texts: How does the Electrical Grid React to Large Changes in Supply or Demand?

texts:
Background

I'm performing some research for a software project that monitors power generation and consumption for a large fictional spaceship. My rationale is I'd like to first understand how real-world power generation works before starting to make the app feel as authentic as possible when using it.

Basis

My question stems from my current understanding of how the electrical grid works. Energy is generated through whatever mechanism (steam/mechanical, photo-voltaic) and is then stepped up via a HV substation for long distance transmission. Large factories (Steel Mills, Microchip Plants, etc.) may have a substation dedicated to them for their operations. Otherwise, a substation steps HV down to MV for smaller scale distribution (factories, large office buildings, etc.). This is repeated again for LV, for delivery to homes and small businesses. It's a simple model, albeit misleading because it presents a linear chain of flow from source to load, with a single source generator of power. In the real world, there are multiple stations that are running to meet the demand, and they adapt as the demand changes over time.

Question

Suppose a large event such as a generator station unexpectedly shut down. What equipment would be involved in "rerouting" power to minimize the possibility of blackouts? Or, if a rolling blackout was temporarily implemented because of high demand, what equipment or process would be involved?

Related Questions

For coordinating multiple generator stations: How are multiple power sources synchronized in a grid that uses a distribution ring?
For transient heavy loads: What is the effect of heavy loads on the electrical grid?
Modelling of Electric Power Grid


texts:
How to find the voltage across the capacitor, under DC conditions?
I do know that under DC conditions, the capacitors will be open-circuited.
Since it is open-circuited,

simulate this circuit – Schematic created using CircuitLab
Current will be 1A
V1=30V
V2=40V
Why won't the voltage across the capacitor be affected by the 50ohms and 10ohms resistor? Instead of it being parallel to the voltage across 30ohms and the 60V and 20ohms branch?


texts: STM32F4 Discovery AES Encryption Problem

texts:
I am trying to implement very basic AES192-CBC Mode encryption routine on STM32F407 Discovery board and I want to do that process with the onboard Cryptographic processor in STM32F407 MCU. I copied most of my code parts from ST's exampe projects. Here is my code:

#define AES_TEXT_SIZE    64

uint8_t AES192key[24] =
              {0x8e,0x73,0xb0,0xf7,0xda,0x0e,0x64,0x52,
               0xc8,0x10,0xf3,0x2b,0x80,0x90,0x79,0xe5,
               0x62,0xf8,0xea,0xd2,0x52,0x2c,0x6b,0x7b};                                // key size 192 bits

uint8_t IV_1[16] =
              {0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,
               0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};                                // initialization vector

uint8_t AES_TEXT[AES_TEXT_SIZE] =
                        {0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,
                         0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41};

uint8_t Encryptedtext[AES_TEXT_SIZE];                                                   // Encrypted text
uint8_t Decryptedtext[AES_TEXT_SIZE];                                                   // Decrypted text

/**
  * @brief  Program entry funtion
  * @param  none
  * @retval none
  */
int main()
{
    SystemInit();                                                                       // System initializing
    USART2_Init();                                                                      // USART2 initializing

    RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_CRYP, ENABLE);                                // onboard cryp hardware clock enable

    /* program main infinite loop */
    while(1)
    {
        /* send original text first */
        USART_Puts(USART2, "Original Text:\n");
        USART_Puts(USART2, (char*)AES_TEXT);
        USART_Puts(USART2, "\n");

        /* if encryption process successed send encryptedtext otherwise send "Fail" */
        if(CRYP_AES_CBC(MODE_ENCRYPT, IV_1, AES192key, 192, AES_TEXT, AES_TEXT_SIZE, Encryptedtext) == SUCCESS)
        {
            USART_Puts(USART2, "Encrypted Text:\n");
            USART_Puts(USART2, (char*)Encryptedtext);
            USART_Puts(USART2, "\n");
        }
        else
        {
            USART_Puts(USART2, "Fail\n");
        }

        Simple_Delay_MS(1000);                                                          // ~1 sec delay

    }
}

Its not working properly and thats why I debugged my code and noticed that the problem location is:

  /* Enable Crypto processor */
  CRYP_Cmd(ENABLE);

  if(CRYP_GetCmdStatus() == DISABLE)
  {
    /* The CRYP peripheral clock is not enabled or the device doesn't embedd
       the CRYP peripheral (please check the device sales type. */
    return(ERROR);
  }

This is the part of encryption processor driver code from ST's original drivers. In that case my Cryptographic Processor has not been started properly.

Is that problem caused by the my device's sales type (like it said in driver code) or is there anything wrong with my code routine?


texts: How big does the Schottky Barrier or Band Offset have to be for a junction to be a diode?

texts: Current rectification happens when there is a large Schottky Barrier or a large Conduction band offset (excluding cases such as tunnel diodes). My question is, how large (in electron volts) does the barrier or offset have to be? I know that the answer is not definite, but I would like to know a range, similar as to how we call any material with a band gap of 1-3 eV a semiconductor.


texts:
We want to design a pcb module that should be soldered directly onto customer pcbs (exactly like ICs ect.)

I found a module which does exactly that, please see pdf.

https://www.dropbox.com/s/ky2u9z83ja6snsh/pcb_pads.pdf

But how are these pads made i the pcb layout tool?

It looks like Plated through holes which has been placed half en pcb edge.


texts: Can Induced electromotive force affect itself?

texts:
At first, I want to say that I'm not English speaker, so my question might be very hard to understand. And also this question must be a silly question because I can't find any question like this...

I heard when current varies, inductor make induced electromotive force.
then it disturbs flow of current.

I have a question at this point. When it disturbs current, is this meaning that current slightly altered? I mean that the first altered current make V(=-L dI/dt), V affect dI/dt, then altered dI/dt affect to V', and V' affect to dI'... and so on?

Is (1) L related to sum of all the effect of I, I', I'', ... or (2) just first I?
Or (3) after I(=I', I'', ...) is too small, so ignore it and just calculate and get result(=inductor transient graph)?

To sum up, when I see the graph through magnifying glass, the graph will be smooth or rough(Because speed of field is c, not infinite speed)?

Thank you for reading this silly question. But this was hard to me.


texts: Why does oscilloscope show large amplitude when I touch the probe?

texts: When I touch the probe I see a 50Hz sine wave with an amplitude of about 100V from peak to peak. I understand that 50Hz is the mains hum picked up through my body, which acts as an antenna, but where is that huge amplitude coming from?


texts: How can a parallel capacitor improve the power factor of an inductive load?

texts:
In phasor or vector diagram, a capacitor that is parallel to the supply can improve power factor. I know this is practically true but I don't understand the mathematical equation:

The total impedance (Z) of the following circuit has imaginary part i=root(-1). That means it has a reactants and it will consume reactive power.

If XL = Xc , the reacance should be infinity or has a very large value so it will consume large reactive power.

I feel like algebra does not support phasor diagram... Would you tell me what I'm missing?

Thank you,

Edit:

Here is the opposite case:

If a very high reactance is good for power factor, Here is a circuit with a very low reactance. Does it also improve power factor? If yes, which one is better?


texts:
I have prepared one project. The details are as follows: The motor is turned ON when the button is pressed. Motor gets ON for 35 secs and then gets turned OFF. The whole operation is controlled by one microcontroller. I am using an 8000mAh Lipo battery, 12V 3S.
Motor continuous current: 5.25A
motor oprating voltage = 12V
microcontroller current: 160mA, 5V (LM2596)
The project will be in an ON state for 20hrs(up will be ON) and the motor is operated 10 times during these 20 hrs. Operating voltage: 11 to 12V Battery: Lipo orange 30C 11.1V 3S (Orange)
Question: I want to calculate how many days the LiPo battery can power this project? i.e. Product life cyle when Lipo is fully charged to 12V


texts: Reading ADC output on two microcontrollers

texts:
I'm trying to provide an ADC output to two different microcontrollers. Wondering if this is at all possible. If yes, then how could I be able to achieve it?

simulate this circuit – Schematic created using CircuitLab


texts: Can I use a simple voltage divider with an instrumentation amplifier to measure from 0 to 10V?

texts:
There is a design of a circuit proposed in the following way:

simulate this circuit – Schematic created using CircuitLab

The amplifier has a gain of 80, on R1 when the input voltage is equal to 10 V, it will be approximately 41 mV and when amplified by the OP would have 3.3V, which is the maximum volatje of the ADC of an MCU.

Could there be some kind of problem with this design?

The idea of using the voltage divider is to prevent the negative terminal of the voltage source (0 to 10V) from being connected to the ground of the main circuit, ie to isolate it in a certain way.


texts: BJT: Is \$ R_E || [\frac{R_s'}{\beta}+r_e] = (R_s'+ \beta r_e)|| \beta R_E\$?

texts:
I am trying to find the effect of \$  C_E \$ on voltage gain.

Circuit under AC conditions:

Doubt:

Is \$  R_E || [\frac{R_s'}{\beta}+r_e] = (R_s'+ \beta r_e)|| \beta R_E\$ ?

Reasoning:

Small signal model of BJT, in general, is given by:

To find \$  R_E \$ , we short-circuit the voltage signal source:

Effectively, the input portion of the circuit reduces to:

Therefore, it may be assumed that \$ i_b \$ flows through \$  R_E(1+\beta) \$.

Now, coming back to :

We have

\$ R_e= (R_s'+ \beta r_e)|| (\beta+1) R_E \$

\$ R_e= (R_s'+ \beta r_e)|| (\beta) R_E \$ (approx)

\$ =\frac{(R_s'+ \beta r_e)* (\beta) R_E}{(R_s'+ \beta r_e)+(\beta) R_E} \$

\$ = \frac{ (\frac{R_s'}{\beta}+  r_e)*(\beta) R_E}{ (\frac{R_s'}{\beta}+  r_e)+ R_E} \$

\$ = \beta [R_E|| (\frac{R_s'}{\beta}+  r_e)] \$

\$ \ne  [R_E|| (\frac{R_s'}{\beta}+  r_e)] \$

Why this discrepancy?


texts:
I am building myself a laptop. I have now come to the problem of implementing a lithium battery for it.
It will have to power the SBC and the display I use.

Both require 5V;
the SBC comes with a 2.5A charger,
the LCD has a maximum power consumption of 15W, so 3A.

The charger for the SBC is propably a bit overkill, though I would like to have some room to connect USB devices that also need some power (thinking of harddrives with dual USB for power).

My question is what battery suits my case, and what circuitry I need to not ruin it and to be able to use it in a laptop-like fashion.

First off, I think some UPS-like board would be needed to quickly change between charging/discharging the battery. Do you know where I can get something like that? I searched a lot, but all I find are battery protection boards.

When buying a battery, these will most likely already be included - but can I rely on those when charging and discharging?

And lastly, how does some kind of "fuel gauge" fit in the picture?


texts: Where does the formula for Voltage in AC with inductance come from?

texts:
This is what the textbook says:

I don't understand why does ωLIm equal Vm so if someone knows please explain it to me

Thanks


texts: Experimental tips RC second order circuit

texts:
I'm implementing a RC second order filter in the lab. My results were quite good, but of course not exactly equal to the simulation and theoretical prediction. I'm trying to understand why this is happening. I came up with a few points:

the components are not exactly their nominal value. They have tolerances associated to them that will obviously affect the pole localization and the gain.
some measurements, specially using the oscilloscope, have some errors associated with them: systematic ones, related to the precision of the instruments, and aleatory ones related errors reading the values or placing the cursors.
there is low frequency noise component caused by the presence of lamps. That noise will affect the measurements at low frequency.
there is also noise caused by the wires.

Any more tips about things that might affect our measurements?


texts:
I am working with a 12 volt car battery.  I want to design a circuit to measure its state of charge.
Is there any specific IC to do that?
This battery will be used in an automobile robot, which will be driven by an STM32 controller.  There will also be a display screen, one of its functions is to display the battery state of charge. The battery supposed to work for 5 hours.


texts: Why doesn't electricty flow to earth ground when I connect my oscilloscope ground clip to a floating circuit?

texts:
There are two concepts I keep reading about that seem to be conflicting each other. Firstly, whenever there's a potential difference between two points, and those points are connected, electric current will flow between them, evening out the potential difference. And secondly, electricity needs a closed circuit to flow.

Consider a closed circuit that is floating (battery powered or isolated). If I were to connect the ground clip (connected to earth ground) on my oscilloscope probe anywhere in the circuit, it would be reasonable to assume that the electric potential at that point is different between that point, and earth ground.

Because the clip is connected to ground with a low resistance path, and because the potentials are different, it makes zero sense to me whenever people say that no current will flow through there. If current is the movement of electrical charges, how is it physically possible that connecting a different potential would not result in charge movement?

What I find even more confusing, is that people often quote how the earth has "infinite" capacity to dissipate charge, which does make sense, but then it would act as a capacitor with infinite capacitance? Or at least measurable non-zero capacitance, and since it is so large, there should be a non-trivial amount of current flowing to earth at least in the moment when the ground clip is connected.

On a similar note, if I we just consider a capacitor with no return connection as in this image

I find it very hard to believe that applying a potential difference to one side of the capacitor would not repel the charges on the other side, and even push out the charges at the end of the wire to act as a capacitor against its environment.

I do understand that in the case of a small capacitor this effect might be small enough for us to ignore, as the capacitance of a small wire is probably beyond what we can even measure with test equipment?

But in the case of connecting to earth ground, such as this

how come the "infinite capacitance" of earth ground doesn't cause the charges to flow there through a low resistance path? I would understand if the argument worked for something like batteries, where one could probably say that unless electrons flow in the battery it would not produce more electrons out of it (I'm not sure if this really is true), but in that case I would imagine there would be other power sources for which this is not true, such as if there was a capacitor on the circuit, and the earth ground connection would allow it to discharge itself into earth (because of potential difference) with low resistance quickly.


texts: How to calculate actual hfe for low voltage source?

texts:
The datasheet for a transistor (said 2N2222) give us the hfe asuming a Vcc in the 30V range.

For uses like Arduino projects, the Vcc is usually 5V, and under that conditions, the actual hfe is lower. Insteads of hfe=100, we get hfe=12, like in this example (Ib=4.1mA, Ic=49mA in my tests):

No problem here; otherwise, with a hfe=100, the voltage drop across relay would be greater than Vcc, which is impossible.

My question is how to calculate the actual hfe from the datasheet when application's Vcc (5V in this case) is much lower than the Vcc used by the manufacturer (30V)?


texts: Why does my op-amp swing randomly when the inputs are disconnected?

texts: In Electronics class today we were using a TL081 op-amp. When I disconnected the inverting and noninverting inputs, the op-amp's output (driving an LED) started switching on and off rapidly. What causes these weird oscillations?


texts: Is it normal to be able to hear a high pitch buzz from devices that are charging?

texts:
I have noticed that in ungrounded outlets I am able to hear an almost silent high pitch sound if I plug in earphones into the device being charged.

I think this is the 50 Hz electrical signal that I'm hearing.

I can also hear this when a device is not charging but touching a cable that is charging another device.

Also the noise goes away when I touch the device. I assume this is because of me providing the grounding.

Is this a normal thing? Would it reduce the lifespan of the device in any way?


texts: Parameter vs macros to control which function is called

texts:
I am working on an AES encryptor/decryptor project that can handled AES-128, AES-192, and AES-256. The cipher key length is chosen at compile time. The module I am working on generates the key schedule. The algorithm to do so varies slightly for AES 256 vs the other two, so I have two different functions to handle them. My key expansion module has only one combinational logic block:

always_comb
begin

    expandedKey.expBlocks[0] = key;

    for (int i=1; i<=`NUM_KEY_EXP_ROUNDS; ++i)
        expandedKey.expBlocks[i] = expandBlock(i, expandedKey.expBlocks[i-1]);

end

These are the functions the previous code may call:

`ifndef AES_256 // expanding a 128- or 192-bit key

    function automatic expandBlock(input integer round, expKeyBlock_t prevBlock);
        // ... function body
    endfunction

`else // Expanding a 256-bit key

    function automatic expandBlock(input integer round, expKeyBlock_t prevBlock);
        // ... function body
    endfunction

`endif // `ifndef AES_256

The problem with this configuration is that it makes testing difficult. In my testbench, I want to be able to instantiate this module in each AES_XXX configuration and simulate all three without recompiling to make regression testing easier.

I've considered using parameters instead:

`ifndef AES_256 // expanding a 128- or 192-bit key
parameter logic SELECT_AES_256 = 1'b0;
`else // Expanding a 256-bit key
parameter logic SELECT_AES_256 = 1'b1;
`endif // `ifndef AES_256

always_comb
begin

    expandedKey.expBlocks[0] = key;

    // I chose to put the SELECT_AES_256 check outside the loop so it isn't
    // checked on every loop iteration, potentially generating even more extra
    // hardware

    if (SELECT_AES_256)
        for (int i=1; i<=`NUM_KEY_EXP_ROUNDS; ++i)
            expandedKey.expBlocks[i] = expandBlock_long(i, expandedKey.expBlocks[i-1]);
    else
        for (int i=1; i<=`NUM_KEY_EXP_ROUNDS; ++i)
            expandedKey.expBlocks[i] = expandBlock_short(i, expandedKey.expBlocks[i-1]);

end

function automatic expandBlock_short(input integer expRound, expKeyBlock_t prevBlock);
        // ... function body
endfunction

function automatic expandBlock_long(input integer expRound, expKeyBlock_t prevBlock);
        // ... function body
endfunction

Using a parameter would allow me to instantiate the module in whatever configuration I want, but it has duplicated code, and I'll eventually be relying on synthesizer optimizations to eliminate unused hardware. I don't like either of those attributes.

The Question
Is there a way I can refactor this code so that I can choose which expandBlock function is called when the module is instantiated, without the duplicated code and potentially duplicated hardware?


texts: Verilog: XOR all signals of vector together

texts:
Say I'm given a vector wire large_bus[63:0] of width 64. How can I XOR the individual signals together without writing them all out:

assign XOR_value = large_bus[0] ^ large_bus[1] ^ ... ^ large_bus[63] ?

I'm especially interested in doing this for vectors where the width is specified by a localparam.


texts:
I have a single phase duct fan that that run by a capacitor and its running too fast. I don't need it at this speed.

Motor: Single Phase Motor 78w @ 230v : 2560 rpm

Running capactor: CBB61 2.5uF @ 500VAC : 50/60Hz

I tried running two capacitors in series and it's slow the motor down quite a bit but nowhere near as much, I would like to run at 1/4 the power. I know I could buy a speed controller but unfortunate can't afford one right now.

The question is; Can I run a different capacitor to determine the speed? Or what can I do on the cheap? Thanks.


texts:
I need to make around 500 or more thermocouples type J 30AWG per year.
Currently I am using this thermocouple welder.
The process is quite tedious. I need to strip the wire, sometimes twist the wire and use the pliers to hold the thermocouple and weld it. The success rate is not 100% sometimes I fail to weld it into a bead. The machine is around 6-7 years old.
Currently I am not sure whether should I build a new one (I have no idea how to build a thermocouple welder,) get a new thermocouple welder, or to make a fixture that will help to make the process easier (any ideas on the fixture?)


texts: What "portable" NOC architectures exist for use in FPGA designs to be implemented across multiple vendors?

texts:
I have used Qsys in Intel Quartus and am aware that it generates an "interconnect fabric" that connects the different peripherals together. The generation of this interconnect is done automatically. The user has a certain level of control over its properties but the user is kept away from its details.
I have seen that there are certain modules in Microsemi Libero that can be used to connect AMBA master bus peripherals to AMBA slave bus peripherals. These components expose ports where the master and slave connections can be made. The GUI for these components makes it possible to specify the base addresses for the different peripherals and also specify what address space is accessible by which master.
Now if I create a design in VHDL which is supposed to work across both the Intel and Microsemi FPGAs, I shall have to write the interconnect logic in VHDL also. This should be a simple task if there are just a couple of masters and handful of slaves. Where can I find details of how this can be done? I am aware that in the past, when SoC designs had started to become complex, the designers had to manually design the interconnect.
I am sure instructions on how to do this exist, but am not sure how to find them. It seems that this is an esoteric field of knowledge.


texts: Can Blackfin DSPs boot from 'any type' of SPI external flash?

texts:
So I'm working on a project that contains a Blackfin processor, specifically the BF592 datasheet

One thing that confuses me is how exactly the boot up process will work. During development, I plan on loading programs through the JTAG interface. This will also allow me to debug.

However when I want to actually deploy a program such that it can start up from scratch, I will need to place the program (loader file) on some type of external flash. Looking at it the BF592 datasheet, I can have the processor boot up external SPI flash.

One of the boot modes is described as follows:

  SPI1 master boot from flash (BMODE = 0x2) — In this
  mode, SPI1 is configured to operate in master mode and to
  connect to 8-, 16-, 24-, or 32-bit addressable devices. The
  processor uses the PG11/SPI1_SSEL5 to select a single SPI
  EEPROM/flash device, submits a read command and successive
  address bytes (0×00) until a valid 8-, 16-, 24-, or 32-
  bit addressable device is detected, and begins clocking data
  into the processor. Pull-up resistors are required on the
  SSEL and MISO pins. By default, a value of 0×85 is written
  to the SPI_BAUD register.

I'm confused. How exactly would this work? How would the SPI master know what opcode to submit to the external flash such that memory is retrieved? For example, I've been looking at this external flash IC. It requires an op code of 0x0B to be sent followed by the desired 3 byte address. How exactly would the SPI master on the Blackfin know to issue this?

I've been digging deep into the Blackfin manuals and this part just seems to be hand waved. What exactly am I missing? Is there some configuration registers in the Blackfin where this would be configured? Do I need to purchase some compatible flash IC? Is there some standard for SPI flash where the opcode 0x0B is always used when pulling data?

Thanks!

Update: I was finally able to find the dedicated hardware manual which explicitly explains the 'boot from SPI' sequence. See page 690. This says that it issues a 0x03 or/and 0x0B opcode.


texts:
I'm having a pretty difficult time understanding how tuning works when using harmonics in spectrum analyzers. I'm reading about the topic from Keysight's AN 150.

Question 1

The following plot is showed in the application note:

  [...] we first plot the LO frequency against the signal frequency axis. Multiplying the LO frequency by two yields the upper dashed line of Figure 7-3. As we did for fundamental mixing, we simply subtract the IF (5.1 GHz) from and add it to the LO second-harmonic curve to produce the 2− and 2+ tuning ranges. Since neither of these overlap the desired 1− tuning range, we can again argue that they do not really complicate the measurement process.
  In other words, signals in the 1− tuning range produce unique, unambiguous responses on our analyzer display.

I don't understand why it states that they don't overlap. I clearly see that for a pretty big range of the vertical axis, there will be two image frequencies: one corresponding to 1− (the desired one) and another one corresponding to 2−. In other words, for any signal frequency between 1 GHz (approximately) and 3.6 GHz, there will be two possible possible responses. So why does the text state that they don't overlap?

Question 2

This is a much more basic doubt. I'm not sure I understand the basics of how internal harmonic mixing works. Is mixing with harmonics something that happens and is undesirable, or is it something deliberate that allows us to measure higher-frequency signals?


texts: 2 switching power supplies.....and diodes

texts:
So I'm trying to hook up a simple circuit like this...

V1 is a 3.3V signal that can randomly turn on.

V2 is also the same.

Sometimes one, sometimes both, sometimes none.

I thought I'll just get a couple schottky diodes and everything will be fine.

But when I put 3.3 volts at V1 to test. I read 3.0v at v2(with no power supply hooked up yet at v2). I understand the voltage loss for diodes,  but I don't understand why I'm getting any voltage at v2.

I'm sure I'm missing something simple, but I don't want anything to go haywire...

I've tested the diodes, especially on v2 and it says its good...

What am I being dumb about?


texts: Standalone Atmega328p setup not working properly

texts:
I have been using arduino uno development board for a few months now and wanted to shift to a smaller version of the same. For this, I used Atmega328p AU standalone chip using an I.C. socket (schematic). The schematic doesn't show 22pf capacitors with the crystal I have used.

Everything worked fine till the time I was using my mac to power the circuit. But when I use the wall socket to power my circuit, the setup starts misbehaving whenever I operate (turning switches on or off, rotating the fan regulator knobs to change fan speed etc.) any switch on the switch board to which the wall socket is plugged in. Whole setup isn't related to any other switch or regulator. It is just connected to the 5v wall socket adaptor which I have plugged in the board as shown in the picture below. Whenever I turn the switch on or off or turn the regulator knobs, I think some spikes/surges are ingested through the adaptor. The whole setup just starts resetting regularly or most of the time freezes altogether. However, the problem doesn't show up in the Uno development board plugged into the same adaptor using 5v and GND pin. I do not understand what is making the difference between the two. Is there a need for some decoupling or isolation?

Things I have tried:

Changing the cyrstal
Changing the 22pF capacitor with 18pF ones.
Uploaded the blink code in both Arduino Board and the chip,
still the same problem persists. The blink code and my code both work fine with the
Arduino board but on the standalone chip it gives the same erratic behaviour (LED stays on i.e., the code freezes).
Rewired the whole setup multiple times.
Tried so much on the arduino forums.

Following are some pics of the setups

At the left bottom of this image, the two wires I am holding show the 5V power input to the breadboard circuit. Note that I have given the input to the 5v pin of the chip and not vcc (because it works fine bypassing the voltage regulator).

The fan speed regulator knobs are not connected to the arduino. The only link is the adaptor, I suppose.

Schematic http://files.wooler.me/buildatmega/ATMEGA328P-AU-Wire_guide(2).png


texts: CD4521 frequency divider warms up while RESET is HIGH

texts:
I have a peculiar problem involving the CD4521 frequency divider of which I use two in a redundant configuration as shown in my schematic snippet below:

I noticed that while the devices are held inactive (RESET is HIGH), they both become very warm. I took some measurements with a K-Type thermocouple and established 49°C when inactive and 29°C when active (with a PCB substrate temp. of 21°C) in the middle of the chips' SOIC packages. The temperature is the same between the two units and they both operate reliably (so far).

I'm confused. I don't have floating inputs, the input impedance of the NAND XOR is high enough to not draw significant current and I tried increasing the RST pull-ups to 100kΩ with no effect. What could be causing this? I wasn't born with CD-series logic in hand so maybe I'm missing out something obvious...

Below is the relevant part of my PCB layout - your wisdom will be much appreciated!

Update

I cut the trace grounding Pin 7 as suggested by brhans & SamGibson and the operational temperatures returned to normal!

Also, I varnished over the cut with nail polish to prevent accidental contact due to oxide growth.


texts: Simple solar panel + supercap powered arduino

texts:
Long version (full story, so skip and go direct to questions below if you want to):

I have small arduino mini pro board powered by 230mAh Lithium coin battery used as wireless sensor (with NRF24L01 and different sensors)
I use a 1.8V or 2.4V LDO regulator and modified bootloader (lower frequency = lower consumption). Periodically it take measurement, send it and go to sleep (Board modified to go down to nA consumption). This work well multiple months, I'm happy.

But I found a new greener challenge: Power it without battery only by ambiance luminosity. I want to use a 12V (1.5W max) solar panel (I hope to get at least 2.8V with artificial light, I will verify this by testing) combined with a supercap (10 Farad for example)

I found some examples with IC's to control voltage and limit current: Bicycle example
But I wonder if I could make it simpler directly with only a LDO regulator.

For a 10F supercap and an 2.5V (180mA max) LDO regulator I get:
Charging time = (2.5/0.180)*10 = about 2 minutes 32 seconds

Questions:

Will my first 2.5V LDO regulator survive without current limitation, or do I need a mosfet like this : Instructable. I could add a resistor too, but that's energy wasted no?
Do I need more schottky diode to prevent some current leakage?
Can I use a 2.7V LDO regulator instead 2.5V one or It's better to stay a little away from supercap voltage limit even by loosing some power?
(I will see if power consumption is better with second 1.8V LDO regulator and a lower working frequency or if it's totally useless against using only the first one)

(Sorry for my poor English)

Edit 17/09/2018:

By searching other regulators with current protection I wrote this small tab:

MCP1702 is a better choice cause of thermal protection? But expensive for a SOT23 package : 0€42/piece. LP2985AIM5X-2.5 seems to be at 0€18/piece. I don't find other with Vin >= 12V on aliexpress for 2.5V output (most are 3.3 or 5V).

Edit 17/09/2018-2:

I found this example but for now I doesn't understand it all.
After @HarrySvensson comment suggesting to use MPPT to get more efficiency, I wonder if using some MPPT board for charging Lipo Like this one and putting the LDO regulator after it could be a good idea or absolutely not? (I looked the CN3791 datasheet I don't find any way to adjust output voltage)

Edit 18/09/2018:

And what about This one? Voltage and intensity are apparently adjustable. But I'm not sure this is a real MPPT board, it seems more like a buck converter.


texts: What should the switch pin output of an SMPS look like on a scope

texts:
I'm continuing to troubleshoot a broken SMPS.

At this point, I'm just trying to understand what components are broken, working under the assumption that it saw a voltage spike as a result of input ringing.

Here's what I'm seeing when I scope the switch pin (10uS/div, 1V/div):

The FB pin is sitting at 200mV, output is sitting at 800mV, input is steady at 11.8V.

Given this information, is it possible to guess what is broken? Is it the SMPS IC, the inductor, both?

Circuit for reference:

Switch for reference: http://www.ti.com/lit/ds/symlink/tps62125.pdf


texts: Low voltage relay to control ESC from Arduino

texts:
I have an ESC controlled by Pixhawk (a flight controller which produces a PWM). In case of emergency I need to stop the ESC by inputing it a PWM lower than 50%. Opening the circuit will not work as the ESC will continue to run 3s.
I then chose to use an relay controlled by the arduino which selects the input to the ESC between the output of the Pixhawk and the output of the arduino (which produces the 50% PWM).

Do you think it is a good design? Do you a any advice of a relay I could use? The PWM voltage is 5V and current is <40 mA.


texts: How can the source impedance of an energy source be made zero?

texts:
With regards to the Maximum Power Theorem (Princeton.edu);

  The theorem was originally misunderstood (notably by Joule) to imply that a system consisting of an electric motor driven by a battery could not be more than 50% efficient since, when the impedances were matched, the power lost as heat in the battery would always be equal to the power delivered to the motor. In 1880 this assumption was shown to be false by either Edison or his colleague Francis Robbins Upton, who realized that maximum efficiency was not the same as maximum power transfer. To achieve maximum efficiency, the resistance of the source (whether a battery or a dynamo) could be made close to zero.

I don't know if I am making the same "mistake" that Joule made, however I still don't see how at maximum power transfer, the efficiency is anything but 50%. At maximum power transfer, the source impedance = load impedance, hence equal power dissipated in the source and the load. Am I missing something here?


texts: What is/are the minimum sensor(s) is needed to get inclination/tilt/pitch of project with roll compesation?

texts:
I am planning a project that will measure and log the tilt of my push bike while I am riding it. The fastest that I would be recording is every 0.1 seconds, though it will probably be every 1 second. I am planning on using an Arduino as the platform.

From my research, I am currently unsure whether I just need a magnetometer (2 axis?) or whether I need to add a gyroscope and accelerometer as well?

As I am not located very near either of the earth's poles (i.e., mainland Australia) and am not thinking on going particularly far, so calibration at the start may allow accurate measurements using a magnetometer. However, I am not sure that it can be used like that.


texts: Voltage divider/reduction with no current draw

texts:
I am trying to measure the voltage on an LED in an open circuit (awfully shown below) using an arduino, however the voltages are too high for its inputs.

I have tried:

Using a voltage divider (~10K total resistance), however current flows and the LED lights up (which I do not want)
Bumping up the total resistance of the divider to ~10M, the LED glows extremely dimly (which is fine), but now the arduino doesn't read the voltage correctly (due to noise or something?)

So now, I have decided to use some Zener diodes to drop the voltage before connecting with the arduino, is this (theoretically) going to work?  Or is there some simpler/smarter way around this?

Also stumbled on this: Measure voltage with no current, but it seems a bit more complicated than using the diodes.

Any input is greatly appreciated.
Many thanks

Update: Thanks everyone for all the help, ended up using the pull-up as it was the simplest


texts: Supplying power to two devices at the same time

texts: I have two devices that individually require 5 V, 3 A, does this mean I can use a single 5 V, 3 A DC supply to supply the both of them or would the supply need to be capable of 5 V, 6 A in order to power them both?


texts:
How can I test a DC car blower motor with an external resistor? (note that there is an existing question about testing DC motors, but the assumption there is that it has an internal resistor, and it also assumes the tester has access to a "good" motor or a schematic, which I do not)

The motor has two terminals on it and the associated resistor has 4 different labeled resistance levels: R8K, R40K, R50K, and R70K.

Is testing the motor as simple as hooking a car battery to a high wattage 8000 Ohm resistor and then connecting the leads to the two spade terminals on the motor, or is it more complex than that?


texts: Reading an Image file on FPGA for processing

texts:
I am trying to implement image processing on FPGA. I need to have an image for testing my module. I tested the module for single bit, by just generating a pixel value on test bench, but would want to see the result on a whole image.
Is there a way to load an image file to an fpga for processing?


texts: I'd like to know if I can push 40 volts at 3 amps through an IRLZ44N MOSFET?

texts: I already have the datasheet, it states it can handle 50 volts at 50 amps but I'm worried about spikes since I'm using it to switch the primary side of the transformer at 70 Hz and it will be a square wave signal, so my concern is won't it over heat quickly since I'm near the 50 Vds point? And won't the 3 amps just make things worse?


texts: What is the proper name for this oscilloscope probe accessory?

texts: These used to come standard in the accessory pack that comes with a new o'scope probe, but they haven't been included in quite some time.  They are very useful for checking certain test points, and we are starting to run out.  We would like to buy more, but we aren't sure what the proper name for them is and we haven't been able to find a supplier.  Any ideas?


texts:
I am trying to design a PCB for the biasing circuit. I found this application note from integratech.
As you can see in the application note, it has input detection circuit and SPST circuitry.
I need manual applying of the gate and drain voltage. Is it possible to remove unwanted circuitry and keep the rest?
I have indicated the circuitry I am planning to remove in a black square. I have also indicated the connection I will be making between voltage inverter and amplifier in the red colour line.
I am designing biasing circuit PCB fro this power amplifier:- CGH40120F


texts:
Does anyone have suggestions for soldering a wire onto a thin metal sheet?
I tried soldering directly by placing the wire and adding some solder over it, but the wire keeps on getting separated from the metallic sheet.
I thought about putting a hole and putting a screw through or something similar, But the metallic part that I want to solder onto, is just a thin metal strip on a large sheet.
Any suggestions?


texts:
I want to make a power supply that outputs 90v DC, and I was looking for a 0...100v voltage regulators, but I don't find any...? How can I achieve this if I can't find them? The input voltage of the circuit would be 220V 50Hz.

EDIT: I have 220v to 110v 5A transformer although is really big.


texts: What does the USB bootloader do in the PIC microcontroller

texts: I was wondering what does a boot-loader do, there is one USB Bootloader for the PIC micro-controller and I was wondering as to what its purpose is. How is it different from creating some HID device from the PIC for example? Surely there is no OS running on the PIC than whats the whole point of this "bootloader"?


texts: How can I be sure that a multi-bit-per-symbol encoding schema exists?

texts:
(I came up with this question when I try to understand bit rate and baud rate.)

Suppose I have some data to transfer. And the data is binary encoded as a data amount of N bits.

If I use 2 symbols to represent the binary data, which means one symbol for 0 and another symbol for 1, then I can only transfer 1 bit of data a time. And the effective bit rate is the same as baud rate.

If I use more than 2 symbols to represent the binary data, and each symbol represents multiple bits, then I can transfer the same N bits of effective data much faster. And the symbol change rate on the line (baud rate) is lower than the effective bit rate.

But how can I know such a multiple-bits-per-symbol encoding schema exists for a given data trunk?

ADD 1

I once had some difficulty in understanding the baud rate and bit rate. I think the difficulty comes from the first impression I got from pictures similar to below one:

The pic gives me an impression that what get physically transferred over the wire is the digit 0 and 1. And for each digit, a different voltage level is assigned. So there are always only 2 different signal/symbol/voltage types on the wire. And thus the bit rate is always the same as baud rate.

Now I think this pic just shows some effective result. It is symbol that is get transferred over the wire. The amount of possible symbols is determined by the physical nature of the channel/medium. When a symbol is transferred, the one or more bits it carries get transferred effectively. And how symbols represent bits is a mathematical agreement among the communication parties.


texts: Unity Gain Op Amp Configuration: Stability?

texts: I'm planning to use the ADA4610 in unity gain configuration as a current buffer for a high precision (16-bit) DAC chip. The chip is labeled as being stable in the unity gain configuration. I currently have the chip configured like the image shown below. Practically speaking, should I be adding a capacitance in the loop or is this configuration truly stable? In addition, are there any best practices for this approach to current buffering?


texts: Making an efficient constant current source

texts:
I need help making an efficient constant current driver.
I want to power my home with LED light strips for lighting and decorative purposes. I need to be able to turn each strip on and off individually.
I need 31 small strips in total. Each strip will have 8 LEDs in series. I want to run each strip at 21.04 volts, 55mA.
The best idea I have so far is a 24 V constant voltage power supply and having a simple constant current circuit before each light strip as follows:
https://drive.google.com/file/d/1tjypDpxaherSxHHoGxFWdlf8oasYxr5i/view?usp=drivesdk
Or a variation of the constant current circuit as follows:
How can I efficiently drive an LED?
https://www.instructables.com/id/Circuits-for-using-High-Power-LED-s/
https://www.radio-electronics.com/info/circuits/transistor/active-constant-current-source.php
https://www.electronics-notes.com/articles/analogue_circuits/transistor/active-constant-current-source.php
I don't quite understand the advantage of adding a second transistor or using multiple Zener diodes and I need your help to decide on a circuit. I know it's got something to do with temperature stability and/or stabilising variation in current. I'll also need help picking out the transistors as I'm not quite sure how to pick the most efficient one.
Unless there is an alternative way that you guys recommend that would be cheaper or more efficient?
Should I try to arrange my LEDs differently?
I need the constant current circuit to be on the cheap side as I'll need 31 of them so buck converters/expensive ICs might be out of the question.


texts:
I'm currently working on a project for school and am using a makeshift LED matrix from lilypad LEDs to sew onto a tapestry. Right now I'm just testing with one LED for now (see schematic on my arduino forum post here). I've run into a problem where the light is
1) very dim
2) not responding to my SHIFTOUT command. Regardless of whether the pin on the shift register is off or on, the led just shines really dimly. This is the code:

int clockSource =7;
int latchSource =6;
int dataSource =5;
int clockSink =12;
int latchSink =11;
int dataSink =13;

 setup(){
 pinMode(clockSource,OUTPUT);
 pinMode(latchSource,OUTPUT);
  pinMode(dataSource,OUTPUT);
    pinMode(clockSink,OUTPUT);
      pinMode(latchSink,OUTPUT);
        pinMode(dataSink,OUTPUT);
}
void loop(){
digitalWrite(latchSource,LOW);
digitalWrite(latchSink,LOW);

shiftOut(dataSink,clockSink,MSBFIRST,254);
shiftOut(dataSource,clockSource,MSBFIRST,4);

    digitalWrite(latchSource,HIGH);
digitalWrite(latchSink,HIGH);

}

For clarification, the wire I'm using is 9 ohms/foot conductive thread, and Lilypad protoboards for the shift registers, even though it doesn't show in the attached diagram.


texts: rc circuit for electrical noise: why are these circuits similar?

texts: I am studying about thevnin's Theorem but i having an issue understanding why this two circuits are the same.  I get that when you short out the AC voltage, the circuits are basically wired the same way but i get lost when i take the switch into account.  For the second circuit wouldn't you be shorting out the RC when you turn on the switch?


texts:
I made a ZCS buck converter for the following specifications:
12 V to 5 V, 50W, 200 kHz switching frequency.
But in reality, the source might not be 12 V always, and may have fluctuations. Is there any way to address this problem? Something like sensing the input voltage and adding associated control (I know it is the output that is "fed back" to get the required output)? Initially I thought this could be addressed by current-mode control, but I am not sure it pertains to the fluctuating source issue.


texts: How can I generate a sinusoidal voltage and current waveform using half-bridge or full bridge inverter?

texts:
I know how a half bridge and full bridge circuit looks like. What I don't understand (and I simulated it) is that whenever I drive the switches using a pulse generator I get a square wave as an output. I am not filtering it.

So my question is: Can I get a sinusoidal voltage waveform and a sinusoidal current waveform using sinusoidal PWM (so dutycycle of PWM varies constantly in order to change the average DC value to create a sinusoidal waveform)?


texts:
I've tried to find recent articles about how to save electricity at home. I remember the most basic instruction was to unplug everything that was not being used at that moment.

My problem is that I don't find this recommendation on newer articles that often and I'm now in doubt if some devices may actually save more power by staying in "stand by" mode if turned on and off very often. (Obviously not talking about a refrigerator or home life-support systems, I'm referring to devices like home theaters, gaming consoles, and everything you could have at the tv-room in general).

Is the sentence "Unplugging appliances that aren't being used saves power." still valid for modern devices?


texts: Hot-plug protection: series resistor thermal considerations

texts:
I have a circuit in place for the Linear Technology LT3502A switching regulator (datasheet here). To prevent blowing up the whole thing during hot-plugging, I have chosen to add a small parallel ceramic cap and series resistance instead of an unnecessarily large electrolytic. As so:

The LT3502A is the 3V3 output version.

I shall be using 100V rated ceramics (1206 size) (or perhaps 50V is also okay, to meet the maximum input voltage of 40V for the chip).

I was just wondering what size resistor I should slap on there. I suppose I should be fine with an 0603 (0.125W)?

My logic being that the maximum output power of my chip at full load (which it will never reach) is 3.3V*0.5A = 1.65W. Multiply that by say, 2, to account for power losses and an additional safety multiplier (~ 3W). Presuming VBUS >= 12V (not going to put a 1W resistor there), the worst-case current through R7 is 250 mA, implying 0.0625W dissipation. An 0603 rated for 0.125W should be okay, I think? Just making sure not to release any magic smoke :)


texts: I have read that R, L, C, power source and Voltage/Current controlled Voltage/Current source are enough to represent any circuit component. I searched for an RLC model for a diode(any type) and could not find any. Can diode be modeled as RLC circuit or should it be defined as a separate object in an electronics simulation?


texts: Capacitance modulation to maintain current-voltage (IV) character

texts:
The ideal capacitor DC analysis shows the time constant to be a function of the load resistance and capacitance.

Since the load resistance will be constant during discharge, is there any research on modulating the capacitance with a feedback to maintain the current? This may be naive/illogical to the practicing engineers who know the in depth physics... but as a novice I wish to know.


texts:
There are so many resources online talking about how to represent and extend signed numbers in Verilog, but I still can not get it. Let's say I have a number 244, which is 'b1111_0100, or 'hF4. If I want to represent this number in signed decimal, should I need to declare the size with one extra bit for the sign?

8'sd244 or 9'sd244               // signed 244?
8'sb1111_0100 or 9'sb1111_0100   // which one is correct 244?
8'shF4    or 9'shf4              // Do I need 0FA, or it is assumed?

Even more confusion comes with negative numbers: do I need to represent them in 2's complement format? How about the size? It would be nice if someone could give an explanation with example in the <size>'<signed><format><value> format.


texts:
Okay, so here I am starting to get acquainted with SAMD series MCUs from Atmel and initially I just want to use ASF APIs and get one project done, however I thought ASF provides APIs for every piece of configuration.
I saw this in datasheet.

However the only option ASF provides is

So like what should I do to select last config i.e. OUTPUT;Input Enabled?


texts:
How microprossesor perfoms substration by 2's complement for 5 + (-3) ?
I know this might be basic, but to be honest I didn't get it at all.

5 = (0101)

3 = (0011) ---> it's 2's complements  is 1100+1 which is 1101

now

     0101
     1101
     ______ +

     10010

why is the result 10010 ? it's not even 2 in decimal.

Thanks.


texts: Why the emitter is earthed in the Common-Emitter configuration of a Transistor?

texts:
While reading the Common-Emitter configuration of a Transistor from a book, they said that the Emitter is earthed...? Then I Googled it and found the same thing... So my question is that why it is necessary to earth the Emitter

simulate this circuit – Schematic created using CircuitLab


texts:
Here is what I used for calculating ESR:

Here is a random datasheet which gives the ESR under certain conditions:

Suppose I want to calculate the ESR @ 100 kHz for the 220 µF capacitor:
I apply the following equation:
$$
\mathrm{
ESR = \frac{0.1}{2*PI*100^{3}*220*10^{-6}}
}
$$
Which is not equal at 0.18 Ohm which is given in the datasheet.
Where is my error?
We actually do not know at which frequency the dissipation factor is given, but I supposed that it is given for 100kHz.


texts: Transistor as a Switch in Cutoff and Saturation

texts:
1) An NPN transistor in cut off mode:

"To get a transistor into cutoff mode, the base voltage must be less than both the emitter and collector voltages. VBC and VBE must both be negative. In reality, VBE can be anywhere between 0V and Vth (~0.7V for silicon) to achieve cutoff mode."

a) I've also read that both the base- emitter and base- collector junction will be reverse biased in cut off mode. But how? If the emitter is earthed, then even if Vbe (=Vb?) is less than 0.7V, the base is at a more positive voltage than the collector and consequently it is forward biased, right?

b) Also, why do we need to ground the input and the base if Vbe is already less than 0.7V? (How is the base grounded in the figure? I can see only the input being grounded)

2) In Saturation mode

a) This, I can understand because the collector voltage becomes close to zero during saturation and thus both Vc and Ve are less than 0.7V (and are thus forward biased)

b) But, why do we connect the input and base to Vcc?


texts: Why do people hand wind flyback transformers?

texts:
I'm intending on building this circuit, but re-specified for an output of about 150V @ 5mA.  Enough to light two neon bulbs from a 12V supply.

Why do flyback transformers such as the Wuther's seem to be either specially made for this purpose, or hand wound in the DIY world?  There are numerous web examples of people hand winding these things with spooled wire onto various formers.

This circuit comes with an LTSpice model.  LTSpice treats all transformers and inductors similarly, and the model does not mention things like "magnetic saturation, eddy current, flux density".  The simulation works very well (it's what LTSpice was written for) so there seems to be no modelled difference to using a standard mains step down transformer.  Indeed, this item available on a well known auction site clearly shows a 12-0-12 mains transformer-

There is a 1:10 transformer in my original above example.  That's very similar to a standard 230v – 24v transformer backwards.  Why hand wind or look for the elusive Wurth?


texts: Identify which bus, mobile phone batteries use?

texts:
Mobile phone battery bus are usually 3 pin or 4 pin which are  usually 2 wire buses (I2C) or a similar type of serial interface for a 1 wire bus. Does anyone know of a method for checking which bus type it is.

I don't believe a thermistor is solely used for Li batteries, that idea came from fast charging of other types of battery.


texts:
I'd like to have a light switch that turns on for at most 1 hour. My idea is to put a USB charger (110AC -> 5DC) + arduino + relay inside the wall. When the switch is turned on, it will turn the arduino, which should be programmed to close the relay, sleep 1 hour, open the relay.

Then I'd need to turn off/on to restart the arduino or just optionally turn off in order to save power.

But I feel this solution is a bit overkill (and not too nice). Maybe a physical button that turns off (using a spring?) after a timer? I couldn't find it; or some other suggestion?

Oh, and it would be nice if the solution doesn't have a high probability of setting my house on fire.


texts: Confusing regarding sub domains of main specializations EE?

texts:
I want to apply for masters program in Hungary in EE

As shown  attached snapshot, there are listed 3 secondary specializations:

Smart city
Smart systems integration
Optical Communication

I know that subject number 3 (Optical Communication) is secondary specialization of Main specialization (Multimedia Systems and Services)

But i am confused regarding the remaining two secondary specializations(smart city and smart systems integration), regarding to which main specialization (Electric power systems or embedded systems) they both belong/refer to?


texts: I would like to use an ultrasonic transmitter and three receivers to be able to determine the position of the transmitter relative to the receivers. The distances to be measured are around 3-4 ft. I want to understand how the receivers orientation relative to the transmitter can affect the distance measurement. I attach some simple pictures for illustration, in the first one the receiver is placed directly in front of the transmitter and opposite which is the ideal situation. In the second picture the receiver is placed in front of the transmitter but it is facing away from it. In the third picture the receiver is within the beam angle but is facing almost tangent to the beam. Basically as long as the receiver is within the beam range does its orientation matter?


texts:
I've been learning about ACF for doing a chip-on-board application, but I'm having a little trouble finding enough information about it. My main questions are:

How is alignment done for very fine pitch chips?
Are there guidelines to follow for how large to make the footprint pad for each connection?
Does the die have to be manufactured specifically for ACF application? Are solder bumps required?


texts: Is it possible to manufactrure a stencil for this paste-mask using the usual stencil making methods?

texts:
I have this footprint from the KI-CAD footprint library (LFCSP-32-1EP_5x5mm_P0.5mm_EP3.1x3.1mm_ThermalVias).

The paste-mask shows several circular paste areas under the thermal pad.  The separation between the paste areas is only 1-mil.

The areas between the paste circles in this paste mask would need to be entirely supported by 1-mil thick strips of metal.

If the stencil could even be manufactured using the usual methods, I seems that it would be exceptionally prone to breaking in that spot.  It seems to me that it would be better if the paste circle diameter was reduced by 5 to 10 mils.

Is it possible to manufacture a stencil for this paste-mask using typical stencil making methods?


texts: What are the disadvantages to using an MCP2551 as a CAN transceiver for GMLAN / SW-CAN?

texts:
I made my own version of the Canalyze Linux CAN interface. I plan on using it to study the CAN traffic on a Buick Regal. Since this is a GM vehicle, part of the traffic is on a GMLAN or SW-CAN network.

The Canalyze circuit doesn't directly physically support SW-CAN, so I cut the OBD-II - DB9 cable and plugged the wires straight into the appropriate pins on the car's OBD port, and it worked just fine. I can both send and receive messages, and the MCP2551 does work with GMLAN.

I plan on changing the circuit by adding another two or three MCP2551s so that I can connect to multiple networks simultaneously. Multiple sources indicate that I should use a dedicated SW-CAN transceiver such as the TH8056, but they do not mention why. Thus, my question: are there any disadvantages to using the MCP2551 for interfacing to SW-CAN?

I would prefer not having to mix different chips and I don't see why I would since MCP2551 seems to work with both SW-CAN and high speed CAN.


texts: How greatly can heat increase resistance?

texts:
A conductor has a resistance of 0.001 Ohms, at room temperature, by increasing the heat x100  degrees Celsius how greatly would that effect the conductor's resistance?
I'm trying to find the correlation of heat and wire resistance.


texts:
I am thinking of using the MAX882 IC to protect my battery from overdischarging. What I could not understand from the datasheet I provided is that, if I use the STBY pin to set a threshold for my battery max discharge, when the battery reaches that voltage, and the output turns off (i.e. no current drawn anymore), wouldn't the battery voltage go up? As a result, wouldn't my circuit turn on and off with the battery voltage swinging around the threshold voltage set at STBY?
To sum up, there seems to be no hysteretic or latching functions, that could prevent the swinging from happening. Is that right?


texts: What is the difference between Manufacturing/Design process of CMOS IC for Automotive Grade 1 and Grade 2

texts:
I see various CMOS IC in the same datasheet has Automotive Grade 1 [125 deg.C] and Grade 2 [105 deg. C] part numbers.
Can you explain what are the possible manufacturing or design differences between those two grades?
Assume for example
https://www.nxp.com/docs/en/data-sheet/MC9S08MP16DS.pdf
Look at Section 3.1 for the part number in the datasheet.
You will see 3 temperature ranges.
Question is what is the manufacturing or design differences for the part.
I need some idea about the possible differences either from design perspective or from manufacturing perspective.
Thank you.
Regards

Also another datasheet with multiple temperature range
https://www.nxp.com/docs/en/data-sheet/MC9S08EL32.pdf
Appendix B shows the order info


texts: How to view wire values in Altera Quartus Prime

texts:
I would like to be able to view waveforms showing internal nodes in a circuit specified in Verilog in Altera Quartus Prime. I am having trouble doing so when a wire is an output of one module and an input of another. For example, my top-level entity includes:

module cpu(input [9:0] SW, output [9:0] LEDR);
    wire [7:0] pc_in;
    wire [7:0] pc_out;

    assign LEDR[7:0] = pc_out;

    pc my_pc(pc_in, SW[9], Continue, pc_out);     // pc_out is an output
    instruction_memory mem(pc_out, instruction);  // pc_out is an input
endmodule

(There's more, but I left out irrelevant parts.)

Here is the full definition of pc:

module pc(data, clock, enable, q);
    input [7:0] data;
    input clock;
    input enable;
    output [7:0] q;
    reg[7:0] q;

    always @ (posedge clock)
    begin
      if (enable)
          q <= data;
    end
endmodule

While I can find pc_out in the Node Finder and add it to my waveform in the Simulation Waveform Editor, it shows up as an input:

Note that it is logically equivalent to the LEDR output.

I tried changing the type of pc_out from INPUT to BIDIR, BURIED, COMB, OUTPUT, and REG, to no effect. (The only difference is the initial values.)

Whatever type value I set it to, that is how it appears in the output waveform shown after functional simulation:

The same thing happens if I add the q output of my_pc (which is a basic register) and is equiavlent to pc_out.

I've successfully viewed signals by connecting them to outputs, but the chip I'm simulating only has 10 LEDs. (I'd be willing to switch to another real or fake chip with a huge number of outputs, if that's the best solution.)


texts: Parallel LCD screen to serial? (1 dedicated microcontroller?)

texts:
I'm a newb with electronics and was wondering if there's an IC or PCB that could convert a parallel LCD connection to Serial so I can use 2 wires to communicate with the screen using an arduino and still have open pins on the arduino to use for something else.  If this isn't the case, then do people usually have a dedicated microcontroller for the LCD screens or do they handle this a different way entirely?

EDIT: For example, this LCD screen requires approximately 11 pins  which is a lot to use on an arduino.


texts:
I've sourced some HT7333-A LDOs in SOT-89 package from random AliExpress seller for my battery-powered project. They were quite affordable and I saw some posts from people using these in batter-powered apps.
Datasheet on that IC states it has about 4 uA quiescent current and requires only 2 x 10 uF capacitors. I've soldered 2 (input and output) SMD ceramic caps in 0603 rated and 10 uF and measured to be around 9.3 uF in fact.
Casual Li-Ion battery are used as input, at 4.083 V, the output from LDO are at 3.263 V (ok for me, within datasheet specified range). But when I measure current flow while output are left "floated" it reads at around 1.2 mA, which is definitely not good for battery app.
I haven't connected real load yet. But why is it sinking 1.2 mA while no load are connected? Am I "happen" to get some sort if fake ICs or flawed component (I've checked only 1 IC from the strip so far)?

PS: Asking more out of curiosity, I've already ordered other low quiescent current LDOs from reliable supplier.


texts:
I'm trying to transmit Ethernet through relays. I'm using relays because I need them to switch to another signal path, and I'm specifically going to use relays and not other switching devices so that things are fail-safe and still provide a path when my device controlling the relays is off. So, I wonder if anybody out here knows can I safely transmit 100 Mb/s Ethernet through relays? I'm a bit worried because the spec says that Ethernet must be transferred through 100 Ohm impedance (unshielded twisted pair).

Will the signal be ok?
Are there timing issues or any other issues with doing this?


texts: Building a powerful electromagnet for repulsion

texts:
I have to make an electromagnet for my project. The role of the electromagnet is that I want it to repel a permanent magnet so that its hard to press down at that point an N42 ring Neodymium magnet (Outer diameter 26,75 mm: Inner diameter 16 mm: Height 5 mm) from around 2-3 inches distance. So that if a pulsing voltage is provided to it, it makes a vibration to be felt by permanent magnet.

EDIT

I have now some results to talk about.

I bought few EM from market but they are too weak for this purpose probably not built for repulsion purpose. I have made 4 electromagnets so far with different specifications and have positive results. Now I want to get some feedback for what now on I am thinking to do based on what results I got so far.

Here are specifications & results of my 4 build EM:

I used Ferrit core of diff dia and height and enameled copper wire of diff dia. To give repulsion from more distance, I put a permanent NeoDem-magnet on top of core. It provided more distance for repul and finished attraction of core to magnet. Total distance of repulsion that felt becomes once I provide power to EM 30-35 mm with diff repulsion push from diff EMs, so 30 mm by permanent magnet that i put on the core and added 5-7 mm by EM. Under is a table listing specifications of core and wire & then how much repul each give to permanent magnet on switching ON/OFF EM.

From these results, I concluded going for core with more diameter and using wire of 1.0 mm is way to go. Now I am thinking to use more thicker core i.e. 4cm, 6cm, and may be 8cm. I have few questions regarding this:

Is there any formula or online tool available to calculate what size core with what size wire is optimum or is any rule to make maximum powerful magnet. I am thinking like there may be a saturation point so to use more thicker core than that has no effect or adding more turns only add resistance. There is one available but that is for air core online electromagnet calculator. It's very helpful though for finding resistance of coil and number turns.
Any suggestion based on these results for what I am planning to do next will be very helpful.


texts:
Could anyone tell what is the advantages/disadavantages of using half duplex SPI over full duplex SPI communication. I know using half duplex, we can save one pin. But is this the only advantage of using half duplex? Is the rate at which master reads the data from the slave same for both mode of communication?
Please reply

Regards


texts:
I have got the SparkFun kit with the AD8232. The schematic is:

I wish to use only 2 leads; how do I ground the third lead RLD? I'm collecting the signal from the hands. The datasheet only gives application for cardiac monitor wherein the electrodes are placed near the heart. Can someone give me an idea? My first option was to connect two \$10\:\textrm{M}\Omega\$ resistors from RA (-IN) and LA (+IN) and then from the other end connect it to RLD. However, this is not producing optimum results.


texts:
I made a little program on my Synapse RF Engine to detect some vibrations and then turn on a light basically.

What I want to know is how do I get this prototype to an actual PIC that I can connect the piezo sensor, led lights and power source? How do you choose a PIC? And is this the way to do this? The programming is super simple, just reading the digital output of the piezo sensor and then based on that turn the light on or not.


texts:
I've been using Eagle for the past 10 years, but I recently started wondering about open sourced CAD tools, figuring if I'm mainly designing Open Source Hardware, might as well do it with an open source tools.

I have a mac, and a windows machine, so a solution that's compatible with either will be fine.

I guess one of my top concerns is popularity. When evaluating open source tool, I usually will gravitate with one of the most populars, with a rich community.

I've looked quickly at Fritzing, but that's falls far too short for what I want to do.

What are your thoughts?


texts: Circuit that dumps RF energy on matched load. Can anyone help?

texts:
Background
Trying to protect my home against the RF irradiation by cellular tower nearby. Read an article that proposes 2 things:

Metal film, or fine metal mesh, which is grounded. This is used on all doors/windows which are the points via which RF energy manages to enter the home.
An indoor antenna, with a matched load. This apparently reduces the residual radiation indoors, by absorbing and dumping the RF energy on a matched load.

Objective
While I've already done the first thing, and observed close to 50% drop on my Electrosmog meter (a Cornet ED65) of the RF power inside house, I think I'd need to take the second step to bring it down further.

So, wondering if anyone can help me figure out what this 2nd circuit is and how to go about building/designing it ?

Addendum (April 22, 2012 - Earth Day!!)
Probably a substantial portion of the battle-hardened scientific community (or rather, the more hands-on engineering community), might have a good laugh at the expense of this question (and I do not mind that), and brand folks like me a dumb tree-hugger. However, let me also say that there are many amongst us, who have a genetic predisposition of being more easily afflicted (than others), by often-untreatable life-threatening conditions, aggravated/hastened/catalyzed by EMF. For such people, doing what they can, to protect their loved ones and themselves, to the best they can, is important. There is sufficient quantity of very believable scientific literature, that is facts based, based on through, deep, long studies, that point to strong correlation of EMF and some of these ailments/conditions.

Just to answer some of the interesting questions like what do you do about the microwave oven, (or other such sources s.a. Wireless router, wireless broadband, cordless phone, wireless baby-monitor etc.), when living inside a faraday cage, let me state that I am not trying to reach zero radiation, but only bringing it to a level which, by today's international standards becomes acceptable, which it clearly isn't, as-is. In any case, I have already gone back to what might appear as a cave-man status. We do not use microwave, wireless router, cordless phones inside the house. It is a fully wired house, and has 12" thick brick-n-mortar walls, concrete roof. With the metallized film application, the level of radiation that "leaks in", apparently through the windows/doors has already come down, but not yet to be within acceptable limits.

So, if someone can please answer my original question, or feel free to ask for clarifications, i.e. is it feasible / possible to create an indoor antenna, that supposedly reduces the effects of cellular (850MHz/900MHz/1800MHz) EMF, by absorbing the RF energy and apparently dumping it on a "matched load".


texts: Life cycle of power MOSFET as a switch in SMPS circuits

texts:
In many SMPS application (BOOST converter in particular), power MOSFET is used as a switch and it is driven by a PWM/IC at a frequency in a range of hundreds kHz (f = 200kHz for instance). This means that if a SMPS is used, says for 1 hour, the MOSFET would have switched \$f \cdot 1 \cdot 3600 = 72 \cdot 10^7\$ times !!

Does this amount of switching shocks anyone? I imagine that each MOSFET is designed to sustain a certain amount of switching (for instance \$10^9\$ times). If this limit is reached, what will happen to the MOSFET?

Thank you in advance for your answeer !!


texts: How to drive multiple LEDs from a Li-ion battery (with varying voltage)?

texts:
I want to supply constant voltage to my LED's but the supply varies from 3.7V to 4.2V (Li-ion battery). I cannot use 3.3V voltage regulator as it will need at least 4.3V voltage at the input but my battery can supply only 4.2V max.
so is there any other way I can supply regulated 3.3V to my LED.

RGB LED = 3.3V, 60mA
Battery = 3.7V - 4.2V, 3000mA
Number of LEDs = 24
The LED's are connected in parallel


texts: What is the spark, caused by opening/closing a circuit, dependent on?

texts:
I have a DC circuit that runs 1 A current in it when it is closed. When I close the circuit, i notice that there is a spark between the terminals of connection when they're brought close enough, just before completing the connection. I understand that this is due to the electrical breakdown of air but the air is such an excellent insulator (breakdown voltage=3000V/mm).

Is this sparking dependent on the closed circuit current (higher current, higher probability of sparking) or the potential difference between the terminals or some other factor?
How would there be a difference in potential if it's just two broken ends of a circuit which are going to be joined together to make it live?
If it is dependent on the closed circuit current, what is the threshold current to cause the sparking?


texts: Substitution + Superposition with RLC circuits

texts:
Consider the following circuit:

simulate this circuit – Schematic created using CircuitLab

\$E\$ is a constant voltage source.
The switch is closed at time \$t = 0\$.
The request is to calculate the generic equation for \$i_L(t)\$.

Using the PSC convention i get the following Kirchhoff equations:

1) \$L{ {d i_L} \over {dt}} -v_c = 0\$ (KVL)

2) \$v_c -E -i_R R= 0\$ (KVL)

3) \$-i_R -i_C -i_L = 0\$ (KCL)

After few substitutions and algebraic manipulations I get the differential equation which describe the circuit:

\$-{d^2i_L \over dt^2} -{1 \over CR}{di_L \over dt}-{1 \over CL}i_L = -{E \over CLR}\$

(Replace \$i_C\$ with the capacitor law on the 3. Replace \$i_R\$ form the 2 in the 3 then replace \$v_c\$ from the 1 in the 3.)

The answer is correct but I want to find the same equation using a different method. By assuming the state variable as known I can replace \$L\$ with a current source and \$C\$ with a voltage source (I just applied the Substitution theorem). Then using the Superposition theorem I obtain these three circuits:

simulate this circuit

The current directions are the same of the original circuit.
I get these two equations:

\$v_L = 0 + v_C + 0\$

\$i_C = -i_L - {v_C \over R} -{E \over R}\$

After replacing \$v_L\$ and \$i_C\$:

\$-L{di_L \over dt} = 0 + v_C + 0\$

\$-C{dv_C \over dt} = -i_L - {v_C \over R} -{E \over R}\$

However by replacing \$v_C\$ in the second equation with \$-L{di_L \over dt}\$ I can't get the same equation obtained with the Kirchhoff laws. Not only the signs are different but also the coefficients of each term are different.

What am I missing ?
Can this method applied for every AC circuit ?


texts:
I want to build a Magic Eye Tube VU. This tutorial http://www.antimath.info/electro/vu-meter-em84/ says:

  If this circuit is used with a tube amplifier, the “IN” connection in the picture is connected to the anode of the last tube in the amplifier. For an input from another signal source, a preamp stage with a BC171 transistor ( a MOSFET would be a better choice for high input impedance ), is needed.

The tube needs -22v to fully close, but 12v will be enough for me.
I want to use my computer output with the VU meter. There are some diagrams and schematics on the internet, but i don't think they will work with design. Could you recommend a preamp circuit that will work for me.


texts: How to scale a device for the second derivative of Amps/Volt?

texts:
I'm testing parts for a lab at school that measure current as a function of voltage. With different sized devices I can scale the results easily lets say I want to estimate the current of a device that is twice the size of the original device, I multiply the current by 2 at that same voltage.

However, I am being asked to find the d2I/d                                                                                V2, second derivative  of the curve. I believe this results in a unit of Amps/Volt*Volt, A/VV, A/V2 as I am looking for the how much the current changes over voltage with respect to another voltage.
How would I scale a device that's twice as big for a second derivatives, A/VV2.
please let me know if i am confused and probably have confused others with this post. One thought was that I scaled it using 22.
Looking forward to any help/understanding you guys can provide
Thanks!


texts: How can we provide a stable reference voltage to a voltage regulator if we don't have a stable source to begin with?

texts:
In voltage regulator circuits i always see a "reference voltage", that is supposed to be used to tune the regulator to the voltage we want to regulate the output to.

But since we don't have a regulated source to begin with, how can we provide that stable "reference voltage" ?


texts:
What I want to do is have a circuit with a 555 timer (which is what I have available) that works the opposite of what a monostable circuit should do—well, kind of. What I mean is, on a regular monostable circuit, when the trigger is connected, out turns HIGH and remains HIGH for an amount of time depending on the RC network, right? What I want to do is to have the trigger impulse start a countdown and only after the countdown, the output turns HIGH for—I don't know—a pulse, something between 0 and 1 seconds. How should I do this?

I need to be able to regulate the time it is off before turning on, the on time should stay the same.

The purpose is to "fool" an automatic door to think the close limit is on so the motor stops after the output goes high, this way I can open the door like 30% or 50%, depends on the time the output on the 555 is low.


texts: How do you measure nano volt order signals?

texts:
If you have a blackbox that gives you nanovolt signal in the output, how would you collect and process it? Signal to noise ratio is very low.
How do you filter the noise? Let's say the frequency range is 0-80Hz in that application.
What amplifier would you use? what type of circuit? Thank you


texts:
A source power with $$v(t)=5\sin(\omega t)\text{ V}$$ and frequency 1kHz is connected thought an \$RL\$ parallel circuit. The maximum current is 5mA and the resistor current is 4mA.
What is the value of the inductor?

We did:

Il=Vin/jwL
thus:

L=(5;-90)/j6283
L= 0.8H
Is it correct?

Ir=Vin/R
Ir=5v/5^10-3
Ir=1250ohms


texts:
I have a device which implements a CAN bus and I need to connect 10 other devices to it.  The descriptions I've seen of how these are wired show pictures like this:

The rig I'm making is a one-off (well, two-off actually, to support 20 devices total).  I'm just trying to see if there is a some normal way one would make a pair of wires and then "tap it into them" at 10 different places.  Obviously I can chop the wire and make a soldered connection at each point.  I could also just run a separate pair of wires to each of the 10 points, all converging back to one point (but this makes a "star" instead of a "bus" which may screw things up).

Maybe this is a dumb question but is there some common tool that is used for this?  To clip onto/into a wire in a case where you want to attach something to the line without having to cut it, solder the 3 contacts together, re-insulate it, etc.? (Wire nuts are an option too but also seem like it may be an inappropriate approach.)

EDIT: So far it looks like daisy-chaining them is the most practical approach.  Whether it's with screwed-in contacts or other type of connector, just make sure I have two connectors on each device and then chain them together.  That's where I'm at after looking at this off and on over a few days (and taking into account @Araho's advice).


texts:
Reading the ULN2803A datasheet, especially the part "Figure 13. ULN2803A as Inductive Load Driver" and after various fails to properly drive 12v RGB led strips, as i can't find the proper mosfets. i was thinking to get more of those ULN2803 and use them like a "mosfet".

  500-mA-Rated Collector Current

  Total substrate-terminal current –2.5 A

This means if i connect one pin of my 3.3v or 5v microcontroller to all 8 intputs , and all 8 outputs (gnd) to the leds , basically solder them all together, i get a max of 12v@2.5A=30W on one ULN2803A.

Using PWM on 3x ULN2803A, doing the same as above, would allow me to get 12v@7.5A=90W Led strip to run properly.

Would i be able to properly power the 2x 5m led strip or less, assuming i have 7.5A@12v=90W and the strip consumes 7.2W/m*10m=72W, without problems (except the obious voltage drop on a 10m strip)?

Said that, if it's correct, the ULN2803A is for 3.3v & 5v and so has already all the protection and logic stuff inside, so i don't need any resistors, diodes, transistors or whatever to protect my Microcontroller?

Basically i just need to connect the Arduino(5v) OR Raspberry (3.3v) signal pins to the ULN2803A inputs, the GND of the led strip to the outputs and the ground to the microcontroller and 12v powersupply.

simulate this circuit – Schematic created using CircuitLab

note.: i use a industrial 12v 10A/5A(with a shorter led strip) power supply if everything is clear

btw if i connect the Raspberry that has very low output (20-40mA) on one single 3.3v PIN
 how much current sucks each ULN2803 input?

  II(on) Input current VI = 3.85 V, See Figure 6 0.93 1.35 mA

So if max is 1.35mA, let's say 1.5mA*8inputs=12mA there are no problems to power them all with just one pin???

And regarding the length of the strip this would also allow me to easely gie power at every 1-2 or 3m to have a nice stable 12v....And so i would have no voltage drop.

What about PWM on 8in and 8out... it could create some errors on the linearity of the PWM signal???

"No, your totally wrong, the reaspberry has not enough mA to power all 8 inputs with one PIN" or "Yes, you can handle 7.5A at 12v and the Raspberry is safe" would be enough as answer.

I'm not a electronical enginer. So sorry for my low knowledge about electronics.

Are my assumptions correct?


texts: Identifying strange amplifier types of amplifiers in a 1979 CB radio

texts:
I'm trying to fix an old Midland 3001 CB radio and I came across a few strange types of amplifiers in the receive stage of the radio. I was wondering if anyone could identify the type of amplifier used.

In the screenshot the direct input from the antenna is coupled through C101 on the left I believe. Then there are some diodes which I assume are used to protect the receive stage. The L101 is a variable transformer that couples the signal to the transistor Q101.

What kind of amplifier circuit is the Q101 transistor involved in (is it common emitter, common collector, or something else entirely)?
What is L102 doing at the output (I believe it is a tunable LC
filter)?

I have also attached the full schematic diagram for the radio.


texts:
How to turn on a buck transistor via a bootstrap circuit?

In my circuit, I use a AVR microcontroller to turn on and off a buck switch.  What circuit should I use here?

Previously, I used optocoupler which does not have a fast response. I like to turn on and off the transistor for no more than 500 ns on/off transition.

There are some high side low side ICs which are designed for bridges and I am not sure if they would work for here.

Solutions with BJT/Capacitor/Diodes are very pleasant to me though I dont limit myself to only those solutions.


texts: ATmega328P firmware flashing interrupted - is it fixable?

texts:
I am working on some PCB with an ATmega328P on it. I use a Pogo connector because we have to program and test the PCB outside.

I program with usbTiny, (mosi/miso/rest/clk/power)

Anyway, many times during programming I move a little bit which disturbs the Pogo pin contacts and get a verification error. Then I start again and flash it successfully.

But sometimes, after a movement and a mismatch on verification, I can not flash it any more, like now.

I get :

avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

An error occurred while uploading the sketch

I got extremely tired from manufacturing again and again :( and I am sure the chip is still OK. This will probably happen again.

I have read that there are ways to save it, like serial programming or oscillator.

How exactly can I do this with serial?

VERBOS:

       Using Port                    : usb
         Using Programmer              : usbtiny
avrdude: usbdev_open(): Found USBtinyISP, bus:device: 020:013
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : USBtiny
         Description     : USBtiny simple USB programmer, http://www.ladyada.net/make/usbtinyisp/
avrdude: programmer operation not supported

avrdude: Using SCK period of 10 usec
avrdude: initialization failed, rc=-1


texts: What is the best method to determine bypass capacitors for each chip in Mixed-Signal Systems?

texts:
In datasheets of chips, usually they have reference designs and to those designs bypass capacitors are predetermined. But, when I examine some high level designs of those chips I see different bypass capacitors. For example, if the bypass capacitor in the reference design is shown as 1 uF only, I see 0.1 uF, 1 uF and 15 uF capacitorsin a specific application circuit of that chip. So in mixed-signal designs, the designer takes extra cares for bypass capacitors.

I want to know the calculation of the capacitance values and which type of capacitor I should use in each specific application, power range and frequency range. To make this question more clear, I draw this example mixed-signal system below:

There are digital blocks, analog blocks an an RF block in the system. To make a case, let say there are two digital chips work in 400 MHz and 200MHz and draws 100 mA and 50 mA drain pulses sequentially. And in analog blocks, there is an ADC which processes very sensitive signal(let say about a few nV's) in 10 - 50 MHz range. Other Analog block is also can be considered sensitive and works in 5 - 20 KHz(Acoustic) frequency range. Then there is a RF block which transmits 1GHz, 20 dBm carrier waves. So, if we also add MCU to the system, how should we calculate the bypass capacitors and how to choose capacitor types as well. Please make your case with calculations and reasons. please be deterministic rather than empirical.


texts: 12V Relay Actuation Depending on PWM or Constant DCV Input

texts:
I am looking to actuate a 12V SPDT relay depending on weather or not a 12V PWM signal is received or not. Headlamps use a reduced power PWM signal for daytime running lamps. I want to be able to detect that signal separate from a 12VDC source (normal headlamp operation) and actuate a relay based on it to relocate that daytime running lamp to another location. I am an ME by trait but have limited experiences with circuits.

I have been able to use a simple RC circuit to turn that PWM into a lower constant voltage. Trouble is, I don't know how to compare the full 12V and the reduced voltage and also still carry enough amperage to control a relay coil.

Looking for something as simple as possible. Some have suggested using a using a 555 as a retrig monostable missing pulse detector or an RC circuit with a comparator. I don't know if either of these would work or how to specifically design them. Any help would be greatly appreciated!


texts: Problem getting board to board I2C communication to work on STM32

texts:
I have two boards working on STM32F030R8 and F030C6 respectively. I have been trying to get the boards communicate with each other using I2C but so far, no good. One of my boards run at 48MHz and the other at 20Mhz. I have configured I2C normal mode with 100Khz and 100ns of rise and fall time. I've tried using both DMA and ITs. While using DMA, my master board was simultaneously trying to receive and transmit so my code logic was not working as expected. But then I switched to interrupts and I was able to get it work. But the problem is, after power on, it communicates just ones and then it goes into HAL_I2C_STATE_BUSY. Then I have to turn the board on and off for it to work again. Even resetting the MCU proved futile.

I2C Init code for Master:

  hi2c1.Instance = I2C1;
  hi2c1.Init.Timing = I2C_TIMING;//check in .h file
  hi2c1.Init.OwnAddress1 = 0x123;
  hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_10BIT;
  hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c1.Init.OwnAddress2 = 0xFF;
  hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
  hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  if (HAL_I2C_Init(&hi2c1) != HAL_OK)
  {
    Error_Handler();
  }

for Slave:

  hi2c1.Instance = I2C1;
  hi2c1.Init.Timing = 0x00101D2D;//0x00201D2B;
  hi2c1.Init.OwnAddress1 = I2C_ADDRESS;
  hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_10BIT;
  hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c1.Init.OwnAddress2 = 0xFF;
  hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
  hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  if (HAL_I2C_Init(&hi2c1) != HAL_OK)
  {
    Error_Handler();
  }

This is the code that transmits:

if(HAL_I2C_GetState(&hi2c1) == HAL_I2C_STATE_READY) {
    if(HAL_I2C_Slave_Transmit_IT(&hi2c1, (uint8_t*)aTxBuffer, 10)!= HAL_OK) {
    /* Transfer error in reception process */
        Error_Handler();
    }
}

And this receives:

do {
   HAL_I2C_Init(&hi2c1);
    if(HAL_I2C_Master_Receive_IT(&hi2c1, (uint16_t)I2C_ADD_CHILLER, aRxBuffer, 14)!= HAL_OK) {
        Error_Handler();
    }
    State = HAL_I2C_GetState(&hi2c1) ;
    Teor=HAL_I2C_GetError(&hi2c1);
    HAL_I2C_DeInit(&hi2c1);
  } while(Teor == HAL_I2C_ERROR_AF);


texts:
So as we know that the cutoff frequency of a filter can be determined from graph by dropping 3dB. But, how do we take the 3dB drop? From the highest point or from 0? In this case, this graph highest point is 1.2dB, so the 3dB drop should be -1.8dB or just -3dB?
Thanks.


texts:
I try to implement a full adder circuit using square arrays.

I've used Digital software to design it. Also I've tested it. It works fine.
But my implementation is quite different from the circuit shown by the lecturer.

As you'd see, to be able get correct results I switched the outputs (S and Cout)
Also as you'd recognise the layout of NFET gates are different.
Is the layout of NFET gates correct? Thanks.
Update:
My temporarily solution is like this.


texts:
I’ve been noticing that my PC monitor turns off for a second when I turn the light switches on. My electrician said that this was completely normal due to “Induction”. I’d argue otherwise, like the monitor getting power for a second or two after I turn it off may be due to the induced current in the reverse direction, but this? I suspect a power drip when I turn something on. Like my lights dim down for a second every time I turn my PC on, so it might be the same case for the monitor.
Am I right?


texts:
I am wiring up a house where the kitchen has multiple LED strips. All I have is a wire hanging out of the light strips. And as the LED lights are built into the cabinets I cannot get inside them to see any labels on current, voltage etc.
I have multiple LED drivers in the house but are not sure which one goes on which light.
Is there an easy way to figure this out?


texts: Need for Temperature Compensation of Current Mirror

texts:
I am currently learning about current mirror configurations. I have made two of them so far. Both of them worked as desired but, when heated or cooled, the current through the right side (the side where the output is taken from) decreased or increased significantly with small temperature differences.

simulate this circuit – Schematic created using CircuitLab

\$R_{load}\$ for both circuits was low or shorted to +10V. Both circuits were set to mirror the current of 500 uA. All transistors were hand-matched (they are all very close to each other as far as beta is concerned).

Without emitter degeneration both circuits were significantly affected by temperature, especially Fig. A, where the current through \$R_{load1}\$ changed by 100 uA or more (1 second of heating) as I touched either of Q1 or Q2 with a finger tip; but as the transistors Q4 and Q5 were touched with a finger tip, the current through \$R_{load2}\$ changed by 50 uA (1 second of heating also), which is less then in the first example but still too much.

With emitter degeneration both circuits greatly improved their temperature stability. For example (the \$R_e\$ added were 1 kOhm) if I refer to Fig. B, the current through \$R_{load2}\$ changed only by 10 uA (when heated by approx. 1 second), while the result with Fig. A was a bit worse.

Both circuits are improved as emitter degeneration is added to Q1/Q2 or Q3/Q4. In both examples, current through Q1 or Q3 was approximately constant at all times but the current through Q2 or Q5 wasn't even close to that.

I there any way to compensate either of circuits shown here, due to varying temperature? I thought that Q5 was going to correct the temperature variation error in current but obviously didn't.


texts: What is the official name for these jumper wires?

texts:
What is the official name for the kind of prototyping wires seen at this link?

I noticed that on this thread the above kind of wire (with the "square" end) was referred to as a "jumper wire".  Some other sources refer to the ones with a "round" end as either a jumper wire or a breadboard wire.

To make matters more confusing, the Wikipedia entry for Breadboard refers to the "round end" type as "jumper wire".

When buying these wires off some websites from Taiwan, I noticed that the sellers will sometimes refer to them as "杜邦頭跳線" (Dupont Header jumper wires).  Googling for "Dupont header" does indeed show me the kind of pin header suited for the wire in question.

So is that its real name?  A Dupont Header jumper wire?


texts: Which MOSFETs can I use to replace these faulty obsolete ones?

texts:
I've had some transistors fail on a PCB, but I can no longer source them as they have long reached EOL and are now obsolete.

The part numbers are as follows (linked to the original data sheets):

2SJ142
2SK815
2SK611

I've contacted RS Components' tech department in the UK to ask them which MOSFETs I can replace these with but they're not getting back to me.

There are thousands of transistors listed on their website; I don't know where to start.

What do I need to be looking for when choosing new parts to replace these faulty transistors?


texts:
I have 2 DDR3 x16 chips (MT41K256M16xx) interfaced with an FPGA (M2S150TS-1FCS536). I plan on using point-to-point data & fly-by address/command topologies.

I'm using ECC with a 16 bit bus, so 18 bits total. Because of that, one of the chips is mostly unused. I tried to disable the upper byte by pulling UDM and UDQS high, and UDQS# down with 1k resistors.

How should I connect the unused DQ pins on the partially used byte? How about the unused byte?


texts: In this schematic, what do the Schottky diode like "barbs" mean on some of the BJTs where the base is connected? I haven't encountered this symbol before.