texts:
I have built a photodiode circuit using AD712 (precision bifet) and the circuit is working as expected. I have added a programmable gain using a multiplexer which lets me choose a gain from 1 to 100 in 8 steps. I noticed that when my gain is set to maximum, I am picking up some signal which is insync with the frequency of ambient lights (however, the sensor is enclosed in a box).

To make sure that the signal is due to optical noise, I shorted the inverting and non inverting  inputs of my OP AMP which leads to no signal (0 value) for all gain setting.

Detail about circuit: Photo-diode to a trans-impedance circuit -> 2nd stage gain -> RC -> Buffer -> ADC.

While reading about other photodiode circuits, I saw various implementation using OP07C with offset nulling techniques.

I am not sure that if I do need to do some offset as there is 0 signal when photodiode is shorted - which makes me believe that I should focus on optical noise.


texts: Ideal inductor in series with a resistor:

texts: The question is to find the  thevenin equivalent circuit across a and b. The inductors are ideal transformers. I stretched the inductors 180 degrees to make the circuit easier to analyze. From there, I can see that the left hand inductor is parrallel with the voltage source and is in series with the 2 ohms resistance. An ideal transformers has infinite inductance and zero resistance. In my book, it is said that the LHS inductor has a voltage drop of \$ 1\angle 0\$. But, how can that happen it would leave no voltage for the resistance??


texts:
Here is a picture of 3 mounting holes on three different PCBs.

The red one is what I prepared on Eagle CAD and used "hole" button on the left side menu , something like this:

Do I need to use "via" in order to have the same style mounting hole on the other PCBs?
As far as I can see, they are vias on the blue PCBs. Isn't it better to isolate the mounting holes on a PCB? What I am thinking to have a risk to get an unwanted signal or voltage to your ground plane as it is unisolated? or Does it improve grounding or tying grounds of unconnected PCBs?
Is it a gold finish on the mounting holes? Why would I want to have a gold finish on a screw hole that would increase the cost?
The mounting holes on blue PCBs have several holes on it, what is the purpose of having holes on the screw holes? Fabrication-wise, it seems it would slow down the production a little bit as each individual mounting(or screw) hole requires drill holes on it.

The upper blue PCB is from a projector, the bottom one is from a harddisk of a PC.


texts: Is writing in FeRAM memory cell destructive?

texts: I have read that writing in Ferroelectric random access memory is not destructive. But in a WL||PL memory architecture, if I try to write a '0' in a cell and the adjacent cell holds a '1', shouldn't it damage the stored value of that adjacent cell? I mean, both the WL and the PL of the adjacent cell is high also and BL is floating, and due to the parasitic capacitance of the BL, shouldn't it affect the polarization and therefore, the stored value? I mean we perform the read operation based on the charge sharing of parasitic capacitance, right?


texts: LTspice: How can I show multiple probes with waveforms using stepping parameters in different colors?

texts:
I'm using LTspice IV (4.23I) and I am using the .step command to vary the capacitance of a capacitor, so that I can see multiple waveforms for a single probe.

If there is only one probe, then the stepping values have different colors (see below).

My issue is that if I add another probe, the stepped waveform(s) generated from a single probe become the same color. (See blue waveforms below)

How can I keep them as different colors, while also keeping multiple plobes on the same plot?

Circuit for reference:


texts:
I am working on 8 Transistor full adder which is based on 3 Transistor XOR cell.

I have studied many IEEE Papers for 8 Transistor Full adder. All have same ckt as above.But the full adder is not working properly for all inputs values. I am using Tanner EDA at 180 nm tech and 5v supply voltage  for simulation purpose.


texts:
My problem is the following:I tried to write VHDL testbench for shift register with parallel load in active HDL. The waveform is good till the parallel load part where it doesn't want to load p into q.Why is that? could someone please help out a bit.

library ieee;
use ieee.std_logic_1164.all;

-- Add your library and packages declaration here ...

entity shiftregister_tb is
end shiftregister_tb;

architecture TB_ARCHITECTURE of shiftregister_tb is
-- Component declaration of the tested unit
component shiftregister
port(
    d : in std_logic;
    p : in std_logic_vector(3 downto 0);
    clk : in std_logic;
    clr : in std_logic;
    load : in std_logic;
    q : inout std_logic_vector(3 downto 0) );
end component;

-- Stimulus signals - signals mapped to the input and inout ports of   tested entity
signal d : std_logic;
signal p : std_logic_vector(3 downto 0);
signal clk : std_logic;
signal clr : std_logic;
signal load : std_logic;
signal q : std_logic_vector(3 downto 0);
constant clk_period:time :=10 ns;
-- Observed signals - signals mapped to the output ports of tested entity

begin

-- Unit Under Test port map
UUT : shiftregister
    port map (
        d => d,
        p => p,
        clk => clk,
        clr => clr,
        load => load,
        q => q
    );

clk_process :process
begin
    clk <= '0';
    wait for clk_period/2;
    clk <= '1';
    wait for clk_period/2;
end process;

  -- Stimulus process
  stim_proc: process
  begin
    d<='0';
    wait for 10 ns;
    d<='1';
    wait for 10 ns;
    d<='0';
    wait for 10 ns;
    d<='0';
    wait for 10 ns;
    clr<='1';
    wait for 10 ns;
    clr<='0';
    d<='0';
    wait for 10 ns;
    d<='1';
    wait for 10 ns;
    d<='1';
    wait for 10 ns;
    d<='1';
    wait for 10 ns;
    clr<='1';
    wait for 10 ns;
    load<='1';
    p<="0011";
end process;

END;

configuration TESTBENCH_FOR_shiftregister of shiftregister_tb is
for TB_ARCHITECTURE
    for UUT : shiftregister
        use entity work.shiftregister(behavior);
    end for;
end for;
end TESTBENCH_FOR_shiftregister;


texts:
I want to make a device for USB which is connected through usb to PC and offers an usb port.
The device should have a button which ejects (in Windows) the device plugged at the port of the device.

After some  research...
First I wanted to solve this problem through a C# program- but I really have no idea how to access through C# on "my button".
(the project's code isn't available anymore-if you know where I could get it-I would be really really happy.)

So I did some more research...
now I plan to use the WinAPI in combination with some C to accomplish this...(writing a device driver using the KMPF(Kernel module of windows).

→But: I'm completly new to this.

How should I start?

Any suggestions/links which microcontroller would be good for this?

Is it possible to use the WinAPI (KMPF) to access on hardware input/my device's button?


texts: How to understand the open-loop gain of a op-amp?

texts:
According to the book Electrical Engineering 101, the open-loop gain of an op-amp can be very high, say 5000. When the difference of the 2 inputs is 1V, the calculated output can be as high as 5000V.

But if the op-amp is actually connected in to a circuit, the real output voltage is much lower than the calculated value. Say, it can be as low as 5V.

How is this open-loop gain measured? Do we use some kind of special voltage meter to measure the voltage across the output and the ground? But if so, it is not open-loop at all. It's kind of a dilemma. Or do I derail from the correct path of Electrical Engineering thinking?
What's the point of the open-loop gain if the actual output voltage can never be that high?

(I just want to expose my mental difficulties so that precise answer is possible. Hope I made myself clear. Thanks.)

some notes

(I am not quite familiar with some jargon in EE field. So I will collect them below as necessary.)

I guess rail are the lines in the yellow rectangle since I see someone talking about rail-to-rail output.


texts:
Is MIMO the wireless version of link aggregation in wired networks?

I'm not asking if MIMO is a similar link aggregation protocol like LACP or PAgP. What I'm asking is, if it is the same concept as bonding multiple links to act as one channel.

Let's say for example, we have a pair of 2 x 2 MIMO transmitter and receiver. If the transmitter is to send two packets to the receiver, does it mean packet 1 will be sent through antenna 1 and packet 2 will be sent through antenna 2 simultaneously, and the receiver will receive packet 1 through antenna 1 and packet 2 through antenna 2 simultaneously?

If yes, how do the two signals not interfere with each other? Is it because they are orthogonal signals? Also, is OFDM always required in MIMO because it is the only way to generate orthogonal signals?

If no, then how does MIMO increase capacity? What is the main point if MIMO?


texts:
When considering a simple DC regulator such as a Texas' LM22677 on a PCB, should it use the digital or analog portion of the ground plane?

EDIT: Contextualizing, I have a 12V input feeding two LM22677 regulators to achieve a 5V and 10V power lines. The 5V is then used to power and Arduino, and the 5V/GND output of the Arduino is then used to power several analog/digital ICs. Should the ground plane of the DC regulators be common to the rest of the circuitry, or should it be separate?


texts:
Let's imagine a strip of 30 LED, each of those controlled by daisy chained shift registers and a micro controller.

I would need 4x 8-Bit shift registers like the SN74HC595, and the last 2 outputs wouldn't be used.

If this strip of LEDs (and associated shift registers) was part of a module assembly where you could chain modules one after another, and the output of the first module would get shifted to the input of the following module, etc... This would work fine with multiple of 8 LEDs, as the SN74HC595 includes an output for daisy chaining.

But the strip is 30 LED only so the 6th output of the last shift register should be shifted to the next LED strip, thus by-passing the last 2 bits.

Is there an easy way to do so ?

EDIT: Looking for a hardware way of doing it, as 30 LED is an example but let's assume the length of the LED strip can be any number, and I want my code to work with any combination of LED/number of modules.


texts:
I've got a Streamdeck that has a USB 2.0 out as a fixed cable. I've bought a USB C 2.0 board that I want to wire up so I don't have a fixed cable anymore.

My issue is I don't know what the two black cables are, as I assumed red is for power, white is for D-, green is for D+ and black is ground. That's as much as I know when it comes to this sort of stuff and I don't know what the last black cable is for. I've read it's something to do with OTG or something, but how would I then wire that up or would I not need to? Should I just wire it to ground?

Thanks in advance.

USB C 2.0 Breakout Board that I have.

Streamdeck PCB USB wiring (USB 2.0)


texts: Using a voltage regulator to power MSP430 microcontrollers

texts: I'm trying to power a MSP430 microcontroller at 3.0V. I have a voltage regulator whose output is 3.6V, but I have a Bluetooth module that can only tolerate 3.0V. I plan to use a voltage divider to convert the 3.6V output of voltage regulator to 3.0V. Are there any recommended values for resistors? Will impedance mismatch be a problem?


texts: Matched biasing transistor vs. emitter resistor in current mirror

texts: If adding emitter resistors can reduce the temperature variation in \$V_{BE}\$, why do we still need to find a matched pair of transistors to construct a current mirror?


texts:
I have a small circuit with a battery and a lamp. If I close the circuit the lamp will turn on, otherwise will turn off.

I want to create a very small wireless switch. It will have only 2 signals to understand:

Turn On (close the circuit)
Turn Off (open the circuit)

The circuit will work with a 3V battery. And it need to be as small as possible. So, I think the Bluetooth will be the best. There are other good technology?

What I want is a start point. Where can I find a good book/tutorial to start this project? Or, if this is easy to say, how I build this switch?


texts: Cockcroft-Walton multiplier - capacitor sizes

texts: When building a CW cascade people rarely talk about the size of the caps. Surely they must be a certain size for the circuit to work?


texts: Noob trying to select resistor for 3 LEDs

texts:
So I'm making a parallel LED circuit using THREE CREE x-lamp LEDs which typically run at ~ 3.1v @ 350 mA, but they can max out at 1000 mA. I'm putting a resistor for each LED.

So my logic may be flawed here but this is how I'm thinking (sorry if I seem stupid):

My power source is 12v and 1 amp, which means if I use three equal resistors, each LED will draw .333 mA, close to the typical value.

Calculation of resistor: R = V/I ------ R = (12-3.1) / .333 (3) = 8.9 ohms   (I believe I'm supposed to multiple the denominator by amount of lights I have, correct? So I would use a 10 ohm resistor.

Wattage of resistor: P = VI ------- P = 8.9 ohms * 1 amp = 8.9 watts. So I would use a 10 ohm, 10 watt resistor.

Is this correct?

Also, say I had only one LED. would it draw that maximum amount of amps from the power source, so 1 amp?

Sorry, I am really new to this stuff. I don't know if I'm doing the correct calculations or not.


texts: Flow of current through human body to the floor

texts:
I'm having trouble understanding the flow of current from a live wire to the floor via a human.

Is the floor that we stand on conductive in nature? How does current flow through us if we stand on a wooden floor or tiled floor, and underneath the floors there'd be cement and bricks? So how does a conducting path even come into being if we are in contact with a floor?

In the same sense, how does current flow to the mud in the earth ground if the mud is non conducting in nature?


texts: I don't know what size to choose. Does SMD capacitor package matter in my case, Is it wrong to choose 0805 package?


texts:
Giving the following schematic:
What is purpose of R1 and the diodes ?


texts: How does this electrical ballast need to be wired to the flyback transformer?

texts:
I just got myself a flyback transformer and an electrical ballast for fluorescent lamps as I heard those can be used together.

The electrical ballast is supposed to generate a high frequency which is exactly what a flyback needs to generate high voltage arcs.

I identified the primary coil of the transformer (it has a 1.8Ohm resistance, the other coils have a resistance of 0.8Ohm and lower) and connected everything but it didn't work. I didn't get sparks from any of the pins to the high voltage cable.

I am assuming that I'm not using the ballast correctly so I will include several pictures for you.

assembled ballast

left connector (to the mains, I guess)

right connector (to the lamp/transformer, I guess)

top of the circuit board

bottom of the circuit board

I hope one of you knows the answer to my problem.


texts: What is effect of echo canceller on QAM signals?

texts:
During data call or fax call echo cancellers are switched off in entire path from phone to exchange and exchange to phone.
Echo canceller are used to cancel echo during voice call. Modulation in data and fax call also done in baseband carrier.
Why echo cancellers are switched off during fax or data call.
Why echos has dont effect on fax and data call signals.


texts:
I am trying to get through this section of a course: http://hamsterworks.co.nz/mediawiki/index.php/Module_9

I am trying to write the 30 bit counter module (Project 9.1 on the page). I have the counter wrote in a normal .vhd file from the previous sections in that course. Here is the code:

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

entity Clock_Signals is
    Port (  switches : in STD_LOGIC_VECTOR(7 downto 0);
                buttons     : in STD_LOGIC_VECTOR(3 downto 0);
                LEDs     : out STD_LOGIC_VECTOR(7 downto 0);
                clk      : in STD_LOGIC
         );
end Clock_Signals;

architecture Behavioral of Clock_Signals is
    signal counter : STD_LOGIC_VECTOR(29 downto 0) := (others => '0');
    signal incHighNext : STD_LOGIC := '0';

    signal buttonsPrev : STD_LOGIC_VECTOR(3 downto 0) := (others => '0');
begin
    LEDs <= counter(29 downto 22);

    count: process(clk)
    begin
        if rising_edge(clk) then
            -- Allows for a step through
            --if (buttons(0) = '1') and (buttonsPrev(0) = '0') then
                --counter <= counter+1;
            --end if;

            counter(29 downto 15) <= counter(29 downto 15)+incHighNext;

            if counter(14 downto 0) = "111111111111110" then
                incHighNext <= '1';
            else
                incHighNext <= '0';
            end if;

            counter(14 downto 0) <= counter(14 downto 0)+1;

            -- Update state
            buttonsPrev <= buttons;
        end if;
    end process;

end Behavioral;

But when I make a module, I can't figure out how to translate it over. Here is my current module:

module mymodule(
    input [3:0] clk,
     input [3:0] enable,
    output [3:0] count
    );

endmodule


texts: How to calculate the weight my DC motor can move?

texts:
I've that 12V DC motor with gearbox in the picture.
These are the specs of that motor:
Voltage = 12V
No load current = 250mA
Sall Current = 5 A
Stall Torque = 20 Kg/cm
Motor Rated RPM = 133
Shaft Diameter = 4 mm
Motor Length (without shaft) = 53 mm
Motor Diameter = 25 mm

I want to attach that motor directly to one of the rear wheels (4-inch diameter rubber wheel) of a toy (with 4 wheels), how to calculate the maximum weight this motor can move?


texts: Relationship between resistance, amperage, and propagation length of signal

texts: n electrons sent into a wire of length L, and n/2 electrons sent into a wire of length L/2, diameter unchanged and wire material unchanged, does the "signal" of electron propagation reach twice as far in the first example, or, is the relationship not linear?


texts: Is it possible to have too much decoupling?

texts:
In most of my designs recently I've been quite liberal in using decoupling caps (especially 0.1uf X5Rs) on most if not all of the supply pins for anything that performs some remotely significant switching (especially when the datasheet/application schematic specifies fewer caps than it has supply pins).

Is this an ok/good practice or is it important to stick to the manufacturer guide and just use what they specify?


texts: How to choose which usb connector type is best for Processor working as a device mode?

texts: Based on my processor specification, USB device mode is supported.USB has different kind of connector based on its host/device/ OTG modes. IF USB-OTG mode supported processor used Micro AB usb connector, Then if my processor only support USB device mode, which is the exact connector should i use?


texts:
I'm trying to interface MCP4728 with STM32F0.
The commands are transmitted by controller and same are received successfully by DAC MCP4728.
I2C transmit function also returns HAL_OK on I2C transmission.
But, the corresponding channel is not getting activated with the count I've entered.
Also, I've tied the LDAC pin of DAC permanently to low so that output gets updated continuously.
Can anyone help me with this issue? I need to get output on DAC on count sent by microcontroller.
EDIT 1: I've done the coding according to the the commands given in datasheet. These functions successfully return HAL_OK. Also, I've found the binary equivalent of the commands form datasheet and verified the same on DSO.
EDIT 2: This the the waveform captured. Exactly the data sent in below functions. Blue is clock pulse, yellow is data.

Note: I've used a union for sending data as my max data size is 12 bits but I2C commands of STM32 allows only 8bits to transmit.
Is there any method or step I'm missing due to which I'm not getting output?
EDIT 3: Whatever i send in command, only 9 bits are transferred. 8 bits of slave address and 1 acknowledge bit. Further data is not being passed.
Is there any mistake in I2C?
void SelectVref(uint8_t Channel,DACChannel* AnalogChannel,uint8_t Vref)
{
    uint8_t ret1;
    uint8_t TxFrame[10];
    AnalogChannel[Channel].VRef=Vref;
    TxFrame[0]=(DAC_mcp4728_VREFWRITE)|((AnalogChannel[0].VRef)<<3)|((AnalogChannel[1].VRef)<<2)|
                            ((AnalogChannel[2].VRef)<<1)|(AnalogChannel[3].VRef);
    //ret = HAL_I2C_Master_Transmit(&hi2c2,DAC_mcp4728_ID,TxFrame,1,10);
    ret1 = HAL_I2C_Master_Transmit_DMA(&hi2c2,DAC_mcp4728_ID,TxFrame,sizeof(TxFrame));
}

void SelectGain(uint8_t Channel,DACChannel* AnalogChannel,uint8_t Gain)
{
    uint8_t ret2;
    uint8_t TxFrame[10];
    AnalogChannel[Channel].Gain=Gain;
    TxFrame[0]=(DAC_mcp4728_GAINWRITE)|((AnalogChannel[0].Gain)<<3)|((AnalogChannel[1].Gain)<<2)|
                            ((AnalogChannel[2].Gain)<<1)|(AnalogChannel[3].Gain);
    //ret = HAL_I2C_Master_Transmit(&hi2c2,DAC_mcp4728_ID,TxFrame,1,10);
    ret2 = HAL_I2C_Master_Transmit_DMA(&hi2c2,DAC_mcp4728_ID,TxFrame,sizeof(TxFrame));
}

void WriteAnalogVal(uint8_t Channel,DACChannel* AnalogChannel,uint16_t AnalogCount)
{
    uint8_t ret3;
    uint8_t TxFrame[10];
    AnalogChannel[Channel].AnalogCount.AnalogCntIn16=AnalogCount;

    TxFrame[0]=AnalogChannel[0].AnalogCount.AnalogCntIn8[HI];
    TxFrame[1]=AnalogChannel[0].AnalogCount.AnalogCntIn8[LO];
    TxFrame[2]=AnalogChannel[1].AnalogCount.AnalogCntIn8[HI];
    TxFrame[3]=AnalogChannel[1].AnalogCount.AnalogCntIn8[LO];
    TxFrame[4]=AnalogChannel[2].AnalogCount.AnalogCntIn8[HI];
    TxFrame[5]=AnalogChannel[2].AnalogCount.AnalogCntIn8[LO];
    TxFrame[6]=AnalogChannel[3].AnalogCount.AnalogCntIn8[HI];
    TxFrame[7]=AnalogChannel[3].AnalogCount.AnalogCntIn8[LO];

    //ret = HAL_I2C_Master_Transmit(&hi2c2,DAC_mcp4728_ID,TxFrame,8,100);
    ret3 = HAL_I2C_Master_Transmit_DMA(&hi2c2,DAC_mcp4728_ID,TxFrame,sizeof(TxFrame));

}![enter image description here](https://i.stack.imgur.com/s3vON.jpg)


texts: Is there any benefit from installing 2 resistors in parallel instead of 1 resistor?

texts: I'm restoring an old tube radio. When looking into the schematics I noticed that they drew 2 resistors in parallel instead of  1 resistor, between the power transformer and the rectifier tube. Is there any benefit from installing 2 parallel resistors instead one resistor?


texts: How big does my wireless charging coil need to be?

texts:
Background: I need to wirelessly charge a battery at about 100W. However, there seems to be a gap in the wireless charging market. There are plenty of wireless power transfer systems operating in the sub 20W range for mobile phones, and several in the multi kW range for charging cars. But nothing I can find in the 100W range.

So I'm thinking of designing my own. Before I go too far, I'd like to sanity check my idea to make sure it will fit within the size and weight constraints of my system.

Question: Is there some way to estimate the size and/or weight of the coils required to wirelessly transmit power; some equation or rule of thumb?

Added: I haven't thought about the frequency yet, as I'm still trying to determine if this is feasible. So far, I can't find much information about sizing coils. However, I've just realised that I'll be able to have the ferrites of the coils touching, so this should improve efficiency.


texts: Can I use a 28 VDC 10 A relay to toggle a 10 kV DC 0.03 A source?

texts:
Neon signs use transformers that can output at 10 kV DC at 30 mA = 300 W. I want to toggle this power with a common 5 V relay, but the DC rating for these are about 28 V DC at 10 A = 280 W. Does the output of the transformer exceed the rating of the relay?

If so, why would the same relay (with a 125 V AC 10 A rating) work on the input of the same transformer if its input is rated at 125 V AC 0.9 A? Am I confused about the power limits of the relay?


texts: Does "open source hardware" only apply to controllers or to all components?

texts:
I'm new to the hardware world and am coming from a software background, and am trying to build a small device to attach to my PC via USB. I've heard the term "open source hardware" in reference to controllers/MCUs/CPUs, but was wondering if it can also apply to any hardware component, such as:

Power Supplies
Transceivers
Motors
LEDs
Speakers
RFID Scanners/Tags
Motion Sensors
Light Sensors

If not, then why? If so, then how does one tell an "open source" component, such as an "open source transceiver", from a closed source/proprietary one?


texts:
I am new to "electrical engineering" and I am working on a little arduino project.  I want to have a SPST switch be used as a digital input on the board.

I have one of the switch leads connected to posative and the other connected to the digital input.  The problem with this is that when the switch it off I can't be sure the input will be grounded.  How can I make sure the input is grounded when the switch is off?

Would it work if I connected the digital input to a resistor that is connected to ground so when the switch is off it will be grounded, but when the switch is on it wont short out -- would that work?


texts:
I'm trying to design a smart card interface using one 8051 UART and a Pierce oscillator circuit.

The project seems to be working, because I'm getting response from the smart card. However, I'm having difficulty controlling the clock.

The sequence after card insertion is:

power the card. I'm using p3.3 for this;
take reset pin high. I'm using p3.6;
start the clock.

I'm using a NOT gate to power the oscillator circuit. The pin3.7 is connected to the input of the gate, and the output is connected to the VCC of the Pierce oscillator circuit (which also consists of a NOT gate which drives the output high).

I also tried a ULN2003, with a pull-up at the output.

However, this sequence doesn't seem to work fine.

But, if I disconnect the VCC of the oscillator while the code is waiting for response, and connect it again, I get full response, which is consistent over many tries, and valid according to 7816 protocol.

That made me believe that the circuit that turns the clock on and off is not working fine.

I've attached the two circuits I'm using, I want to know if there is a better way, or if maybe, I'm doing something wrong


texts: Impedance Matching of Antenna and Amplifier

texts:
I've been doing a lot of research on impedance matching and I am just having a hard time understanding some of the specifics and I was wondering if someone here could help me out.

I have a 50 Ohm Antenna connected to an amplifying circuit which then outputs to a 50 Ohm sma jack.  As part of the amplifying circuit there is an amplifier and a combination of other components.  For your reference I have the amplifying circuit below.  I also have the S parameters for the amplifier.

So the sample circuit I posted is designed for a 500 MHz signal.  I would like to redesign it for a 150 MHz signal.

I'm not really sure how to go about it, but my current thought is to try and get the combination of S11+Impedance(6.8 NH)+Impedance(100pF) as close to 50 ohms as possible, and the same for the output but with using S22+impedance(100pF).  So I would adjust the values of these components to get the best fit.

Is this even in the ballpark of being correct?


texts:
I am designing the front end(single ended to differential) for the ADC using LTC6406 to interface with the 20MSPS ADC. My input frequency is 140 MHz.
Simulation Sch is shown below:

L1, L2 and C1 are used to make the filter of 140MHz. When I fed input of 140MHz 2Vpp with DC offset of zero, it works fine. Waveform shown below:

But when I fed this circuit with 140MHz, 2Vpp with DC offset of 1V, I get the waveform shown below:

Can the output waveforms shown in both the figures be fed to ADC and ADC will give same response.

I am unable to make out the modification in circuit for 140MHz, 2Vpp, 1V DC offset. And looking into part numbers of L1, L2 for 140MHz filter, the datasheet of the inductor talks about self resonant frequency and Q factor of inductor. How Q and resonant frequency of inductor will affect my filter.

Final Edit: Here is the rectified Sch with waveform:


texts: Can I use a potentiometer to reduce sound level in a speaker?

texts:
I want to reduce the level of sound in a speaker (i think 6Ω 30w rms). I wonder if it is that simple to put a potentiometer in one of the cables.

If this can do the trick, how do I calculate the resistance needed?


texts: Detect multiple Hall Sensors on one input

texts:
I'm new here and to the electronics world, so my question may be dumb one!
I have multiple Hall Sensors (A3144) that I wire to the digital inputs of my arduino:

I am able to test in the code if each one detects a magnet (when the input is LOW).

However I have 5 Hall Sensors and in my use case the only information I need is if they are all detecting a magnet or not (so 0 when they all detect a magnet and 1 if at least one sensor does not detect a magnet).

Is it possible to put the sensors in parallel in order to have only one input wire?


texts: How does a digital logic NOT (inverter) gate work?

texts:
I've read several so-called explanations on the web of how a NOT gate works, but they all explain WHAT it does, not HOW it actually works. I know what it does.

Consider this schematic of a NOT gate:

When A is low (0), switch T1 is open, and OUT is high (1). That I understand: Current passes from the positive voltage (+Vcc) through R2 to OUT. Is this correct?

What I don't understand is what happens when A is high (1) and T1 is closed. OUT is supposed to be low (0) in this case, but I don't see what's actually happening in terms of current. There is a path through T1 from +Vcc to ground, but how does that result in OUT being low (0)?

Can someone who understands this please explain in terms of voltages and current flow exactly what's happening?


texts: Voltage drop measurement result doesn't match my theoretical calculation

texts:
I have a \$1.5\Omega\$ resistor and \$8.84V\$ battery. My multimeter tip's resistance is \$0.3\Omega\$.

I've tried to compare the calculated voltage drop (which is \$8.84V\$) with the measured value.

What I've tried

I've connected the resistor to the battery and then connected the tips to the battery terminal to measure the voltage between terminal. (The time was short. About 3 seconds)

The value should be \$0V\$ but it was \$0.34V\$ (means the voltage drop is \$8.5\$).

Why is there a difference?


texts: CircuitsClouds: Why is led voltage not dropping?

texts:
Today I used the website http://circuits-cloud.com/ for the first time.

I created the circuit below. I assume N is the forward voltage of the LED.

What I would expect: VoltMeter 2 equals the forward voltage of LED2 (which is N = 1.8 V).
What I see: VoltMeter shows 0.03 V

As a side note, when I add two more LEDs, resulting in 3 times the forward voltage of 1.8 V which is 5.4 V, while the voltage source is only 5 V, VoltMeter2 still shows a value.

Do I do something stupid?


texts: How do you calculate average absolute value of a sum of sin functions with different amplitudes and frequencies?

texts: I cant seem to find the answer anywhere. I remember there was a simple formula for doing this but I dont have the book with it anymore. Finding where the function is positive and where is negative and than integrating it would be too tedious.


texts: How much does Igss vary with temperature?

texts: I was looking at a transistor (BUK98190-100A/CUX). I see that Igss is 100nA at 25C. How does Igss vary with temperature? Is there some way to guesstimate the max at 100C, given that the max at 25C is 100nA? I will be biasing the gate with a high value resistor. Just trying to get a grip on how much leakage I should allow for.


texts:
Most designers when are controlling an LED have to make the same old circuit of Vcc -> Resistor -> LED -> Transistor (you need the transistor in case your MCU/MPU pins can't handle the LED current, and many MCU/MPU can't give you more than a few milliamps).

I wonder if there is a LED that comes ready to just be connected to Vcc and GND with a signal pin to turn it on or off, this might save some board space, but I never heard of them. Does anyone know if they exist and their name?


texts:
I am designing a low noise SMPS like this
http://www.ti.com/lit/df/tidrgc2/tidrgc2.pdf switching from 40-90 kHz.

I have a weird problem, on the output we are seeing a spike of noise at 5.5 kHz and multiple (decaying in a few multiples), tested with differential amplifier and correct techniques.

We have no idea where it comes from (maybe ringing of secondary transformer inductance + caps)?

Noise capture

Update:

We added a C and R across transformer, 1000 uF and 20 ohm and we seen a 6 dB reduction on noise. We are experimenting with different values to lower the noise. The only LC tank we are seeing is diode capacitance (and the RC snubber across it) and transformer secondary winding.

Second update.

We used 2x47uF parallel across pin 6/10 + 50R and spike is slightly lower .


texts: Using TTL logic, is it better to use a JFET or MOSFET switch for power?

texts: Using a 3.3V (max. 8 mA) output pin off an Intel Galileo development board, I need to turn on and off a 18V DC motor. Is it better to use a JFET or MOSFET transistor?


texts: Determining output impedance for a pulse generator

texts:
I have a basic question about determining the output impedance of a circuit. Output of this circuit is through R6 in the Figure above. This will be an input for a data-acquisition hardware channel which has 1Gohm input impedance. Setting R7 and R6 an equal resistance, the output can be adjusted to 6V pulse.

So far so good.. My question is as follows:

If I choose R6 = R7 = 1k or R6 = R7 = 10k or R6 = R7 = 100k I get the same voltage output with different currents.

Seems as long as R6 = R7, all works if you just want to have 6V output. But it kind of didn’t satisfy me choosing an arbitrary resistor values.

So in my case which R6, R7 resistance you would choose for an optimum circuit design perspective and why? What is the basis principle of choosing the output impedance here? Is that the current drawn?


texts:
I am trying to calculate the wavelength on microstrip transmission lines. From what I have understand I should use the following relationship:

\$ l = c/(f*\sqrt(Er))\$ where Er is the dielectric constant of the material I use (Rogers 4350B), c is the constant value for the speed of light and f the frequency. Is that the correct formula? Does this change in case I use a differential coplanar waveguide?

Thank you


texts: Controlling dc motor in arduino with and without a load

texts:
I wonder if there is an alternative solution to this problem:

I have a 3v water pump being controlled by an arduino, which pumps water out of a bucket. I would like the pump to turn off once the bucket is empty. My idea for this was to measure the voltage at the pump (which in theory should change depending on the load; that is, very small if bucket is empty and the pump is not pumping/ has no load). The pump will remain on as far as the voltage drop is large and will turn off if the voltage does not drop.

The alternative is to add a water level sensor, but my arduino run out of pins.

Is there another way to control the pump from the arduino, depending on the dc motor load?


texts: Will it work if I place hall sensor heads facing magnets in outrunner brushless motor

texts: Will it work if I place hall sensors facing the magnets like in the picture below? I cannot put it in between the teeth because the hall sensor is bigger than the gap.


texts:
Power driver IC's (like the L298) have absolute maximum ratings for peak current, continuous current, and temperature. I get why overtemperature could cause the IC to fail, but, assuming I kept the temperature below that with a big heat sink, why does the maximum continuous current rating apply?

We know the driver can tolerate more than the max continuous current because it can take bursts of up to the max peak current, which is considerably more. So, if I kept the temp low, why couldn't the driver source that max peak current indefinitely?

Note that I gave the L298 as an example. I am asking about IC's in general.


texts: Bluetooth Headset to Bluetooth Transceiver

texts: I have a little bit of experience with Bluetooth and Arduinos but I was wondering if anyone might be able to tell me if it is possible for a Bluetooth headset to be linked to a Bluetooth transceiver connected to an Arduino microcontroller? I know that when you link a Bluetooth headset to your smartphone, there are usually some steps you have to take on your phone to confirm the headset. And if its not possible to link it like you would normally link to a smart phone, could I manually assign it to connect to only one headset in the code on the Arduino?... Sort of like a static address assignment for the Bluetooth Personal Area Network. Any thoughts or comments would be appreciated.


texts:
I have a multiple SPI busses running through a ribbon cable which is 15cm long. What is the best CS, SCK, MOSI, MISO orientation to avoid the cross talk between each wire and is it enough to use ground wire separation between each SPI connection pair?
Thank you.


texts: Could someone explain the RS485 section of the EVALSTPM3X-3PH board?

texts: The schematics under question is a 3-phase metering board. It uses a number of isolators. The main MCU of the board is STM8S003K3. Its RX/TX pins are connected to the input an isolator (ADUM1412) and the output of the isolator is connected  to FT232BL and through some transistors to an RS485 chip (ST485B). I understand the connection between ADUM1412 and FT232BL, what I don't get is how RS485 fits in the picture.


texts: Can SPI programmer interfere with other components on same pins?

texts:
I'm building custom made Arduino board, with SPI header.

SPI pins on Atmega328 are 13,12,11 Arduino pins which I use in my project already.
Can other components conected on these ports interfer with programer during bootstrap ?

Here are mentioned resistors separating Arduino from other components, are my 1k R[6-8] resistors enough to prevent such interference ?

BTW This is my first board, any ideas are welcome :)

EDIT : Image in high resolution http://i.imgur.com/tHznP2L.png


texts:
I just stumbled over a quirk in my simulation. I have a fairly standard PMOS gate drive with a capacitor C1 for controlling inrush current during turn-on.

EN input is normally high and pulled low when fault is detected. Since the fault detection logic is only active after VDD provided by a Zener has stabilized Q1 should be open, but the gate is pulled up by R2. Furthermore, Q2 is controlled by voltage detector that pulls to VDD once the detection circuitry is online, thus Q2 also blocks.

What I don't understand is, how M1 can turn-on by a step on Vin when it's gate is pulled to Vin by R2 and the connection to ground is blocked by Q3.

Also, what can I do against this behaviour? Or is this a non-issue and only present in simulation?

I checked also with rise time up to 10ms but the effect is still there.

simulate this circuit – Schematic created using CircuitLab


texts:
I have a mains track (230VAC, 50Hz) on a custom PCB routed to multiple Solid-State Relays, and I want to measure the power going through this line.

I'm looking into Current Transformers (CTs) to sense the current on the mains track, rated at a max intensity of 2A.

I understand the principles behind the transformer itself, the burden resistor behind it, etc. I am not able to understand some of the electrical properties found in such transformers datasheets.

For now I focused on a WE-CST PCB-mounted CT from Würth Elektronik, whose electrical properties are presented in the following picture:

Here are my (mis)understandings:

The Voltage-Time (Voltage-µSecond) constant somehow rates the maximum achievable voltage ramp without reaching the core saturation. Is this for the primary or secondary coil ? How does this relate to my specifications ?
What is the Rated Voltage ? Is this the maximum allowed voltage across the primary coil, or the maximum rated voltage across the burden resistor on the secondary ?
Some CTs also specify a frequency range (e.g. 40KHz to 100KHz), can I use such CTs with a much lower frequency (50Hz in my case) ? What additional parameters and bias should I take into account in this case ?


texts: PWM over DMA on STM32F100 behaves strange

texts:
I try to drive WS2812B LEDs with the STM32F100 chip. I read a lot of sources and stopped on the following thing.

I have a repository with latest version of code: https://bitbucket.org/ruslanpopov/stm32-ws2812b-dma/commits/branch/armka

I did debug print to USART and saw that everything is OK there.

I connected a Saleae-like analyzer and different version of reality that also is proved by the LED's behaviour.

I sent RGB=0x550000. The PWM buffer has the right values. But the analyzer takes RGB=0x660000. I don't understand how 0b01010101 becomes 0b01100110. What is the reason?


texts: How Do Intermodulation Products Manifest in Transmitting Equipment?

texts:
What I Understand Already:

Intermodulation products manifest in receiving equipment as a result of several near-by transmitters, each operating at different carrier frequencies, mixing at the receiving antenna.
The signal sensed at the receiving antenna produces an alternating current that contains a mix of each carrier frequency (plus harmonics thereof, for each carrier).
Presuming that frequency selective components before the RF amplifier don't attenuate the power at each carrier too much, non-linearities in the RF amplifier will produce intermodulation products at frequencies which are linear combinations of each input carrier.
Some of these intermodulation products fall near the receiver's tuned bandwidth, creating undesired power in the side-band (which is why it's worth modeling intermodulation effects).

But...
However, I've learned that transmitter intermodulation products can be important to model as well. How do these intermodulation products manifest themselves in a victim transmitter?
Let's consider a two-carrier mix at the input of the RF amplifier (block diagram shown below).

The first carrier is easy to explain: it is passed through the IF-stage into the RF-stage, to the input of the RF amplifier. However, there are only two possible routes for the second carrier to be passed to this victim transmitter's RF amplifier:

The second carrier penetrates the victim transmitter's casing (seems nearly impossible, saying that a Faraday cage sole purpose is to attenuate external radio signals)
The second carrier impinges on the victim transmitter's antenna, producing an alternating current that is passed through the output of the amplifier into its input (seems more likely, since there wouldn't be any protective casing over an antenna)

producing an alternating current that is passed through the output of the amplifier into its input

So far, I've accepted this as an explanation for how these IMPs manifest themselves in a victim transmitter. But, I realize that it's very hand-wavy. Can some provide a more technical explanation of this, if my understanding is even correct?


texts: What is the difference between electrical engineering and electrical engineering technology?

texts: I have recently found that someone can get a BS. in Electrical Engineering and a BS. in Electrical Engineering Technology. I'm trying to find the fundamental difference between the two, but the only thing I can find is that EE deals more with AC currents and power, while EET is more focused in device-controlling circuits. What are the fundamental differences between the two? are there an parts of EET that shouldn't be discussed on EE.SE?


texts: Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse? Is it necessary for practical calculations and analysis?


texts: Parasitic Source inductance and switching Mosfet

texts:
simulate this circuit – Schematic created using CircuitLab

Consider the above circuit, (the values are not correct). When I want to turn off the MOSFET, the output of the driver would be 0. If I have a large di/dt and a large parasitic source inductance, the voltage across L2 would be large and the driver won't be able to close the MOSFET, at least it will oscillate betwenn turn on and turn off until the di/dt be not enough significant for producing a voltage Vgs superior to Vdriver-vth ? Is this possible ?

It will help to turn off ...

Thank you very much.


texts:
In VHDL I can write (0 downto 1) and will generate a Vector with 0 elements.

I want to do this to "rightalign" a field in a union, if needed.
Samplecode:

module example #(int ITEMS=3)(output logic[4:0] result);
union {
  logic [4:0] result;
  struct {
    logic systemstatus;
    logic [4-1-ITEMS-1:0] padding;
    logic [ITEMS-1:0] itemStatus;
  } bitfield;
} myStruct;
endmodule;

I want to generate a struct that looks roughly like this:

systemstatus | 0padder | item3 | item2 | item1 //ITEMS==3
systemstatus | item4   | item3 | item2 | item1 //ITEMS==4

As you can see the padding field disappears for 4 items. However the code above will not do what I want in system verilog since instead of creating a vector with 0 elements, I will always create a vector with at least one element ([0:0]), and when the expression becomes negative ([-1:0]]) I will create a vector with two elements.

Is there a way to let padding "decay/degenerate" to an empty vector? I know I could make myStruct.bitfield.itemStatus simply always the right size and always access a subvector. But the point is to do the magic once in the struct and not worry about it anymore in the rest of the code.


texts:
Using pic32mx340F512H and XC32 compiler and ICD3 debugger on MPLAB.

So I'm working on displaying colors on a screen using VGA protocol and, thus, need to max the clock speed.
The standard for a pixel clock is 25.175 Mhz, however 20Mhz should work just fine with some timing tweaks.

My issue is: I need an interrupt every 1/20,000,000 seconds (20Mhz), BUT, I've tried everything (or everything I can think of) but I can't get enough speed.

(Maximum about 3 Mhz measured on a pin with a multimeter and a basic while(1) {LATDbits.LATD1 ^= 1}

I first tried with almost every combination, but this "should" normally work (I only wrote the ones that matter):

#pragma config FPLLIDIV = DIV_2
#pragma config FPLLMUL = MUL_20
#pragma config FPLLODIV = DIV_1
#pragma config FNOSC = FRCPLL    // Tried FRCPLL PRIPLL and multiple other possibilities
#pragma config FSOSCEN = ON
#pragma config IESO = OFF
#pragma config POSCMOD = HS      // HighSpeed mode
#pragma config OSCIOFNC = ON
#pragma config FPBDIV = DIV_1    // Pb_Clock is Sys_Clock / 1

And my tests where with SYSTEMConfigPerformance(80000000), I even looked up the code and made myself the function since in my project I can't use plib.h.
It behaves exactly like the plib function and even better since SYSTEMConfigPerformance only sets CHECON to a submaximal value.

Tried shadow registers too, but since even with one instruction in the main while loop, I can't get enough speed, i don't think the issue relies on the interrupt or modules but on the sysclock not being fast enough.

To sum up: I need an interrupt every 1/20,000,000 second and an adequate clock speed, but with many attempts and quite some research, I can't get even close to these values. If anyone has an idea of how i could get this working I would be very pleased and thankful to hear it. Thank you :).


texts:
I need a high turn ratio transformer in a small package. Is it feasible to put two small transformers together, as follows:

Two small turn count transformers would be smaller than a single transformer in the sizes I need.

Can I use this transformer pair somewhat equivalently as a single transformer? Anything I should look out for? Thanks!


texts: How to turn on high-side MOSFET of a buck converter

texts:
I'm trying to simulate some buck converters with real MOSFETs instead of ideal switches. The problem is that I don't know exactly how to properly turn on the transistor.

The simple buck converter would be

simulate this circuit – Schematic created using CircuitLab

Theory says that the MOSFET should enter the triode region when

$$
v_{DS} < v_{GS} - V_{t}
$$

but this seems complicate to use because how could we determine the voltage between the transistor and the inductor in a real situation?. So this solution came to my mind:

$$
v_{DS} < v_{GS} - V_{t} \Rightarrow v_{GD} > V_t
$$

So my questions are:

Is that correct? Then sould I apply \$(9+V_t)\$ to the gate to turn it on properly?
Is there any other way to make this? Maybe with a lower voltage on the gate?


texts: Reading a 16-bit word via SPI from a current sensor [STM32 & CubeMx]

texts:
I'm having problems to read my current sensor, which is located at the emitter leg of a power IGBT.

This is my sensor datasheet TLI4970

This is my routine every 10ms:

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET); //Bring slave select low
HAL_SPI_Receive(&hspi1, (uint8_t *)&SPIRx, 2, 10); //Receive data
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET); //Bring slave select high

However, I get random values even when the current is zero. I'm getting values like:

0x8800

0x8803

0x8801

0xA7FF

0x87FC

0x97FE

0xA802

0xA801

0x97FD

0x87FD

0xA800

0xA7FE

According to the datasheet, these are sensor status messages, but none of them are Sensor Current Messages. The hardware seems okay. This sensor is not so common I think. I haven't found much help. What do you think the problem is? I can upload the whole code generated by CubeMx if needed.


texts: DIY Hearing aid T-Loop. Tweaking the resistance of inductance coil

texts:
I'm trying to set up a simple hearing aid T Loop circuit to experiment with.

From what I've read so far I'll need an inductance loop powered by an amplifier and the T coil in the hearing aid should pick up its magnetic field.

Surprisingly to me, other than ensuring the magnetic field is strong enough and that the two coils are close enough together it doesn't seem to need any thing else in the way of setting up to tuning in to make it go. Am I wrong? (Mechanical engineer! Already way out of my depth!)

So for an amplifier I planned using something with a standard headphone jack line out. E.g. a radio, MP3 player or sound card. If this doesn't give me enough power I'll switch up a to stereo amplifier.

I understand I need to match the impedance of the amplifier and the inductor being connected to it otherwise I'll overload the amplifier.

My question is: can I use a resistor to bring the T loop inductor up to the required resistance? As I'll need quite a lot of wire to get anything close the 33 Ohms I measured my headphones to be. I assume a small stereo speaker would be even more.

Would the ratio of extra resistance from the resistor to the resistance of the inductor matter much?

My guess is both of these shouldn't matter, as it's not a tuned RF circuit, just a rather large, rather weak electromagnet?

Couple of sources:

http://www.mreilly.com/WebPages/loop/loop.html
http://www.marcspages.co.uk/tech/deafloop.htm


texts: Why would a common Gate MOSFET (instead of a resistor) reduce noise in a TIA?

texts:
simulate this circuit – Schematic created using CircuitLab

I am reading a paper on TIA for optical recievers. On one of the improvements regarding the noise the writers replace the feedback resistor with a common gate MOSFet biased on the triode.

I can see how the MOSFET provides better flexibility regarding the value of feedback resistance (as it can be manipulated through Vg), but I can't tell why, as they say, it is used "in order to optimize the noise".


texts: Why is a half adder implemented with XOR gates instead of OR gates?

texts: Half adder circuits are implemented with XOR gates for the summing. Why can't the adding function be implemented with OR gates? What is the difference between using XOR gates and OR gates?


texts:
First of all I am new to this whole circuit building thing so please don't be too harsh on me.

I recently tried to build my first adder with NAND gates. So I went to a shop and bought some CD74HCT03E devices. To get started I just tried out the NAND gate but it didn't work.

I had a really really basic setup: a NAND gate, the power supply, and a LED. I already verified this circuit with my physics teacher and he sad that everything is fine. I also checked every pin with my voltmeter. Every input (A/B grounded) were at 0V and the output (Y) flicker but were also at 0V.

Here is an image of my circuit:


texts:
I was wondering if there is a way to cut power to my stepper motor when it is not in use. I dont particularlily need it to hold its position because in my setup it doesnt really need to torque agaisnt any outside force when its idle, and it also has a a sensor to indicate position so losing steps isn't the end of the world.

I thought of having a relay cut power to the VCC of the H-Bridge Motor Driver. Is there a better way to do it?


texts: Is it possible to get power from an electric motor using wireless?

texts:
I have an electric motor (see description below.) At the same time I  have a micro-controller attached to it which consumes (0.3W-0.4W) powered by a USB port.
I'm wondering if it's possible to power this micro-controller using a wireless charger system (like wireless chargee.)
Does this motor produce a magnetic field to use as a wireless charger?
Hope my idea is clear.
Power Rating    7.5 kW
Efficiency Class    IE2
AC Motor Type   Induction
Supply Voltage  400 V, 690 V
Phase   3
Output Speed    1465 rpm
Number of Poles 4
Mounting Type   Foot
Shaft Diameter  38mm
Shaft Length    80mm
Width   256mm
Length  535.5mm
Maximum Output Torque   49 Nm
Current Rating  14.7 A
Depth   262mm
Series  1LE1
Dimensions  535.5 x 256 x 262 mm
Rotation    Reversible


texts: Strange oscillations in Simulink for a buck-boost converter connected to a solar panel

texts:
I am building a model of a solar power system. In it, I connect a string of solar cells to a buck-boost converter. I use Simulink and Simscape Electrical to perform simulations. I am encountering an oscillation issue limited to a certain range of duty cycles.
I am modeling the cells using an ideal one-diode model for now, seen below.

The entire system is built up like this; the switching frequency of the converter is 250 kHz.

I have encountered a strange issue. For most duty cycles in the acceptable range, the current, power and voltage curves looks like this:

However, for some duty cycles (around 14-15%), the input current begins to oscillate heavily:

By examining the oscillation closer, I can see that it has a frequency of about 125 kHz. However, I cannot see why the oscillation would be there in the first place. Looking at the input voltage trace, it can also be seen that it seems to be "capped" at a certain value.
I cannot explain why this happens; especially confusing is the fact that it only appears for a small range of duty cycles. For example, a duty cycle of 10% once again produces a clean trace. Therefore, I suspect that the model of the solar cells is at fault here. At the same time, it is extremely simple and does not include any parasitics.
What could be the cause of this oscillation? Is it a consequence of the simulation environment, or should I expect similar behavior in a real circuit?
I would appreciate any advice.


texts: How to best understand cache associativity?

texts:
AFAIK this definition is the most clear and physical:

Associativity number = Number of comparators.

Is it correct? Could you make a more precise / better definition?

The wikipedia illustration is somewhat difficult to look at:


texts: Find the inductance using function generator, oscilloscope, capacitors, resistors, multimeter, voltage generator

texts:
I am trying to find the inductance of a inductor. I have tried many different methods such as putting the inductor in parallel with a capacitor to form a tank circuit and in series with a resistor with 1% tolerance.

The specific sites I used are:

wikihow.com/Measure-Inductance

youtube.com/watch?v=GF4AbbBGa5M

===============================

Problems I encountered with links
1) The oscilloscope I use outputs voltage/div. I do not have a current probe.

2) When I run a sine wave, or any wave form, from the function generator. The waveform I see on the oscillator is the same wave I used from the function generator; Same frequency.

3) No option to adjust current output from function generator.

4) My oscilloscope outputs a normal sine wave. I don't see a decreasing/increasing sine wave.

5) I know that the readings are wrong because when I switch capacitors, the math shows that the inductance has changed. I have a fixed inductor that I used to test also.

=============================

Other stuff to mention:

The oscilloscope I am using

pd.infn.it/elettronica/Strumenti/Immagini/MSO4104.JPG

The function generator I am using

tek.com/sites/tek.com/files/media/image/AFG3000C-Arbitrary-Function-Generator-Datasheet--346462-1-L.jpg


texts: How much power loss is included when charging a cell phone via inverter?

texts: So I know my power loss with my inverter is around 20 percent, and with the phone rectifier it's basically nothing but still measurable. I'm trying to figure up the actual wattage used to charge 2 cell phones from an inverter 120v 60hz modified sw. I can say it's the wattage of the two chargers but that's not accounting for the 20 percent loss.


texts: technology to search small objects like pendrive, key-chains etc

texts:
I am a web developer by profession. few days back I lost 8gb pen-drive :(  I don't it is in home or somewhere else.... So now I am thinking of a device which can be attached with small objects so that their location can be detected ...like

Clap of sound
Amplitude modulator transmitter attached to pen drive which can transmit special signals
Or any Bluetooth detector ....which can be used from mobile to detect

any thing I don't know

It should be effective , energy efficient and small

Can you suggest any thing :/

I was searching for sound and AM transmitter ....


texts: how to make a latching circuit with ground

texts:
I have a pump, represented by a lamp in my schematic, i want this pump to be running once i switch the Activate switch, and when ever an alarm(i have 2 different) is triggered (Alarms are ground) the pump should stop. That is working correctly on the schematic below, there is no complication on that.

My problem is that what i am looking for is that when an alarm is fired then the pump will deactivate and won't activate again even if the alarm goes off, for it to reactivate the activate switch should go off and on again. I have been experimenting with different latching circuits but since the signals are ground i am having a difficult time achieving the result.

simulate this circuit – Schematic created using CircuitLab


texts: In case of a Flyback converter, the RCD clamp is supposed to dissipate only the energy stored in the leakage inductance. However, in case of a Forward converter it would dissipate the energy from the magnetizing inductance (and by that resetting the core). But isn't that power dissipation so much that it makes it unacceptable?


texts:
I've designed the following over-current shutdown circuits, for both positive and negative rails, with only elementary and relatively ship components. In spice simulations, they work under a wide range of voltages (simulation works for 2-40V) and current limits (0-5A range at least) but I have not tried to build them yet. The power consumption is low.
What issues can occur with these circuits?

In the following schematic (negative rail), the current limit is set to 1A, while the voltage can range from 2-40V (the picture is small, but zooming the screen works fine). When the current exceeds 1A (e.g. short circuit), the circuit shuts down until the cause of the failure is removed.

The next schematic is for the positive rail; same principle but a bit more complicated because I know no "high side" version of the LM393, so I've divided the compared voltages by two.


texts: Rapidly switching on and off a 12v power supply, bad idea?

texts:
I was just wondering if this would be a bad idea, the power supply is connected to the mains power and would only undergo this at a max of 10 minutes at a time.

would this cause any damage to the power supply or cause any problems with my mains power?


texts: My non-inverting amplifier doesn't work correctly (the Gain isn't correct) [ICL7650S Op-Amp]

texts:
I'm working with ICL7650S(online datasheet). I made a non-inverting amplifier but I don't know why the Gain isn't correct! this is my circuit:

The Gain should be (841k/2.14k)+1=393.99 but when I applied 6mv in the postive input I got 283mv and when applied 13mv, I got 584mv in the output. why?

Edit1: cirtuit:

simulate this circuit – Schematic created using CircuitLab

Edit2: I measured the voltage of some parts and result:

simulate this circuit


texts:
I see a lot of RF systems use downconverting schemes in signal reception, like the LNBs for Ku-band TV signals. From what I read, digital downconverters do not harm the signal in the sense that no information is lost.
But this really makes me confused.
If downconverting is not that cost-expensive (Uhm, presumably. I have little knowledge in RF signal processing) and preserves the information, then why doesn't every RF systems in this world use one? There are tons of transceivers tuned to a specific range of frequencies like L/C/S/X/Ku/..., but wouldn't it be much simpler if we, say, have only one kind of transceiver and use an LNB to tune the incoming signal into the transceiver's frequency?
So I guess there are some kind of drawbacks, whether it's about cost or decoding problems, seeing people still make things like expensive SDRs. What drawbacks does downconverting have, if any?


texts: P-Channel MOSFET Inrush Current Limiting

texts:
I have been searching EESE and Google for several weeks now for a solution to this problem, and while I found some proposals that seemed promising, the real-world implementation fell short of expectations.

I have a voltage regulator on a board with 10uF input capacitance, to help protect against brownout conditions. I have a fuse in series with the power supply sized to 125mA for various reasons, and just to be clear, I have not found any slow-blow versions that meet my requirements. The power supply can be anything from 5 volts to 15 volts DC, most likely a lead-acid battery. When the battery is first connected I see an inrush current with a peak of approximately 8 amps over 8us, which very quickly blows the 125mA fuse. Okay, so I need to limit the inrush current. No big deal, right?

I tried a number of different options, but this is the one that seemed most promising:

R1 and R2 form a voltage divider that limits the Vgs to prevent damage to the MOSFET, and along with the capacitor form an RC delay that allows the FET Vgs to increase more slowly, keeping the FET in its ohmic region for a longer amount of time. Makes perfect sense. Higher capacitance = slower turn-on = less inrush current.

Well that's all fine and dandy, except that after increasing the capacitor from 1uF to 4.7uF to 10uF, I realized I bottomed out at an inrush current of around 1.5Apk over 2us. After reaching that point, no matter what capacitance I added for C1 (I tried up to 47uF) the inrush current wouldn't drop any lower than 1.5Apk. Obviously this current was still much too high and would blow my fuse in an instant. I can't increase the current rating of the fuse, so I need to find a way to make this work.

My current hypothesis is this:

Cgs and Cgd are the intrinsic gate-source and gate-drain capacitances of the MOSFET, and while they are relatively very small (50pF-700pF), my theory is that they are acting as a pass-through when Vin is first applied. Since these capacitances cannot be reduced, they (especially Cgd) are the limiting factors that prevent me from lowering the inrush current below 1.5Apk.

What other options are there for limiting inrush current? I have found various one-chip solutions for hot-swap applications, but they have a similar topology to the above circuit and I imagine they would have similar drawbacks.

Vin can be as low as 5 volts, so if I take into account reverse polarity protection provided by a Schottky diode, the voltage drop across the fuse, the drop across the MOSFET on-resistance, and drops due to the cable (can be fairly long) connecting this board to the supply, my voltage drop is becoming fairly significant (the voltage regulator this is feeding into requires roughly 4.1V in order to regulate properly). A series current limiting resistor is unfortunately not going to be an option.

The other restriction I have is space. I have approximately 4.5 x 4.5 square millimeters to work with. The above circuit was just barely going to fit, so adding even more components is not really an option. Otherwise this would have been a slightly easier problem to solve.


texts:
I am animating a small toy using three HXT900 servos controlled by a standalone ATmega328p.
Space is very tight indeed!
I am considering using two li-ion or li-poly 3.7v (700mAh) cellphone batteries; one for the ATmega and the other to power the servos separately.

I can remove and charge the batteries in a cellphone, so no charger chip is necessary.

I am also aware that the Li-ion/poly batteries should not go below a certain voltage, but believe that there is a protection circuit inbuilt which obviates the need for an external protection cct.

Does the readership think this is feasible?


texts:
I've  missed some classes and I'm struggling to do this. I need to "design a linear power supply with 12v output, with simple series regulator, providing a 2A current from 220V AC (60Hz)".  I don't know how to calculate the values for the components.

Is there any document that can help me with this?

UPDATE

Here's my design so far:

is this a valid solution?


texts:
I've got a SMPS which I'll be supplying with 230Vac. It outputs 24Vdc. Maximum power output is 600W. The efficiency is 89%.

I know that on the DC side, I'll be drawing 240W, or 10A. How can I work out the AC power draw?

Also, what cable size should I be looking at if I wanted to draw the full 600W from the PSU? On the input side, I would have thought 2.5mm^2 is ok, but surely not for the DC side with over 20A.


texts: When you are designing a device with a CPU that only supports ddr3, is it possible to use ddr2 in that design instead?

texts:
Sitara™ AM57x Processors

I want to make a system and have access to ddr2 ram slot design files only. How can I re-route the controller to use ddr2 sodimm memory with a ddr3 interface. I am designing my own board.


texts:
I need to drive a bunch of 7-segments and 14-segments led display (in total, 105 LEDs with common anode).

I bought an HT16K33 to drive them, but did not take into account the common cathode requirement...

I can't manage to find any chip that could drive them correctly. I need an I2C interface with at least three addresses, 105 LEDs minimum. Dimming and Blinking feature would be great but are not required for my project.

I also thought I could invert the signal from the HT16K33 output, but I'm not sure this is a good idea...

Any help on that ?


texts:
I'd like to do some experiments involving high frequency (1.296GHz to be exact) that involve an 50ohm inductor that has minimal RF losses.  The obvious candidate is to drive a Rogowski coil (driven as though an air-core current transformer without a secondary running through the centerline) since it generates no external fields -- only a dynamic B-field within the minor radius of the torus.

The problem is when I look at the application of Rogowski coils to current sensing, the frequency limits seem to be a factor of 10 lower than my target.

What limits the frequency of a Rogowski coil to below the GHz range?


texts: Do waterproof RJ45 connectors with integrated magnetics exist?

texts:
I've been searching for days and can't seem to find a rugged RJ-45 Ethernet connector with integrated magnetics. Probably it would be good enough if the connector was just potted so water cannot leak through.

Is there a reason why such items don't exist?


texts:
I am looking at the STM32 F4 series Discovery board. I have the eval board on my desk currently. I want to use this system to send data from USB to a 3 byte parallel data bus using an external clock source. I am using the STM32407 chip. I need to input data from a PC through the USB bus. My wish list is for the chip to handle a 2 MHz external clock rate and load the 3-byte GPIOs every clock cycle.
 That would be 2MHz x 24bits = 48 Mbits/s or 6 MBytes/s if my math is correct. The output from the STM32 GPIO would need to be smooth as the USB would be in packets.
Is the 2 MHz possible? Can I go faster?
Thank you very much.


texts: How am I supposed to interpret transformer value only given in impedance?

texts:
I am reading a definition where only the transformer impedance is given.
120kVA
0.023+0.041iohm

Is this value for the primary side or secondary side?
How would I substitute the per unit base for it?


texts: Why do some switching regulator require tantalum or electrolytic capacitors instead of ceramic?

texts:
I'm looking at this switching regulator: http://www.ti.com/lit/ds/symlink/lm2675.pdf.

For its input and output capacitors it recommends tantalum or electrolytic capacitors. It mentions in section 9.2.1.2.4 that a ceramic capacitor on the input can cause ringing. Admittedly, I haven't had to make a lot of power supplies but the ones I've used have been fine with ceramics.

I ask because I am space limited and a ceramic capacitor at the same value and voltage rating is much smaller. Why does it specify only tantalum and electrolytic capacitors in the datasheet?


texts:
I'm on a quest for wireless coffee.
I've succesfully hacked my Nespresso with a NodeMCU that will now let me wirelessly make a coffee. That is, when the machine is already on.  I need to figure out a way to turn it on programatically also, but the button for turning on is different.
After opening up my Nespresso Lattisima+ (model EN520) I found this push button - a kind of button that I don't know.

How do I find out how it works (i.e. which pins to solder my relay onto in order to switch it on programmatically) without killing myself?
I see a F5 and SW1 next to some pins, but on the back of the printboard I can see that there are pins "hidden", meaning big white block as well.
Thx for helping me stay alive and curious :)


texts:
Inverting Schmitt Trigger was rigged up in the lab using uA 741. The values of R1 and R2 is taken as 10K and Vsat at 12 V and Vin at 1 V sinusoidal input.The oscillation from +Vsat to -Vsat occured at around at aroud 11.6 V input(increased from 1 V gradually) which is expected.

But when I increased the input more I noticed the positive part of the input was clipped a little (I guess it was some kind of loading at the input) due to which I noticed  a small increase in the -Vsat part, just a small notch like.

I changed the op-amp but the effect was same.

What might be the reason for this effect. What test circuit will help me know more about this effect.


texts: Powering 33063 Buck Regulator near its Vmax

texts:
I usually work with 12VDC or less, but I needed to get a quick ~350mA@5VDC supply out of a 24VAC transformer available to me.  "No problem," I think: "I'll bridge rectify, filter a bit, and feed it to this Recom 7805-like switching regulator I have in my parts box."

So I do that, and test it by feeding the rectifier both ways from my 12V testing battery, everything looks good.  Hooking it up to the 24VAC transformer, though, releases the magic smoke.

Turns out, you gotta figure you'll see ~80Vp-p when you're working with a 24VAC transformer (24 x 1.414 = 34, but unloaded you might see 28VAC or 30VAC).  Rectify and you might still be looking at 40V.  Recom is only good to 28V, so ... lesson learned.

Next thought: I can use a trusty 33063.  I have some of those, and I know how to work them at lower voltages.  But Vmax is 40V, and I know that's close to what's lurking in the rectified transformer.

So my question: what do people who work with AC in the range from ~25-75 do here?

It seems like I could use a 5-10V linear regulator to drop 40V down to a comfortable range for the 33063.  If I use an external transistor to feed 40V to the inductor, I should be OK, and the linear regulator only has to provide ~5mA to run the buck controller.

Is there a smarter approach, or is this something an actual competent designer might do?


texts:
I am trying to rebuild the circuit in the Toyota Supra electric mirror. There are yellow ceramic capacitors that don't seem to conform with any of the identifying marking I can find.
Can anyone tell me what I need to replace them with?


texts: Monitoring voltage state without interfering

texts:
I have a CO2 laser cutter, and I am designing as circuit to turn on some outlets whenever the laser is firing.

The laser is turned on by a 5V logic connection to the high voltage power supply. If I can intercept this signal, I can tell when the laser is on.

But how can I check whether or not that line is HIGH or LOW using an Arduino without interfering with the circuit on the laser cutter? I thought of two ways, but I have a problem with both.

1) Simply connect the signal wire to one of my Arduino's digital I/O pins. Problem: the Arduino is operated on a PSU seperate from the laser cutter, so the ground pins would not be the same.

2) Use an optoisolator that reads when the line is high. Pros: the Arduino and the laser cutter don't have to have the same ground. Cons: I would have to run the signal line throught a 1k ohm resistor and into the optoisolator. This would add resistance to the signal line AND prevent bidirectional signals.

So, in conclusion, how does one check the voltage state of a signal line without interfering with the signal line?


texts: What's the difference between dual-address and implicit DMA?

texts: For detached DMA's there are two addressing approaches. One is dual-address and one is implicit. What the difference between the two and why does dual-address take twice as many bus cycles?


texts:
For data recovery I need to desolder a BGA 153 eMMC chip from a dead phone. I'd like to maximize my chances of NOT destroying the eMMC chip in the process (the other remains of the phone do not matter since these are dead already). I've already watched various instruction videos and I'd say I have an idea of the general process.

I do have a cheap Chinese hot air station where the temperature can be set between 100-500 degrees Celsius (but I don't know how accurately that actually works) and where air speed can also be selected.

For target practice I just unsoldered some DDR3 chips from some old PC's memory PCB (these chips where not glued on - it was just the solder that held them in place). I used a nozzle about the same size as the chip and put flux all around the chip before heating. I always used a low air speed (2 on a scale to 8). I progressively increased temperature and each time heated for 2 minutes to test at which minimum temperature the chip would come loose. For the DDR3 chip it actually took me 385 degrees celsius (but maybe the displayed temperature is just wrong)!

With regards to the eMMC chip I had so far found information that 240 degrees should be sufficent to unsolder it (supposedly its solder melts at 225 degrees).

Is it to be expected that an eMMC chip would come off at a so much lower (240 instead of 385) temperature than a DDR3 chip? Or is this just an indication that the temperature reading on my hot air station is way off?

Should I rather be using some higher air speed for this kind of job?

Would it make sense put some thermal isolation on the backside of the phone's PCB to reduce heat emission?

What type of low melting point solder should I use if I wanted to directly solder some wires to the eMMC chip? Or what would be the right type for reballing (leaded, lead-free, etc) if I was so put it onto some kind of breakout board?


texts: Electronic component identification and sourcing

texts: I'm trying to repair a electronic component but don't know what it is called and where I'd get a couple of them.  The 2 to the right have the number on them.  425 BGT is what it looks to be.  Any help is appreciated.  Thanks.  Perry


texts: Arduino Mega 2560 not detected when connected to USB port

texts:
I've just received Funduino Mega 2560. This is a Chinese product and should be the exact copy of Arduino.

I am having problems connecting it to my computer and have spent several hours trying to figure it out to no avail.

My operating system is Windows 7 x64 and here are the steps that I tried:

Restarting Windows.
Pressing Reset button on the device.
Switching to other USB ports on my computer.
Using different cables (including the one that works with my printer).

None of this helps. The device is not listed in Device Manager and Windows does not produce the sound when connecting plug-and-play device. Because of this, I am unable to get to the point to install the drivers for it.

I have also tried to put the device in DFU mode by shortening RESET and GND next to Mega8U2 chip in order to try to upload a new firmware. The device is not responding.

Here's the video footage when the device is plugged in. Power LED is constantly on and L LED is flashing in a specific pattern.

Can anybody help me on how to get this thing detected by my computer?


texts: Balanced and unbalanced short circuit voltage of transformer

texts:
This might be trivial, but I'd like some hint on where to start.
I'm calculating power flow for three-phase-four-wire distribution networks. Positive sequence and zero sequence short circuit voltages of transformers are given. For example:

But to build one-line equivalent (balanced) model, I need short circuit voltage (in %) and its real component (in %). I am wondering how to convert such parameters.
Other parameters, like iron loss, are the same for balanced and unbalanced model, I presume. The Python package I used is pandapower. Here is the documentation for transformer:
https://pandapower.readthedocs.io/en/stable/elements/trafo.html#pandapower.create_transformer_from_parameters


texts: FreeRTOS crashing when adding new queues

texts:
I am new to FreeRTOS

At the beginning I created 3 queues and everything worked fine. Until I needed a new 4th and 5th queue.

When ever I initialize the queues with xQueueCreate() The system crashes.

I tried to increase the task depth. Also tried to increase the total Heap size with no success.

I have only two tasks.

This is my code

/**
 * Define the FreeRTOS task priorities and sizes
 */
#define configGUI_TASK_PRIORITY                 ( tskIDLE_PRIORITY + 3 )
#define configGUI_TASK_STK_SIZE                 ( 950 )

/*
** CDL Task Configurations
*/

#define configCDL_TASK_PRIORITY                 ( tskIDLE_PRIORITY + 2 )
#define configCDL_TASK_STK_SIZE                 ( 950 )

/*
** FreeRTOS Queues
*/

xQueueHandle msgGuiRqst;
xQueueHandle msgCdlStatus;
xQueueHandle msgCdlRspnsBool;
xQueueHandle msgPlatformsStatusData;
xQueueHandle msgPlatformsWeightData;

int main(void)
{
    msgGuiRqst      = xQueueCreate(1, sizeof(char));
    msgCdlStatus    = xQueueCreate(1, sizeof(char));
    msgCdlRspnsBool = xQueueCreate(1, sizeof(bool));

    // Problem started after adding these two queues
    msgPlatformsStatusData = xQueueCreate(2, sizeof(bool));
    msgPlatformsWeightData = xQueueCreate(2, sizeof(int));

    xTaskCreate(GUITask, (TASKCREATE_NAME_TYPE)"GUITask",
                configGUI_TASK_STK_SIZE,
                NULL,
                configGUI_TASK_PRIORITY,
                NULL);

    xTaskCreate(CDLTask, (TASKCREATE_NAME_TYPE)"CDLTask",
                configCDL_TASK_STK_SIZE,
                NULL,
                configCDL_TASK_PRIORITY,
                NULL);

    vTaskStartScheduler();

    while(1)
    {
        ;
    }
}

I need suggestions to figure out the issue.


texts: Equivalent circuit of a simple transformer?

texts:
EDIT: My question is: How can you translate the first circuit into one that uses simple (linear) electrical elements and, as a result, can be solved using mostly Kirchhoff's laws?

I am trying to analyse how the frequency of the input voltage affects the amplitude of the output voltage in the following circuit.

simulate this circuit – Schematic created using CircuitLab

Everything we need to know is given: \$V_{in}\$, angular frequency \$ω\$, \$a\$, \$R\$ and \$C\$. I think this circuit is supposed to work like a band-pass filter, but I am not used to working with transformers. That is why I am trying to find the equivalent circuit of this element. Is the next circuit equivalent to the above? Likely, it is not, because transformers are supposed to change the voltage across the secondary coil, at the cost of current. If not please suggest the correct one, or explain a better way of understanding the circuit (What kind of impedances might occur, if the transformer is not ideal?).

simulate this circuit


texts:
Hi everyone I'm trying to minimize this boolean function F(A, B, C, D) = ∑m(7, 8, 9, 12, 13)
don't care terms(2, 3, 6, 10, 11, 14). My main question is about the row of don't care terms in the bottom row, do I include this as a group of 4 when minimizing? I assumed I should and got this product-of-sums AB'C + AC' + ACD' + A'C + B'C. I'm also, not that great at simplifying so do AC' and A'C cancell to get AB'C + ACD' + B'C? Any and all help is appreciated especially if you could give an explanation on how you simplified, thanks.


texts: Confused about the definition of voltage gain

texts:
I found these formulas for different gains of an amplifier/filter on logarithmic scale. The topmost is power gain, simply 10 times the logarithm of the ratio of output to input power. The next one is voltage gain. But isn't the voltage gain here the exact same as the power gain, since $$P = \frac{V^2}{R}$$?
Aren't the two gains equal?
Why isn't power gain defined as $$10 log\frac{V_{out}}{V_{in}}$$?
EDIT:
Here is what my textbook says:

The ratio of input and output amplitudes
$$|T(s)|=\frac{|u_o|}{|u_i|}$$
is usually expressed in decibels
$$|T(s)|_{dB}=20*log*|T(s)|$$

So why does the factor of 20 make sense here? Doesn't this give the ratio of the squares of the voltages in dB rather than the voltage gain in dB?   Isn't "voltage gain" using that definition still power gain


texts:
I recently did an experiment aiming to verify the magnetization curve of the cores of a single-phase electrical transformer. I applied a sine within one core and I observed this one and the other one responses over the time.
The circuit builded for the experiment and the output of this, that is a snapshot from the oscilloscope that I've used to make the measures, we can see at the images below.

I then exported the graphics raw data into CSV files to manipulate it with some computer software, like Matlab or Excel. I mixed the data from both graphs in a manner that I could plot one as being the X-axis (1st CSV column) and the other being the Y-axis (2nd CSV column), and indeed it worked with Matlab. With the data organized I executed the following within Matlab:
Array=csvread('F:\workspace\Matlab\XY.csv');
r1 = Array(:, 1);
r2 = Array(:, 2);
plot(r1,r2);

The result is the transformer hysteresis graph as expected and showed bellow, and we can see a lot of noise within the signal.

Finally, I could calculate the area from the graph through:
trapz(r1,r2);

The obtained result is 4.3768e+09, analyzing the data I would say that, if the X and Y axis was expressed in terms of Volts units, the resulting area would be 0.43768.

My doubt is:
I know that the encountered area represents somehow the energy loss within the transformer core, but...
How do I express it in terms of energy?
Is the encountered result (0,43768) expressed in [N/m^2]?


texts: Why the current on this vector diagram have coordinates like this?

texts:
It is an example from a textbook. It is a really basic example and the purpose of the example is to show how vector diagram works.

Here is the example:

and this is the vector diagram:

What I don't understand here is why \$I\$ has these coordinates. Shouldn't \$I\$ have coordinates \$ 1.5 + 1.5j \$ because \$ 1.5 \sqrt{2} \angle 45 = 1.5 + 1.5j\$ ?

On this picture it looks like I have coordinates \$ 5 + 5j \$ .

Can someone please help?

Source of pictures: faculty of electrical engineering and computing Zagreb


texts:
To many electronics engineers this might seem a stupid question but I was given by my boss the task to find a solution to drive approx. 5A through a coil.
The coil's resistance (not considering inductance which would be ~15mH) is about 90 Ohms. The signal is sinusoidal with a frequency of about 3kHz. Since he made this sound pretty easy I am a little bit unsure of how to proceed.

Considering Ohm's law, driving 5A through a 90 Ohms would result in 450V which doesn't seem so trivial to me.

I have a feeling that I'm overlooking some fact but I cannot figure out which one.

A possible idea would be to use a OPA549 which gets at least roughly into that area (bandwidth, output capability) but again, I think that I'm overlooking something. All power amplifiers I can find are intended for audio applications and typically drive a 4 Ohm or 8 Ohm load.

I'd be really happy if you could tell me where I'm wrong or if this actually isn't such an easy task.


texts:
I'm trying to mate with a P992G1 Anderson connector and need to find a suitable PCB-mount receptacle to design into my board (footprint, STEP model, etc.). The P992G1 is connected to a battery/solar panel set up that will power my PCB.

I looked around on Newark's website and it seems they have some that will match with this but not in stock. I couldn't find anything suitable on DigiKey or Mouser, which seems odd because there must be a popular receptacle used by everyone to connect to their PCB...


texts:
I have recently built a circuit with a 555 set in monostable mode which was supposed to turn on three bright LEDs for 51 seconds when a button was pressed.The button was connected with some long wires.After I built it,I decided to connect the battery and was surprised to see that the LEDs turned on even if nobody was pushing the button.I connected and disconnected the battery several times and it kept happening.

simulate this circuit – Schematic created using CircuitLab

It worked poorly in this configuration and after I added a resistor between the positive rail and the trigger pin it seemed to work fine,but I didn't check it too much.What made the IC go mad?Did the long wires make it sensible to static electricity?Was the missing resistor causing the problem?


texts: Does a passive LCD's screen have 1 pin to 1 segment?

texts:
I'm very green in electronic engineering. But I have a 1997 Yamaha AN1X synth with a custom LCD screen that is only half operating and was thinking of making a replacement from todays parts with some controller to translate the information coming from the board. But I see that today's displays are operated with a square pulse and is not trivial.

The LCD has probably 50 tracks on the glass edge. Do these passive displays also have square wave controller pulses to operate ?


texts: Program counter goes to the end of code and 8051 Restarts

texts:
I have an 8051 MCU which I use keil to program it with C. My problem is that the micro-controller restarts at the end of some functions while they should return.

Using a debugger I tried to check it line by line. And I figured out the the MCU is not restated right after the end of the function. The PC(progam counter) goes to somewhere else (sometime somewhere that there is not any code to execute) and then it increases one by one until the end of code. It is very strange for me because I write my code in C and never seen the type of error previously.

I think this problem might be related to the compiler settings and thus I post the settings here:

Assembler settings:
XR GEN DB EP NOMOD51

Compiler settings:
DB OE BR LARGE OPTIMIZE(11, SIZE) DEFINE(SILABS_PLATFORM_WMB912) DEFINE(SILABS_WMCU_SI106x)

Linker settings:
CODE REMOVEUNUSED CLASSES(BIT(0x20.0-0x2F.7), DATA(D:0-D:0x7F), IDATA(I:0-I:0xFF), XDATA(X:0-X:0xFFF), CODE(C:0-C:0xFBFF), CONST(C:0-C:0xFBFF))

I tried both large and small settings but the problem remains.
Kindly help me if you know the reason.


texts: How hot does a florescent light filament get?

texts:
I understand that a florescent light bulb radiates light as a result of exciting mercury in the bulb with electrons and those electrons are emitted by a filament.

What is the highest temperature that the filament ever gets? At what point does it reach that temperature: startup or some time later? Does the filament glow at any point or does it emit electrons without glowing?


texts:
I have been trying to create a countdown timer using ARM7 micro-controller, once an switch input has been detected. So far I managed to create a delay function of 1 minute, and detect a switch input. However, once the switch is released, the countdown will stop.

First I have set up 2 Seven Segment displays which detect a switch input and can increment or decrement the minutes.

I have set the delay_MINUTE function as follows which is basically a 1 minute delay. I have checked this using an LED and this part of my program is working:

  void delay_MINUTE(void)
{
 T0TCR = 0x0;                   //Resetting Timer0

 T0MR0 = 499999;                //Loading match register value

 T0PR = 600;                  //Loading Prescalar register value

 T0PC = T0TC = 0;             //The value in the register increments with   every     input pulse or Processor clock fed into it.

 T0MCR = (1<<0) | (1<<2);     //Generates interrupt and reset on match.

 T0TCR = 0x1;                   //Starting Timer

 while(!(T0IR & (1<<0)));       //Waiting for interrupt
 T0IR = (1<<0);               //Clearing interrupt
}

I am getting stuck in a simple part of the program. When a switch input is detected on P0.14, the current display should decrement by one, every one minute.

If I simply do:

     int y = 0;
     unsigned int SW3;
     if((SW3) == y)  //detecting switch input
    {
        delay_MINUTE();
        num_right --;
    }

the number will only decrease by one when the switch is pressed, and not keep on counting down until it reaches 0. Any suggestions on how I could change my code to detect one switch input and continuously decrement after it has been released would be appreciated.

EDIT I have also tried creating a for-loop inside the switch statement such that when the switch is pressed, the countdown will start depending on the current digit being displayed. I am not sure if this is a good idea or not.


texts: What system would I need if I want to store large amounts of text data and be able to control a TFT LCD display?

texts: My goal is to build an electronics project where I can store large amounts of text data (books) where I want to display that text on a TFT-LCD display. Right now, I have my display hooked up to an Arduino Uno and I can display very little text (not enough memory to store more) and I would want to be able to display books (large amounts of text). I would need the project to be physically small. How would I go about doing something like that? Is there some type of PIC or an IC that can control a display and be able to store large amounts of text data as well?


texts: Load current computation of complicated resistance network

texts:
I'm reading Electronic Principles 6th edition by Malvino. Problem 1.28 describes a network of resistors that I would like to know how to solve mathematically instead of experimentally (as described in the book).
 I got the response below from another site. The author used a slightly different schematic which I accept, although his answer looks reasonable, it was not confirmed by my simulation.
 Using his schematic is he right? How can the math be done if the resistors are not all the same at 1 ohm?


texts: How to draw ~1A from Li batteries without damaging/over-stressing them?

texts:
I have designed a micropump driver powered by 2x AA (Li) batteries, the pump is piezoelectric and requires 27V.

The pump requires a switching waveform, at the battery side this draws (including inefficiencies and driver consumption) 400mA and 900mA at the battery voltage which is nominal 3V (depending on the pressure being created by the pump), the batteries won't really see the switching because I am using a H-bridge and so there are two signals that are orthogonal to eachother and other than the small (ns) deadtime between them the boost converter will only see a DC drain (and even the deadtime will get lost in the feedback loop response time of the SMPS).

Several problems have arisen:

After a failed life-cycle test I measured the voltage across the batteries, one was sitting at 0.2V the other 1.47V, they are used in series, so why would one battery have such drastically different voltage? Does this suggest damage? or simply one is much more drained that the other?
I'm using boost solution that can boost from ~1.5V up to the required 27V. I have noticed that the someway into a test the battery voltage drops off during a pump cycle, very quickly dropping below 1V and after the cycle ends quickly recovering to 2.8-2.9V, does this suggest I am drawing to much current out of the battery? or that the battery is damaged or simply running dry?

I assume my design is damaging or stressing the batteries somehow, are there any standard practices to be used in this scenario?

Based on a constant discharge test with reference to the battery manufacturer I estimate that the batteries that drop off in voltage drastically after a period of time being used are less than 1/3 discharged. I.e with a load drawing a defined constant current and measuring teh voltage across the terminals and comparign this with a the discharge curve (http://data.energizer.com/pdfs/l91.pdf)

Unfortunately I can't upload schematics due to confidentiality agreements with the customer, however I'll provide whatever additional information I can.


texts:
I get confused on the low-level physics of electricity from time to time. It came up in "Which way does electricity power a circuit," and I don't totally get it.

How fast does electricity flow? Is the speed of an electron different in say a resistor than in a wire? Does it matter? Or are the effects of the electron the only important thing, with lower levels of abstraction not useful in practice?

I know there are already materials on this topic, and I have read some of them. I think having the question on this site might inspire some interesting answers to the age-old question.

Bonus points for:

Identifying and clearing up common misconceptions
Explaining in a way that someone with a high school diploma could understand, without oversimplifying it so much that its incorrect


texts: Identifying rows of a parameter sweep run in LTspice raw results

texts:
I want to use a parameter sweep with transient analysis and parse the output results. Unfortunately, I cannot identify where the results from one parameter sweep ends and the other starts in the raw output results.
1967        2.563416514428829e+000
    2.400000000000000e+001
    4.493277543997481e-004
    -1.061473136170760e-003
1968        2.572499072839490e+000
    2.400000000000000e+001
    1.122131554555143e-003
    -1.061432747027046e-003

point 1968 should be from the next run, but how can I identify that from the output? Just guessing the number of points in a run (TotalPoints/NumOfRuns) also does not seem to work properly. There is some information in the .log file, but I am not sure how to use it.
Even if I identify the correct points from the different runs, can I trust that the previous run does not affect the next one?


texts: Multiple SPI devices with different logic levels

texts:
I'm going to use one of the PIC32MX795F512L SPI peripherals (master), 1 to 4MHz, to communicate with multiple devices (slaves):

Wi-Fi module MRF24WG0MA (3.3V);
uSD card (3.3V);
9 modules with sensors and ADCs with SPI, on their own boards, connected to the main board through 10cm cables (powered by 5.0V from main board);
3 external optional modules with sensors and ADCs with SPI, on their own boards, connected to the main board through 25cm cables (powered by 5.0V from main board).

I can only use one SPI in the MCU since all other have their pins already in use. I have enough pins for the CS lines.

The sensor boards can have any ADC with SPI, currently I'm using MCP3551 and AD7798. If some ADC does not enable the MISO pin only when their CS input is asserted I will use one input buffer (5V) in their respective board for the MISO line, activated with the CS signal.

I will use a resistor in series with the output of the driving device for line termination as described at TI's LVC Designer's Guide.

For logic level translation I will use:

Quadruple bus buffers 74AHCT125 for 3.3V to 5.0V in the main board (SCK, CS and MOSI from MCU to the modules ADCs).
Octal bus transceivers 74LVC245A in the main board for 5.0V to 3.3V logic level voltage translation, from the modules ADCs MISO pins.

I've never worked with these buffers before. I can't figure if the 74LVC245A has open-collector outputs. Can I join and connect all the 74LVC245A outputs direct to the MCU MISO pin, like I do with MISO pins from 3.3V peripherals?

Edit: added tags.


texts: How do I compute \$V_{out}\$ in a MOSFET?

texts: Did not understand my lecture about MOSFETs. Specifically, how do I compute \$V_{out}\$ in the circuit below?


texts: Why so many pins for the MOSFET's drain?

texts: The FDC855N comes in a 6-pin package, 4 of which are connected to the drain, and only 1 to the source. Why this difference? The source sees the same current as the drain, doesn't it?