texts: Get internal temperature or voltage STM32L0

texts:
I'm trying to obtain the internal voltage and temperature of my STM32L073RZ with the mbed librairy (Intialize and read an internal channel with ADC). Currently I didn't know how to do that and all the tutorials speak about other version of my chip.

How do I get the internal temperature of my STM32L0?

EDIT: This script work for me

/#define TEMP130_CAL_ADDR ((uint16_t*) ((uint32_t) 0x1FF8007E))
/#define TEMP30_CAL_ADDR ((uint16_t*) ((uint32_t) 0x1FF8007A))
/#define VDD_CALIB ((uint16_t) (300))
/#define VDD_APPLI ((uint16_t) (330))

int32_t ComputeTemperature(uint32_t measure)
{
  int32_t temperature;
  temperature = ((measure * VDD_APPLI / VDD_CALIB) - (int32_t)*TEMP30_CAL_ADDR );
  temperature = temperature *(int32_t)(130-30);
  temperature = temperature /(int32_t)(*TEMP130_CAL_ADDR -*TEMP30_CAL_ADDR);
  temperature = temperature + 30;
  return(temperature);
}

void ConfigTemperature(void){
    RCC->APB2ENR |= RCC_APB2ENR_ADC1EN;
    ADC1->CFGR2 |= ADC_CFGR2_CKMODE;

if ((ADC1->CR & ADC_CR_ADEN) != 0) /* (1) */
{
 ADC1->CR &= (uint32_t)(~ADC_CR_ADEN); /* (2) */
}
ADC1->CR |= ADC_CR_ADCAL; /* (3) */
while ((ADC1->ISR & ADC_ISR_EOCAL) == 0) /* (4) */
{
    pcMain.printf("Calib");
}
ADC1->ISR |= ADC_ISR_EOCAL;

ADC1->ISR |= ADC_ISR_ADRDY; /* (1) */
ADC1->CR |= ADC_CR_ADEN; /* (2) */
if ((ADC1->CFGR1 & ADC_CFGR1_AUTOFF) == 0)
{
 while ((ADC1->ISR & ADC_ISR_ADRDY) == 0) /* (3) */
 {
     pcMain.printf("Enable");
 }
}

ADC1->ISR |= ADC_ISR_ADRDY; /* (1) */
ADC1->CR |= ADC_CR_ADEN; /* (2) */

ADC1->CFGR1 |= ADC_CFGR1_CONT; /* (2) */
ADC1->CHSELR = ADC_CHSELR_CHSEL18; /* (3) */
ADC1->SMPR |= ADC_SMPR_SMP; /* (4) */
ADC->CCR |= ADC_CCR_TSEN;
uint32_t measure = ADC1->DR;
pcMain.printf("Measure %i\n\r", measure);
pcMain.printf("The temperature value is %i\n\r",ComputeTemperature(measure));

}

int main(void)
{
    ConfigTemperature();
}


texts: I am working on a project with a Virtex-5 FPGA, the only method for uploading bitstreams is over JTAG, if I remember correctly; is it possible to do it any other way? I am trying to save space on the PCB.


texts: How to make a PCB based on ATtiny easily updatable by end users?

texts:
I've made a prototype PCB containing an ATTINY 4313:

Each time I want to change the program, I upload it with an Arduino used with the "Arduino as ISP" sketch.

If one day I sell such a module to consumers, obviously I cannot ask them "please use an Arduino as ISP to update the new version of the firmware".

Which components should I add to a simple ATtiny to make the firmware updatable via a USB cable for end-customers?

The ideal UX for customers would be:

people download the new firmware
they connect the PCB to computer via USB
if possible with no software to install on their computer, they can update the firmware  (maybe by just dropping a file on an USB appearing as a disk / flash drive?)


texts: Can I replace the 433mhz modules on my homemade remote controller with a nrf24 transreciever

texts: I built a simple 4 channel 433mhz transmitter and reciever because I can't afford a remote controller, the range is limited to 3 feet and nrf24 transreciever have longer range, so my question is can I replace the 433mhz modules with a nrf24 transreciever and it'll work?


texts: What is the use of OFFSET IN/OUT constraint for FPGA design when using register in IOB?

texts:
The following is asked in the context of Xilinx FPGAs (my experience), but may also apply to similar technologies offered by other vendors.

Background: When writing constraints for FPGA I/O, there are OFFSET IN and OFFSET OUT constraints. The purpose of these constraints, to my understanding, is to provide guidance to placement and route processes to ensure that the timing of the input/output signal relative to the FPGA pin/pad is constrained. For example, without this constraint the tools would be free to route your signal from the pad around the IC 6 times, through 100 levels of logic, and then it finally hits your first register.

Visually:

There are also constraints offered in the UCF to "suggest" to the tools that a register be packed into the IOB. This places the FF/register in a special (fixed) location, closest to the pad/IO. Short of using some other FPGA hardware mechanism (e.g. IDELAY/ODELAY) there is no way to adjust the timing from the pad to the register, or from the register to the pad (the register site is fixed, the pad is fixed, and the route between them is fixed).

I say "suggest" because there are reasons that the first register may not be packed into an IOB for an input, or the last register may not be packed into an IOB for an output. But for this question, assume that the first/last register actually is successfully placed in the IOB, next to the pad.

Question: Do OFFSET IN and OFFSET OUT constraints add any "value" to a UCF? Do they provide the tools any more information about your design that is needed for the I/O timing to be correct?


texts: Replace SMA Connectors with Direct Connection

texts:
I am combining the layout for two PCBs, one with an RF output SMA jack, and the other with an input jack, into a single PCB.

We were originally connecting the separate boards with a ~3" segment of SMA coax cable.

In the combined layout, can I simply join the output and input together with a short where the SMA jacks were previously, or are there other considerations to make at this junction?


texts: high speed microcontroller - pc communication

texts:
I have a project where I have to sample a 4 bit bus every 100ns continuously for a data logging application (I need very low sampling jitter as well). I have a uC that can go up to 300MHz so speed isn't an issue, but rather getting data off the uC to a PC is my current challenge.

40Mbit/s pretty much rules out UART or similar, leaving USB and Ethernet as possibilities. Are there any other more quick 'n dirty ways of achieving this speed? Or if not, what is the best way to get started as I have never used Ethernet/USB on a uC design before.


texts:
I want to model several electrodes (say 3) and GND on a resistive substrate.

simulate this circuit – Schematic created using CircuitLab

To characterise it, I apply a current on one electrode to GND. Then I measure the voltage on all electrodes and divide it by the current.
I then repeat this for each electrode

I obtain a matrix as follow (symmetrical):

r1   r12  r13
r21  r2   r23
r31  r32  r3

Note: this matrix is not a proper matrix of resistances, it describes the interaction between electrodes.

This matrix is used to model the substrate with voltage sources as follow:

simulate this circuit

Now I would like to model it with a network of discrete resistors. The resistances R1, R2 and R3 are connected form electrode to GNDand R12, R13 and R23 are resistances between electrodes:

simulate this circuit

How can I convert my matrix into values of resistances in the network?

Note: the solution must be scalable as many more electrodes could be used.


texts:
What does m% mean?

Like in this datasheet from TI at the gain error graphs: http://www.ti.com/lit/ds/symlink/ina149-ep.pdf?&ts=1589388038122

Is it supposed to mean per-cent-mille (10^-5) or per-mille (10^-3) or ppm (10^-6)?

Update:
Here is an other datasheet with the same unit: http://www.ti.com/lit/ds/symlink/ina226.pdf?&ts=1589357516155

Here the gain error is given without a unit in the table section (unlike in the first one where it is %FSR), but the values still don't match up with the graphs.


texts: Analog Audio Tape Equalization: Why a Time Constant instead of a Corner Frequency?

texts:
For recording or playing back audio signals with analog tape, frequencies on the low and high ends of the audio spectrum are run through filters (equalized). The filters are standardized. The goal is to obtain a flat frequency response with a system that has a number of nonlinearities and non-ideal properties (high frequency noise, ...) as detailed in this document.

In a nutshell, while playing back, and depending on the standard used, low frequencies are sometimes boosted, and high frequencies are always cut.

Opposed to most other filters used in electronics, the filters used for tape equalization are not characterized using corner frequencies, but time constants (e.g. 3180 µs and 70 µs for CrO2 or Type II tape, corresponding to 50 Hz and 2.27 kHz, respectively). What's the reason for using time constants instead of corner frequencies?


texts: I've had a number of issues getting good stable analog readings from an RTD temperature sensor. The temperature readings have a tendency to bounce as much as +/- 5 Deg C. The circuit is very basic, a voltage divider is formed between a fixed resistor and an RTD connected to ground. The voltage at the RTD is then fed into a programmable gain amplifier set at 16 V/V. The analog signal output from the programmable gain amplifier is then fed into a 10-bit ADC on a PIC microprocessor. I've implemented a low pass filter in software to attempt to fix the problem, but the temperature readings are still very unstable. Does anyone have any suggestions about where I could look to find the source of the problem and correct it?


texts:
How do I calculate Vo? I used the nodal voltage method combined with KCL, but it is not working out for me. I have:

At non-inverting port:
$$ (v-.4V)/4kohm=0 $$
At inverting port:
$$ (v-0)/2kohm+(v-Vo)/35kohm=0 $$

I solve these equations and end with \$v=.4V\$ and \$Vo=.75V\$.

I make the assumptions that the voltage at the input node equals the voltage at the inverting node and that the entire bottom wire is ground. The bottom wire is a super node connected to the negative side of Vo, so the entire bottom wire should have a voltage of 0.


texts:
Whats the simplest electr(on)ic(al) method for heating a coil or similar  element to a specific temperature?

Generating heat is easy; dictating and regulating a specific temperature is the hard part.

For example, a modern kettle might have a wax thermostat that opens/breaks the circuit once it reaches 100°C, but it doesn't maintain, hold or regulate that temperature. The water doesn't continue to boil indefinitely. It simply reaches boiling point and then the heat is removed. I'd like to reach the desired temperature, but not exceed it, and then just stay that temperature.

Some consumer products with this kind of capability:
Inductive cooktops, laboratory hotplates, heating mantles, crucibles, furnaces, climate control devices, etc.


texts:
I have verilog code that looks like this

begin
  if (condition)
       if(condition2)
       else if(condition3)
       else if(condition4)
  else
   ..logic..
end

This code compiles and simulates. My question is how would the simulator interpret the last else branch? Would it consider the else as a part of the nested if-else-if construct or the outer if construct.

Also, would synthesis result in an inferred latch for which of those constructs?

Programming languages generally do no mandate the use of else branch even for a if..else if construct.

But I want to know how Verilog being a HDL handles this? I could not find any specific mention in the LRM.


texts:
I have a INA126 IN-Amp. I hope to use it with a ph probe. But I am not sure exactly how to do that. should I put the probe in series with a branch of a resistive wheat stone bridge, or just tie it to the refrence voltage?

I am using +5V with a reference at 2.5 volts. A schematic would be really nice if anyone can show me something like that.


texts: Clarifying line-to-line versus phase voltage of 3-phase rectifiers

texts: For example, my supply is 415 volts RMS (line-line). So if I multiple it by sqrt2 to get the peak voltage. That’s a phase voltage, I believe. If I rectify this supply and get an output voltage waveform, it’s the peak of this voltage waveform a line to line voltage or a phase voltage?


texts: through hole soldering vertical fill problem ground and pwer planes connected points

texts:
We have a PCB having three AD584 (TO5-8 Package) and two DC-DC converters THD 10-2423.

PCB has total 6 layers including top and bottom planes.
Three pins of AD584 are connected to ground on two internal ground plans as well as top and bottom planes through spokes.
Four pins each of DC-DC Converter are connected to ground planes and rest of four connected to power planes.
Components are new and have clean pins and have shiny appearance.
Components as well as PCB surface finish are pro lead compatible.
AD584TH pin diameter is 0.45mm and Plated through hole internal diameter is 0.85mm.
DC-DC Converter diameter is 0.5mm and Plated through hole internal diameter is 1.0mm.

We are trying to solder these components manually as well as passing through wave solder machine. After soldering, solder joints on these ground and power plane connected pins don’t fulfill acceptable criteria of IPC-A-610D class III 7.5.5.1 Sported Holes – solder- vertical fill (A). Rest of the 5 pins on these three AD584 meet target condition in this respect (i.e. there is 100% fill).

For manual soldering, we are using bottom heat plate for PCB preheating up to 120°C and soldering station temperature set to 450°C (iron 150W).
For wave soldering machine, preheating temperature up to 120°C, peak temperature 245°C to 250°C and dip time 5-6 seconds.
Possible reasons for this problem and recommendations for its solution are required.


texts:
I am trying to drive a 74ACT299 shift register with a Microcontroller. Looking at the datasheet I thought it was pretty simple. Set the data bit then pulse the clock, repeat. After I wrote the code, I set up a test circuit with on LED on each output. When I run to the code to light each led in order, I get some weird results. The LEDs generally light two at a time. They do so in increasing order, but something in a pattern like the following. I varies slightly each iteration.

loop 1: none
loop 2: none
loop 3: LED 1
loop 4: LED 1, 2
loop 5: LED 2, 3
loop 6: LED 3
loop 7: LED 4, 5
loop 8: LED 5, 6
etc...

I figured maybe my code wasn't shifting the bits out properly so I connected a logic analyser and it produced the following waveform.

Each clock pulse is ~7.80 µs and the time between clock pulses is ~37.5 µs.

The circuit is setup as seen below. The Data, Clock, and Enable lines are being driver by an MSP430 at 3.3v.

simulate this circuit – Schematic created using CircuitLab

The code running on the MSP430 is listed below.

#include <msp430.h>

#define OUTPUT_ENABLE BIT5
#define DATA BIT4
#define CLOCK BIT3

void shift_out(unsigned char data, unsigned char data_pin, unsigned char clock_pin);

int main(void) {
    WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer

    P1DIR |= OUTPUT_ENABLE | DATA | CLOCK;

    // set everything low
    P1OUT &= 0xFF - (OUTPUT_ENABLE | DATA | CLOCK);

    int x;
    for (;;) {
        for (x = 0; x < 8; x++)
        {
            // Disable the outputs
            P1OUT |= OUTPUT_ENABLE;

            int out = 1 << x;
            shift_out(out, DATA, CLOCK);

            // Enable the outputs
            P1OUT &= 0xFF - OUTPUT_ENABLE;

            __delay_cycles(500000);
        }
    }
}

void shift_out(unsigned char data, unsigned char data_pin, unsigned char clock_pin)
{
    int i;
    for (i = 0; i < 8; i++)
    {
        // set data pin to value
        if ((1 << i) & data) {
            P1OUT |= data_pin;
        } else {
            P1OUT &= 0xFF - data_pin;
        }

        // clock high
        P1OUT |= clock_pin;

        // clock low
        P1OUT &= 0xFF - clock_pin;
    }
}

I have fought with this for a few days and can't find any errors. I assume I am either missing something about the shift register or something. I would be most appreciative if someone could point me in the right direction about where the error might be. I am at loss of where to look next.


texts: Make an SD card installed on PCB readable through USB

texts:
I work on a circuit that logs data onto an SD card.

I want to know how I can read the SD card data directly from my PC using USB.

I am thinking of using a type of SPI to USB converter because there is SPI communication between the SD card and PIC32 .

Does anyone have suggestions?

(I think that I need a FTDI chip for the USB-SPI communication; and a "Level shifter"  for the adaptaion of the voltage betwen the USB PC and SD CARD)


texts: Does current matter more than resistance when building circuits?

texts:
I am trying to understand how to build simple circuits as well as work with Arduino. My interpretation is that voltage doesn't matter as much as current that passes through a given electronic component. In other words, whether I have a 100 volt battery or 1 volt battery, if I have enough resistors, my LED won't blow up. Is that correct? Do we really just care about the current that will pass through a component?

I know if I put 8V into the 5V pin on my Arduino board, it will break some components. Is that because the resistance on the board is quite low, meaning the current passing through a component will be high, therefore destroying that component?


texts: Why are 2.4 GHz amplifiers costly while RF amplifier IC's are cheap?

texts: A lot of 2.4 GHz amplifiers on eBay are sold for $30-50, but the amplifying chips are available on Digikey < $1. Why? The PCB's are two layers and other SMD components are quite cheap too, then why such a high price? Is there anything sophisticated in it?


texts: Brushless motor dynamics (BLDC transfer function)?

texts:
I am building a quadrotor and want get a reasonable estimate of the dynamics (voltage to rpm transfer function) of the motors. I am wondering:

1) Is the transfer function for a typical BLDC 1st or 2nd order?

2) Does kv rating relate to any constants in the transfer function?

The motors I have are 3-phase 2300kv with 12 windings, but other than that I have had a hard time finding useful information about them.


texts: Circuit board layout: wifi ceramic antenna next to a electromechanical relay

texts:
Is it okay to place a small ceramic antenna not far from a electromechanical relay? Would the magnetic field generated by the relay coil (when on) affect wifi operation?

clarifying edit:
not far = ~1 cm away (from casing)
both the relay and wifi will operate at the same time


texts: I was reading about microcontroller interrupts and how they work, but I can't figure out how the context switch really happens. Can someone please explain it to me in more detail?


texts: Listening in on ANT+ device communication?

texts:
I have TACX iGenius cycling trainer, which uses an ANT+ USB stick to control the resistance on the bicycle wheel. (You play a video in their software, and it matches the resistance on the wheel to your location in the video.)

TACX used to have the ability to record your own GPS tracks and videos and use them, but they have deprecated this option.

I want to understand the signals sent from the ANT+ USB stick to the trainer to control resistance, without interfering with the function of the trainer, so that I can try to write something to control it from my own videos without their software.

Is there a way to listen in on the data sent to and from the USB stick?   Or is there a better way to do what I'm trying to do?


texts: Is it possible to charge 6 series Ni-MH cells using bq25703a or bq24780s?

texts:
I am planning to use BQ25703A or BQ24780s for charging system of 6 series Ni-MH(1.5V charging voltage per cell) cells. But datasheets says “Charge 1- to 4-Cell Battery from Wide Range of Input Sources and Battery voltage regulation 1.024 - 19.2 V” in BQ25703A and "Charge 1- to 4-Cell Battery Pack from 4.5- to 24-V Adapter" in BQ24780s .

Would it be nice to use these parts for my product(for 6-cell ni-mh)? Which is better?
If is it available, why usually datasheets says only "1 to 4 cells" ?
Would I have a disadvantage if I use these IC ?

BQ25703A: http://www.ti.com/lit/gpn/bq25703a

BQ24780S: http://www.ti.com/lit/ds/symlink/bq24780s.pdf

Thanks.

Best regards.


texts: What is the effective speed-control range of a BLDC motor?

texts:
I've just signed-up for this group, searched for an answer, couldn't find it, but am impressed with the knowledge here.

My requirement is to drive a leadscrew at a fairly constant rate, but with a large speed change for traversing quickly.  Thus I need a motor whose speed can be controlled fairly tightly at low r.p.m., and then can be told to 'take off' at a speed maybe 50 times the normal 'controlled' speed.  The load is light and fixed, and the motor will have to be geared-down quite a bit anyway, affording substantial torque multiplication.

Originally I was going to use a micro-stepped stepper motor, but the rotational output really needs to be more 'analog' than 'digital'; that is, very smooth, not composed of small, fixed incremental steps. I have not played with a BLDC yet and will probably start with one off eBay, along with a ready-made controller board.

Obviously the higher get-there speed can be close to motor's maximum; again, the load is very light.  So my question is, can a speed between 1/25 and 1/50 (4% to 2%) of the top speed of a BLDC motor be electronically controlled with decent precision, maintaining that lower, 'working' speed within a few percent, assuming that the load does not change appreciably?  And... what characteristics of the motor and ready-made controller (DC or PWM speed input) should one watch out for?


texts:
I was wondering if it would be possible to connect an IO extender (MCP23017-E/SP) to an ATMega32u4-AU via an USB cable.

I figured that if you connect up the SCL pin to the Data+ of the USB and the SCA pin to the Data- of USB, ground the 4th pin and power the 1st it should work.

Am I correct with this?

Image example in Kicad schematic:


texts: What's the meaning of current rating of BLDC motor and it's relation to a phase peak and RMS current?

texts:
Considering battery powered BLDC motor having rated voltage and current specs, what is exact meaning of the rated "current"?
Since BLDC motor is NOT powered by a DC current (enjoy the twisted logic of terminology) rather it is another device - a motor controller - which generated controlling AC phases in a form of PWM sequences, then, if I understand the "rated current" spec as a maximal current allowed from the rated maximal voltage, how could it be translated to the true motor spec? In other words if my understanding is correct stating that rated current and voltage are maximal specs drawn from the DC source, then these specs cannot even be applied to the motor directly! Hence my question.

For simplicity let's assume that efficiency of the motor controller is 100%, then how can we translate these manufacturer' provided (virtual) specs into actual specs of the motor itself? As we know the electromagnetic field and MMF which drives the rotor is caused by a current flowing through the coils of the stator, so we need to "translate" the rated current from manufacturer into the peak or RMS current of the motor phase(s). If it is so then how to do this translation? Assuming the peak of PWM driving phase is equal the rated voltage, can we get a peak and max RMS current of a single motor phase?

I am guessing that total RMS current of the 2 phases (out of 3) which are in ON state at any time should be about equal to the max "current rating" of the motor (minus whatever losses "on the way" through the motor controller), but I am not sure if this is correct - need your confirmation or denial :)

Added 4.29.18  : consider this example REX 30 motor from http://www.rotexelectric.eu/products/bldc-motors/rex-series/
Their units might be confusing, this motor is almost the same but cleanly defined parameters ( I am running this motor): http://www.nt-power.eu/doc/nt-power-datasheet-motor-15kw.pdf


texts:
I want to be able to create simple oscillator circuits for clocking in digital circuits and am wondering what is the most simple design people know of?

I could use a simple ring oscillator which is pretty simple

simulate this circuit – Schematic created using CircuitLab

but this would run way quicker than I want - ideally looking to hit around 0.1Hz to 10Hz.

At the moment I have been using a bi-stable oscillator like this:

simulate this circuit

This works well and I can control the frequency by varying the capacitor and resistor values, I am just wondering if there are better/simpler schemes? Specifically I'd like ones without the passives, but not using anything more complicated than basic logic (NOT, NAND, NOR etc).

Any contributions/ideas would be great, thanks!


texts:
My question is about interpreting a given circuit as being itself a linear system. We know that a linear system needs to satisfy the superposition principle: if \$f(ax_1+bx_2)=af(x_1)+bf(x_2)\$. This means that a zero input should result in a zero output. Circuit components like ideal resistors, capacitors, inductors, etc. are linear since their element laws obey superposition (\$ V_r = IR, \hspace{6pt} V_i = L\frac{dI}{dt}, \hspace{6 pt} V_c = \frac{1}{c}\int I\hspace{2pt} \mathrm{d}x\$, etc).

But given a circuit that contains current or voltage sources, for example, isn't this now a nonlinear system?

Take for example some Thevenin circuit equivalent like the one below with its i-v curve at its port. The i-v curve doesn't pass through the origin since the Thevenin equivalent has a voltage source inside of it and so it has a nonzero open circuit voltage, so this system has a technically nonlinear i-v relationship.

So some bottom line questions:

Sources have nonlinear i-v curves; are they included as part of "linear" circuit theory since they should actually be considered inputs as opposed to components of the circuit itself?
A circuit containing resistors with i-v characteristics of the form \$V = IR+V_0\$ where \$V_0\$ is some constant could not be considered a linear circuit and you could no longer employ superposition analysis or Thevenin/Norton analysis, correct?
Does it even make sense to try to define an input/output of a two terminal device? I was originally going to say that the Thevenin equivalent circuit below had nonzero "output" current for zero "input" voltage but I'm not sure if that's even meaningful to say.


texts:
Consider the basic MOS current mirror bias circuitry

I am really trying to understand on how Vbias when M3 is 'on' can be any other value other than Vt because M3 is diode connected (Vds= Vgs) and this means that the Vds of M3 will always  be equal to Vt.

So all that I can vary is only the W of M3 to control the current sunk because Vds=Vbias=Vt is always fixed ?


texts: How did old television screens with a light grey phosphor create the darker contrast parts of the display?

texts:
Many old television screens have a very prominent "light grey" color to the glass, I'm guessing from the phosphor, create darker areas if the effect of electrons make the phosphor glow?
Is it an illusion due to contrast between the brightly lit and darker unlit phosphor or can the screen actually darken somehow?
Here are some photos of old TVs from the 70s:


texts: On/Off control of step-up DC to DC converter

texts:
I simply want to on/off control Vout of "step-up DC to DC converter(NCP1402)" ; toggling chip's CE pin by AVR GPIO, but Vout does not go 0V when CE pin set to Low(<0.3V = disabled).

The datasheet says [When voltage at pin CE is less than 0.3 V, the chip is disabled, which means IC is shutdown.] and "shutdown" means stop output Vout in my understanding...does this wrong?

The shematic I am using is [NCP1402 Evaluation Board Schematic] showed in the datasheet, and CE pin directly connected to AVR GPIO pin in my shematic.

[NCP1402]
http://www.onsemi.jp/pub/Collateral/NCP1402-D.PDF


texts:
I have a 3-phase blower motor that I am looking to control from a Danfoss VLT 2800 that I purchased on eBay.

I have in the shop a receptacle that looks like this:

If I put a meter from neutral (horizontal middle) to either hot side (the verticals) I get 120v.  Across the hots I get 240v.  The table suggests that for single phase I should only be connecting two wires, including a neutral.  But with the neutral I have I only get the 120v.  Should I just be connecting the two hots?

For reference, our building has high-leg delta service.


texts: Transfer function and gain at \$\omega_0\$ in unusual op amp bandpass filter


texts:
I have a signal that goes high at random intervals, and I would like to have each rising edge toggle an output. Something like this:

I've looked into flip-flops, but they all seem more complicated than what I'm looking for (I don't understand why most of them need a clock). Is a flip-flop the appropriate component to achieve these results? If so, which one?


texts: How long of a wire and how big of a load can I have for SPI bus?

texts:
I have a system where I will connect up to 128 identical magnometer ICs up to an FPGA. I am trying to decide between SPI and I2C for comms. If I use SPI the setup will require 128 + 3 wires IF all sensors are on the same bus.

How do I decide/calculate if this is feasible and the sensors and wire won't load the circuit with too much capacitance or resistance?

The sensors will be distributed across several circuit boards so most of the wire length will be connecting sensor boards to each other.

I guess a general answer would be nice but just in case I am using these sensors and FPGA.

https://embeddedmicro.com/tutorials/mojo/
http://www.st.com/web/en/resource/technical/document/datasheet/DM00057547.pdf

EDIT: I appreciate any helpful advice on changing the system but what I'm looking for is how to calculate how many wires and sensors I can add before the capacitance is too great.


texts: Using thermal overload protection in AC-DC PWM motor driver circut

texts:
i'm having some difficulties with calculating the value of the thermal overload fuse in this circuit.
The thermal fuse is used to protect the motor and the circuit behind it. The deal problem is that the thermal overload fuse is in the live mains circtut and not after the AC-DC PSU.

And i cant seem to understand how to calculate the value. Could someone please help me understand what the formulas are and try to explain it to me? I have talked to other people and they say that its should be able to calculate the value.
I already have the thermal fuse for this its this module(Moeller PKZM0-0,25)

Supply voltage = 230VAC
Motor nominal current 3A
Motor Voltage 12VDC
Adjustable Range of overload fuse = 160mA - 250 mA


texts: Can I replace a 32 A switch with a 32 A MCB?

texts:
A switch for a water heater in my apartment is broken (image attached).
It is an "Anchor Roma 32 Amp 1-Way Switch with indicator".

Can I replace it with this or this switch?

Would the installation be similar or the same?

Background:

I am a software engineer; I am not an electrical engineer but I have replaced switches 8-10 times in the past. However I have always purchased the exact same switch.

Should I be paying attention to anything other than the Amperes?

I am in a highly effected (by covid19) red quarantine zone in Mumbai, India and the switch I am replacing is unavailable. I am also unable to get an electrician because my block has been cordoned off.


texts:
So when exactly is termination of a digital signal required?

In my case, I'm dealing with a 1.8V signal that comes from an FPGA. This signal connects to a high impedance input of an OpAmp. The trace on the PCB is just about 5cm (about two inches).

The maximum frequency that I'll drive this signal will be 4Mhz. Right now I have no termination in place and everything works just fine, even with the huge impedance mismatch.

I want to learn the best practice and some rules of thumb when to care about termination and when it can be left out.


texts: DIP Dimensional drawings: multiple values

texts:
I am checking out for dual-inline packages for my application and I came across some products from Analog Devices and Texas Instruments with three different dimensions for each measurement.
Does that mean that these DIPs are available in three sizes, or these are the individual dimensions of each measurement in a single device size?


texts: Why sound wave is the best choice for many location detectors?

texts:
So I'm currently working on my high school final project, which is basically a Radar :) ...

I'm using the SRF05 detector to detect objects that are near the surface of the device. My current assignment is to learn and summarize all the different components that will be assembled at the end. (UART, MAX232 74HC244 etc, if you want to know :)

My teacher told me that the more I will know about these components, the better I will do at my work, and in the exams. So here is my question: Why sound waves are the best choice for the SRF05? Furthermore, why UltraSonic ones? What are the benefits of using sound waves, but not invisible light waves, heat or any other means that can do the job? Light, for example, travel much faster, thus creates a better result and will probably be more effective than sound.


texts: What is the simplest way to make an oscillating signal?

texts:
Imagine you have a black box with 5VDC and ground inputs and you have to create one output that is an oscillating signal. What is the simplest circuit that can do so? Can you create a tank circuit with an inductor and capacitor?

The output signal will be detected by a PIC. The frequency is not important but should be rather low (between 10 and 500Hz). The PIC will not measure the frequency but only detect if the oscillating signal is present or not present based on whether this "box" is connected or not. That means the signal can be sin, square, saw-tooth, whatever, the shape doesn't matter.

Bonus points for the cheapest, lowest component count and lowest real estate solution!


texts:
Is it possible to trap some electricity in the object even though the object is grounded? For example if we ground a conducting sphere over a resistor, will all electricity leave the sphere once it's grounded?

let's say the sphere now gets charged, will it become neutral ? I apologize for asking such a simple question.


texts:
What are the difficulties restricting the development of wireless power transmission over long distances?
Could wireless power transmission be harmful and/or dangerous?


texts:
I run an animated Christmas light show on the house, and that interferes with my garage door opener whenever the lighting electronics are on.  The lights themselves don't have to be on, the problem occurs when there's data on the wire.  The neighbors don't have any interference problems so it's pretty local to my house.  The receiving antenna on the opener is the factory original piece of wire.  I understand basic electronics and am good with a soldering iron, but I don't know much about RF.

Other: I built a quarter wave ground plane antenna for an FM transmitter and don't seem to have any interference problems in either direction.  No problems pulling TV off-air either (US ATSC).

The opener runs at 372MHz and the data rate on the LEDs is adjustable on the controller and tends to work best at 800-900kHz.

My thought is to build a receiving antenna for the opener that favors 372MHz and then a bandpass circuit to reduce the noise.  I've looked at various antenna designs and can find online calculators for element lengths, etc, but I really don't know which antenna design I need, nor do I know the bandpass circuit I'd need.  Any ideas?

Thanks.

EDIT: It's not very clear above, but the lights are completely hard-wired, not wireless.


texts:
I have at my disposal a photosensor (Optical encoder) with "C9017-80055", it has three cables: Black, Green, and yellow. I want to know the circuit (GND, VCC, output) to connect it with Raspberry pi, there is a problem if I connect it with raspberry pi without a resistor?.
Please find this related question about the same Photosensor Photosensor but I'm in trouble to understand.
Thank you.


texts: What is the actual cmos technology node of China and Russia not licensing major process technology from outside?

texts:
There are a number of Russian fabs but from what I can see they are just using liscened technology ie Sitronics using STmicroelectronics at 90nm node or  Angstrem-T using AMD see yet in the past there was chip equivalents made with their own technology within the Soviet countries.

The same I hear is true of China.

So what is the actual cmos technology node of China and Russia not licensing major process technology components from outside?


texts: What is a suitable frequency for 15V/3A DC motor? Is there any effect on the motor when the frequency is changing? I am confused with this until now and the Internet shows a lot of theory that confuses me.


texts: Shorter transmission lines or nearer high frequency bypass caps

texts:
I have an application where I have a sensor which communicates with an FPGA with about 15 differential pairs of data clocking around 300 Mhz.  Due to constraints, the board can't be taller than 35mm and the surface mount header which receives all this high speed data has to go horizontal smack dab right in the middle of the back of the board.  This leaves no room on the front of the board for the FPGA not to overlap the sensor header on the back.  Now technically they are both surface mounts so you could say it isn't a problem, however the FPGA (Artix7 200T) has high frequency bypass caps requirements which are supposed to be put on the opposite side of it right where the header has placed itself.
I am wanting to know if anyone has design horse sense from experience as to know if it is less risky to

shift the FPGA 2 to 3 cm off to the side to get it off from behind the headers which would lengthen the differential pairs or
Make exceptions for the proximity of the high frequency caps on the back of the FPGA?

I will eventually have more experts looking at this but need initial decision just to get keep things going until I can get to that point.


texts: How does a microcontroller boot and startup, step by step?

texts:
When C code is written, compiled and uploaded to a microcontroller, the microcontroller starts running. But if we take this uploading and startup process step by step in slow motion, I have some confusions about what is actually happening inside the MCU (memory, CPU, bootloader). Here is (most probably wrong) what I would answer if someone were to ask me:

Compiled binary code is written to flash ROM (or EEPROM) through USB
Bootloader copies some part of this code to RAM. If true, how does
the boot-loader know what to copy (which part of the ROM to copy to
the RAM)?
CPU starts fetching instructions and data of the code from ROM and
RAM

Is this wrong?

Is it possible to summarize this process of booting and startup with some information about how the memory, bootloader, and CPU interact in this phase?

I have found many basic explanations of how a PC boots via BIOS. But I'm stuck with the microcontroller startup process.


texts: How does the microcontroller distinguish char, signed/unsigned int, broken and whole numbers and float?

texts:
I am reading a book about microcomputers. There were information about unsigned and signed dual numbers, whole and broken dual numbers and how to convert them to other number systems.

My questions are:

How does the microcontroller represent the dual number 1001,0001 in the registers with a comma? Where is the comma?
How does the microcontroller know that for example the number 1001 is -1 or 9?
How can it distinguish between the different types?


texts:
First let me say ignore the step e and step f, it's a typo.

Basically the Boolean expression is: (A./B) + (B.C)

Now it says convert it into NAND AND NOR function forms separately, which is confusing as hell because I don't know if the output is supposed to be the same, if they want 2 completely separate circuits one with a nand gate and one with a nor gate or what.

Now the next question says to construct the new circuits separately but then it says confirm ITS operation in accordance with THE truth table. I have the truth table and circuit for the first expression. Do I have ADD or is this question extremely vague?


texts: Voltage spikes in triangular waveform generator circuit using LM324 op amp

texts:
I recently made a triangular waveform generator circuit using LM324 op amp. But the output of the generator had some sort of periodic spikes in it. However I was able to suppress the spikes by lowering the load resistor (<=1Kohm, 680ohm completely killed the spikes). What can be the reason for that? My first guess was that there may be a pole somewhere in the feedback loop due to parasitic impedance and the lower load resistor has compensated for that.

I tried the same circuit using TL084 op amp which has JFET inputs. This time the spikes were never there even when the load resistor was not connected! So if there was a pole in the feedback loop, then the spikes should have appeared in this circuit also. I am wondering what can be the REAL cause for the spikes and how did the load resistor kill it? I really appreciate some help from someone with an experience in this field.

Note: I used a solder-less breadboard for constructing the circuit

Schematic:

simulate this circuit – Schematic created using CircuitLab

Waveform (LM324)

Waveform (TL084):


texts:
I have to measure the current flowing inside a SoC through a multimeter. In the board schematics, I found that the SoC provides a structure to measure the current:

Now, I should connect them with a shorting jumper, but the headers don't have built-in pins. Should I have to solder the pins or is there a more lightweight solution that permits me to avoid soldering?


texts: op amp as comparator/switch - strange behaviour

texts:
I have the following schematic (extract):

The purpose of this is to enable a pin (chip enable) and to disable the 5V supply ("5V consumer") if the threshold at the signal IN is above a certain threshold (VRef=0.5V). So far so good, the circuit works fine under "normal" circumestances.

The problem is that when I use the PCB with different power supply and input signals (for testing purposes), th op amp does not switch any more. Here are the differences:

power supply:

normally: USB(5V) -> battery charger IC -> 4.2V
testing: 5V from Raspberry Pi -> battery charger IC -> 4.2V. In this case I noticed that the 5V are actually about 4.8V, but that's still enough.
In both cases, no battery is connected so the battery charger is acting as a voltage regulator.

signal IN:

normally: analog audio signal with a bias voltage of 1.3V and no more than +/- 0.4V peak-to-peak voltage.
testing: 1.3V DC voltage

So when testing, I measured the 1.3V at the signal IN pin and the 0.5V at the VRef pin of the op amp, but it did not switch, i.e. the chip enable pin remained low and the 5V consumer voltage was still enabled.

The total power consumption of the PCB is under 50mA, so it should not be a problem for the Raspberry Pi to power it. The power supply unit is also rated at 1000mA.

Any idea why this happens? Am I overseeing something?
Thanks!

UPDATE

Maybe it's relevant, so I added the circuit which switches the ~1.4V at the signal IN pin:

One thing I noticed: while sweeping the input signal ("signal IN") from 0V to about 2V, I noticed that the op amp does switch above the threshold of about 0.55V, but the output voltage jumps from about -15mV (input under 0.55V) to only 60mV (input over 0.55V).

UPDATE 2

I disconnected the output of the op amp (no load) and now it does not switch any more at all (using the testing method). The output remains low.

I also measured the output of the op amp with an oscilloscope (both with and without load) and it does not switch fast high and low (so it averages to 60mV), as Spehro Pefhany suggested. The voltages are pretty clean, i.e. no spikes or large AC variations.

UPDATE 3

In the last update I said that the op amp does not switch without a load. That was a mistake from my part: it still does switch, but the ON-voltage is at about 30mV.

UPDATE 4

If I power the board (first schematic) normally (5V from USB) and use the Raspberry only to switch the signal (second schematic), the op amp switches correctly! So I tend to think that there is a problem in my power supply. I power the board with the Raspberry very similar as I switch the signal IN (second schematic), except without the R18 and R21 (so I basically feed-through the 5V). The 5V (at Q8) are coming directly from the Raspberry pin header.


texts: pyocd programming is slower than expected

texts:
I am using pyocd to program a MAX32660 using a MAX32660-EVSYS via SWD.
pyocd is reporting a bit rate that is less than 1/5 of the clock frequency I chose.
pyocd flash build/test_debug.elf --target max32660 --frequency 10000
[====================] 100%
0037168:INFO:loader:Erased 0 bytes (0 sectors), programmed 0 bytes
(0 pages), skipped 8192 bytes (8 pages) at 0.23 kB/s

This result is surprising because the SWD protocol itself appears to have less than 2X overhead. In this example the flash is not actually programmed because there is no change in the data, and in any case the flash is much faster than the time this programming takes.
This becomes a major issue if I want to use SWD wiring that is more than 3 inches long, as apparently there is a very weak driver in either the MAX32660 or MAX32660-EVSYS, requiring the frequency to be set extremely low.
What can explain this very slow operation?


texts: Does anyone know which acceleration sensor was used in the HTC Touch Diamond mobile phone?


texts: how to imagine the logic of the interrupt setting for timer DAC in cubemc STM32

texts:
In my manual the DAC settings on one hand we set the trigger out event,So my logic says its using an interrupt.
but they uncheck the NVIC option as shown bellow.
So i cant see how these two play together.
I cant see the trigger interrupt logic of how this thing is going to run.
Thanks.


texts:
I amb trying to desing a very simple Gate Driver for a Class-D audio amplifier.
In order to introduce the Dead Time my first thought was to use a RC conected to a comparator as an imput of an AND gate. Something like this:

simulate this circuit – Schematic created using CircuitLab

But then I realised that, since I'll be working at a frequency arround 300 kHz I'll need a very fast Op Amp (something arround 50\$V/\mu s\$, right?)

So in order to reduce costs, can I ommit the Op Amp and connect the RC to the AND gate?

If so, how do I ajust the dead time? Through trial and error?

Thanks in advance


texts: Signal multiplication in AM transmitter circuit

texts:
According to Wikipedia, amplitude modulation is achieved by multiplying the carrier signal with message signal.

Where is this multiplication performed in this AM transmitter circuit?

It seems to me (noob) the transformer only steps up the voltage of the message but does not multiply it with the carrier signal (1MHz) generated by the crystal?

Here is a video of the circuit in action.


texts: ADC startup time in AT91SAM7 - what is it?

texts:
I'm working with ADC in AT91SAM7S micro-controller. Apart from parameters like ADC clock frequency prescaler and 'sample and hold time' (that I'm familiar with), there is a parameter called 'Startup time' which I don't really understand.

The documentations says: "Each ADC has its own minimal Startup Time that is programmed through the field STARTUP in the Mode Register ADC_MR." My feeling is that this may be related to sleep mode so that when ADC was sleeping and later started it needs some time to 'wake up'. But I don't use sleep mode. Probably ADC is sleeping by default until it is really requested to make conversion.

If I set this parameter to zero then first conversion after program start gives zero code, although channel "End of conversion" flag is set. All subsequent conversions work normally.

What is the physics behind this parameter?
Why should I program it? Why ADC can't just automatically wait needed time and don't set 'end of conversion' flag until it really woke up and finished conversion?
How do I calculate it?


texts: Xbee traffic/bandwidth limitations for a real-time-ish application

texts:
I am planning on making a wireless sensor network with 4 Xbees going to 1 Coordinator. I want each of the sensor nodes to transmit continuously at ~5Hz.

Is this feasible with Xbees? What sort of traffic limitations does the protocol have in regards to collisions, dropped packets, latency, etc.?


texts: Questions about advanced use of oscilloscope

texts:
At my university, I'll be using the ELENCO S-1325 oscilloscope for a instrumentation lab. Since I'm a mechanical engineering student and not an electrical engineering one, I don't know exactly how to use all the functions though I am familiar with the basic use and operation of it. However, I want to know how to use some of the more complex functions of the oscilloscope.

On an oscilloscope, why would anyone move the variable knobs off their “calibrated” positions? the variable knobs (red VAR knob) for voltage measurements? the small gray “var sweep” knob for the time base?

Isn't it a good thing to keep things calibrated rather than use uncalibrated settings?


texts: PMOS unexpectedly passing current with capacitor on drain

texts:
I am designing a circuit to get a pulse when a switch opens. When the voltage source V1 is connected, the switch SW1 starts closed. I want Vout to briefly go high when SW1 opens. The circuit I designed looks like this:

simulate this circuit – Schematic created using CircuitLab

However, I get the opposite behaviour to what I expected when the circuit is turned on. When SW1 is closed, I would expect the drain of the MOSFET to be at 0V and pass no current. Instead, it charges the capacitor up to 2V. Then when the switch opens, the capacitor is already charged, and I don't get a pulse. According to the theory I read, when the MOSFET vSG = 0V then iD = 0A. Why is current flowing; do I need a more sophisticated model?


texts:
My question relates to the accumulated AC voltage that will appear on the screen of a length of coax:

If the cable is properly terminated at one end and fed with data (or any signal) at the other end, what will be the voltage on the screen relative to ground? Will it be ground potential(?) or will it be some other potential(?), and if so, will it be potentially acting as a "radiator" of the data?


texts: Do these multimeter readings even make sense?

texts:
I'm measuring resistor values and I believe I've set the multimeter correctly. I verified some pre-known values.

Measuring this one resistor, I get 3.0 on the 200M scale and 0.03 on the 20M scale and no reading on the 200K scale.

Does it make sense?

I assume 0.03 on the 20M scale - means 30k Ohms. Then shouldn't I be able to read 30 on the 200K scale.

I'm new to electronics.


texts: Can I use an insulator as heating element?

texts: If the resistance is what make heating elements heat up , then is it ideal for me to use something close to an insulator as a heating element?


texts: Is the risk of releasing toxic compounds into environment higher for older or newer electronic devices?

texts:
Electronic devices such as computers or laptops contains many toxic elements or compounds. While I'm sure for majority of them a care is taken so that they're not released into the environment of their users, I'm also sure that there are companies that simply don't care (unless forced by somebody).

I'd like to know if the risk of an electronic device releasing toxic compounds is higher when it's new or when it's old. As it gets older, most volatile elements that could have been released are already gone, however more compounds can be released from decaying parts of the device.

As a lay consumer, what steps can I take to prevent such a risk?

(I'm not sure if this SE site is the right place to ask, I found it closes to my question. If there's another, better suited for the question, please let me know. Feel free to add suitable tags.)


texts: Radiation Pattern Intergration method for calculating Antenna Radiation Efficiency

texts:
I need to calculate Radiation Efficiency for my customized Antenna simulated using CST software.The sampled data of cst simulated radiation pattern need to be fed to the formula as mentioned below

$$\int_{\theta = 0}^\pi\int_{\phi =0}^{2\pi} p(\theta,\phi)*sin\theta d\theta d\phi$$

As mentioned earlier, I have discrete power data points in respective theta and phi co-ordinates.But as the mentioned formula is in integral format I couldn't use the sample data points.
I need help with the discrete formula with Radiation Integration Method or any idea how to discretize the double integral formula.


texts: Choosing Stepper Motor - Driver Combination

texts:
This is my first attempt at designing/building my own circuit and PCB, so please bear with me. I am building a small, portable device that makes use of a small, accurate motor. My goal is to make the unit as small as possible while still achieving a higher torque capability.

Finding A Stepper
Initially, I began laying out the motor features I wanted: high degree of accuracy, efficiency (low power requirement), small size with reasonable torque capability, and 360-degree rotation.

Ultimately, I resorted to the 28BYJ-48 stepper because I was having a difficult time finding something between the slightly more expensive/bulkier NEMA and the microsteppers -- neither of which met both goals of the project. I have a few concerns regarding the quality of these motors, namely, the efficiency and life of the motor.

Figuring Out The Correct Stepper Driver
I know that the L293 is a common choice for driving small motors, but clearly I'm a glutton for punishment and decided I'd find a different option! After hours of mindless surfing, I had to remove myself from what became a sand trap. (I will say, I have a much greater respect for the development( invested time) of those little PCBs that carelessly end up in landfills).

Anyways, I digress, I am going to stick with the road already travelled and use the L293DD (surface mount). Is there a better option that someone might recommend, or perhaps a better method of searching for components?

ATTINY10 (1024bytes) to upload a small program I wrote that details the operation of the motor.

Is the driver a good choice for my small project. I know that these motors can be purchased with their own driver board, but I've just started using Eagle and would like to design my own PCB -- outfitting the board with different parts and minimizing the overall size of the housing and the design layout to one PCB. There will not be a lot of load on the motor, so I don't intend the combination to reach any maximum values.

Can anyone recommend a good resource to learn about PCB design?


texts:
Similar to this question, I need a replacement for a programmable unijunction transistor [PUT]. Specifically, I'm trying to emulate the behavior described in the 2N6028 datasheet.  However, I would like to build my own from normal transistors rather than buying one.

I found this page on the Makezine forums where someone asked the same question. This links to this page on edaboard which includes a schematic, but I'm not sure what the OP means by "two base B1 B2" or whether the following schematic:

indicates that I need exactly those particular transistors or if I could substitute in other bipolar transistors (e.g. BC548B).

This is a curiosity, I am not saying that it is a functional project, but I am instead interested in attempting to build a component out of others. I may learn something, I may not. I look forward to finding out.  I'm working through the Make: Electronics book, and several of the critical beginning experiments call for a PUT.  I am aware that PUTs are old, but I'm interested in this as a curiosity.


texts: what size/kind of capacitor is needed 12VDC automotive

texts:
I want to have a light bulb as a daytime running light that is located next to the turn signal (blinker). Since that daylight running light is kind of bright (having a clear lens) I want it to turn off while the blinker is on (flashing) and MAYBE stay OFF for ~2+ seconds after the blinker is stopped.

What size and kind capacitor is needed to smooth out the signal from the blinker? (given that the capacitor has the time to charge while the blinker is on)
The Blinker has less than a 1 sec frequency.

1994 BMW 840Ci is the vehicle if anyone wants or knows how to find more info.

Blinker               - 12v 21W
Daytime Running Light - 12V 21W
NC Relay
NO Relay ACC - Accesories turned on

Any suggestions on how else this could be done, would be greatly appreciated.

And here is a diagram with what I was thinking. I hope someone would make some sense of it.

Best regards,
Gio

Thank you for the inputs, I have made a new schematic that makes sense to me right now. oh boy!

https://www.circuitlab.com/circuit/896vjn68c232/bmw-840ci-drl-schematic/


texts: I was going through Nema 17 stepper motor, and I saw that it was given 1.2 A/phase. What does the phase mean in a stepper motor?


texts:
This is my first real circuit I've built. I've learnt a lot here, but have some problems that I don't quite understand.

It's pretty much just an over engineered alarm clock. The micro-controller running at 5 volts updates the display, and when the timer reaches 0, uses PWM to buzz the speaker. I wasn't happy with the volume at 5v, so I built an overkill boost circuit using the LM2577-Adj following the instructions provided. This created a much louder circuit that works really well, however I've currently got a bit of a feeling that this isn't the way to do it.

A simplified version of the circuit is shown below:

simulate this circuit – Schematic created using CircuitLab

(The 5V Arduino is acting a power supply right now, naturally will be replaced with batteries in the real deal, which is why I have the regulator there.)

When the alarm started, the circuit restarted, I was able to fix that by sticking that (again overkill?) capacitor in there. It doesn't restart any more, however, the led display dims whenever the alarm is buzzing.

I don't have access to an oscilloscope, but I managed to rig something up to graph the voltage with the Arduino and a few voltage dividers.

The red, blue and green graphs are voltages measured at each of the marked locations on the circuit. This is a single pulse of the alarm. The part where the red goes crazy is the duration of the tone.

(Please ignore the purple and orange, they were for debugging the makeshift oscilloscope itself.)

I'm really confused by this. So I guess my question kind of is:

Why does the arduino voltage (green) drop and the circuit voltage (blue) rise when the alarm buzzes?
Why does the display dim when circuit voltage is high? My only thought is that it must be to do with how the TM1367 handles the higher voltage.
What could cause the sudden drop in levels for the amp (red) and the circuit (blue) and the sudden rise in the arduino voltage (green) part way through the alarm tone?

Sometimes it happens earlier in the cycle, sometimes it doesn't happen, sometimes the arduino voltage is always higher than the circuit voltage. My hypothesis is that it's to do with the voltage regulator built into the arduino, but not sure what would have that kind of effect.
Is this the normal method of amplifying something like this? I assume not, but I don't know where to look to find the proper answer.
What's the worst that's going to happen beyond the dimming of the display? Anything else I should be worried about/do differently?


texts: Is an LVTTL output fully compatible to a TTL output?

texts:
My company is building a device that is specified to have TTL outputs and I shall test them.

Reading about logic levels Wikipedia, EN (the German version has a nice table), I find the voltages of TTL and LVTTL:

  TTL 5V out: low <= 0.4V , high >=2.4V

  LVTTL 3.3V out: low <= 0.4V , high >=2.4V

As you can see, there is no difference in the voltages between TTL and LVTTL.

So, as far as I understand, the difference is only internal, whether our ICs operate at 5V or 3.3V and thus the maximum voltage differs, which seems not important for outputs to work properly.

Given the device was implemented with LVTTL 3.3V technology, is it fully compatible to TTL technology and should I consider the test as passed or is there anything else I should consider, e.g. current?


texts: Eagle: polygon pour leaving funny blank areas

texts:
I am doing ground pours on both the top and bottom side of a two-sided board.  The top side fill seems to work fine, but the pour on the bottom layer is leaving a bunch of odd shaped blank areas (see image on the left).  I haven't routed any traces yet, so the bottom, which has no components, should be a solid blue.

The image on the right has both the top and bottom layers turned on.  You can see the slightly darker red areas, that correspond to the blank areas on the bottom.  Note these areas don't correspond to any features on the top layer, so it is not a matter of keep out or restrict areas.

I am using Eagle 7.5.0

Anyone know what is causing this?


texts:
I need to repair one board of Plasma TV which has a faulty ceramic capacitor, but I'm not sure whats its value.

Is there any way to identify the value of the blown capacitor ?

Please advise

Thanks
Sam


texts: Can I increase current using AC resonance?

texts:
In a resonance, specially if we resonant at the natural frequency, the generated waves' intensity will add up thus resulting in a wave of ever increasing intensity.

This phenomena is responsible for taking bridges down, when the wind reaches the resonant frequency of the bridge material, and the wind force starts adding up to the already resonating waves and the bridge material fractures and collapses.

I wonder if we could do the same for electric current.

Given an AC voltage source (not a very high voltage), with constant upper and lower boundaries for the source AC voltage, could I feed it to a "resonant circuit" such as the current measured by the amperemeter over time would be like:

And use this as an artificial way to increase the current in a load? (knowing that this would probably be the recipe to burn down everything for excess of current)


texts: Which part of this circuit plays the role of filtration?

texts:
Can anyone say which part of this circuit plays the exact role of filtration and which part plays the role of amplification? How can I find and learn the calculations related to these parts?
It's going to be used for an antenna of a radio telescope. After receiving signals it filters out high frequency ones and amplifies low frequency ones.


texts: Transmit high current with low voltage on a lightweight system

texts:
I have a moving system at 20meters from, say, a base station. The system consumes more or less 200W at 12V. I used until now a battery to power the system. The main drawback is that I have to recharge the battery quite often.

Therefore I need to find a solution to power the system. The system should be lightweight. This leads to some limitations. I was thinking of leaving the battery solution and choose to connect the system to the base station.

If I try to transmit directly 16Amps at 12V, I will have to use a huge cable (and heavy).
I would rather transmit a bigger voltage with a smaller current and then use a small DC-DC converter on the system.

I was thinking of these kind of lightweight DC-DC converters:

VPT
DV200-2812S or DV200-2815S In 16-50V, Out 12-15V, Out power 0-200W, 115 grams, 6x6x1cm
http://vpt-inc.com/Products/?prod=5
XP Power
QSB35048S12, in 48V, out 12V, out 29.2A, power 350W,
114grams, 6x6x1cm http://www.xppower.com/pdfs/SF_QSB75-350.pdf
MTM Power   132-200W
PMD200 48S12 UHB In 48V, Out 12V, Out max 16.7A, 6x6x1cm
VICOR DC-DC converters

What is your opinion on this solution?

Remember:
Voltage 12V
Power around 200W
Distance from base station to main system 20m
Main system must be lightweight


texts: On most of the schematics it is RS (Register select) but I can't figure out what D/I (pin 4) mean, I haven't found anything about that. What could it mean ? The datasheet indicate it's the register select pin, but I'm interested in the D/I meaning


texts: What do I connect the ground and power symbols in this schematic to?

texts:
There are 5 grounds and 3 power source (12V).

I bought a 12V and 1A wall adapter. It has a plus and minus end. Can I connect the other 2 12V sources in parallel. Will the reduction in current affect this device.


texts:
I have a simple circuit that generates +5V under normal conditions but goes down to 0 when something is wrong. I need to feed this voltage into a PC (running Ubuntu) and write a program to monitor the system.

At first, I thought I simply need to connect the wire to pin 2 (RX) and start polling the serial port in my program. For each byte that I read, if I get a value 0xFF, it would indicate normal operations.

After doing some more reading, I am a bit confused. It seems the serial port requires a handshake signal as well. Plus, it is a looking for a start and end marker. Moreover, the serial port seems to require -3V to -12V for logical 1. My input is +5V.

I am wondering if there is an easier and inexpensive solution to feed 2-state voltage into PC. Serial port seems to be an obvious choice but there may be a better option.

FYI, the current sensor circuit that I have is on a breadboard but am considering putting it on a PCB and use a PCI slot as a holder for the PCB.

Thank you in advance for your help.

Regards,
Peter


texts:
What is the thermal voltage of a Ge diode?I know for a silicon diode is about 26mV at room temperature.
I have this circuit:

simulate this circuit – Schematic created using CircuitLab
and a set of equation where X = Current through the diodes , Y = Voltage drop of Si diode and Z = Voltage drop of Ge diode:
x = (3-y-z)/1000
x = (10^-12)*(e^(y/0.026)-1)
x = (10^-9)*(e^(z/Vt(Ge))-1)
and I need it (at room temperature) so help really appreciated.


texts: I would like to build a circuit to control 4 LEDs via an inducted current. I would like the inducted current to provide the power for the LEDs, however I would like the LEDs to be lit in a certain arrangement depending on the current. That is I would like a certain signal to correspond to a a portion of the LEDs to be lit at a certain intensity. I would like to have relatively high granularity to control each LED (at least on a percentage level / 0-100 with steps of 1). What is the simplest circuit I could use to do this from primitive parts (gates, diodes, capacitors, etc...) not ICs or anything complex? Any suggestions would be highly appreciated.


texts: In a constraints.ucf, how do I tell it to that an unconnected pin is ok?

texts:
I'm new FPGAs, and working through the "IntroToSpartanFPGABook" PDF.

I'm looking at the "constraints.ucf" file, and (because I'm lazy), it occurred to me that I could create one "constraints.ucf" file for my (Papilio) Megawin, which I can then use for all projects, without modification. Switch 1 will always be on the same wire.

This works ok, except that everything that I DON'T use generates a warning:

WARNING:PhysDesignRules:367 - The signal <switch_1_IBUF> is incomplete. The signal does not drive any load pins in the design.

I understand that it is 100% correct, I am not using that switch (or LED), but if I remove the declaration, I need to have a different constraint file for each project (commenting and uncommenting as I go).

Is there a way of saying the following:

NET led_0 LOC = "P3" | IOSTANDARD=LVTTL DontGenerateWarningsIfNotConnected;


texts:
I have developed an app client that sends a string/comand by socket for another pc app server and the app server sends a string for the arduino over the serial port.

The problem is: how can I send bytes for arduino?

Sorry my bad english

Update: The code, it works! ;)

See the explanation in the code.

The code of my C#  app server that sends a String over the serial port:

using System;
using System.Windows.Forms;
//
using System.Threading;
using System.IO;
using System.IO.Ports;

pulic class senddata(){

private void Form1_Load(object sender, System.EventArgs e)
{
//Define a Porta Serial
    serialPort1.PortName = textBox2.Text;
    serialPort1.BaudRate = 9600;
    serialPort1.Open();
}
private void button1_Click(object sender, System.EventArgs e)
{
        int cmd = 1;
        byte[] b = BitConverter.GetBytes(cmd);
        serialPort1.Write(b, 0, 4);
}

}

The C code of the arduino:

#include <Servo.h>

Servo servo;

void setup()
{
    servo.attach(9);
    Serial.begin(9600);
    servo.write(0);
}

void loop()
{
    if(Serial.available())
    {

     int cmd = Serial.read();

         if (cmd> 0) {

         servo.write(cmd);

        }
  }
}

For you to understand my problem better I put this code. Because the value of servo goes from 0 to 180, and this way don't work.


texts:
I'm trying to reuse a board with nixie tubes and drivers. Originally it was used inside a measuring device and I removed everything but the tubes, anode resistors and K155ID1 drivers (russian 74141 clone).

The weird part: The k155's have no connection to Vcc and the GND is connected via 10M resistors to the IC pin of the Z574M nixie tubes only.

The A,B,C,D inputs were tied to unknown logic ICs (I think some kind of russian serial to parallel or decade counters)

I know how to make this board work for my purposes but I am curious how this setup could work, I was under the impression the drivers need a 5V Vcc and GND to operate.

Schematic summary:

Driver inputs A,B,C,D come from logic chips (decade counters)
Driver Vcc are not conected
Driver Gnd are connected via 10M resitor to tube IC pin
Driver 0-9 output pins go to tube cathodes
Tube anodes connected to HV power supply

Datasheet of the nixie driver: http://tubehobby.com/datasheets/k155id1.pdf
Z574M tube: http://www.tube-tester.com/sites/nixie/data/z574m/z574m.htm

It's a two layer PCB (front and back). Low quality enough that one can see through it with a bright light. No other layers or planes. Also measuring the resistance between any of the driver's supposedly unconnected GND pins reads nothing - it should read close to 0, same for Vcc's if they were actually connected to hidden planes as someone suggested.

The part around the drivers is intact so unless wires went directly to drivers Vcc and GND pins and were very cleanly removed there were no connections that could now be gone...


texts: Why do I have clipping in this emitter follower

texts:
I am trying to design a class A amplifier buffer stage (I know it is not efficient.)
I am starting from the simple emitter follower and the next step is to replace the RE resistor with a current source. I have read it is the right thing to do, but I want to understand why.
This is the circuit so far (Please not that I have used the trick in this question so the voltages are V98 and V99 or +/- 9V):

This is the output:

I am struggling to understand why I have clipping on the lower half of the signal. According to The Art of Electronics 2rd Edition (page 81, 2.2.3.D):

Current flow in one direction only. Notice (§2.1.1, rule 4) that in an emitter follower the npn transistor can only source (as opposed to sink) current. For instance, in the loaded circuit shown in Figure 2.17 the output can swing to within a transistor saturation voltage drop of VCC (about +9.9 V), but it cannot go more negative than −5 volts. That is because on the extreme negative swing, the transistor can do no better than to turn off completely, which it does at −4.4 volts input (−5 V output, set by the divider formed by the load and emitter resistors). Further negative swing at the input results in back-biasing of the base–emitter junction, but no further change in output.

I can see the divider between RL and RE and if I try to recreate it separately I get this:

If I do a DC sweep I obtain this result that shows that I should be able to swing VE down to -9V:

I am clearly missing something fundamental.
I guess what I do not understand is why \$V_{BE}\$ decreases or, in other words, why \$V_E\$ cannot go further down.


texts: Alternative Gigabit Ethernet Connector - considerations for impedance, signal integrity, and EMC considerations?

texts:
I have a design that does not have enough vertical clearance for a standard RJ45 socket. I'm hoping to use a connector like this one from Molex.

I will use Cat5e cable when building my cable with the alternative plug.

The question I have is what considerations need to be made when doing this from an impedance, signal integrity, and EMC perspective? (especially at gigabit speeds)


texts:
I’m currently in the process of automating
my orchard. I have a string of 87 irrigation solenoid valves, 24v 60hz, holding amps is 200 mA.

I would like to connect them in series and use a single switch at each one.  Control them via computer.

So my question: Is there a switch on the market that is activated via signal? I need to be able to activate each switch individually from a single location
without having to run individual sets of wires to each switch.


texts:
What I am trying to understand is how the diode is placed inside of the encapsulating glass container such as that pictured in the following:

I've tried to read some patents, where I more or less couldn't understand any of the language. How do manufacturers get the glass to encapsulate the actual semiconductor material without destroying it?


texts: charge extraction from solar cells in low light conditions

texts: This is probably not that deep a question, but how can one extract power from panels in low light? A 6V panel would dip to ~2V or so, and power output would sink lower. In conventional systems, how is power extracted (and stored) in such conditions? MPPT would only find the max power point, which would be terribly low. A battery wouldn't get charged because there isn't enough potential to drive current. But the sum total of this power throughout such a day would be quite high. So how can this power be extracted and stored?


texts: Why are we substract V(BE) in Emitter Biased Configuration?

texts: Guys I am working on electronics devices been a while but everything gets more complicated.I am confused.I can easily solve questions but I could not understand the main idea when we are writing the KVL equation at these kind circuits.Why are we subtract the Vbe?Please can you guys make me understand the logic at here?


texts:
I have a simple 12V 10 A power supply with just a transformer and a rectifier. After doing some research and simulations, I've added 3 10 mF capacitors in parallel to smooth out the output.

My problem is that after turning the supply off, capacitors remain charged for quite some time. I can get small sparks after shorting the output even 5 minutes after turning the supply off. Right now I only have a single LED connected to the capacitors and it takes more than 10 minutes for it to turn off completely after powering the supply down and the capacitors still aren't fully discharged when it turns off.

The most obvious way to solve the problem would be to put a resistor and a switch on the output and connect the resistor to the capacitors after turning off the supply by hand, but I'm hoping to get something a bit smarter and a bit safer.

Another point is that I want to use the supply's original case which has very little free volume now that I've added the capacitors, so just putting a ceramic 11 W resistor could be a problem because there would be very little free space around it for safe cooling.


texts:
I would like to place some decoupling caps for an IC. The IC is on the top while the caps will be on the bottom, opposite side. How should I route them:

A single VIA that connects the IC pin, power plane and cap
Two VIAs, one that connect cap with power plane and another that connects cap with IC pin

Please excuse me if this has been asked previously, but I read a load of resourses and could not find an answer to this. Thanks in advance.

Edit: More detailed picture of the 2 scenarios

(But first, I want to thank everyone for the great answers and comments!)

I have decoupling cap. One pin of the cap is connected to the ground plane by a VIA. That is for both scenarios. The other pin of the cap will be connect a) to power, b) to IC input. Thus, three things have to be connected together ultimately: IC pin, power, cap pin.

Scenario 1: A VIA connects the 3 of them, that is a trace from IC pin goes to the VIA, the VIA is goes through power plane and actually connects with power plane, a trace connects this very same VIA with the cap pin.
Scenario 2: A VIA is connected to power plane and a trace connects cap pin with this VIA. Then another VIA connects the IC pin with the that trace, but the second VIA although it goes through the power plane does not connects with it. So you have two VIAs: one that connects the cap with the power plane and another that connects the cap with the IC pin.


texts:
Do you know this connector? I tried in vain for hours using a variety of search terms.

Pitch is 2.54 mm and width of arc-bent contact is 1.4 mm. I just wish to find a part number, manufacturer and/or a different connector that is very similar to this.

EDIT 1


texts: Simple solution to send a short pulse to Solenoid for milliseconds?

texts:
Imagine a Ding Ding doorbell scenario where we want to save our solenoid from burning if a visitor keep the button pressed for a long time.

For a 12v Solenoid If power button is turned on I want to send a short pulse to Solenoid i.e It activate it for milliseconds and then deactivate immediately and then when power is turned off it again sends a similar short pulse

I am basically an Arduino guy and do not know much about basic electronics I can make this circuit using arduino but for this to work my arduino needs to remain working all the time whereas I am looking for a simple solution for it where I don't have to keep anything ON 24/7,

Any help will be much appreciated

Thanks


texts: Join two pipes with independent rotation?

texts: I'm planning to build a table tennis robot using an Arduino controller for the location/placement logistics and control, but I'm stuck on one physical detail and don't know where else to ask. I want to be able to rotate the end of the pipe independently of the base, but I can't find any fixtures that would allow for this. To clarify what I'm looking for, think of joining two pipes together axially - typically the joint will be fixed and they won't be able to rotate in the coupling. I'm looking for a coupling that will allow one end to rotate independently of the other end with minimal friction so a small servo can perform the rotation (obviously being water tight is not a requirement :-) ). Anybody know what the terminology for such a coupling is, or an exact example of one? I'm looking for an opening that can fit a ping pong ball, so 2" inner diameter should be plenty. Thanks for any insight!


texts: XBee Coordinator API not receiving data from Router AT pin 20

texts:
A Xbee Series 2 in Router AT configuration with a potentiometer wiper output connected to XBee's pin 20 AD0 is supposed to send the analog data every 100 ms. It was set with ATD02 and ATIR64.

A Xbee Series 2 in Coordinator API config is connected to the computer.

Using XCTU terminal, we can see that the Coordinator is constantly receiving Explicit RX Indicator frames from the Router. However there are no frames containing the analog data read by AD0 on the Router XBee.

Using Python with the XBee module, we also notice the same thing, just rx_explicit frames being received and nothing containing the analog data samples!

{'profile': '\xc1\x05', 'source_addr': '6T', 'dest_endpoint': '\xe8', 'rf_data': '\x01\x00\x00\x01\x02(', 'source_endpoint': '\xe8', 'options': '\x01', 'source_addr_long': '\x00\x13\xa2\x00@\xb1\x92\x13', 'cluster': '\x00\x92', 'id': 'rx_explicit'}

{'profile': '\xc1\x05', 'source_addr': '6T', 'dest_endpoint': '\xe8', 'rf_data': '\x01\x00\x00\x01\x02I', 'source_endpoint': '\xe8', 'options': '\x01', 'source_addr_long': '\x00\x13\xa2\x00@\xb1\x92\x13', 'cluster': '\x00\x92', 'id': 'rx_explicit'}

{'profile': '\xc1\x05', 'source_addr': '6T', 'dest_endpoint': '\xe8', 'rf_data': '\x01\x00\x00\x01\x01\xeb', 'source_endpoint': '\xe8', 'options': '\x01', 'source_addr_long': '\x00\x13\xa2\x00@\xb1\x92\x13', 'cluster': '\x00\x92', 'id': 'rx_explicit'}

{'profile': '\xc1\x05', 'source_addr': '6T', 'dest_endpoint': '\xe8', 'rf_data': '\x01\x00\x00\x01\x01\xce', 'source_endpoint': '\xe8', 'options': '\x01', 'source_addr_long': '\x00\x13\xa2\x00@\xb1\x92\x13', 'cluster': '\x00\x92', 'id': 'rx_explicit'}

What do you think may have happened? I checked the value at AD0 by reading it with an Arduino and indeed there is a value to be read.


texts:
I was looking at the datasheet of the THAT 1510 mic preamp IC, they suggest the following application circuit:

In the datasheet it says that the T network formed by R1, R2, and R7 gives a common mode input impedance of R1+2R7 = 45K to the right of the coupling capacitors (thats without counting R3, R4, R5 and R6), however I dont know how they got the 45K figure.

According to my analysis a common mode input voltage is the one applied to both inputs, something like this:

simulate this circuit – Schematic created using CircuitLab

In that case it is clearly seen that R1 and R2 are in parallel and both are in series with R7, so the common-mode impedance should be 22500 ohms, what am I doing wrong?

Also, just for the sake of argument, the differential input impedance should be around 2K.


texts: Is there any online or free to download (for Windows 7) AVR simulators?

texts:
I'm currently using CodeVision AVR to write a code. Let's say I have a compiled HEX file and I'd like to try it running on a virtual processor (ATtiny861A).

Google gives me some results but I'd appreciate if you will suggest me which one will be most free and easy to use.

Thanks!


texts: Diode circuit with parallel voltage source

texts:
What will be voltage V if all diodes are considered ideal

simulate this circuit – Schematic created using CircuitLab


texts:
So this is the Optocoupler I will be using:
https://html.alldatasheet.com/html-pdf/505064/FAIRCHILD/FOD3182/978/2/FOD3182.html
My question is with the schematic of the data-sheet. Using Ni-multisim I can't find any components that have a similar internal schematic, and it looks like most are just some sort of photo-diode connected to a transistor, but their internal schematics are significantly different.
I have another post called "Driving Power MOSFET with Optocoupler Problems (Component FOD3182)".
I guess with this post I'd like to ask if anyone can clarify or expand on what kind of optocoupler this is? And I'm wondering what Rail-to-Rail means and if I am just underpowering this device on the isolation side?
The purpose of this circuit is to make sure the PWM signal is passing through the Opto. I don't have access to test equipment so the way I am doing this is by modulating the intensity of the LEDs.
The program I'm running will incrementally increase and decrease the duty cycle of the PWM signal to make the LEDs on both sides of the coupler increase and decrease intensity at the same ratios, allowing me to visually check that it is working correctly.
I do have a basic multi-meter but the coupler does not seem to be blocking the voltage from the supply at all, and is not modulating the intensity of the isolation side LED.
I know it's not a defective product as I have 12 and this is happening with each one I use.
Once I get this working I'm wanting to use it this to drive some power Mosfets instead of the LED, so I can drive a sensored BLDC motor.
I'm also a bit new to this site, so any pointers or tips of any sort regarding my problem or Stack Exchange in general are welcome.

simulate this circuit – Schematic created using CircuitLab


texts: Including and extra product term on same chip in a PAL implemntaion

texts: To implement a circuit we have a PAL requirement 4-input,4-output,(2,2,2,2) product terms.We are using a chip with 8 inputs,8 outputs(4 reg, 4non reg)(2,2,2,2,2,2,2,2). But it happened that we made a calculation error earlier and now find out that 1 of the output requires 3 product terms.Can it be possible to still implement the circuit using same chip by using leftover input and output pins.


texts: Why do electrical systems have neutral, live and ground when electronic systems have only VCC and ground?

texts: Wouldn't it be simpler if electrical systems take away the neutral and just have live and ground similar to electronic systems?


texts: I need a reasonability check for the safety of a home-hacked power supply

texts:
I am in the process of building myself a fancy schmancy Raspberry Pi "laptop", and am trying to power it with a single cord/power supply. My strategy is to put together a small project box with 120VAC inputs, and the innards from a couple wall warts to provide 5VDC and 12VDC power. Before I start wiring crap together, I wanted to run my idea past some more experienced electri-gurus to make sure I'm not missing anything safety-wise. It seems like its the perfect solution in my mind, but want to make sure I'm not missing anything that I'd be expected to know if I wasn't self-taught.

My parts:

I have an old laptop power supply that I've gutted. It's basically the cord and an empty plastic shell (2" x 3" x 5"-ish) with the male end for the plug, and the wires that were clipped from the PCB from the male cord receptacle.
I've gutted 12VDC/2A and 5VDC/10A wall warts; I'm left with PCBs that have wires leading to the board, and barrel connectors coming off the board.

If I connect the three hots, the three neutrals and the three grounds from the PCB and power supply inputs, this will leave me with 120VAC feeding the box and getting shared by 2 PCBs that, upon testing SHOULD be putting out 12VDC, 2A and 5VDC, 10A.

Am I thinking about that right? In my mind, it's like I've got two wall warts in a power strip, minus the power strip.

Here's my power needs:

The Raspberry Pi: 5V, 700-1000mA
A powered USB hub: 5V, 1A (based on the 5V, 1000mA PS that came with it)
A powered USB WiFi interface: 5V, .5A ('cause it's USB...amperage is a TOTAL guess based on no information whatsoever).
A portable USB keyboard: 5V, .5A ('cause it's USB...amperage is a TOTAL guess based on no information whatsoever).
A 4" LCD monitor, 12V, 0.53W (which, by my math is way under 2A).

The 12VDC barrel fits the 12V monitor, so that's set. The 5VDC output needs to have the barrel connector replaced, and as long as I'n stripping wires, I'll be adding 3 USB ports to the power supply for device charging, and plan to split the 5VDC output between the individual USBs and the cable that will supply power to the hub--the hub will supply power to all the Raspberry Pi devices, 3A. With 10A supplied, those 3 extra charging ports won't be an issue unless my phone decides to draw 7A+ for charging. Am I good with that concept as well?

Please let me know if I'm missing any fundamental safety concepts for putting this thing together, and if appropriate, an appropriate link for where I can research & read about these concepts.


texts: Flashing SPI flash using DediProg while having intersection with other device

texts:
In my design for PCIE to USB converter board. I use VL805 Host Controller to do the conversion.
the chip needs a firmware that I flash it to SPI FLASH (U25) using DediProg.
I added a special 6-pin header (J14) to which I connect wires to DediProg.
my plan is to flash the firmware through the header, and supply voltage to the SPI by using Dediprog VCC.
at the flashing time, VL805 won't be connected to power. the signals {SPICS#, SPICK, SPISI, SPISO} are connected to that Host controller.
I was wondering if there could be a problem with the connection at the intersection between the SPI FLASH and the HEADER although the signals {SPICS#, SPICK, SPISI, SPISO} will be connected to a device that has no power.

My Solution:
Note: the VL805 sits on a PCB that will be connected as an external device to mini-PC motherboard.
Since there is a possibility of having ESD protection diodes at the SPI pins inside VL805 Chip, if we decide that we turn off the motherboard (3V3AUX_IN will be off) then turn on the programmer (DEDIPROG) in order to flash, we can risk powering up the chip again by supplying voltage to 3V3AUX_IN when the SPI signals {SPICS#, SPCIK, SPISI, SPISO} are high:

NOTE: that's just an image for clarification, I still have no information about whether ESD protection diodes exist in the VL805 or not.
So, to fix that, I thought of adding an N-MOSFET transistor that will pull down the (Power on Reset - PONRST) pin which will reset the chip at the time the Programmer device (DEDIPROG) is ON and is delivering VCC_DEDIPROG (which eventually will turn ON 3V3AUX_IN, and that's O.K because we want the CHIP to be ON when we do reset):

This means VCC_DEDIPROG will supply voltage to 3V3AUX_IN (which in a normal mode it should come the motherboard, but the motherboard at the flashing time is turned off) and that will help the transistor pull the PONRST node down.
the DIODE 101 will prevent current from passing to the programming device when 3v3AUX_IN is supplied from the motherboard (which we will turn it on after we finish flashing the SPI ROM).
Diode D100 will help discharging the C601 capacitor in cases where 3V3AUX_IN is suddenly down as result of power being cut-off or noise, in that case a system reset should be performed through PONRST pin.
What do you think of my solution?


texts: Issues with this USB ESD protection circuit?

texts:
I've used this ESD circuit on four boards for hobby projects.  I have had no issues on two boards.  On two others, the TVS diode for VBUS conducted when the board was plugged into a USB port, causing an overcurrent condition and destroying the ESD suppressor (the host is grounding the USB shield). The two working boards have probably just not seen a transient on connection.

Is there a better design for this?  Should there be a resistor between the suppressor and shield ground?  I have not seen this in the reference designs I see published by companies that make TVS diodes and worry this could slow transient response or prevent conduction.

The ESD suppressor in the circuit is a TI ESDS314DBVR, which is four TVS diodes in one package tied to a common ground. Digikey link https://www.digikey.com/product-detail/en/texas-instruments/ESDS314DBVR/296-ESDS314DBVRCT-ND/9745477.

The PTC is a LittleFuse rated for the power requirements of the board.


texts: Circuit draws no power from battery supply, but draws 60 mA from programming header

texts:
I am working on a project where I have three different power inputs. The first two are programming headers (for a msp430 and atmega328) and the third is a battery input. All three will power the entire system when plugged in, but the battery is disabled when either of the headers are plugged in.

My circuit is showing some strange behavior. Firstly, I am able to program the MSP430 through its programming header and blink a test LED. This draws about 60 mA due to the power MUX, diode, and voltage regulator. Everything is fine at this point. My confusion comes when I plug in the battery without either of the programming headers. Nothing happens, no LED blinks. I've tested all the points along the battery path and there is about 3 volts on the output of the voltage regulator..but the power supply (simulating a battery) shows no current draw, or at least less then 1 mA so I can't see it. So it would seem the MSP is not receiving sufficient current to turn on. However, I soldered a test lead to the output of the regulator and was able to light an external LED. So I know the regulator is working correctly. All grounds are common throughout the board.

In my testing, I found that with the battery input there is a voltage drop of about .7 V from the input of the regulator to its output. With the MSP header there is less then .1 V drop across it.

So my question is, why is there such a large voltage drop across the regulator when the battery is plugged in but not when the MSP header? Where is this mysterious impedance coming from? This is my second version of this board and I did not run into this problem on the first.

To clarify, the IC on the left is the power mux for the two programming headers. Its output leads to the input of the regulator (buck converter) which shares a node with the battery, as shown.

I'd appreciate any ideas or comments. Thanks!

Edit: RST in wired like this:

So RST doesn't have a connection from the battery. I am confused though because in my first revision of this design, I used the exact same diagram for RST and it definitely works with the battery.


texts:
So I got this small circuit that plugs to the mains as power source. as for its DC converter, it's one of those transformer-less ones that drops the voltage with a resistors and filters before rectifying and smoothing it. the ones that can only deliver small currents.

well, after that, it uses two IN4737 zeners in series to create a reference of 15V. I needed to find how much current is being drawn between the 1) DC converter (as described above) and 2) the zeners and the rest of the main larger circuit. so I disconnected the positive wire between these two and put in series an ammeter.

the measurements were odd. using my multimeter, it's here as follows (as I recall it properly):

20A range - 0.06 A

200mA range - 0.006 mA

20mA range - 0.060 mA

2mA range - I can't remember

200uA range - I can't remember

It was a weird set of readings (and yes the number I gave above for each range are exactly as they showed up in my display, even the units). I restored the original connection and the whole thing won't work anymore. I then found out that the IN4737's were blown and shorts at a few milliohms in both direction each.

so what went wrong?? the only difference was the ammeter in series for the positive wire between the converter and main circuit. aren't ammeters specifically designed to be passive and attempt to be a perfect conductor in all cases??


texts: What capacitance should be added over the inputs and outputs of a voltage regulator?

texts: Is there a nice rule/formula for this or do we always need to go off of the datasheet? I read today (in a datasheet, no less) that the capacitance should be customized for a given application (no further explanation provided), and I was also told that added caps are not required if the input voltage is stable.


texts: Forward Voltage VF Max 1V does this mean that the full wave w10 bridge rectifier can only allow 1 volts via it

texts: I want to use a full-wave bridge rectifier. My circuit needs 2 amps of current and operates at 12volts (12V @ 2A). I found this https://www.tanotis.com/products/vishay-2w01g-e4-51-bridge-rectifier-diode-single-100-v-2-a-through-hole-1-v-4-pins?gclid=CjwKCAiAzanuBRAZEiwA5yf4ujDS2suLmVHQSYIiL1mhfKOS6jPyQ9xhstmW5uRF4465WDaRHoD6bhoCjXsQAvD_BwE and now I doubt whether it can deliver or allow me to pass 12V via it or not. And please correct me if am asking a dumb question. I am a computer science student and I have no much experience with these things. I am on my way to learn things so please correct me if this is a dumb question.


texts: No hotspot in a component created in Altium

texts:
I have added a component to an SCH library in Altium.
I have just drawn the component (just the schematic and not the footprint!) and added to it a model that I found on the TI website. I just need the model because I just want to do a simulation (not a PCB).

I think I have mapped the pins correctly but when I try to connect this component to my circuit, there is no hotspot when I connect the wire (no red cross indicating me that the connection is correct).

I thought the problem may come from how I set the pins, but I don't really know how to solve this.

If you could help me that would be appreciated !

Thanks a lot


texts:
I cannot find anything related to this problem anywhere, does it mean it's impossible?
I want to have a chessboard with piece type recognition.
My idea is to plug pieces into the chessboard using some connector, which is connected to a resistor inside the piece, different in each piece type.
I would like to use single 8-channel ADC, which would connect to rows, and then scan one square at a time by switching one column on and others off.
I would have to use pull-down or pull-up resistors for unoccupied squares, and probably diodes to prevent current from flowing back to gpios, therefore changing the value read.
My question is, is this even possible?
Will the read speed be high enough to suit the purpose?
Will it work as good as using 64 analog inputs?

Please include diagram if wiring improvement is needed.

I'm not a native english speaker and write on mobile keyboard, so I am sorry for mistakes :/


texts: Not Getting Proper Result From Counters in Proteus Simulation

texts:
Circuit Description: This circuit should works as a over counter. Which should  count from 0 to 5 then it will give the pulse to the next IC
Problem : I found a circuit from online where they build a MOD-6 counter . Their circuit working just fine. I am trying to build same circuit but mine is not working . its not counting from 0 to 5 moreover in the IC-74LS90 i can see there is not enough power going to Light test (BI,RBI,LT) pin
what is worng with my circuit
Circuit That i found Online

Circuit which i made