, but I do not think turning interupts on and off is a good solution.


texts:
I am using a very tiny motor (GM15, to be precise) for an application where optimizing weight is the biggest challenge. The motor weights around 1.1 g. I opened up the motor and weighed all the different parts and found that the outer metal casing of the motor (along with the bronze bushing) alone is around 650mg.
For those who are curious about weights of different parts: copper coils - only 120mg, permanent magnets ~ 60mg, gearbox - 220 mg.

So my question is on the exact utility of this casing. I know iron is used inside
motor rotors because of their high magnetic permeability but for the purpose of outer casing, does the use of metal offer any advantages other than structural robustness?
If I were to take out all the motor parts and assemble it back in a plastic casing with half the weight, would the performance of the motor be the same in terms of torque production and current cunsumption?

I couldn't find much info on the subject with a quick google search. I would appreciate if someone can point to any standard literature on this.


texts:
I want to put relay SPDT in the output of the below circuit to connect with circuit working in 12v.

when the buzzer run the relay switch on or off to another circuit automatically

I want to run it in mulitsim  also if some one can explain in details the circuit how it is working and the use of each components I the circuit


texts:
I am working on a color organ and want to use a design similar to this.
I understand the gist of the schematic, but I have a few questions about it and how it works.

First: I understand that it is trying to tell me how to hook up my input audio signal, but I don't understand what it is telling me.

Second: This is describing a potentiometer connection, right? If so, do you know why having a potentiometer here is advantageous over having a static voltage divider?

Third: The active band pass filter used is slightly different than the band pass filters I see on google, so what does the resistor that is highlighted do?

Fourth: I want to increase the number of band pass filters so I can control more LEDs at different frequencies. To do this, I believe I would have to have a higher Q value and smaller band widths per filter, correct? How do I increase the Q of my filter so it is a smaller band pass?

Fifth: What is the point of this bit of circuit? Can't the op amp output go straight to the transistor?

Finally: They don't have transistor models marked. Since they are powering lots of LEDs, would you suggest a power transistor? Or maybe a darlington pair for better control?

Thanks in advance for your help! I really appreciate it!

EDIT: Quick followup question: Should I assume the VCC in the red squared part of the schematic is 12V as well?


texts: How to safely connect a 1.8v push-pull output to a 3v MCU input?

texts:
I have a fuel gauge which has a push-pull interrupt pin working at 1.8v. I need to connect this pin to a MCU working at 3v. Theoretically I don't need a level shifter since the 1.8v are above the high level threshold of the MCU.

My concern is that the absolute maximum input rating of the fuel gauge pin is 2.75v so if I accidentally program the MCU pin as an output and I set it to high it might burn the fuel gauge, yes, I know that it sounds crazy but these kind of things happen sometimes.

So the question is, how I can connect this pin keeping the fuel gauge safe?


texts: Change closing transistor to opening in a Microwave Radar Switch?

texts:
Preamble: I have little knowledge of electronics in detail, but I know how to solder, have a working brain and am fearless :)

There are many low-cost Microwave Radar Switch PCBs out there (very popular is the RCWL-0516). I just came across the rather unknown XZG-LDK-6: The neat feature of this board is that it works on the power it is switching (as long as it is between 3.3 and 12 volts). In other words: It simply sits between the PSU and whatever device (lamp, motor etc.) you intend to power.

In my case I want to power (5v USB) a wall-mounted Android tablet, which I use as Smarthome controller. The idea is that the tablet is sleeping/in screen-saving mode, but immediately wakes up (= shows the control panel) as motion gets detected: disconnecting the USB power from the tablet for a moment does the job.

The catch is that I need the Microwave Radar Switch to operate in reverse mode: When motion gets detected it should NOT close the circuit, but open it. So constant power to the tablet with no motion, no power with motion detection. As if one would unplug and replug the USB plug on the tablet.

Unfortunately I can't find a schematic of the XZG-LDK-6 on the web and it seems impossible to figure out the manufacturer (there are trading companies on Alibaba and AliExpress, but no manufacturer).

When looking closely, one can see that the B1261 transistor (Q2) seems to be directly providing the output power.

My question is: How to revert the NO (normal open) to NC (normal closed) behavior? With a relay this would be easy, but how do I do this with this transistor? Are there NC and NO types of transistors? Do I simply rewire the existing B1261 transistor?


texts: Terminating SDRAM on opposite side of board

texts:
I have a 4-layer board with the micro and sdram on opposite sides, the ram signals are short, but I still want to terminate them (I can test the board later and determine if I really need termination), the problem now is that I can't use series termination because traces are running under the micro and ram:

So what other choices do I have ? I've been reading an app note and it mentions parallel termination at the destination, which would be perfect for my situation, but it says signals should be pulled up, and another one says they should be pulled down, so which way is it ? does it matter ? and how do I determine this resistor ? and which lines need termination ? clocks and data/address ? what about control signals ?


texts:
How would i disconnect and reconnect 12vin every 2 hours to my circuit board?

I was thinking about using a 555 timer to reset the power but i'm not sure how to do it using a 555 time


texts: How to simulate a 2 MHz crystal oscillator using LTSpice?

texts:
I'm a newbie in using this LTC software.

Here is a crystal oscillator circuit. I have been searching for a tutorial and guide to put in the value or what type of analysis should I use, but I can't find any of them.

Can anyone guide me what functions should I choose for the voltage source? Either pulse or sine? I tried many values, but the output didn't shows a repetition of sine wave. This circuit expected to produce an f0 ~ 2 MHz.


texts: Atmel AVR Studio 6 - remove invalid target device - how?

texts:
Okay, so I had an STK500 driver connected on USB on virtual COM3. However, after installing and uninstalling some software, the drivers futz'd up, and ceased to detect the programmer.

So, I've reinstalled STK500 drivers, and set device to use COM4, as COM3 appeared to be in use and couldn't be re-selected.

Now, Atmel studio 6, under tools / Device Programming, there's STK500 on both COM3 and COM4. It's annoying, as for some reason my project tries to use COM3 instead of COM4 when clicking 'Debug'.

How can I delete the COM3 device from there? I can add devices under Tools / Add target, but I can't find anything like 'Delete target' anywhere.


texts:
Basically I have sliding gate which has contacts to turn lamp when it's open or closed (two different ones) that are rated 24v AC max 3W.
I would like to use those contacts to know if the gate is open or closed. I'm a total newbie in electronics, googled a bit, and found that what I probably want to use is optocoupler.
And found a scheme like this:

Explanations seem logical, I can get 4N45 at my local shop and for diode I would use 1N4148.
The thing is that I already have low amps (0.125) so will it be enough to drive the 4N35?


texts: Lightning protection for Antenna Connector

texts: I want to add lightning and ESD protection for the antenna used with my PCB (Wireless Gateway). The antennas that will be used with my PCB are Pole Mount Antenna. There are three different types of Antennas needed with my PCB: 4G LTE, GPS and LoRa Antennas. Currently, I am using SMA PCB Connector. I want to know how to connect shielding of these connectors. Should I connect it to the enclosure's shield or to the ground (for RF)?


texts:
My brother-in-law is buying an underwater camera for use with his marine biology studies.

Here are the electrical specs for the camera.
Input voltage 12 VDC
Power Consumption: 1.4 W
Cable: 30, 50, 100m (basically a really long cable with an RCA connection)
21 LED lights
Image Sensor: Color CCD

He's trying to understand the options that he has available for the Battery Kit.
He can choose from:

4.5 A Battery + charger
7 A Battery + charger

Why would he get one over the other? Is it actually paired up with the length of cable that is connected to the camera?

Doing some quick Math:
P = VI => I = P/V
I = 1.4 W / 12 V = .12 A.

So the camera doesn't really require that much amperage. So why would he choose the 7A Battery over the 4.5 A Battery b/c that seems more than adequate.


texts: How to tell if battery is fully charged?

texts:
I have 12-volt, 200-ampere lead acid battery. I want to know how much capacity is left in the battery, expressed as a percentage.

What is the exact mechanism to be used to determine find that, and what exactly is the logic behind it?

I am so curious about how mobile cell phones show exact percentages of charge remaining; how do they do this?

I found some articles which say that if your battery voltage exceeds 12.06 volts, it means it has charge, I mean it's not clear.

I would like a professional answer to this question.

Thank You

Edit:

My question could also be read as:

What tools and devices should I need to check if my 12-volt, 200-ampere lead acid battery is fully charged?


texts: How to detect when current exceeds a set point

texts:
I need to detect when current being drawn exceeds 7.5a and then operate a relay to switch another circuit. Originally this was done using a large relay (1930's technology ) which is missing from the control box. I do not want to use microprocessors etc, just something nice and simple.
Can anyone advise?

Cheers
Chris


texts: I have seen a documentary about making BGM-71 TOW (an anti-tank missile - the Iranians make it). You can see it in this link (part 1). Between 6:08 to 6:40 minute of clip, you can see a gyroscope. I would like to know how this gyroscope works. How did they connect it to their electronic circuits?


texts:
Folks,

I have been playing with STM32F2 (probably the most advanced ARM Cortex M3 in the market). This is not a processor specific question nonetheless.

I have a set up where I have 0V sampled by several ADC pins. I read and dump the values. When I examine the values, I expect to see all zeros, instead I see mostly zeros but bunch of values up to 100. (i.e. this is a 12 bit ADC with 4096 levels, so 100 is roughly means ~3.3/4096*100 = 80mV)

I know for a fact, my 0 volt is really 0V (i.e. ground).. So, 100 out of 4096.. Is this expected? I have never fiddled with other ADC enabled chips so I cannot gauge this much error is expected or not. Any insights?


texts: Gateworks5910 + TI CC1352 Radio reboot SoC

texts:
I am a beginner in embedded systems programming, so forgive me if this is the wrong place to ask, but I could really use some direction.
I have a Gateworks 5910 running Ubuntu Linux, which has a TI CC1352P Wireless microcontroller on it.
I have been able to use OpenOCD to flash images to the board, and one of the example programs for the TICC1352 uses an AT interface on /dev/ttymxc2 of the Gateworks board to allow for user interaction with the device. I am able to successfully do that using screen.
As far as I know, /dev/ttymxc2 is the only way to interact with the CC1352, but I would like to know how can I tell how the chip is "wired" to the board. For example, every once in a while, the CC1352 gets in a hung state, and I would like to "reboot" it. How do I reboot the chip without rebooting the host board?
Shouldn't I be able to send a signal to some GPIO pin or something, which would reset the SoC? Please let me know if I can provide some additional details about the configuration.  As I am new to this, it is unclear to me how a "soldered on" chip's pinouts work. Here are the links to the manuals for the GW5910 and the Technical Reference Manual for the CC1352
http://blog.gateworks.com/?wpdmpro=gw5910-manual
https://www.ti.com/lit/ug/swcu185d/swcu185d.pdf?ts=1604780624696&ref_url=https%253A%252F%252Fwww.google.com%252F
Right now, all I know is this is my OpenOCD configuration file chain:
cat << EOF > gw5910.cfg
#
# GW5910 CC1352P JTAG Interface mapping
#
# PAD_DISP0_DAT14__GPIO5_IO08 TMS gpio-136
# PAD_DISP0_DAT15__GPIO5_IO09 TCK gpio-137
# PAD_DISP0_DAT16__GPIO5_IO10 TDO gpio-138
# PAD_DISP0_DAT17__GPIO5_IO11 TDI gpio-139
#
# PAD_DISP0_DAT23__GPIO5_IO17 RST# gpio-145
# PAD_EIM_A25__GPIO5__IO02 BOOT gpio-130

interface imx_gpio
transport select jtag
imx_gpio_peripheral_base 0x020ac000
imx_gpio_speed_coeffs 100000 5
imx_gpio_jtag_nums 9 8 11 10
imx_gpio_trst_num 17

adapter_khz 20000
source [find target/ti_cc13x2.cfg]

jtag_ntrst_delay 0
jtag_ntrst_assert_width 0
adapter_nsrst_delay 0
adapter_nsrst_assert_width 0

reset_config trst_only
EOF

root@bionic-ventana:/# cat /usr/share/openocd/scripts/target/ti_cc13x2.cfg
#
# Texas Instruments CC13x2 - ARM Cortex-M4
#
# http://www.ti.com
#

set CHIPNAME cc13x2
set JRC_TAPID 0x0BB4102F
set WORKAREASIZE 0x7000

source [find target/ti_cc26x0.cfg]
root@bionic-ventana:/# cat /usr/share/openocd/scripts/target/ti_cc26x0.cfg
#
# Texas Instruments CC26x0 - ARM Cortex-M3
#
# http://www.ti.com
#

source [find target/icepick.cfg]
source [find target/ti-cjtag.cfg]

if { [info exists CHIPNAME] } {
    set _CHIPNAME $CHIPNAME
} else {
    set _CHIPNAME cc26x0
}

#
# Main DAP
#
if { [info exists DAP_TAPID] } {
    set _DAP_TAPID $DAP_TAPID
} else {
    set _DAP_TAPID 0x4BA00477
}
jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_DAP_TAPID -disable
jtag configure $_CHIPNAME.cpu -event tap-enable "icepick_c_tapenable $_CHIPNAME.jrc 0"

#
# ICEpick-C (JTAG route controller)
#
if { [info exists JRC_TAPID] } {
    set _JRC_TAPID $JRC_TAPID
} else {
    set _JRC_TAPID 0x0B99A02F
}
jtag newtap $_CHIPNAME jrc -irlen 6 -ircapture 0x1 -irmask 0x3f -expected-id $_JRC_TAPID -ignore-version
jtag configure $_CHIPNAME.jrc -event setup "jtag tapenable $_CHIPNAME.cpu"
# A start sequence is needed to change from 2-pin cJTAG to 4-pin JTAG
jtag configure $_CHIPNAME.jrc -event post-reset "ti_cjtag_to_4pin_jtag $_CHIPNAME.jrc"

set _TARGETNAME $_CHIPNAME.cpu
dap create $_CHIPNAME.dap -chain-position $_CHIPNAME.cpu
target create $_TARGETNAME cortex_m -dap $_CHIPNAME.dap

if { [info exists WORKAREASIZE] } {
    set _WORKAREASIZE $WORKAREASIZE
} else {
    set _WORKAREASIZE 0x4000
}

$_TARGETNAME configure -work-area-phys 0x20000000 -work-area-size $_WORKAREASIZE -work-area-backup 0

set _FLASHNAME $_CHIPNAME.flash
flash bank $_FLASHNAME cc26xx 0 0 0 0 $_TARGETNAME

reset_config srst_only
adapter_nsrst_delay 100


texts: If I made a commercial product that utilized radio waves, which frequencies could I use?

texts:
Let's say, hypothetically, that I design some product that uses radio communication. Maybe something like a wireless lock. Or a scanner that tells you if a tag is near (in range of a few feet). Or a homemade radio.

If I didn't tell anyone, I assume I could (perhaps illegally) use whichever frequencies I fancied. However, imagine I wanted to sell one of these products. Which frequencies would I be allowed to use? Does it depend on how far the radiation is designed to travel for the given application?

I am aware that the information regarding FCC frequency allocation and regulations is out there. However, I came here because I was a bit overwhelmed by the information I got from other sources. What frequencies can safely be used?


texts: Variable DC Supply "Ignoring" Potentiometer

texts:
I printed a board meant to supply a variable 5–250VDC from this open-source schematic:

This was my board

with this schematic (excuse my silly device symbols)

but I can't get the output voltage to vary. With the 5k potentiometer (the box at the bottom center of the board), it measured ~320V, invariant of the pot's setting. For a 10k pot, it measured the same voltage, again invariant.

Here's the soldered print (excuse the poor quality, someone else has them currently):

Is something shorting? Is it somehow "skipping" the potentiometer? Is there anything obviously incorrect or any likely errors I could test for?


texts: How to map LPC FMC pins to FPGA pins on a Zedboard?

texts:
How to map fpga pins to actual physical pins on the FMC connector on a Zedboard?

Of course I have looked into the user's hardware guide and the master constraint file, but all I have found is a list of the FMC pins out on the FPGA side but nothing on how it is mapped to the LPC FMC pins.


texts: Sigma Delta ADC vs SAR ADC, for multiplexing signal

texts:
We are using PIC32MZ series Microcontrollers for our energy based application where we are measuring voltage and current for electric consumers. One single meter can monitor current for upto 10 consumers hence we used multiple pin interface to the ADC. The current ADC resolution is 12 bits which I guess is fine.

Now what I read online, Sigma Delta ADCs are suited better to measure power esp in low frequency range because they give more accurate reading and they can filter out noise from transmission lines. The problem is most MCU come with SAR ADCs (which work fine generally) but in our case I think Sigma Delta would suit us better, the problem is Sigma Delta are usually dedicated and does not have channels (we need 12 channels at least).

What is your proposed solution in my case? My question is, it is worth going from SAR to Sigma Delta for better accuracy and secondly would it is feasible design if I add an external MUX IC to I can use the same Sigma Delta for 10+ channels? This Pic MCU PIC24FJ64GC006 comes with sigma delta ADC with sampling rate of 244 to 62.5 Ksps. For single channel, I am ok with 6.4KHz sample rate per channel. Thanks


texts: FM Radio transmitter and receiver circuits

texts:
I'm planning on building a FM transmitter and receiver circuit for an electronics project. I was just wondering if these two circuits would work together. Also would they be suitable for transmitting and receiving audio?

The transmitter circuit uses the ba1404 chip, link to circuit info here:
http://www.circuitstoday.com/stereo-fm-transmitter-using-ba1404

The receiver circuit can be found here:
http://circuits-projects.blogspot.co.uk/2014/07/simple-and-mini-fm-receiver.html

Any other advice would gratefull


texts: Traces to support Type-C's 5 Amps. How wide? How to connect?

texts:
USB Type-C is able to provide up to 5A. When I look at trace width guidelines, I find my traces have to be 110mil/2.79mm wide for 1oz default traces. The thing is, 100mil is literally more than 5 pins of Type-C including distance between them. It's like 1/3 of the entire Type-C connector. I've never built circuit that can have such current, so I'm looking for advice from more experienced people.
What would be the correct way to implement Type-C port with high current? At least 3A, up to 5A would be best. Type-C has 4 VBus pins. So this is my list of the questions, I would appreciate, if you could give an advice and explain why it has to be certain way, please.

Do I need to connect all VBUS pins together on my PCB?
How wide should my traces be?
They can't be wide near the pins themselves, how do I organize it then so that I don't burn anything?

Unfortunately, googling it only gives general guidelines like "so many amps - trace this wide". I tried several synonymous searches, but couldn't find any lead. It doesn't really discuss the narrow-pin-bottleneck of the Type-C port. I'm pretty sure it's hidden somewhere in power delivery specs or something, but I couldn't google out the exact part, and from what I remember, USB specs now compete with "War and Peace" in volume. But a link to the spec, if it contains an answer to my question, would also be appreciated. Thank you!


texts: Designing a Carry lookahead unit using EEPROMs, creates oscillator

texts:
I have read something about CLUs (Carry Lookahead Units) and want to build one. I have settled on design using eeproms as adders and CLU. On the picure below you can see a schematic CLu implementation. In my version i think the best would be to swap the schematic blocks by an EEPROMs. ( One EEPROM per adder and one for the CLU, there are plenty chips available for this format)
But the more i looked at it it seems that we will create some sort of an oscillator.
Let me explain.
Lets assume that one eeprom has 200us (just for example) delay before the data on the output becomes valid. Meanwhile the output can be "whatever" it wants. But in that time, the outputs of the CLU eeprom are sending back to individual adders their Carry in signal. so if that signal changes, the output changes and again, we have 200us delay before the data becomes valid. So that means the individual adder can change its outputs (Propagate and Generate) And that completes the circle back to the CLU and it loops again. So we have basically an oscillator.
Am i right? I yes, how can we make it otherwise than to latch it and wait for next clock cycle?
Thanks

CLU picture URL


texts: Best way to power a 3.3V circuit from 3.3V-to-5.0V source

texts:
I'm working on an add-on board that needs 3.3V power (~500mA) and should take power from its host board. The host can operate at 3.3V or 5V and I'd like to avoid using jumpers that would require the user to select the host power.

I was thinking of using a boost converter to generate, say, 6V from the host board and then use a buck regulator to bring it back to 3.3V. Is there a better approach?


texts: Voltage spikes in h-bridge inverter square wave output

texts:
I apologise if this is a repost but I couldn't find the problem anywhere else.

I am trying to power an ultrasonic transducer using an h-bridge inverter design to convert arduino signal into a higher power ac square wave (shown in the circuit below). It was working well, then suddenly I started getting high voltage spikes in the rising and falling edge of the square wave. I am using a high varying driving voltage of 15v-60v (VDC in the schematics) and I have seen that increasing this voltage distorts the output more. I am hoping to drive the transducer from 20kHz to 30kHz.This is a zoomed in picture of it. You can see that the top of the square wave is collapsed slightly as well as the spikes on the bottom left of the picture. I've tried rebuilding the circuit using new components on a different pcb but I'm still encountering the same problem. I am thinking it might have something to do with the  mosfets (irf4227), but I have changed them to a different type of mosfets (irf540n) and the problem still continues. I have also changed the bootstraps capacitors to a larger value of 330nF from the 22pF in the schematics but it did not do anything for the distortion.

Thank you very much for any help you can give.


texts: Power Supply AC/DC Power OK Signal Control

texts:
I will combine 4 ac/dc converter (1000 W) by using  parallel operation mode to create 4 kW unit. I will add 4 LEDs to observe converter signal health.
There are digital output including POWER ON SIGNAL, AC GOOD SIGNAL and POWER OK SIGNAL. I added related piece of datasheet. And I added a design. Can you say that whether it is true or not.

I want to ask that can I use these digital outputs to drive directly 5V LED or do I have to use a external microcontroller (like Arduino) to determine HIGH/LOW state and drive LED by usign external microcontroller(like Arduino) digital outputs?
And which of AC/DC converter digital outputs (POWER ON SIGNAL and POWER OK SIGNAL) should I use to determine that output DC is OK? Can you advise me a way?


texts: Reduce voltage going from absolute encoder to MCU

texts:
My absolute encoder need 24VDD (minimum is 11v) and send the same VDD to the output pin.
But My MCU only tolerate 3.3v or 5v
I could use a resistor but if the amp slightly change for any reason, it could be a problem for my MCU.

I was considering using a MOSFET, what do you think? is it better?
I'm not familiar with this kind of stuff
THank you

Encoder datasheet:
http://download.schneider-electric.com/files?p_Reference=W915601910811&p_EnDocType=Instruction%20sheet&p_File_Id=1391814451&p_File_Name=W915601910811_A06.pdf


texts: how to modify my AVR so headphone jack does not shut off speakers

texts:
Being a bit deaf, I like to use my headphones while my wife listens to the speakers. Unfortunately my Samsung TV does not have an audio out plug. There is an optical audio out but it cannot be used at the same time as the HDMI ARC. While my Sennheiser 195 headphones have an optical input, I cannot get it to work with the TV even when the TV is set for optical audio out.
My Denon AVR has a headphone jack, but when inserted it shuts off the speakers. It seems to be impossible today to find an AVR with a switch so that the speakers can be either on or off when headphones are connected.
It there an easy wiring change so that speakers and headphones will work at the same time? When by myself, I can just turn the speaker volume down to zero.


texts:
I have a brother label printer that usually runs on 9V DC source or 8x1.5V standard AA batteries. The DC input jack on brother died so I decided to replace it and try to upgrade it to Li-po battery source.
I have purchased 1350mAh 3.7V LiPo battery pack and hooked it to tc4056a based charger. On the input side I connected 5V source from DC jack for charging, and on output I put step up converter based on LM2577 which is tuned to 12V.
What happens now is that in standby mode the battery draw is 0.5A which is due to conversion I guess. When running the label printer it prints for a while until it shuts itself down (My guess is that the battery internal protection turns it off as I have to remove and insert battery to turn it back on)
Although while on charger and battery, the printer works just fine and the draw on LiPo battery is under 1A (It spikes to 1.2A and then gets down).
What could I do to make it fully working on LiPo battery? Should I put three batteries in series to get 11V and get rid of step up converter? How do I charge the batteries then?
Thanks in advance,
Leo.


texts:
I'm a beginner in EE, learning about the forward active mode of transistors. The equation, Ic = Ib * BETA, and Ic=Ie * ALHPA, are referred to as the ways to figure out what base resistor you should have when running forward active mode. What is Ic and Ie? Do these mean the amount it lets in, or some ratio?

Along with this, how do I use these numbers? On this site, https://learn.sparkfun.com/tutorials/transistors they give an example where they say Ic is 100mA. From my understanding, that means that if it hooked straight up to the positive and negative terminals it passes 100mA. But what if there are resistors in series? What effect does this have?

Thank you very much. I'm sorry if there is a term for this I don't know, by all means give me something to google.

-edits-

Thank you for the name suggestion.


texts: Significant figures on component's values

texts:
I'm reading a book where resistor values are discussed:

I did not understand about how 3 significant figures can cover uncertainties from
1 to 0.1  % as stated in the 1st paragraph 6th line of the book.


texts: How to force variable voltage fast charging power bank to output a certain voltage?

texts:
I am trying to power up my raspberry pi 3 with a Xiaomi 10000mAh fast charging power bank through the L298N motor controller. The motor controller can receive from 7 to 35V, and it has a 5v output, which I use to power my pi through the 5V pin. I also use a USB 2.0 to TTL UART Module 6Pin Serial Converter (https://www.aliexpress.com/item/CP2102-USB-2-0-to-TTL-UART-Module-6Pin-Serial-Converter-STC-Replace-FT232-Module/32534146426.html).

I read a bit about fast charging and how they control the voltage, and this is how the charger decides what voltage to output using the d+ and d- pin:
http://4.bp.blogspot.com/-nMZFNxoTcA0/VHX8GRZCLFI/AAAAAAAAAXA/VCn0OxdThAM/s1600/USBVoltage.jpg

The first problem is that the usb converter doesn't have the D+ and D-, but I believe it should be the RXD and TXD pin. I want my power bank to output 9V to the motor controller so I tried plugging a 3.3V to the 0.6V to the RXD and TXD (tried both way) but it doesn't change the output voltage. The second problem is that if I just plug the power bank to the motor controller, which it will automatically output 5V, it doesn't turn on the Pi.

I am new to these kinds of stuff so any suggestion on how to do this will be really helpful. Thank you.


texts: I'm having a little trouble understanding as to what the voltage drop across an LED actually does in terms of the electrons. I understand that the potential difference across an LED causes the electrons to move and then undergo recombination to emit light, but why does it only happen significantly at a certain potential difference. What happens at lower potentials?


texts: Is an edge coupled microstrip / stripline a differential pair or any two adjacent traces?

texts:
I got a suggested layer stack, and and it makes mention of "edge coupled offset stripline" and "edge coupled coated microstrip".

Are edge coupled traces differential pair traces or are they any adjacent signal traces ?


texts: Can I cut off the 5v output of the IOIO to the Android?

texts:
I'm working on a project using Sparkfun's IOIO for Android (https://www.sparkfun.com/products/10748) where power consumption is a concern. The IOIO board provides the phone with 500 mA charging if I'm correct, which is too much for continuous operation.

There's a trick I have in mind where I want to power the phone and the IOIO board separately from the same external power source (Of course the phone gets its 3.7v while the IOIO gets 5v). The catch here is that I want to cut off the 5v line on the cable from the IOIO to the phone, leaving the GND, Rx and Tx (Which are good enough for any serial transmission).

simulate this circuit – Schematic created using CircuitLab

(Middle lines are those in the micro-USB cable)

I'm kind of limited on USB cables so I don't want to make a mistake. Is my theory feasible with the IOIO? Or will the Android OS not detect it?

(NOTE: My project uses a magnetometer, so I can't resort to bluetooth which might interfere with the readings)


texts:
I recently ordered this Peltier module so that I can make a thermoelectric generator (using heat to create some voltage.)
How can I measure the current produced using a multimeter?
I'm relatively new to electronics and I recently got my first multimeter.  When I watched a video, it stated that you need to make the multimeter part of the circuit otherwise the fuse will blow. I'm not really sure how to do this as there are just two wires coming off of the module with nothing else attached and I don't want to fry my multimeter from directly putting the probes onto the wires. What should I do?


texts: 4-Channel Level Converter outputs voltage when it shouldn't?

texts:
I am converting 5V to 3.3V (for a rudimentary Raspberry Pi project). The level converter scenario below behaves as I would expect:

Because HV1 is connected to 5V, the voltmeter connected to LV1 and ground reads 3.3V. This looks right to me (please correct me if I am wrong).

This next scenario is the one that doesn't make sense. Same wiring, except that HV1 is no longer connected to 5V:

This no longer makes sense to me. Should I not get 0V on LV1?

For reference - although I am not sure where to find the datasheet for it - this is the (Amazon) link to the converter component.


texts: Debugging burned out TRIAC for vacuum cleaner motor speed control (inductive load)

texts:
I have tried to use  speed control for vacuum cleaner  like below (2000W):

I have tried  this circuit with two different control methods for the TRIAC (BTA24 -24A):

Arduino base by MOC3063
DIAC for TRIAC control method.

I have a pin header for switching between  above input, which is not shown in the circuit schematic below (the values are selected based on photo below):

When I tested the above circuit with my drill (650W,) it worked fine but when I used it with the vacuum cleaner, it started to work at lower speed than normal, and can not be controlled by the TRIAC.  When I tested the TRIAC according to these instructions, I found that MT1 and MT2 are short circuit, so the TRIAC is burned.
Why did it burn out? Is there an error in the schematic like in the list below?

Need to increase the MOC3063 to MT1 resistance to 500kohm similar to this schematic:

Need to add more capacitance between the DIAC (DB3) and resistor (R1), similar to this schematic:

The load snubber circuit is not selected correctly and needs some inductor coil similar to this schematic:

Update:
About the heatsink:

The test duration was around one or two seconds, the TRIAC would not be so hot, also, I have added some simple heat sink on it (a piece of home key metal as heatsink), which is removed during the TRIAC burning test and is not shown in the uploaded photo.

My TRIAC IC was BTA24 which i have dome a mistake in question as said BTA41 Instead of it (Fixed now!).


texts: Discrepency with experimental vs. simulation of AC-DC circuit

texts:
I'm analysing a PIR Circuit's power supply, but I'm having a large (almost double) discrepancy between simulation/theoretical current values and experimental values (experimental is almost half theoretical)

This is a similar circuit to the one implemented in the sensor, however it is 240VAC, the capacitor is 0.39uF, resistor is 150 ohms and the Zener voltage (I'm assuming, given that the voltage at the chip is 9V) ~10V.

Here's my simulation circuit of the power supply with no load:

The current through R1 is Irms = 24.3mA, and doing maths gives the same answer. However, when I measure the circuit (when it's on standby, ~100uA current draw from spec sheet), my multimeter says it's drawing 12.75mA, almost half of the theoretical value.

Where have I gone wrong? The capacitor marking is 394, which I'm assuming is 39p * 10^4 i.e. 0.39uF. Further, the meter is a true rms.

Edit:

I calculate a value using:

\$ I = V / Z \$

\$ = (240 - 10) / (150 + 1/(j100*pi*330n)) \$

\$ = 230/(150 - j9645) \$

\$ = 24.8mA < 89.1^o \$

The waveform from the simulation is


texts: I'd have a question about fundamental circuits. What role does Q2 play in this circuit? It's inital bound like a diode. Thank you so much!


texts:
I want to detect the presence of a 8.4V voltage source from an Arduino, so I'm using a voltage divider to step it down to a voltage safe for the Arduino to read with an digital pin.

However, for when the Arduino is powered off, I also want an LED to light when the voltage is present.

How do I combine these two circuits? So the divider didn't waste power, I was using high values 2/1M ohms, but I have to lower those if I want there to be enough current to power the LED. I calculated the maximum resistence needed to light a red LED would be around 400 ohms. Will this circuit work?

This circuit essentially sits "between" a battery charger and a battery, allowing an Arduino to detect when the charger has been attached.

EP (external power) goes to an Arduino digital pin.

S1 is a normally-open magnetic reed switch closed by a magnet on the input voltage source plug. I added it because Vin is attached to a battery's positive terminal, so that's there as a safety mechanism to ensure the 8.4V contact doesn't expose live battery leads when the external plug is unplugged.

D1 is necessary to keep EP pulled low when the magnetic plug closes S1 but no power is present, indicating the charger itself is unpowered.


texts:
I was going through this :
http://tangentsoft.net/elec/opamp-linreg.html

Vis-a-vis Jung 2000 Regulator:

I had a few doubts, maybe someone could clarify :

1) What is the idea of putting the green LED D1 in the base circuit of Q2 ?

2) Can we use any NPN in place of D44H11 with an equivalent current rating ?

3) Can we use any FET OpAmp in place of AD825 ?


texts: How can I identify these capacitor values?

texts:
I’m trying to build the power supply from this schematic.

I’ve been purchasing the parts, but am confused about the capacitors I’ve labeled, especially became their numbers start with “R”. What are their values? What common sense can I use so I can continue to find this out myself?


texts: How to Control the Temperature of Heating element using its resistance

texts:
In my test of a thin Film heater. I derived its Temperature coefficient of Resistance. This alpha number symbolizes the resistance change factor per degree of temperature change.
My question is, Is there any setup out there that can use the change in resistance at varying temperature to control the heater.

I am looking for a circuit that could do this. Measure the resistance of the operating heater and stop it at a set resistance.

@ MKeith,
I meant, just knowing the R does me no good if I cannot use it to keep the temperature at the point I want it to be.

I want to keep track of the increase in resistance (The resistance of our heaters increases at a certain rate with increase in temperature of the heater). So keeping this in mind, I want to then control the heater with the resistance.

Say I want the heater to stop at 100degC and the resistance will go from A to B at that temperature, I need ways to use this resistance B to control this heater. If I need the heater to go to another temperature, all I will do is adjust my setting to get this. Basically R is serving as temperature control instead of thermistors or RTDs.


texts:
I got the CJMCU-2317 MCP23017 I2C Serial Interface 16 bit I/O Expander Serial Module to use on a split keyboard as an extension matrix.

This seems like an all-in-one solution so that I won't have to solder extra capacitors and resistors. I wired Vcc to 5v, GND to GND, SDA to D1, SCL to D0 (Teensy++ 2.0) but I'm not sure about the RESET if I should connect it to Vcc or not and if so should I use some resistor ?


texts: ATMega32, PetitFS, writing measurements to file

texts:
I'm trying to write measurements from external sensor to the file (lets say 1 per second). I'm using ATMega32 and PetitFS. At this moment I'm able to write one measure:

int main(void){

    BYTE result;
    WORD s1;

    for(;;){
        sprintf(buff, "Measure: %d\r\n", mes);
        s1=4;
        result = pf_write(buff, sizeof(buff), &s1);
        write_close();
    }
}

Now I'm trying to extend above code with pf_lseek to append another measure after previous one. Can someone give me a hint/suggestion how to achieve this?


texts:
If I were to pulse those mini DVD lasers in sequence, assuming that they were all trained on the same target, could I produce temps high enough to be a decent laser cutter? Or do lasers just not work that way.

I think that If I train 40 of those lasers and run them at 1 watt for 1/40th of a second each, I should be able to produce a significant result.


texts: Splitting a power supply to two monitors

texts:
I'm working on a project that requires 2 (identical) LED monitors, each of which has a separate power supply that outputs 19V 1.3A. To save space, I would like to instead use a single power supply with the same voltage, but more amperage (3.4A in this case), and use a basic Y-cable to split the output to individual monitors. Is this something that can be done, or would I need to build additional circuitry to split power output?

Also, at some point I plan to add a relay, so that one of the monitors can be turned on and off. Would that change the situation at all (i.e. require any additional changes?).


texts: Discrete implementation of High-Speed High-Low Side MOSFET Driver?

texts:
The IR2101 is a popular driver choice for MOSFET half H-Bridges. Its functional diagram is as follows:

I would like to implement a high-speed high and low side driver using only DISCRETE components, with BJTs for the push-pull circuitry. I do not need undervoltage detection or a high voltage level shift, as I am using a high-side logic level P-Channel FET. Abstractly, what would this circuit look like?

High-Side: AOD403
Low-Side: IRLR8726


texts: How can I wire up an quad channel amplifier to become stereo with 2 times the power?

texts: I have an TDA7388 IC. This is an quad channel amplifier 40w on every channel. Is it possible to wire it up to become a stereo amplifier with 80w per channel? Circuit


texts: Voltage on opamp input is not right - how come?

texts:
I've run across strange opamp behaviour I can't understand. Voltages on TP1 and TP2 change drastically when I connect them to opamp inputs. Even more - when I swipe R2, voltage on TP1 changes too. Nevertheless, the circuit works ok - when voltage on R2 drops below voltage set on R1, opamp output goes high and then voltages on both pots seem to be right.

Opamp is LM6152. I thought that maybe i killed the opamp, but another brand new device works exactly the same.

If I change opamp to, say, LT1638 everything works as in ideal opamp tutorial.

Could someone explain me what's going on? Is it current feedback opamp? It's nowhere mentioned in the datasheet. Input bias current is 500nA. One strange thing is it lists maximum input current +-10mA in maximum ratings.

Edit

MOSFET really is FDD6692.


texts: Differences Between Buck-Converter and Linear Current Booster

texts:
Thinking through a design that interfaces a solar panel to a 12V diaphragm pump, and considering the interfacing options.  I've come across the term "Linear Current Booster", and wanted to explore this idea further.

While the concept of "MPPT" controllers is fairly well documented for solar panel to battery systems (and ICs are marketed for this purpose, like the fairly fancy Linear LT8490), I'm not seeing as much documentation around the Linear Current Booster.

I understand the concept of a Linear Current Booster as a DC-DC converter that:

Reduces a solar panel voltage to a lower output voltage, and increases output current,
Ensures that the minimum output voltage is above some threshold (how does it determine this?) to ensure that the pump does not run at 0V; which would be effectively running at 0 RPM and burn out the windings in time,
Ensures that the maximum output voltage is limited, to ensure that the pump does not overspeed.

The advantage (as I understand it) is to be able to operate in lower light conditions; when the panel could not provide enough current to the pump to give it enough torque to start moving if it was directly connected.

Some examples of commercially available Linear Current Boosters:

EAST LCB
SolarConduit LCB
Clean Energy Brands LCB

So, does anyone here have any insights on the difference between a DC-DC buck converter and an LCB?  I think that all of the functions of an LCB can be accomplished with a buck converter that implements an output undervoltage/overvoltage lockout.  Is my understanding correct?

EDIT -
It looks like the author of this buck converter design indicates that "Another application for this circuit is as a "linear current booster" (LCB). Common LCB uses include running motors and other devices directly from a solar panel with no battery. In the LCB mode of operation, it is possible to use the circuit to change a low current solar panel input to a higher current (but lower voltage) output."


texts: Controlling multiple floating power supplies from a single point

texts:
I have assembled a power supply from five HP dps-750rb common slot power supplies. All five units are in series. I have the first grounded electrically and have the other four units modified and floating (with all cases earthed).

Each of the power supplies contain a pin between the control board and the power board which supplies a consistent 2.500V. By varying it, it is possible to control the output voltage of the supply at the expense of the inbuilt current limiting (I have overcurrent protection on the 0V low side sorted separately), from just under 1V-13V per supply. (Aiming for the assembly to be variable upto 60V or 60A or 3000W max output before my set cutout, which is operational)

I can do this quick and dirty by having five separate pots and controlling each of the five units separately. I HAVE to use separate isolated pots because each of the 2.500V signals is relative to the low side of each of the floating supplies, so at 12V output per supply, the signal is 2.500v for first supply, 14.500V for second, 26.5V, and so on...

From looking, 5 gang linear pots seem impossible to come by...

So I am looking for ideas please, on how best to approach controlling all of these together. I would welcome using a DAC and uC, however I am still unsure what might be the easiest way to achieve my feat?

Thank you in advance. I would provide more details on the supplies but it seems unnecessary as I only wish to achieve the signals required, rather than be concerned with reverse engineering the unit any further. If it would help I can try to provide further information.


texts: input stage (pre opamp) for voltages between 0 and 240V AC

texts:
I want to play with a custom DSO design:

sub 1MSPS
Mostly measuring 0-6V signals
Some audio signals
Power line signals

The hardest thing for me is the power line signals. Sometimes I just
want to look at the power line itself (full 250V range) and sometimes
look at the power line communications signal right after the zero
crossing.

I looked at the talk on  How does the input circuit on this oscilloscope manage to accept such a large range of voltages?
and understand the concept of the voltage divider and using that to start with.

I also get the concept of varying the gain on the opamp stage via software analog multiplexers and resistor networks.

Looking at the design for the  Seeedstudio DSO (http://www.seeedstudio.com/wiki/File:DSO_Quad_Schematic.zip) I can see the multirange stage that controls the opamp gain.

What I can't understand is how the input range is 80Vpp (x1 probe). Their design is above my head. I can't see how they are clamping the voltage that goes into the opamp.

If I want the opamp to be protected for up to 250V no matter what range is configured I figured my only option is:

Put the proper voltage divider in front of the opamp
Have a configurable gain
Clamp the output of the opamp to protect the ADC

My concern is that doing it only on the gain may introduce noise or unanticipated signal degradation issues. If possible I would like to also put the input signal through different paths to control its attenuation and filtering, but I need to protect the opamp clamping its input no matter what.

Is there a resource that explains this kind of input stages?


texts: Superposition on a circuit with just one source

texts:
I'm trying to analyse this circuit (state variable filter):

All the places on the web I've found solve it first using superposition, creating an equation of the form \$ V_2 = kV_1 + kV_4 + kV_3 \$.

However, I can't understand how they use superposition in this circuit. There is only one source so how can it work? How can they get to that equation?


texts:
We are using an inductive coil transformer for a sensor. We excite the signal with a low frequency (1kHz-3kHz), and what we measure on the secondary indicates the proximity of a part.

Generating the signal and receiving the secondary signal has been completed, but one important feature we absolutely need to figure out is how to in circuit detect if either of the coils has been disconnected.

A simplification of the overall schematic :

Any suggestions on what circuitry we could add for coil detection? DC offset does not effect the performance of the transformer sensor.

Thank you


texts: How to convert capacitor impedance to ESR?

texts:
I select an output capacitor for a DC / DC converter (LM2596), it is said that it needs a high ESR (50-60mOhm). In the characteristics of electrolytic capacitors there is no given value, but there is impedance. How can I get ESR from impedance?

I'm considering the YXF series from Rubycon, data sheet here


texts: How to interpret Vcc and GND on integrated circuits?

texts:
I am a little confused about power supply markings on ICs. For example, if I have an IC named U1 stating that Vcc should be 5V, can I connect it this way:

simulate this circuit – Schematic created using CircuitLab

Or this way:

simulate this circuit

Or this way:

simulate this circuit

etc.

Are these correct or am I missing a point?

Also, if these are correct, then the problem would be calculating the voltage drop on the parts located between + and Vcc AND GND and -, since we don't know the resistance of the IC right?


texts: Solar charger in commercial application based on an LM317 IC

texts:
I have been working on a project of a commercial LoRaWan node. I want it to be powered by 3.7 battery and I consider to add a solar charger. For now, I have implemented a circuit based on an LTC3652 IC and it works quite good.

I found such solution today. What do you think of this one?

I'm not hiding that this solution is way cheaper and easier. Have you ever dealt with this circuit? What's your experience on this one?

Is it safe to implement this circuit in commercial solution or you think I'd better stay with the circuit mentioned in the beginning?


texts: Still audible noise after using a DC DC isolator

texts:
My setup consists of a DSP board with the ADAU1701 chip on it. Signals will come from my phone through an AUX-cable to the DSP. After processing the signals with the DSP they will be converted through 4 PCM5102 DACs into analog signals. The analog signals will then be transmitted through a cable to 25 PAM8403 amplifiers.
First I connected all the electronic (DSP, DAC, PAM8403) to one cheap 5V powersupply but when I turned up to ~15% of volume everything sounded like crackling and clipped noise. Below that everything was somehow okay.
Then I got myself a DC DC isolator (Gaptec 3S4A_1UP) and connected only the DSP and the DAC with output of the DC DC isolator. The input of the DC DC isolator is connected to the same cheap powersupply like all the PAM8403 amplifiers are.
The problem with the volume was gone completely but in all stages of volume I could clearly hear a sharp random crackling (every 0.5-1 second.)
After I connected the DAC and DSP to a seperate USB powersupply and the PAM8403 amplifiers to the cheap power supply there were no more problems anymore.
My questions are:

Why doesn't the DC DC isolator deliver clean power or why does it produce noise into the system?
What are the sharp crackling noises?
What other options do I have to prevent them?
Why did everything clip at low volume when connected together to one powersupply?

Edit:
Here are some usefull Hyperlinks:
Recorded example of crackeling noises,
PAM8403 Amplifier Datasheet, The amplifier module I use,
PCM5102 DAC Datasheet, The PCM5102 module I use,
ADAU1701 Datasheet,DSP board I use,
The DC DC Converter Datasheet,
I am looking forward to every answer.


texts: What does it mean to soft switch a relay?

texts:
I am specifying a relay I/O card for a Beckhoff PLC.

(Link to an overview of Beckhoff digital output slices, scroll to see Relay section)

Some of the relays have a soft switching characteristic called out.  For example, see the description for Beckhoff's EL2602-0010.

What does soft switching mean, in the context of specifying a relay?

Bonus points for explaining how soft switching physically works.

This article may be relevant, but I found the explanation hard to grasp.


texts: Confusion about sampling rate of a scope and its bandwidth

texts:
In sampling theory the BW is determined by the half of the sampling rate. But in a scope things seems to be different if I'm not mistaken.

But for example if you look at the front panel of the oscilloscope model TDS1002B, among other things two things are written. It is written 1GS/s and it is also written 60MHz.

So the BW is explicitly given here as 60MHz. On the other hand if we apply Nyquist law we could have also conclude the BW is half the sampling freq. so 1GHz/2 = 500MHz. So where am I thinking wrong here?


texts: How does this circuit, from an LED night light, work?

texts:
I broke open a dead LED night light before discarding it, and found this circuit:

simulate this circuit – Schematic created using CircuitLab

I'm wondering how it works.  The diode bridge (actually in one package) and the low pass filters for the DC power supply seem fairly clear, but I'm puzzling over the arrangement of the initial capacitor and resistor.  My guess is that the capacitor and the rest of the circuit (bridge and right of it) forms some sort of voltage divider, sized to give the right voltage to the LED; I could imagine the need for a bleeder resistor, but I don't see how R1 does that, quite.  Any insights?

Certainly a minimal AC-DC power supply!


texts:
I intend to build an electric kiln for pottery, clay ( an other materials ) sculptures.
The internal dimensions would be 40cm(height) x 40cm(width) x 40cm(deep).
Therefore, its internal surface is 9600 cm2. I need a maximum temperature of 1300 Celsius.

1) I would like you to confirm or correct this information. I was informed that in a typical kiln the calculation of the total Electric Power necessary is given by this formula P ( Watts ) = 0.6 X Total Internal Area ( cm2). If that is true, then I would need 5760 Watts. However, I found in the internet values that are different from 0.6. So, if you are an expert please give me your informed opinion on that.

2) In order the temperature inside de kiln could be as much homogeneous as possible, its internal walls should be filled with as much heating element wires as possible. But there is a trade-off to be made. The more heating wires the bigger will be the resistance and the weaker will be the production of heat.Furthermore it may unnecessarily increase the cost of heating elements. Additionally, there will be the need to carve too many grooves on the refractory bricks to fit the elements inside which will weaken and possibly fracture them. By looking at the pictures of many different kilns it seems that the optimum distance between two parallel coiled wires is about 7cm ( axis to axis ). But if the grooves should be carved directly on the bricks and in the middle of their height then the distance between parallel grooves would be equal to their height or a multiple number of it.
Would you agree with my reasoning or do you have a different one ?

3) It seems to me that 3 resistors ( heating elements ) electrically connected in parallel is a good circuit because they would use only three relays and probably could be controlled by an electronic controller. What is you informed opinion on that ?

4) Another important aspect of the kiln design is the coiled wire ( heating element ) diameter. The bigger its diameter the bigger will be its durability. However bigger diameter reduces the resistance of the heating element and produces lesser heat. I intuitively think that a diameter of 1.30 mm would be OK. ( Of course, later on, I should also consider the coil diameter and the distance between its turns ).
Do you have a better informed proposition ?

( later on I may need further advice on the same project )


texts: How to create .VCD file or Simulation activity file of verilog code?

texts:
I have Verilog's code. It is simulated correctly and synthesize too. I wanted to write.VCD(value change dumped) file.
I got from internet few command to generate VCD file as given below:

initial begin
$dumpfile ("invchn26.vcd"); // Change filename as appropriate.
$dumpvars(1, t.uut);
end

But have few amount of confusion:
1. The above lines will be written on the testbench. Am I right?
2. I have below files:
testbench: stimulus.v ,
 the main file named F_E. it is instance by name call in stimulus file. like written as F_E call (a,b,CLK,x,y);
I wrote below lines in stimulus (testbench file) :

 initial begin
    $dumpfile ("crt.vcd"); // Change filename as appropriate.
    $dumpvars(1, stimulus.call);
    end

But its giving error.
How DO I create .VCD file with verilog and xilinx.
Please suggest hints.


texts: Driving high current through an LED using PWM

texts:
We are trying to use an LED as a high frequency light source, using PWM implemented through an Arduino. We use an NPN transistor to boost the voltage drop (and current flow) through the LED, per the figure below. The TTL pulse is supplied at Vin and an external voltage (5V) is applied at Vcc. Our application requires that the LED is on for a very short duration (4 microseconds).
We find that when we set the PWM for such short pulse durations, there is a very low voltage drop across the LED (~1V) and hence not much light from the LED. Is this to be expected? And is there any way to boost the light output?
Vin is a TTL pulse, Vcc is 5V DC, Rb is 500 ohms, Rc is 15 ohms
LED is Broadcom / Avago HLMP-CM1A-560DD
Transistor is 2N3904


texts: DC load flow calculation in various programs

texts: I am using PSSe, PSLF, MATPOWER to run the DC load flow. The modeling for dc load flow should be straightforward i.e., to compute \$\theta\$ in the equation P=B \$\theta\$. Here B is the susceptance matrix and by solving linearly using the injections, we should be able to get the value of \$\theta\$ without any iterations. Infact, that is how it is performed in MATPOWER. However, in programs such as PSLF, when I solve the DC power flow, the choice is given to choose the number of iterations. So, how DC power flow is computed in PSLF, PSSE?


texts: Impedance matching in multi-layer circuits

texts:
In a new circuit design, I need some impedance matching for some high speed traces (i.e. Ethernet, USB, SD card...). Usually I define tracks width with this web tool https://www.eeweb.com/tools/microstrip-impedance

Now for the first time I have to use a 4-layer board and I would like the traces in one of the 2 internal layers (so I can better shield these signals).
Which one of the types of microstrip should I choose? (Embedded Microstrip, Asymmetric Stripline...?)

And also, since there will be other traces to match that are close to each other,  will they influence each other?

Thank you very much.


texts:
I am using a lead-acid battery in a solar charging system.  I am writing for an ATMEGA328 to determine the state of charge of the battery.  Its my understanding that this will require a sort of data sheet for the battery cross-referencing:

  Charge Percentage - Voltage - Temperature - Discharge Rate

How is this information usually passed from the manufacturer to the programmer?

Iv'e found many visual charts but what I'm really looking for is some kind of data file with a 4-dimensional array.


texts: NPN transistor not switching 12V from microcontroller

texts:
simulate this circuit – Schematic created using CircuitLab

I'm at a complete loss over here. What I'm trying to do is switch 12V voltage with a NPN transistor (the switched signal later goes to a P-CH-MOSFET). My problem is that nothing works. I've tried a simple circuit as this with a 1K resistor, tried adding a pull-down resistor (tried 1K and 200 ohm values), tried using different transistors (TIP122, BC337, PN2222a), tried using different controllers (Arduino, Intel Edison) and nothing works.

To elaborate, the problem is that I add the load to the collector (whether it's a LED strip, a single LED with a resistor, multimeter) it constantly stays on. Also I do have common ground, I have the power supply and controler's grounds connected to the same rail on the breadboard.

What are the possible problems? Is there hope to solve this or are somehow all of my components are fried? Appreciate all the help.

EDIT: added one of the schematics that I tried. For load I'm actually using a RGB LED strip, so the load in this circuit is just an example.

EDIT2: adding a picture of the circuit on the breadboard.

EDIT3: small update, forgot to mention that my transistor is BC337-40, the difference is that it has hfe of 250.


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it's my first question on here so please be nice.
I want to design a 3 way switch that works with a MOSFET. Aka I want it to work in the same way as a household light would work where it is able to be turned on or off with either switch:

simulate this circuit – Schematic created using CircuitLab

I have designed a MOSFET circuit already to be controlled by the microcontroller that I am using:

simulate this circuit

The switch in parallel with the MOSFET just doesn't do what I want to achieve though and I am struggling to think of a way to achieve this.

To clarify:
If the MCU is holding the lamp on, I would like to be able to actuate a switch to turn the lamp off. If the microcontroller is holding the lamp off, I would like to be able to actuate a switch to turn it on.

I hope my problem makes sense.


texts: Altium: Via stitching not connecting to plane?

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I'm experiencing an issue in altium where my Via stitching vias on the GND net will not connect to my ground plane. Individually placed vias will connect fine through from the top layer polygon GND pour, the plane, and the bottom later polygon pour. As you can see below, the GND plane won't connect to the stitching vias (sides) in the same way it does to the single via (middle) despite being the same net.

I have looked at the stitching layer properties and it seems the plane is not present on the via layer editor when I look a the via style in 'full stack' mode.

I don't know why the plane layer wouldn't show up, yet all the signal layers of my 4-layer board will.

Any ideas?


texts: Is there a simple circuit that can change the AC output voltage from a transformer or AC-AC power supply?

texts:
I have a device that requires 9V AC and rated for 2.1 amperes.  I thought I could modify the output of either of the following voltage supplies to meet those values:

A power transformer that outputs 24V, 50VA
A power supply wall-wart - output 15VAC, 1.5 amperes

Is there a simple way to do this - any schematics/component values possible?


texts: I've got a twisted pair cable that I'd like to use for connecting distributed systems that use 1Mbps CAN network. The problem is that I don't have a clue what's the impedance of this cable and I know that these systems have 150ohm terminating resistors. How can I evaluate the cable impedance to verify if it matches this network?


texts:
I have an electromagnet-based SPDT relay that I am considering using inside a model rocket. It is estimated to experience between 10-20G of acceleration.

Should I worry about the acceleration overpowering the electromagnet? I could use a solid-state relay, but I don't have any handy and would have to wait for shipping.

For context, I am using the relay to discharge capacitors (in parallel) into an electric match to set off a second-stage motor. An Arduino Nano will be used to control ignition.

Relay failure could result in the parachute not deploying (out of the second stage), or even the second stage going off before the first motor disconnects from the body.

EE is not my background (better with CS, but still crap at both). I have researched enough to have a decent understanding of the peripherals needed to launch rockets.


texts: ERROR(ORPSIM-16103): Invalid value when attempting AC Sweep in PSpice

texts: When I attempt to run an AC Sweep in PSpice it gives me an error


texts: Virtual ground concept in electronic circuit

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This is my current sense circuit that I connect to Arduino in order to measure how much current a load draws.

As you can see at the bottom of the image there is a -5 V voltage source connected to the instrumentation amplifier.
The -5 V voltage source I design is this using TLE2426CD.

I get stuck trying to connect that -5 V to the instrumentation amplifier. I try different connections on the simulator but I not get same results as the first picture. I think my problem is in the concept of virtual ground.