texts: How to select line to a 1:4 demux in verliog from a NIOS II softprocessor

texts:
I am new to verilog. I'm using this 1:4 demux as described on this webpage (code supplied).

1:4 Demux verilog code

My question is in relation to the select line. I have a soft processor NIOS II on the fpga with an application written in c running on it. How would I control the select line from the NIOS? I presume that you would write a value to some location but I am unsure as to how it would work precisely.

Appreciate and tips of suggestions.


texts:
I have started working on proteus two days ago for my college project and I’m having some problem in the solar inverter.

Diagram which I refered for making this inverter:

And I tried to recreate this in proteus 8

where I’m getting -3.34v instead of 9V

I want suggestions on how can I fix this problem.


texts: Most efficient way to power both 12V and 5V off a battery

texts:
I'm building a lighting project for Burning Man and I have both 12V inputs and 5V inputs that need to be powered off of batteries. Here are the max loads:

ATmega328p - 25mA at 5V
Addressable LEDs - 100mA at 5V
Ultra-bright LED - 1.1A at 5V
EL Sequencer/wires, 15 meters - 300mA at 12V

Looks like peak load of 1.5A, although it'll average closer to ~500mA at rest. The LEDs will be dim/off until somebody engages with it.

What would be the best way to power the whole setup? I'm going to have 20 of these, so multiply everything by 20, which may change which power source I use. I also have to run this for 7 nights (12 hours * 7 nights). I want to avoid using a generator due to noise considerations.

Would a couple car batteries be enough? Should I run the addressable LEDs and ATmega on individual 4⨉AAs and the rest on a couple shared car batteries, or would the conversion from 12V to 5V be negligible compared to the ultra-bright LED and EL wires?


texts: I want to make a battery pack for my electric bike from protected PCB cells NCR 18650b, that's 24v, 13.6 Ah. My question is: Do you need to add the appropriate BMS to this battery pack since the cells themselves already have protection against overcharge and minimum discharge.


texts: Electrical circuit for detecting and charging a battery at 12 v

texts: I have an input source of 12 v at 6 amp. How can I use a toggle switch or a circuit that can detect if the source is active, it should let the voltage pass if present otherwise not. Also what is the best way to detect and switch on a led in case the battery that is operating has an output less than 12 v.


texts: Do hand tools such as cutters and pliers have to be replaced to switch over to lead free soldering station to be compliant?


texts: Analysis of three phase star star connected transformer

texts:
What is going on  this circuit(below) and what would be current measured by ammeter(zero or non zero)?

Description-
These two transformers winding are star star connected and a  balance sinusoidal three phase voltage source is applied on primary side (without neutral)
Problem in my analysis-
Due to load Z there should be a current (or loading current) in only one winding on secondary side(an) because other two are open but if current flows through one of  secondary side of winding it causes current flow in primary side of winding AN to balance mmf in the core but if current flows through AN then it must be also flow through other two windings of primary side to complete the path of current (because there is no neutral connected between primary and supply) .
But if current flows through two other windings of primary side then it causes current to flow through other two secondary windings  (again to balance mmf in the core ) but this is not possible because other two are open circuited so what is actually going on in this circuit ?
Assumption - take these transformers as ideal as possible to avoid any unnecessary complexity and assume no harmonic effects


texts: Can I combine Comment field from other Parameters in Altium Designer?

texts:
Comment can be set from Parameter like =Parameter:

=Value

where Value can be set as 100nF for example Comment Properties.

Can I combine several individual parameters into Comment? to get something like:

100nF; 16V

I tried following

=Value; =Voltage

and it didn't work.


texts: software for wiring and designing electric panel

texts:
I need some help in designing an electric panel. I have designed some pcb's (Power, control, relays...) and I want to place all of them in a nice way (As shown in the pic. The pic is taken from https://www.youtube.com/watch?v=KZiqUZGjGc0). I want to know what kind of software you use for the design of the panel and wiring it up.

I apreciate your help.
thanks.


texts: How to set MSP430 Driver Library timerA configurations

texts:
I am using MSP430F5529 and MSP430 Driver Library.

As you can see, I set upMode timer configuration, compare mode configuration and enabled the initial interrupts. However, timerA interrupt is not working, I set an indicator whether cod jumps into interrupt or not: ucsFault should be different than 0 if interrupt is working but obviously not. And I don't know where am I doing wrong. I appreciate any help. Thanks in advance.

#include "driverlib.h"

uint32_t fq_SMCLK = 0;

uint32_t ucsFault;

void setConf(void);
void clockConfiguration(void);

int main(void) {

    WDT_A_hold(WDT_A_BASE);
    P1DIR |= BIT0;
    P1OUT &= ~BIT0;
    clockConfiguration();
    setConf();
    fq_SMCLK = UCS_getSMCLK();

    while(1);

}

void setConf(void)
{

    Timer_A_initUpModeParam upMode =
    {

        //uint16_t clockSource;
        TIMER_A_CLOCKSOURCE_SMCLK,
        //uint16_t clockSourceDivider;
        TIMER_A_CLOCKSOURCE_DIVIDER_64,
        //uint16_t timerPeriod;
        ((4000000/16/64)/120),
        //uint16_t timerInterruptEnable_TAIE;
        TIMER_A_TAIE_INTERRUPT_ENABLE,
        //uint16_t captureCompareInterruptEnable_CCR0_CCIE;
        TIMER_A_CCIE_CCR0_INTERRUPT_ENABLE,
        //uint16_t timerClear;
        //TIMER_A_DO_CLEAR,
        TIMER_A_SKIP_CLEAR,
        //bool startTimer;
        1
    };

    Timer_A_initCompareModeParam comp =
    {
        //uint16_t compareRegister;
        TIMER_A_CAPTURECOMPARE_REGISTER_1,
        //uint16_t compareInterruptEnable;
        TIMER_A_CAPTURECOMPARE_INTERRUPT_ENABLE,
        //uint16_t compareOutputMode;
        TIMER_A_OUTPUTMODE_TOGGLE_RESET,
        //uint16_t compareValue;
        ((4000000/16/64)/120)*4/5
    };

    Timer_A_initUpMode(0x0340, &upMode);

    Timer_A_initCompareMode(0x0340, &comp);

    Timer_A_enableCaptureCompareInterrupt(0x0340, TIMER_A_CAPTURECOMPARE_REGISTER_1);

    Timer_A_enableInterrupt(0x0340);

    Timer_A_startCounter(0x0340, TIMER_A_UP_MODE);

}

void clockConfiguration(void)
{

    P5SEL |= BIT2+BIT3;                       // Port select XT2

    UCS_initClockSignal(UCS_SMCLK, UCS_XT2CLK_SELECT, UCS_CLOCK_DIVIDER_16);

    UCS_turnOnXT2(UCS_XT2_DRIVE_4MHZ_8MHZ);

    UCS_turnOnSMCLK();

    UCS_setExternalClockSource(32000, 4000000);

    UCS_enableClockRequest(UCS_SMCLK);

}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void __isr_Timer_A(void)
{
    ucsFault = 1;
    switch(TA0IV)
    {
    case 0:
        Timer_A_clearTimerInterrupt(0x0340);
        Timer_A_clearCaptureCompareInterrupt(0x0340, TIMER_A_CAPTURECOMPARE_REGISTER_0);
        Timer_A_clearCaptureCompareInterrupt(0x0340, TIMER_A_CAPTURECOMPARE_REGISTER_1);
        P1OUT |= BIT0;
        ucsFault = 2;
        break;
    case 2:
        Timer_A_clearTimerInterrupt(0x0340);
        Timer_A_clearCaptureCompareInterrupt(0x0340, TIMER_A_CAPTURECOMPARE_REGISTER_0);
        Timer_A_clearCaptureCompareInterrupt(0x0340, TIMER_A_CAPTURECOMPARE_REGISTER_1);
        P1OUT &= ~BIT0;
        ucsFault = 3;
        break;
    }
}


texts: Without the use of any software, what would be the cheapest way to connect my broken laptop's keyboard to my desktop?

texts:
I am trying to use an old keyboard from a laptop as a new set of keybindable keys for my desktop. I will worry about software side later what I need here is this: How can I use the keyboard from my laptop as a USB or bluetooth, etc. input to my desktop?

I have searched around and I see often that when people don't use software from a laptop to desktop (Which I cant do due to the laptop being broken and unreasonable to fix) and they actually have the same question as me, it doesn't get answered because people just say "it isn't worth it"

I know it isn't worth it, but I still want to do it. Is there any electrical wiring solution to my problem? Again, I want to connect the ribbon cable from my laptop's keyboard to my PC somehow as an input device.


texts:
For this IGBT I-V curve say I have a Vge of 10V and no biasing resistor on the collector with 5 Volts being supplied by some supply providing up to x watts. According to this I-V curve this should be pushing out 550 amps.

Now say I have a Vge of 10V and once again no biasing resistor with the collector being held at a 100V by some supply providing up to x watts. According to this I-V curve this should also be pushing out 550 amps.

Also is it typical to not use biasing resistors to set Vce for IGBTs?
The above should be true as long as my supply is supplying the correct wattage correct? This wattage needed would be the Vce*Ic with the correct voltage and current ratings?  If we 1/2d the wattage available would we just push out less current than the I-V indicates assuming the same Vce? I just want to verify im looking at this the correct way thank you.


texts: Create binary sequence to use less inputs

texts:
Let's say I have 63 buttons, but there are only a few inputs on Arduino. I want to know which one was pressed. To minimize the number of inputs used, I could tell from a binary sequence. If I press button 61, I need to have six inputs returning 1,0,1,1,1,1. How would I convert the button number to binary?

If you know any easier way tell me, it's the only that came to my mind.


texts: F-SW22 vs F-SW33 flux. What to these figures mean?

texts: I was thinking of purchasing a no-clean flux pen from my supplier, but there are two options, F-SW22 and F-SW33. What do these codes mean and what types of job is each suitable for?


texts: A question about the argument part of impedance

texts:
The definition of impedance is Z = V/I. I'm trying to understand the idea behind the argument part of the impedance concept in a capacitor.

First here is what I know briefly so far:

I will begin this by assuming the voltage across the capacitor is sinusoidal as:

Vcap = A* sin(w*t)

one can also write:

Vcap = Im{A* e.^(j*w*t)} * (1/j) //complex representation

Current through the capacitor Icap is the derivative of the voltage so that:

Icap = C*dV/dt

Icap = C*A* w*cos(w*t)

Icap = Re{A* e.^(j*w*t)} * C*w //complex representation

So we can therefore write the impedance Zcap as:

Zcap = (1/j*w*C) *  [Im{e.^(j*w*t)}] ./ [Re{e.^(j*w*t)}]

or one can also write the following:

Zcap = Vcap./Icap

Zcap = (1/w*C)*tan(w*t)

tan(w*t) = -j * Im{e.^(j*w*t)}] ./ [Re{e.^(j*w*t)}]

My question is about the impedance's argument part:

Zcap = (1/w*C)*tan(w*t)

or

Zcap = (1/j*w*C) *  [Im{e.^(j*w*t)}] ./ [Re{e.^(j*w*t)}]

Reactance is defined as Xcap = |Zcap| = 1/(w*C)

But to hold the above equation the following must be true:

|tan(w*t)| = 1

or

| -j * Im{e.^(j*w*t)}] ./ [Re{e.^(j*w*t)}] | = 1

How can they be equal to one where they are time dependent?

Is reactance the maximum impedance?

Is there a way to illustrate or explain the argument part of the impedance in this case?

EDIT:

My confusion comes from the following fact:

In the above plot red represents the voltage, blue is the current accross the capacitor. They have 90 degrees phase difference.

And since we defined Z =V/I:

Look at now the green encircled region where voltage becomes max and current becomes zero at the same time. If we freeze the time at that moment, as you see V/I goes to infinity. What is going on here?

The impedance Z = V/I changing by time, even goes to infinity sometimes; yet we associate the reactance with what??


texts:
I wanted to create a sinewave at 10kHz with Vpp of lets say 90v. The current draw of the output sinewave will be 1uA.

My plan was to drive a mosfet at 10khz which will (I thought atleast )create a square wave of 0 to ~100V. I will then pass this high voltage through 3 passive RC filters to create a sinewave.

f=1/2*piRC; C=1nF; f=10000
--> R ~ 16K
Vgs of the mosfet = 10v
mosfet = IRFB20N50K

as you can see below the circuit is simple, however when I run the simulation the square wave at the drain of the mosfet is not even 10v and therefore the sinewave Vpp is very small.

Can someone please tell me what obvious concept am I missing? isn't this the way TTL mosfets work? I have just simply increased the voltage to 100V.

If this is just bad practice then can someone please suggest another method?

Thanks guys


texts: How To Source Transformer Component for Bug Zapper Circuit

texts:
I am looking at designing a small bug zapper circuit of the type described in this post: How does this mosquito zapper circuit work?
Here is an approximate schematic of what I am trying to build:

I have done some research into how this circuit works and also taken apart a mosquito zapper racket and tested the circuit firsthand. From this I've gain a basic understanding of how the circuit works via self oscillation and flyback.
What I'm confused about is how to correctly source the transformer component. I know I need one with 6 leads, but other than that I'm kind of in the dark. The transformer from the unit I took apart had no distinguishing markings so it wasn't much help.
Can anyone tell me what specifications I need in a transformer for this circuit to work?
Thanks!


texts:
I am seeking guidance on this problem regarding RL circuits because me and my study group are getting two different answers and we don't know why.
Question: After being open for a long time, the switch in the circuit closes at t=0.

Determine I1(t) for t>0 by finding time constant
Determine steady state current
determine Initial Current I1(0+)

As t->infinity, I am:

doing a KCL at the bottom middle node
getting the equation for Il(t)
doing the KVL around the loop to find my Ix
plugging my information into the equation.

I keep getting Il(t) = 19/9 A.
Yet they are getting Il(t) = 5/3 A.
The inductor is where I(L) is and has a value of 18 mH.
Thank you for the assistance.
[![enter image description here][2]][2]


texts: +/-5V to 0...5V and not failing for +/-12V

texts:
I'm trying to convert a voltage that is between -5V and +5V to the range of 0...5V. These voltages can be found in "euroracks"/"doepfer a100"-systems which are modular synthesizers for music.

This conversion is possible with the schematics found at https://masteringelectronicsdesign.com/design-a-bipolar-to-unipolar-converter/

With a TL074 opamp this works fine on my breadboard.

Now there is a problem with that: the input-voltage for my use-case (eurorack/a100 modules) can be -12...12V in some cases. In that case (e.g. anything that is outside -5...5V) I would like to clamp it to -5...5V.
Limitting to +5 I can do with a LM336Z-5.0 I think but how can I protect against voltages lower than -5V? (or less than 0V after conversion)

The signal I'm converting is a voltage that represents a frequency. E.g. 3.250V is note C4 see wikipedia

The output will be send to an arduino adc pin.


texts: Using a 9V battery instead of a DC power supply

texts:
I have a DC power adapter that has the following specs:
 Input Voltage: 100-240V AC, 50-60Hz, 0.5A
 Output Voltage: 9V DC, 1.5A

I am interested in taking a 9V battery and a snap adapter so I can use my device away from my outlet. However I am not sure how to ensure the output will be 9V DC and 1.5A (specifically the 1.5A).
How can I take a 9V battery plus a snap adapter and create a power supply that would be equivalent to the DC power adapter? Do I need to add a 6 Ohm resistor in the loop to ensure that I = V/R or is that too simple?


texts: Why Op-amp pulse generator circuit do not providing any output?

texts:
I'm trying to design a clock with 1.8V CMOS.  I've designed the Op-amp and individually it works fine (simulated with up to 10MHz pulse input) . But when I use this opamp to draw the feedback circuit , it provides no output.

Output stays tends to zero volts (actually -41 uV ). As there is no desired output,I'v tried many capacitor value and feedback resistor value to see any kind of output pulse, but no luck. As I do not concern with limiting current, current limiting resistor is not used.
I even manually give pulse in input to provide startup condition, no luck there either.

This is my Op-amp circuit:

and here is the of Op-amp simulation in 10MHz input pulse at Inverter input. and zero voltage in non inverting input. (Output is not sharp but is more then enough for my use)

Please, could you give my any suggestion, where could I possibly do wrong? How should I approach next?

thank you for your time.


texts: Forwarding a signal from RX to TX using a USRP with FPGA

texts:
This is a LabVIEW (Software) FPGA (Hardware) question so I don't know whether I should post here or on Stack Overflow.

I have a USRP-2953R and I want to achieve a very simple project. I want to read a signal from RF0/RX1 and output it to RF1/TX1 using the FPGA (not forwarding anything to the host). The signal is centered at 5.9GHz with 10MHz of bandwidth. Is that feasible? What should my approach be?

I have tried different modifications to the "Simple NI-USRP Streaming" project that comes with LabVIEW 2013, but I haven't successfully outputted anything. I'm using LabVIEW 2013 SP1 and I am able to compile and execute code successfully on the USRP FPGA. It simply doesn't do what I want it to do.

Any help would be greatly appreciated.


texts: For gates of same drivestrength, what does gate delay depend on and how?

texts:
I was wondering what the effect of input capacitance or fan-in is on gate delay.

Also, does anyone know of a relation that links gate delay with different circuit parameters (input load (fan-in), output load (fan-out), gate length/width, ..., ...) ?

If I have gates of the same drivestrength, what exactly does gate delay depend on and how ?


texts: What function does this PCB circuitry serve?

texts:
Backside is metal disc with thermal paste between it and the metal mount to which it is screwed.  Input is 6.75V 200mA.

What function does the PCB circuitry serve? Is it stepping down the voltage or limiting the current, or both?

Is U1 a current limiter? voltage regulator?

Is ZD1 a Zener Diode?

Here is an image from someone else:
https://www.eevblog.com/forum/reviews/ikea-led-power-supply/


texts: Noise levels on high voltage power lines

texts:
I'm doing Signal Processing on signals from high voltage transmission lines but I'm unsure of what noise levels I should be expecting and which types of noise occur in a power system (impulse, harmonic etc.)

The idea is to get signals from current and voltage transformers at substations to do fault detection and classification but the methods I employ are dependent on the noise I should be expecting.

I have seen various SNR values thrown around in different papers but I'm wondering whether anyone could point me to a good source on this topic or perhaps give a brief explanation.


texts:
I have some arcade cabinets with computers in them, and I'm using a regular PC PSU for them, which sucks because it takes up so much space.

I know there are pico-psus on the market, but I don't really get why I can't just take 12v and 5v from the JAMMA harness and wire that in to an ATX connector.

Is it possible to do?


texts: How to implement critical sections on ARM Cortex A9

texts:
I am porting some legacy code from an ARM926 core to CortexA9.  This code is baremetal and does not include an OS or standard libraries, all custom.  I am having a failure that appears to be related to a race condition that should be prevented by critical sectioning of the code.

I want some feedback on my approach to see if my critical sections may not be correctly implemented for this CPU. I am using GCC. I suspect there is some subtle error.

Also, is there an opensource library that has these types of primitives for ARM (or even a good lightweight spinlock/semephore library)?

#define ARM_INT_KEY_TYPE            unsigned int
#define ARM_INT_LOCK(key_)   \
asm volatile(\
    "mrs %[key], cpsr\n\t"\
    "orr r1, %[key], #0xC0\n\t"\
    "msr cpsr_c, r1\n\t" : [key]"=r"(key_) :: "r1", "cc" );

#define ARM_INT_UNLOCK(key_) asm volatile ("MSR cpsr_c,%0" : : "r" (key_))

The code is used as follows:

/* lock interrupts */
ARM_INT_KEY_TYPE key;
ARM_INT_LOCK(key);

<access registers, shared globals, etc...>

ARM_INT_UNLOCK(key);

The idea of the "key" is to allow nested critical sections, and these are used at the beginning and end of functions to create reentrant functions.

Thanks!


texts: Why exactly does maximum power transfer happen at 50 ohms (matched impedance)?

texts:
As the title mentioned - I am not sure why exactly the maximum power delivered to the load will be max when R_L is 50 ohms.

If I guess why, it's because if the resistance was greater than 50 ohm then the current will be lower, but if it was less than 50 ohm (e.g. 25 ohm), then the constant 50 ohm resistor would deliver the majority of the power instead of going to the load.

Why does the maximum power transfer happen at 50 ohms?


texts: How to calculate theoretically Output Impedance of a Linear Voltage Regulator

texts:
I am trying to calculate the output impedance of the following circuit, a linear voltage regulator. What is confusing me is the feedback coming from R1 and R2.
I used R4= 500 ohms, R3 = 1K , R1= 25k and R2= 23 K.
I hope someone could explain me how should i do it.

Thank you very much.


texts: Acceleration in the Z direction in Earth frame regardless of orientation

texts: I have acceleration readings on 3 axes from an accelerometer, I'm trying to find a way to get the acceleration in the vertical direction independent of the current orientation of the sensor. I have been trying to google and search on forums but having a hard time finding a coherent answer. Thank you


texts: How does the different types of fast charge affect a lithium battery on a cellphone in terms of heat?

texts:
I know that fast charge technology allow chargers to communicate with the battery management chip inside the mobile phone in order to use different voltages to charge the mobile phone instead of just using 5V and have a high current like 2A or 3A.

But I don't know how that charge is transfer inside the mobile phone to the battery. I know normally batteries are 3.7V.

How a fast charge using the same power (2A x 5V vs 1.11A x 9V) will affect the heat in the battery of the mobile phone ? I know that 2A will produce more heat in the wire/components, but not sure how it will affect the battery.

EDIT: I think the right answer is in another topic here.

  Li-ion cell charging voltage ranges from ~3.7V to 4.2V. 18W/4.2V = 4.29A. The charger has a DC/DC voltage converter circuit which pulses current through an inductor to 'transform' the voltage down and current up. This process is typically 85~90% efficient, so it should be able to deliver 4A for most of the charge cycle.

Help me to understand VOOC fast charging for lithium ion batteries?

So the heat will be the same, since its convert 9V voltage to 4.2V or 4.4V and increase current, no matter the method you use for fast charge.


texts: How to forbid traces under component in Diptrace?

texts: If anybody is using DipTrace in auto-routing shape mode, is there any way to tell not to put traces under certain components?


texts:
For normal operation it is said to remember:

Emmitter Base junction is always forward biased
Collector Base junction is always reverse biased

Can someone explain to me what this means?
My view is that the Emitter is +ve wrt to Base and Collector is ove wrt to Base.
I am new to this topic, please explain?


texts: Noise filtering circuit on a pulled-up 1-wire bus

texts:
The 1-wire bus data line is connected to a microcontroller pin (through a level shifter) with open drain configuration. The bus is pulled up to 5 Volts (DVDD) with a 4.7k resistor.
The communication works but unstable due to a high level of noise measured on the long (~20-30m) bus wire, so I decided to add a low-pass filter circuit to the bus.
My question: should I add the filter in between the microcontroller pin and the pull-up, or should I keep the pull-up next to the open drain pin, and add the filter after this circuit (as it is currently on the schematics below)?

The Schematics:


texts:
I'm having a trouble selecting the proper transistor to switch this LED circuit

simulate this circuit – Schematic created using CircuitLab

The LEDs are 3.6v at 20 mA.

I tried figuring the calculation for the transistor and really the maths escaped me so I just tried out a BC547 I had around.  What really confused me was when the switch was open, the LED's glowed dimly. (When closed they glowed bright as expected).  I was surprised as from what I'd read transistors are either full on or off. The dim glow was effected by me touching the resistor or other spots on the bread board.

If it helps, I'm actually testing this with the aim to replace the switch was a capacitive touch sensor such as this one: http://www.mouser.com/ds/2/42/iqs904_datasheet-8785.pdf

Finally I'm aiming to build this in SMD even though I'm prototyping in through-hole parts at the moment.

Any advice would be greatly appreciated.


texts:
I am trying to upgrade our existing bell with my arduino to detect whether the bell is used and to mute the bell.

The circuit for the bell runs with 9V AC. In order to minimize the wiring I want to serially connect something to the bell such that it is possible with my arduino to turn the bell on and off and I can detect whether the bell was used.

I tried to use two relays: one as a switch which can be used by the arduino and one as a switch which will be closed when the bell is used. They were parallel connected. But since I am a beginner nothing worked as intended :)

Is it possible to do this with two relays? Or is there a better way to make it work?

EDIT

Thanks for the answer. The bell isn't earthed. I tried this:

What is wrong with it? :)


texts: How can I figure out what the forward current and forward voltage will be for an LED given a resistor size

texts:
We're trying to order some boards from our PCBA manufacturer but they're having trouble sourcing our original LEDs (QBLP601-IW).  They proposed an alternative LED (LSM0603443V) and I'm trying to be sure this is a suitable drop-in replacement.
The problem is we're significantly limiting the current on the original LED with a 150 ohm resistor.  We have a 3.26V supply voltage and we're dropping about 2.7V across the original LED (and about 550 mV across the resistor).  If I'm correct, we're pushing 3.67 mA through the LED.
Based on the original datasheet, this puts us right about 20% of 330 mcd.

Now I'm trying to figure out bright the new LED would be with the original 150 ohm resistor.  I'm looking at this chart and basically using trial and error to figure out what my Vf and If would be.

Aside from the fact that I don't understand what's happening to the Vf scale between 2.8 and 3.4, here's what I did . . .
My Naive Attempt
Using the formula below, I started plugging in values for Vf until If landed on the curve.
$$
I_{F} = \frac{(V_{CC} - V_{F})}{R}
$$
That seems to happen at Vf = 2.45V, If = 5.4mA or so.  Is that the right way to figure that out?  I'm a little concerned because if I use this approach, the datasheet for QBLP601-IW leads me to believe that Vf should be 2.54V not 2.7V as I measured (maybe because it's not at 25 degrees C). :(
Is this the right approach?  Is there a better or more accurate way?
Sidenote
The reason it matters so much is that if I look at the Luminous Intensity curve for the new LED, it looks like at 5.4mA the intensity would be about 40% of 330 mcd which would be (I think) twice as bright as the original and could be disruptive to people using our device in the dark.


texts: 4 seconds delay using gates or flipflops

texts:
In my design , I want to add delay of 4 seconds to rising edge of input Vin.

I tried using below circuit , but problem is, in my setup, i am not able to see 4 seconds delay. Though I have checked below circuit externally. Reason might be change in impedance ( change RC when connected in my setup )

Is there any other way to generate delay using hardware (of 4 seconds approx )?

PS. I want to do this with hardware only. And also RC delay is not working in my set up and looking for other options such as gates or flipflops

Thanks in advance.


texts: why are capacitors often not labeled using engineering notation ? (1-999)

texts: i see schematics with values such as .01uF among others... why out of all components are these not labeled using engineering notation


texts:
I know how to calculate proportions of resistor values in resistor divider, but dont know how to jump into "next level" and calculate the precise values of resistors from proportion :

For example to devide 10V to obtain 5V you can use:
- 10 ohm R1 / 10 ohm R2
And as well you can use
- 100kohm R1 / 100kohm R2

Proportion is the same 1/2 but it for sure is different.

What I have to look for, what I have to know to calculate this?

Is time also critical? I want to divide pulsing signal, want change only voltage range, but still I want to keep form/shape of this vawe.


texts: I am using a current to voltage converter (I-V) to convert the current in the form of sine waves from an electrochemical cell (working electrode) into a voltage. I am using op-amp TLE2062 from Texas Instruments to create the I-V converter. At the output of the I-V converter the sine waves are 180 out of phase with respect to the input signal. Can anyone help me with a phase inverter circuit so that the input and output are not 180 out of phase.


texts: Strange plot in PSpice Student after reducing maximum step size

texts:
I have run 10m simulation in PSpice Student 9.1 with Analysis Type: Time Domain (Transient) with max step size 100u and I get such plot:

I wanted my plot to be more smooth so I have changed max step size to 100n and to my surprise plot looks like that:

Can anyone explain me what has happened and how can I smooth my plot ?

EDIT: CIRCUIT

Rc = 5k, Re = 2k, Ro = 10k, Rg = 40k, V1 = 20V, V2 = 6V, VOFF -1V, VAMPL = 1mV, FREQ = 1000


texts:
A 18V 4ah battery contains 10 cells.
A 18650 cell can have a max continuous discharge rate of 20A.

Does that mean that a typical 18V 4ah battery can theoretically provide the tool the equivalent of 3600 watt of power? (10 * 20A * 18V = 3600)


texts: Generate Short negative pulse from an open collector output?

texts:
Ive been teaching myself as I go so please forgive me for any errors. I need the output of an open collector output (goes to ground when active) to henerate a short negative pulse to reset the counter at 6 so it counts 0-5.

I am using a 2 74142 nixie drivers http://chronix.pl/download/74142.pdf (datasheet)
For the seconds and 10 seconds digits. I use a 1Hz clock signal into the first, clear pin is set high and strobe is set low, no problems, the nixie counts from 0-9. I have the Q output cascaded to the 10 seconds digit 74142 which basically makes a 00-99 counter. I want the second counter to reset when the open collector output for digit 6 is active, thus resetting the count.
I think I could do this with a second IC such as a monostable vibrator but is there a simpler way?
Note that the output to digit 6 will remain active for 10 seconds. The reset pulse needs to be at least 25 ns long per the data sheet. After it resets from 5 to 0 the reset should go high again to start the counting over, meaning I want a short pulse as opposed to the reset pin being low for the whole 10 seconds.

I came up with the circuit below modified from an online post. The left represents the open collector output, the spst switch activates or deactivates it. The negative pulse will be taken from the resistor on the far right. Changing C values or R values of the bottom resistors all modify the pulse width and shape. I had to add an inverter.

I got the original circuit from another stack exchange post.

The only other help I found was a forum that stated the Clear pin on the 74142 should have a 2.2kOhm resistor from 5V and a 0.1 uF cap bypass to ground, and if the cap is left out it counts from 0-5. I tried this and sometimes it counts 0-5 and other times 0-6 so it is not a reliable solution.
Thanks in advance for your help.


texts:
Can we use a MOSFET to act like a single inout current regulator? Here is my idea.

simulate this circuit – Schematic created using CircuitLab
If the voltage on the input is greater than the threshold voltage of the MOSFET electrons start flowing from the ground to the 3.3V outlet .
Rb is much much bigger than the ohmic resistance of the MOSFET( width of conducting channel) so any variations won't practically change current.
I am having trouble in making a circuit using only 1 DC voltage source. How to do it?


texts: In my digital electronics labs and lectures we are told to try and make things from NAND gates, because they are the cheapest kind of gate available to buy. Why is this? Why isn't an OR/AND gate the cheapest to buy?


texts:
I am using the cheap 1.5-3v motors from radio shack and I try heating up the connectors on the motor, but I think they are melting inside because in one case the pole now wiggles, and the other case the motor only sorta works depending on how I hold it.

If I don't heat up the metal connectors the solder wont stick, or so ive read.


texts: How to compare VitalDelayType01 to each other?

texts:
I have a behavioral model of an external RAM part. This vendor seems to have used some external library functions or procedure they made.
It has these functions like:
MinDelay (a, b) return c; --where a,b,c are VitalDelayTime01
MaxDelay (a, b) return c; -- ""
Other subprograms such as this are also included.
I have already asked for this common library they used, but in case they don't respond, I was looking into just creating these functions myself. I already got a different procedure to compile. Now I am looking into these which do some type of modification of these two VitalDelayType01 variables.
Could I do a comparison of variable that are VitalDelayType01? If so, what is the syntax for that? What if it is a vector of VitalDelayType01?
ex1:
-- MinDelay (returns lesser of a or b)
if a < b then
    c <= a;
else
    c <= b;
end if;

ex2:
-- a is a VitalDelayType01(n downto 0);
if a(0) < b(0) then
    c(0) <= a(0);
else
    c(0) <= b(0);
end if;


texts:
I have a project where there are 2 board to be connected inside of a metal shielded chassis:

1) 2 layer power/analog/ext connector (usb/spdif/audio)

2) 4 layer digital board (lcd+mpu+fpga)

The board (1) will be placed at the edge of the metal chassis, while the other will be at the top of the chassis, like the image below:

The connection between the two board will be:

-5V power (500mA max)

-24Mhz I2S

-48Mhz SPI

-HS USB 2.0 or ulpi interface

-12Mhz SPDIF

-Some low speed IO

Total count: ~24

The distance between the board is max 3"(7cm).

The questions are:

1) Should I place the ulpi usb transciver in the core board(2)(where signal come from) or the connector board (1)(where the connector will be placed)?

2) What kind of connector should I use to be sure that there will be minimum interference on the signal? Should it be shielded? Or am I overthinking and a standard 1.27 ribbon will be fine?

Many thanks to everyone would like to help!


texts:
My company has been designing PC boards since the early '80s.  However, we haven't formalized our PCB Design procedures or preferences.  Things like preferred PCB sizes, preferred location of mounting holes, preferred component types, etc.  All of this is taught to new hires by existing people already doing that work.

We are looking to the future when people start to retire and are not available to pass their knowledge onto new Engineers and CAD people.

We could start from scratch and build up a set of documents that specify our way of doing things.  However, it seems that it might be much easier to adapt an already-existing set of documents and procedures to our needs.  An added advantage of adapting existing procedures that they might point out something that we are not currently doing or haven't thought of.

What I'm looking for is pointers on where to find such documentation or templates for that documentation.  I don't mind paying for the documentation so long as I can determine ahead of time that it meets our needs.

Our PCB designs are quite simple, although often very dense.  Single-sided PCBs for simple high-volume products using through-hole components, double-sided for almost everything else.  I don't recall ever doing a PCB design with more than two layers, although I've had to fix design mistakes done by others.  But our stuff is simple enough that two layers is adequate.

Please note that I am NOT asking for opinions on how to do this documentation.  Rather, I am asking where I can go search out such documentation that could be considered to be industry-standard.  Even providing search terms would be extremely useful.


texts: How is the dV/dt of the controller voltage constant?

texts:
Theory of operation:
When the switch is turned on, R1 feeds voltage to the FET gates, which will be clamped by the zener diode.
Initally, the controller (-) will be at the same voltage as controller (+).
As the FETs turn on, the controller (-) line starts to pull down, causing current flow through the capacitor.
The dV/dt of the controller voltage will be constant to match the zener current. This will cause the current flowing into the capacitors of the controller to be constant during the precharge. Once the controller is fully on, current ceases to flow through C1 and the gate voltage climbs to 12v. Turning the switch off shorts the gate, immediately turning off the FETs and slowly charging C1.

I request you to let me know how the dV/dt of the controller voltage is constant. Also a brief explanation of this circuit would be appreciated.


texts: I have a problem with determining the type of connector shown in the picture. The female plug looks like the Molex 5557 type. The dimensions of this plug confirm this. The problem is with the male socket - I can not find the right model. External dimensions suggest type Molex 5566, but the positioning of pins (centrally) and the lack of plastic pegs do not match. The pins in the connector are square, the side has a length of 1.15mm. In the back there are also letters "HXH".


texts:
I'm trying to design a module to go on the backs of panels that will be connected in series. The module will have a few sensors connected to an FPGA and it will modulate a signal onto the line with the data from the sensors. I have that part figured out but the part I'm having difficulty with is figuring out a way to have have a voltage regulator connected to just the panel it's on, regulating power for the FPGA and sensors.

I was using a bench power supply to test out a little board that utilized LM2596 that looked to work with a non zero negative (i.e. tested having a supply before it providing power so negative is around 30V and the positive terminal is 60V with another supply adding another 30V).

I am running into issues when I added more than the one coupled to each supply. It overheated fast and then ended up shorting to the current limit on my supply. --EDIT-- (not important because not asking for diagnosing... asking for help with the next statement)

I'm new to this and would love some help with what I should be looking for as far as voltage regulators that are designed for this kind of application without letting out magic smoke. What I need is help understanding what voltage regulators that can be set up like the schematic below and provide 5V with a decent amount of current (100-200mA). What I used is having issues and before I start ordering parts/evaulation boards I figured I'd ask for input if there is already an industry standard (linear vs switching/if there is some sort of circuit similar to how AC has the diode bridge/other configurations I was unsuccessful in finding) to save time/money.

Below is a simple schematic to represent what I'm trying to accomplish, where V1&2 are the bench supplies representing the panels (will want to implement this on more than just two if I can get it working), U1&2 are how I need the voltage regulators, and U3&4 are my microcontrollers and sensors that are not the focus of this question but will run on 5V and 3.3V and need at most a budget of 100-200mA.

simulate this circuit – Schematic created using CircuitLab

--EDIT--
To add some more information about the panels I'm working with -
Pmpp > 240W
Vmpp 30.4V
Impp 7.9A
Voc 37.3V
Isc 8.52A


texts: How to "shift" a logic LOW of 2,5 V to GND?

texts:
I'm trying to control a 24 V LED strip with a device that has its own control mechanism and PWM output. (The output PWM frequency is 1 kHz.) The device itself requires 5 V, and since it does not draw that much power so I'm planning to use a standard voltage regulator there, not that interesting.

My problem here is that the device's PWM output logic is rather weird. It's logic LOW is 2,5 V while a logic HIGH is 5 V.

Here is my schematic:

As for the N-channel mosfet, I'm planning to use the IRLB8721 (datasheet). But this one won't turn off on a 2,5 V logic LOW by my device. The question is; how can I "shift" this logic LOW down to GND?

Almost all Google searches I've tried lead me to logic level shifters that most often let 3,3 V logic devices connect with 5 V logic devices and vice versa...

I did find two interesting topics here on the Electrical Engineering Stack Exchange with almost the same problem, but I could not figure out how to translate the solutions posted there to my specific problem:

Translating to “below ground” logic levels

-5/0 volt to 0/5 volt logic levels?


texts: Understand MIPI-CS2 camera connector on ZYBO Z7

texts: Please take a look at page 2 and page 11 of this datasheet. Why do they bridge the MIPI signals of the connector J2 with a 150R resistor and connect the signals with the FPGA and additional connect each of the terminals of the 150R resistor over a 100R resistor with the FPGA?


texts: Can any part of Intel's (RdRand) random number generator be visually inspected?

texts:
A random number instruction RdRand, has been added to Intel's Ivy Bridge processors that (allegedly) draws upon a hardware entropy circuit.  The architecture is (allegedly) something like this:-

The entire architecture and the instruction itself is highly controversial.  The Linux community deems it suspect. Is it possible to visually inspect or reverse engineer at least the physical circuit?  This would be to validate its design /operation against  the public documents provided by Intel themselves. I guess that the die would have to be exposed with something like a Stanley knife.
This is a six core Intel i7 CPU die with over 1 billion transistors across 11 layers which seems (too?) tricky to reverse engineer.

I'm focusing on the resources and expertise of someone like Imperial College, England or MIT in America. Or anyone cleverer but still in the civilian domain.


texts:
I'm experimenting with MCP73871T-2CCI/ML charger for my Arduino project. I wanted to build one by myself based on datasheet.
I have build circuit on prototyping board, according to this schematic:

Unfortunately charging current for battery is very low. At maximum, my 1400mAh LiPo is charged with current 100 mA, MCP73871 does not switch do 1A charging at all. Even, when I discharged battery completely, it does not switch to high current charging.

I need to add, that I was soldering raw chip to the adapter board by myself, so it might be that I have either broke it or it is not soldered properly.

Could you be so kind to give me any ideas how I can diagnose the reason ?


texts:
I have three transistors that are each connected to 5 LEDs like so.

I am attempting to increase and decrease the current through the LED's in a linear fashion by increasing the current in the base of the transistor. So if I decrease the 3mA to 1.5mA, I want the LED current to go from 16.25mA to 8.125mA. However, currently this setup does not do this. The current in the LEDs does not significantly decrease until the current source is a small percentage of its current value.

The 3mA sources in my diagram are modeling the pwm outputs of a microcontroller. (Their max current.) I need to control the brightness of the LEDs by changing the duty cycle of each PWM.

I'd rather not have to use a LED driver. I'm also aware of the use of lookup tables to correct the exponential factor. Is that my only option?


texts: What's a microcontroller "ordering code"?

texts:
I'm shopping for an ATtiny13A microcontroller for an Instructable, and I see lots of them offered online, but none are named just "ATtiny13A" — they're all things like:

ATtiny13A-PU
ATtiny13A-SU
ATtiny13A-MMU
...etc.

On the manufacturer's page these are listed as Ordering Codes: http://www.atmel.com/devices/ATTINY13A.aspx

Do I need something specific or are they all interchangable?


texts:
Our ADAS Controller is based on Renesas RH850/U2A16 Microcontrollers.  We are using Infineon TLE9255WSK Partial Network CAN Transceivers.  We are using Vector CANoe Professional.
When a CAN message is transmitted on CAN Channel 2 from our controller to Vector CANoe, there is Bit Stuffing Error.  Please see attached filename Bit_Stuffing_error_CAN_Trace.PNG.
Also, attached are files that show our Vector CANoe tool configuration.
We are using 120 Ohms termination resistor.
What might be the problem?  Is the problem in Vector CANoe Tool configuration?  Or is this problem in CAN Driver source code in our controller?[![Bit Stuffing Error CAN Trace[1]2


texts: What does a "sad face with a bow tie" represent?

texts:
Some trains in the Madrid metro network have small metal boxes with this sign on them:

There are no other signs on the box and some signs only have the "bow tie".

I'm guessing it's two Zener diodes head-to-head and some sort of switch, with a rather amusing arrangement.

Can someone explain what are the components represented and their purpose?

EDIT

Thanks to everyone for their comments.

More context: I've seen this on a CAF series 8400 train. The box is approximately 40cm by 30cm, and it's located on the inside of the train, just above the floor, embedded next to a door. Unfortunately the full photo doesn't show much more.

The bow tie: It looks like @Dejvid_no1's comment is spot on. The bow tie seems to closely match a screwed globe valve (source:  http://www.atperesources.com/PDF/Plumbing/plu_symbols.pdf). However, this doesn't explain the line going downward.

The sad face: After some googling, I think it could be a selector switch:

(image source: http://www.allaboutcircuits.com/vol_4/chpt_4/1.html#Selector%20switch)

Does this make any sense?


texts: Hand crank battery charging circuit build

texts:
I'm using a 12V dc motor as our generator for a hand crank power generation system. We've tested our motor without a load we thankfully can generate a maximum of 9V. Our project requires us to generate enough power to charge a phone for a 2min call.

We're almost done, but I'm somewhat struggling with the circuit. I'm using two LED's one to indicate we are charging the batteries when cranking the generator, and the other to indcate the batteries are discharging.

Our input mechanical power that we've calculated would be at least 3.5W(assuming low efficiency), we're using four NiMH rechargeable batteries that is 0.8Ah at 1.2V, they will be connected in series so that the voltage would be 4.8V acceptable for the phone charger. Here is our initial circuit schematic:

I'm assuming the input voltage from the generator when connected to the batteries as the load, has to be in the range or maximum of 4.8V.
The resistors will dissipate some power for the LEDs(20mA at 3V)
Using a blocking diode to block any reverse current.

My concern of this circuit is that when I crank the generator both LEDs will function, and the batteries are being charged, how can I change this so that only LED1 is functional and the batteries are being charged? And when we strop cranking the batteries will light up LED2 and power the load, and the motor I think, should we use switches? While charging/discharging?

Our load will be a phone battery, and we will use this charger to connect to it:

This is an introduction class project, it's quite simple. But while reviewing the circuit realized some mistakes...

EDIT : Final circuit, after help.

simulate this circuit – Schematic created using CircuitLab


texts:
I understand the basics of a diode, a diode allows current to flow in only one direction, but how? By blocking any opposing voltages source so that no current can flow in opposition?

And of course, a diode has its limit. If there is a voltage in opposition that is higher to what the diode can handle it allows current to flow in opposition.
What about the current that is allowed to flow through the diode is it reduced? For example: Current is supplied by a power supply it flows through a diode in forward direction, if the current was 10A before passing the diode will it still be 10A throughout the diode? If the opposing voltage existed does it reduce that 10A?

And how can I relate the forward bias to this?


texts:
I got my hands on a BK880 LCR meter and now it's the second time that I destroyed the device.

It can't hold the measurement voltage - So it always tries to measure with around 0V.

What I am doing is: connect the LCR meter to a pcb which as an analog and digital area. The digital area is powered with 12V and the analog area is measured with an ADC from the digital area. I connect the device to the input of the analog area, but except for the LCR meter I don't put any voltage in the analog area.

The analog area looks like this, where I connect the LCR Meter to FPB-PULSE and GND.

I connected the LCR meter to the PC and used at a while, the next day it was damaged.

What could I have done? I switched between the voltages the LCR meter is able to generate while being connected to the circuit, could this destroy the device?

It's the BK 880 device.

After a night loading and fiddling around with the device, I made the following observations:

The testvoltage of the device is not always working - but just not always. When I connect the device after powering it up and change some settings, the test voltage is ok.


texts:
I’m trying to modify the output of an old Motorola  phone charger which is rated 5V 500mA.  I want to modify it’s output to 1.2V 150mA to charge a small battery.

Can this be done?

I can’t open the charger because it is sealed.  Can it be done with resistors or diodes?


texts: how to switch to backup battery when power fail?

texts:
I have a project running with MCU supplied with a 24V power supply regulated via an SMPS to 9V
also, I have Li-ion battery pack 9V

how to connector these two sources to run the MCU with battery pack when the power failure occurs?

or

what is the best way to switch from battery to power supply and power supply to battery?


texts: The mathematics behind stability are crystal clear. I am very confused, however, as to how these measurements are taken in a real system. Specifically, say I have a power supply. How would one measure the power supply stability including gain margin and phase margin. I am interested in a controlled way, what kind of probes, etc.


texts: What is the relationship between Ground Potential Rise (GPR) and Source Voltage?

texts:
I am looking at the results for an earth grid study for a 50Hz substation.

Primary Voltage (Vp) = 11,000V
Secondary Voltage (Vs) = 415V
Secondary Fault Current (If)= 24kA
Secondary Grid Current (Ig)= 2.4kA
Ground Resistance (Rg) = 1.7 Ohm
Calculated Ground Potential Rise (GPR) = 4080V

I understand that GPR = Ig x Rg, but

What is the relationship between Vp/Vs and GPR?
If 4000+V is available at the earth grid, wouldn't current flow back up the faulted conductor to the source?

Is it related to different reference points?

Appreciate it anyone could help me get my head around this one?


texts: Calculate the capacitor voltage for t  0 for the circuit below

texts: Please help me calculate this. I tried using the thevenin equivalence method however I'm not familiar with two independent sources in a circuit. When I was simplifying using thevenin method the circuit when t < 0 I ended up with two voltage sources connected to the 3 ohm resistor and the capacitor so I wasn't sure...


texts: How can I make an XOR gate with basic components?

texts:
I am a very beginner in logic gates and electronic etc. I am trying to make an XOR gate only with the help of some basic components like transistors in the NI Multisim simulator. I have use AND and NOT gate circuits that I made and that were working alone but when I combine them all to make an XOR gate with those gate then it is not working at all. (My design is given below that I made in the simulator.)
Please help me fix this and increase  my basic understanding of all these topics.


texts:
I'm looking at this amp:
http://s.aliexpress.com/zY3miYNj

It states it requires:
- Supply voltage: double DC power supply +- 58~ +- 70V.

Rated output power: 500W (+- 65V power supply.

Any ideas?


texts:
I'm in a process of writing software for eZ 430 Chronos watch using TinyOS. I want it to be as low-power as it is possible.

Unfortunately, my measurements show power consumption of about 350uA @3.3V on a simple idle program which does nothing, but turn all sensors off, enable external oscillator and go into the LPM4 mode. This value is bigger than the two external sensors can eat.

The original Texas Instruments software (which I've read and found nothing I could forgot to set) consumes about 9uA when idle.

Are there any methods for debugging energy leaks? How should I proceed when checking my code (and TinyOS) didn't reveal any problem?

I measure power consumption using an oscilloscope and an amplifier similar to Dave Jones' uCurrent. I've tested this set on a set of resistors and got correct readings.

The schematics for eZ430 watch are here, on the page 79.


texts: Stripline reference plane discontinuity in reference design

texts:
According i.MX6 SMART DEVICE SYSTEM of freescale layout board, it uses 8 layers, my question is about the inner layers, they are striplines with a continuos GND plane in one side but in the other side they have a power layer that is broken A LOT of times (they make a lot of power islands), and some important signals cross those broken planes and that would mean a difference in Zo of the line, which mean reflections, so te integrity of the signal won't be optimal and  when we are talking about RAM data lines and other kind of sensitive lines that's a big problem, so that thats my question, i mean that's the reference design, but in my opinion is against all theory, can some one tell me if i'm wrong or gimme an awnser to orientate me in this matter please.

This is a screenshot of the internal layer 2 and the power plane that makes the stripline, there you can see the SoC and the RAM lines.

This is the stackup:


texts:
I have a circuit in LTSpice in which I want to measure some differential voltages, currently I'm manually adding the traces using the "Add Trace" menu in the plot view and writing its expressions.

I would like to know if there's a way to do this using a directive so that every time I run the simulations those traces are automatically added.


texts: Is there a way to add a tracking generator to a spectrum analyzer?

texts:
As the question suggest, is there a way to add an external tracking generator to a spectrum analyzer which doesnt have a tracking generator? Specifically speaking the HP 8564e spectrum analyzer without the stock tracking generator.

That analyzer seems to have a sweep output bnc connector in the back, which makes me believe that it can somehow control an external signal generator.

So is it possible? if so, which connections are necessary and which type of external generator is needed?


texts: Using potentiometer to measure distance in linear actuator

texts:
I need to use a linear actuator for a project. From what I understand, the position feedback comes from a potentiometer. Here is an example:

One more example: https://www.servocity.com/html/25_lbs__thrust_linear_actuator.html

Two questions:

1) How does one get the actual position via, say, a microcontroller? It looks like I need to measure resistance, I don't know how to do that on an Arduino.

2) Internally how is the linear position correlating to a potentiometer signal? Is a gear near the end of the gearbox turning a pot nob essentially?

Thank you.


texts: Alternator field winding VS equivalent inductor

texts:
I have a question which I know is going to be more opinion biased than factual. I know this isn't the purpose of the forum, but I would really appreciate some extra opinions so I'm going to ask it anyway.

*Note that I will be practically building this circuit eventually, not just designing the circuit on computer software, simulation etc.

As part of a project I want to design a basic voltage regulator circuit for a diesel genset (3 phase alternator). So basically I am controlling the field voltage, and current with electronics to vary the produced 3 phase voltages. Now I know there are numerous ways to do this.

I am trying to find a easier method to do some basic initial testing as the genset in not available yet. As a basic alternator field winding is simply a copper wound coil containing a series DC resistance and inductance, it would be more practical if I could use an equivalent inductor at a bench with similar values of a typical field winding, instead of starting/running a diesel genset.

Do you think there would be a big difference in operation between the alternator's field winding when rotating, compared with an equivalent valued stationary inductor?

Some issues I can think of, for example, is when the alternator is rotating, the field inductance will change as the air gap varies.

Or temperature increases inside the alternator when supplying 3 phase loads may affect field winding resistance.

Or armature magnetic flux interaction will affect field inductance.

But as the system will need to be closed loop, in theory these above issues shouldn't pose much of an issue for good microcontroller software. Testing can also be done safer with equipment at a bench.

What is your opinions? Thanks.

EDIT

The alternator will have to provide the supply for the field excitation when running after a battery has flashed the field winding initially. I am considering using thyristors for controlled rectification of the 3 phase voltages to create only the required DC field power depending on the generator's load. By modifying the firing angles, the rectified DC voltage can be varied and filtered.

If the field's power requirement is very low (don't know what the alternator specs are yet), I could create a varying DC link according to the load demands and use a power switch like MOSFET or IGBT with PWM, or a BJT to switch the DC voltage across the field, and let the field winding's natural inductance filter the current to something reasonably constant.

I will probably use a variac to step down mains voltage for initial testing.


texts: What would cause a buck-boost regulator to buzz loudly and generate high voltage ripple during certain input voltages?

texts:
I've got a buck-boost power supply design based on the LM5118 by TI. A schematic of the device is shown below:

(Link to TI Workbench)

EDIT Many of the comments mention the layout, hence I've included a screenshot of the top and bottom side of the board here. I've also included the schematic so that the component references match up.

Top side:

Bottom side:

Schematic:

NOTE: The schematic does use slightly different parts than what the TI Workbench suggests. These were calculated by following the process in the datasheet and using the Excel-based calculator TI mention in the datasheet. When this original setup didn't work, the components were replaced to match the ones suggested by the Workbench, but that still hasn't solved the issue.

What I've found is that with a load of 0.5A, between 10-16V input, the device emits a loud whining noise, which appears to be coming from the inductor. At the same time, the output voltage has a 1.5V pk-pk ripple at about 5kHz. Once the voltage is raised above approximately 16V, the noise stops and the power supply appears to be functioning correctly, with a clean 13.5V output.

I've scoped the gate signals for the transistors and noticed that when the power supply is generating that noise, the signals to the gate appear to be discontinuous. The controller will drive the gate at the switching frequency (approx 300kHz) for a period of time then there will be a gap, where the gate is just turned off for a period of time, then the switching resumes. I haven't measured the frequency of this overall behaviour - at a guess, I bet it's not going be too far off the 5kHz.

I had another power supply designed using the same chip that was initially designed for 28V output and worked perfectly fine. The feedback resistors were then modified to provide a 13.5V output and it continued to work fine across the entire voltage range. The only difference between that design and this one were the transistors (SQM120N10-3M8-GE3) and the diodes (MBRS3201T3G).

Any thoughts on what I could look for to help troubleshoot this?


texts: Static and dynamic behaviour of a sensor

texts:
On a slide, i read that i can model the static behaviour of a sensor as:

whereas it's dynamic behaviour as:

Is correct to say that the static behaviour is the steady-state behaviour, while the dynamic behaviour represents the transient?
Thanks


texts: What is the formula for the dependence between modulating input voltage - output current for two transistor constant current sink

texts: In a constant current sink from the two NPN transistors, load and sensing resistor, application of increasing voltage on the base of the transistor produces practically linear increase in output current. How to describe this relation (slope) between applied voltage and output current?


texts: Input impedance of input pin from Xilinx CoolRunner II CPLD

texts:
Is the effective resistance mentioned in the image the input resistance for the CPLD pins? I am using Vccio at 3.3 V.

(Image is from Xilinx CPLD IO guide application note).


texts: How can I switch a high-side transistor from logic referenced to ground?

texts:
Problem: I have a logic signal (represented by SW1), say from a microcontroller, that is either 0V or some low voltage, maybe 5V or 3.3V. I have a higher voltage supply (V1) and a switching device (M1) on the high side of that supply, connected to a load.

simulate this circuit – Schematic created using CircuitLab

Sometimes, there is an H-bridge, or half an H-bridge, and I need to control the high-side transistor(s) (M2), but I think basically it's the same problem:

simulate this circuit

The difficulty is that my logic output is only 0V or 5V, but I need higher voltages, like maybe 50V and 45V, to switch the high-side transistor. I understand that the precise voltages required will depend on the transistors I select -- I'm just wondering how to solve this problem, generally.

Is there a simple way to do this if my application is not very demanding? If I need to do the switching rapidly, say for a PWM application at 50kHz, is there a more complicated way to do it?


texts: Charging a capacitor parallel to a resistor

texts: This case is different to bog-standard capacitor-resistor circuits in that one resistor is also in parallel with the capacitor, which I'm unable to handle. How does that affect the charging of the capacitor over time?


texts: single op amp (NE5532) un-balanced to balanced

texts:
a long time ago I saw a cct using a single op amp (NE5532) to convert un-balanced to balanced lines, it had splt rails where its output pin was grounded and the rails became the output. i.e. because the output was grounded the rail pins shifted creating the balanced output. Anyone familiar with this design and where can I find it.

see attached

Thanks guys.


texts: Circuit analysis / understanding the control board for a heater

texts:
A very old heater unit at work broke down so we replaced one of its ~50 controller boards. All the boards are the same.

Just for the sake of practise electronics, I asked if I could take the board home and play with it. The 74LS00 was completely burned out, but the rest was intact so I was able to make a schematic out of it. See attached image.

What I want to do now is try to get a hunch of what each part / block / area of the schematic does.

There are five terminals on the board (1-5). 1 (top-left) = +12V input, 4 (top-right) = output, 5 (bottom-left) = ground. I do not know what signal 2 and 3 are other than the fact that the board is marked with a square wave beneath pin 2, and a sawtooth beneath pin 3. Obviously these are some kind of signals from the heater unit.

"Analysis" I've done so far:

I have not worked much with opamps before, but what I can see on U1:A is that it does not have any feedback loop, just two inputs. Therefore I surmise that this opamp is running in a comparator setup, although I have no clue what R9 and R7 does. Are these some kind of noise filters?

The two right-most NAND-gates is an R/S-latch, that I can see, so when pin 3 is high and the opamp is high, left-lower NAND gives a zero to R, and the opamp gives 1 to S. This must mean, I think, that for any other combination of opamp + pin 3 the R/S is reset. Opamp + pin 3 = set.

If U1:A is high it must also mean T1-base does not have any bias. I'm guessing this because R2-top = 12V and R3-bottom = 12V, meaning T1-base = 12V, meaning it's cut-off. T1 cut-off means TRIAC U3 is cut-off, so no output on pin 4.

This is what I've found so far, even if it doesn't give me even half the picture. I have no idea what U1:B does, but since Rmess = 15mohm my best guess is that Rmess is a shunt resistor. C1+R10, if that's an RC-filter, perhaps U1:B is measuring the current over Rmess?

LD1 and LD2 are obviously status indicators. R4+C2 RC-filter for T2, if R/S-latch is set then it's an error? If I understand correctly, this would mean, following my deduction above, that U1:A and pin 3 can not be high at the same time.

These are just fair guesses, but I'm really curious about the purpose of U1:B because of its negative feedback which I cannot figure out.

So, question: What does U1:B do here?


texts: 230V mains back up with 12V battery and inverter

texts:
I am looking to have a 12V battery back up if 230V is lost, to supply a mobile router for security cameras (solar charged battery powered) outside a house when vacant.
I have a 130Ah battery in a battery box and will buy a small inverter (small load for router.)
I'm wondering what I need to disconnect from mains supply and connect to inverter after a mains power loss.
Also, it would be ideal to have a system where the battery is trickle charged when mains supply is available.
What is required, in addition to the battery and inverter?


texts: Where can I find the IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines

texts:
I am looking at using the 74HCT4514PW  I want to ensure the footprint I am using is correct (I have screwed up in the past using a 0.4mm "TSSOP" footprint when I should have used a 0.65mm "TSSOP" footprint)

The mouser product page links to a datasheet but unfortunately it does not contain details of the package outlines, instead it references "IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines"

Where can I find this document, it does not appear to be obvious in a google search.


texts: How can I make a failing relay more reliable?

texts:
I have a non-accessible relay that I believe is failing and working intermittently. It doesn't need to actuate more than once or twice a week. It is activated with 12v and switches 12v 15amps.

If I were to increase the activating voltage to say 15, would that make it work more reliably or would it just damage it? My thought process being a higher voltage would generate a stronger magnetic field and work more reliably.

The relay is potted in and cannot be replaced, I would have to replace the entire device which is $2k+.  I realize even if this would work it would eventually fail, but if I can squeeze more time out of this device I will.


texts: Safety Standards for Low Voltage Systems

texts:
I am looking for safety standards which could be applied to the piece of equipment desribed below.

Basically the piece of equipment is a housing which inherits a 24V 100Wh Battery (2x SBS60) and a appropriate, off the shelf, Battery Charger. The used Battery Charger (ABC2430), has a standard AC power cord which in this case is cut to insert a mechnical switch aswell as a different connector which are both installed in the mentioned housing wall.

My question is, which safety standards could be relevant concerning the internal housing wiring of mains voltage carrying cables, insulation of mains voltage carrying parts inside the housing, earthing of the housing, distances to mains voltage carrying parts, etc. The housing can be opened without using a key or any tools.

So far i came up with EN60664, EN60335 and EN60950, but im not sure if i maybe missed one or there is something more suitable.

Edit: I am located in Austria but the equipment should be CE conform basically everywhere. The Box is used as a backup supply for radio communication equipment indoors as well as outdoors.


texts: Is this something a P.L.C. would be able to do?

texts:
I wish to replace the zener diodes with a programmable chip, so that I can program the chip to do exactly what the zener diodes do in this circuit. This will then make the circuit universal to all my applications, and all I would need to do is reprogram the chip to use it on an application that requires different voltage limitations. In this circuit (if you need to simulate it and play with the POT's and the push to make switch to understand it, do so) they are voltage limiters, limiting either the minimum voltage d2, or limiting the maximum voltage d1 & d6.

Please read this carefully before testing. POT's R1 & R2 are attached to the same wiper, so what happens to one must happen to the other. The switch SW1 is a push to break switch.

simulate this circuit – Schematic created using CircuitLab


texts: OpAmp for FOC current sensing on a BLDC/PMSM

texts:
How critical is this pull-up resistor to Vdd for current sensing in a Field Oriented Control of a BLDC or PMSM?

Right now, I don't have that pull up...I'm running the shunt resistor voltage straight into the non-inverting pin. Because of this, I'm only getting half-wave rectified current measurements...I'm wondering whether I really need those or not if using SVM modulation.  I should also mention that I think what I'm doing is wrong, since I'm unable to get a value for the unmeasured third phase, since for 120 degrees, there is no current flowing from the shunt-resistor phases to ground...So, that's obviously incorrect.

In fact, here's a picture of what my current waveforms look like over a full 360 degree cycle (I'm measuring phase A & B...I'm using KCL to infer phase C):

.  Notice that for the first and last 60 degrees, there is no current in either low side leg...So, leaning on KCL is hopeless and it looks like I'm doing a garbage measurement...

Does this help put 0A at mid-rail or something?

What's the purpose of this?  It's not like the current going through any of the legs ever goes below zero in the first place, like in an audio application.  Why bother pulling it up to Vdd?


texts: STM32 dev kit: Which power pin, APP or EMU?

texts:
I need a voltage source for an external peripheral on my STM32 dev kit. (Reference manual available here.) I see from looking at the extension pins that there are two types of power pins: APP and EMU. (E.g. EMU_3V3 page 22, APP_3V3 page 23.)

What does EMU and APP mean? What is the difference between the pins? Which one should I use to power an external temperature sensor?


texts: NMOS CS Amplifier PSpice Simulation Question

texts:
I have a rather peculiar question. I am attempting to recreate the circuit below (from one of my labs) of a Common-Source Amplifier design with a bypassed Source Resistance in PSpice. It has the following parameters:

R1 = R2 = 100k

Rd = 1k

Vsig = 100mV peak sinusoidal

f = 5kHz

So far so good. I have the circuit set up the same way as the figure. For my simulation profile, I just want to see the input and output waveforms for now. My question is:

What do I connect to the Coupling Capacitor at the Drain, where the figure shows Vout?

I tried connecting it to Ground and placing a Voltage Pin at the Capacitor which just gave me a 15V DC waveform. I am also told that I should not connect a Load Resistance across it. I'm pretty much stumped on what to connect there and where exactly I am measuring Vout across...

In all of my homeworks and textbook excercises, Vout has been taken across a load resistance connected between Drain and Ground (for a CS Amplifier with bypassed Rs).

Below is my PSpice Circuit and input/output waveforms after connecting a Load Resistance as suggested. For some reason I am seeing signal attenuation instead of amplification..


texts: What do decimal/alphanumeric suffixes after a slash mean in a schematic cross-reference?

texts:
I'm looking at a circuit diagram for the ChipWhisperer, which is a tool for power analysis and glitch attacks. You can grab the full circuit schematic as a PDF, but here's an excerpt:

What do those alphanumeric suffixes mean after the slash in the cross-reference names? Elsewhere in the diagram these signals are referred to by name, but the suffix is usually different despite it being the same signal.


texts: 5 volt power supply directly from 120 volt

texts:
I would like to use a microcontroller to drive a TRIAC (Z0103MA0,412). The TRIAC will be switching a 120 volt a/c resistive load. I would like to derive a 3 volt or 5 volt CD power supply directly from the a/c line. So, I would be very grateful if someone could give me a schematic (with explanation & calculation for this).
How would I connect the microcontroller to the TRIAC?


texts: Snubber diodes for a DC Motor with 2 relays

texts:
simulate this circuit – Schematic created using CircuitLab

Description:

RLY1 relay switches 12v on or off. RLY2 changes direction of current flow to the motor. I have flyback diodes on RLY1 & RLY2 coils. The relays are switched by an Arudino through a transistor switch. The relays are 12v, as is the motor. The motor draws about 1.5A in normal use.

The code ensures that RLY1 always turns off before RLY2 changes direction. Furthermore there is a 1 second pause between any RLY1 and RLY2 action.

Questions:

Where should the snubber diode go to protect RL1?
(Between 5 & 4 would flow current back into +12v which seems like a bad idea. Between 1 and 2 wouldn't work because when the motor is running in one of the two directions the diode would short. I have reviewed lots of diagrams and descriptions but can't get my head around the correct location. )
Am I correct that the objective is to use the diode voltage drop (.6v) to consume the inductive kickback as current cycles through a circuit containing the diode.
Is inductive kickback a risk to RLY2? I know it is to RLY1.


texts:
Can anyone explain to me the incremental equivalent circuit of this amplifier?

the solution is this :

I have some trouble understanding the resistor RB placement and also the Resistor R1 and R2.


texts:
I want to simulate a a white power LED from Cree in LTSpice. I searched for a LTSpice model and Cree provided one.
By simply putting in this model in LTSpice I get this characteristic.

I do not understand what I am doing wrong and why I don't get the characteristic from the datasheet like this


texts: Amp issue with buckboost plus usbc decoy setup

texts:
First I would like to say that I am a software developer with limited skills in electronics.
I am trying to build a setup to charge my electric longboard batteries from an usbc power delivery input. I have an usbc decoy connected to a buckboost module, which enables me to set to output voltage and amperage.
Now, my target is to have 28.6v and around 1.2a as an output.
The problem is that I can't seem to be able to set the current. From what I understand it needs to be under load to be set, but when I connect the battery the buckboost restarts, I presume some protection kicks in. So I can never see the current of the setup... I just blindly turn the amp knob with no feedback.
I checked the polarity for my setup compared with the originAl charger (see pictures) and seems to be the same.
Any suggestion is highly appreciated!
Thanks for reading.


texts: How can I mechanically secure a headphone cable after soldering on a new connector?

texts:
My headphone (Sennheiser HD 265) has a socketed connection between cable and headphone. The headphone cable had come loose, so I bought a new connector and soldered the headphone cable to it.

The connector looks like this:

Now, the soldering worked fine. However, I don't know how to mechanically secure the cable to the connector. I initially tried just soldering it and letting it leave the connector via the small plastic "tube" (strain relief) on the left side, but it turned out that the cable will be pulled and, worse, twisted when the headphone is in use, which causes it to come loose.

How can I secure the cable against pulling/twisting?

I tried:

squeezing the "tube" part of the connector so it holds the cable
putting sticky tape across cable and connector

but that was not sufficient.


texts: How I can simply measure interwinding capacitance in a transformer with electrostatic shield

texts:
I want to measure which is the effect of the connection of the electrostatic shield (between primary and secondary) to ground (or to neutral) in reducing the interwinding capacitance in my transformer.

How I can simply measure with a multimeter or a LCR the new reduced capacitance between primary and secondary (or the delta interwinding capacitance by using a floating shield or a "grounded" shield)?


texts:
I'm currently designing an equivalent of the mass-spring-dashpot system, and during the design phase I realized I don't fully understand how PID controllers physically work.

Below is an image, the top half of which is the physical setup. There's a mass hooked up to a spring and dashpot. There is some magical position sensor that outputs the position of the mass (ignore how it does this), and there is a motor attached to the mass so we can apply a force to it. The position sensor feeds into a computer, and the computer controls what force the motor produces.

The bottom half is what I imagine the control loop looks like. We have some set point for the mass, and the offset (error) is fed into the PID controller, which outputs a current which is fed to the motor, which outputs a force which acts on the mass, which thus changes the position.

My question is that the input to the PID controller is a position (namely x_set - x_actual), but its output is mysteriously a current. How is this possible? The PID controller computes integrals and derivatives of position, which in no way is relevant to amperage.

Am I missing a component in my control loop - is there something in between the controller and the motor? Or perhaps between the sum block and the controller?

Any help is greatly appreciated. ^^


texts:
I want to build an optical position tracking system based on PSDs (Position-sensitive detectors). I searched online and found this PSD which has a sensitive area of 12 mm*12 mm. My goal is to allow a servo position tracking up to 30 cm or so.

I computed a Matlab model based on some equations I found online and realized that a light source of 1 degree FWHM would produce a beam diameter of nearly 9 mm at an axial distance of 30 cm:

This is not acceptable for my application as the PSD allow for 1 mm detectability which is perfect for my needs.

The best light source I found is this one. It has a reasonable package (TO can) compare to other products that do have a narrower beam width but are not as convenient.

Is there a way to decrease the beam divergence by adding some kind of beam expender on a TO can laser diode? Or is there a type of light source that have the same form-factor as this one but with better divergence?


texts: LTspice XVII solving Thevenin Resistance basics

texts: Thevenin voltage is a snap, but how do I get R Thevenin?


texts:
I'm trying to build what is basically an electronic push button switch - something that would switch an led on an off with the same signal . I figured doing this would require a falling edge detector , thus , I designed this

The idea behind this is that I extend the signal using the capacitor and then AND it with NOT of the signal so only a small portion of the end of the signal remains .

Something is wrong with this and I'm not able to figure out what . I don't think it's the wiring .

Also , is there any better way to make an 'electronic push button switch' ? preferably without complex ICs ?

EDIT : The power source in the end is supposed to be the other way around ;
this is what i'm trying


texts: TPS2559 TI, current switch for circuit protection

texts:
I'm researching a current limit switch but I am a bit confused. I need an IC that works as a current switch. I have a battery with charging and protection at one end, and buck boost on the another. Current must not go above 5A. Is it possible, with the TPS2559, to control just that.  Constant voltage up until 5 amps are exceded? and after that constant current?

My goal is to protect the BQ24075T I have for charging the battery.

The battery max discharge current is 5.2A. Combined fully chargeg battery and USB can deliver way over 5 A.

Datasheet:

http://www.ti.com/lit/ds/symlink/tps2559.pdf
http://www.ti.com/lit/ds/symlink/bq24075t.pdf

Block schematic:

Thanks


texts: Problem in simple LED Blinker Circuit using PIC16F877A

texts:
After a lot of trials & errors I was able to come up with a circuit to blink an LED using a PIC16F877A microcontroller.

Components I use are,

PIC16F877A
LM7805
20MHz Crystal Oscillator
IN4007 Diode
300R Resistor
10k Resistor
22 Ceramic Capacitor
104 Ceramic Capacitor
224 Ceramic Capacitor

My question is, whether this circuit is good enough for learning purposes, or does it has any serious issues with it. These are my concerns,

While programming, S1 switch is put to position 1. After programming, it is put to position 3. Is it the wrong approach? I actually change the position of the jumper wire (No sliding switch).
Also, after programming, I have to remove all the PICkit3
connections otherwise the LM7805 becomes hot.
Further, when I run after programming & removing the PICkit wires, I
get a slight shock when touching the metal silver head of LM7805.


texts:
I have connected a PCA9865 to an esp32. The signal pins are connected to multiple ULN2003 Darlington transistor which drives several water pumps. I'm using the Adafruit PWMServo library  and running the gpiotest example which simply supposed to turn on all the channels one by one. When I run the code, the water pumps turn on appropriately but after a couple of minutes, its goes crazy and all channels turn on at the same time and remain that way till a power reset is done.
I have tried changing the PCA9685 module, but the problem persists. I have also connected my ULN2003 board to the GPIO of the ESP32 directly, and it works indicating there is no problem with the ULN2003 board.
Any help is much appreciated. Thank you in advanced.


texts: Confused on How to Determine Block Size of a Cache

texts: I have some confusion on determining the block size of a cache. I read that to get the block size, you do 2^(block offset bits). However, if you're given a block offset and a byte offset, do you combine the total offset or just use those block offset bits?


texts: A capacitor and a neon lamp focused circuit problem

texts:
Here is the problem I am stuck on.

The lamp starts out as an open circuit. Then capacitor charges up and eventually the voltage \$v\$ across the lamp raises. When the voltage across the lamp exceeds a “striking voltage threshold \$V_u\approx77\,\text{V}\$” the “gas ionizes and becomes a conductor with a resistance of about \$R_B\approx10\,\text{kΩ}\$.” The current through the lamp is larger than the current through the resistor from the battery, so the voltage on the capacitor decreases and so does the voltage of the lamp. As soon as the voltage across the lamp decreases to a value below the “sustaining threshold \$V_D\approx35\,\text{V}\$” the gas loses its ionization and the lamp “turns off” and becomes an open circuit again. The “voltage of the battery is \$V_S=92\,\text{V}\$.

So after the initial transient from  0 V the voltage across the capacitor oscillates between the two thresholds and the lamp flashes.

Here is the graph of how the system oscillates:

So, you are given:

\$R=1.5\,\text{MΩ}\$
\$C=1.0\,\text{μF}\$
striking voltage threshold \$V_u\approx 77\,\text{V}\$
ionized gas resistance \$R_B\approx 10 \,\text{kΩ}\$
sustaining threshold \$V_D\approx 35\,\text{V}\$
voltage of the battery \$V_S=92 \,\text{V}\$.

And asked to find:

  How much time, in seconds, does it take for the capacitor
  to charge from the sustaining threshold to the striking threshold
  How much time, in seconds, does it take for the capacitor to
  discharge from the striking threshold to the sustaining threshold?
  What is the duty cycle of the lamp? (The duty cycle is the ratio of
  the time it is lit to the total time.)

There are also the answers to this problem (see below) but mine differ from them and here is what I don't understand:

Why is there even a \$V_D\$ term in the \$t_1\$ equation? I tried applying a node method and then solving differential equation for t but got different answer.
Same question as the first one.
Why isn't lamp's duty cycle expressed as \$t_2-t_1/t_2\$?  The time the lamp is lit is \$t_2-t_1\$ isn't it?


texts: Error: Multiple analyses requested in LTSpice

texts:
I am running the following simulation in LT spice but I am getting the following error:
Multiple analyses requested
.trans 0 100m 90m 1m
.op

Here is my circuit.
Any help would be appreciated.


texts: How to automatically disconnect when mains voltage is on connection?

texts:
I have this very specific problem and can't think of a simple solution for it, maybe some of you have an idea how to tackle my problem.

So basically what I want to do is have 2 mains connectors, each with a little box containing a µController and some hardware inside. The first box is more or less complete, it contains a 230V~/5+3.3V converter, an ESP for web based energy logging and some parts that go along it. On the other side I don't have much room for components, but I basically want some circuitry that contains an ID the ESP has to check and transmit to the server. The problem now is that I would have to communicate over the powerlines. I'm planning on using the 1-wire interface, essentially needing 2 wires, which I have. That way I wouldn't have to put anything in the second plug except for the 1-wire EEPROM.

When I plug one plug into the other, there is no 230V~, they can freely communicate over the power lines. Then the ESP schould turn on the 230V.
My problem now is, how do I protect the 1-wire part and the ESP from the 230V once activated?

Here's a little schematic to show what I discribed:

simulate this circuit – Schematic created using CircuitLab

The red box is where I would have to add this protection, some way to disconnect the 1-Wire Data and GND line from the AC line.

Biggest problem: The circuit in plug 1 is fixed and I dont exactly know how they build it, but I can only design the circuit inside plug 2!
The PCB in plug 2 can't be bigger as 4x5cm as well..

Does anyone have an idea how to manage this?

EDIT:

I just thought of a switching relay..

simulate this circuit

The relay would switch as soon as a voltage bigger than  whatever I communicate at (probably 10 or 12V) is applied, disconnecting the IC with one pin from mains, which should be enough as only one potential is attached now. But the circuit would probably just fry my IC before the switch is made so that wont help..


texts: how do i create this pulse using the HP 8112A

texts: how do I generate this pulse using the HP 8112A


texts:
I would really appreciate if someone would share his insights on whether an isolated DC/DC converter of a fixed output (12V) can sustain that output even when input is lower than 12V, the datasheet says the input range 9-36 VDC which may be the answer but i would really like to get a confirmation if possible.

Also a side question, this datasheet does not indicate any input or output filters or recommended capacitors for optimal operation except a 10F MLCC at the output , any recommendations on this ? my thought was to throw a few bulk capacitors at the input/output and call it a day.

DC/DC Converter

Datasheet


texts:
Is the following a correct understanding of an NPN transistor?

Basically, a positive voltage source needs to flow through the Base of an NPN transistor and out through the Emitter, so it needs to flow in (via the base) from a more positive source than it flows out (via the emitter).

Is this a correct understanding of what makes a transistor turns on? Is there anything else that might be added to it, such as how much current/voltage is required to turn the transistor 'on' or if there's a minimum voltage/transistor that needs to flow from the through the Base to the Collector for it to 'continue' to flow through.


texts: Can we use nodal analysis without any information about the current

texts:
I learned today Mesh Analysis and Nodal Analysis principe (with KVL and KCL) for a computer project and I am not certain about one thing.

Can we use nodal analysis with only the voltage of the source and resistances of components in the circuit to know all current information at any point of the circuit? And if it's impossible like I think currently, it's correct that I need to use the Loop current Analysis (who is a general Mesh Analysis if I understand correctly) to solve all circuits, planar and non-planar?


texts:
Is this correct magnetic equivalent circuit for this electromagnet system ?

simulate this circuit – Schematic created using CircuitLab

And i am trying to solve it like this example, what should i use as length (l) ?


texts: How to handle these inverted duplexed serial protocol in Arduino?

texts:
I have a device that communicates with an inverted duplexed serial protocol like the following:

I need to communicate with this device with Arduino.
I tried to send

simply UART serial text to channel 1
its inverted signal to channel 0
But failed because, on channel 1, I need to send a tiny signal at start and end.

How can I achieve these protocols with Arduino?
Or is there a standardized named protocol?


texts: Power a 5.5 V/1.8 V microcontroller from a lithium polymer battery: 12 V + LDO = 3.3 V, or just pull from one cell?

texts:
I'm trying to power an ATtiny44 (1.8 V/5.5 V) from the balance port of an RC 2s/3s lithium polymer battery.

The circuit will use very little current, sleeping 29 secs/1 µA?, wake 1 secs/10 mA. The circuit is a Lost Model Alarm, so after 10 minutes, it will blink/beep, and then sleep for 30 secs, then repeat, ideally, for as long as possible (> 3.3 V/cell).

In terms of longest operation (not dropping below 3.3 V on each cell), is it better to power the circuit from an LDO regulator using all available cells (3.3 V/8.4 V/12.6 V), or directly from one cell, and no LDO regulator at all?

I realize that powering from one cell will make the lithium polymer battery unbalanced, but not damage it if the cell remains above 3.3 V.

I guess it will depend on the efficiency of the LDO regulator, but I'm not sure how to work the numbers out. To me, using all cells means the longest runtime, but I'm not sure about dropping from 12 V to 1.8 V/5 V and the loss.

References:

LDO regulator: HT7333
ATtiny44a


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I have a comparator circuit and I need to find the mean value of the output square wave. I have calculated it like this:

\$Vmean=1/T*integral(U*dt)\$ from 0 to T and I got \$Vmean=-0.7896V\$

Can someone please check if that is correct?


texts: Oscilloscope bandwidth and PWM pulse width

texts:
I've been working on a project which involves a PWM signal that operates at 30khz with a 10 bit resolution. I am generating the signal with a Teensy 4.0, which has a 600mhz processor, well above the ~31mhz required to generate the PWM frequency and resolution I need. I was measuring this signal with my oscilloscope, just to verify that everything was working, and I noticed that as soon as the PWM pulse width drops below 200ns, I stop seeing well-formed pulses. 200ns corresponds to ~5mhz, and my scope has a 100mhz bandwidth, so my sense is that is should be able to display the minimum pulse width of a 30mhz signal. Am I wrong about this, or is it possible that something else is affecting the my ability to either emit or measure pulse widths below 200ns (as far as I can tell—the actual point where it stops providing clear measurements might be lower). I checked my probe and it was set to 10x, as was the oscilloscope, so I don't think that's a factor.

Here's a 300ns pulse. I was actually able to measure a 200ns pulse by increasing the PWM frequency to 48khz (sorry about my fingers, but you can see the important bits)

This is the minimum pulse width, which should be about 32ns


texts: Using oscilloscope to measure voltage across a resistor

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I have a board which is powered by a 5V PSU. I needed to measure the current flowing into the processor for computing power. Since there was no resistor that I could find in the path from the supply to the processor, I found an inductor on the path to the processor from the supply and measured the voltage drop across the inductor(ignoring the inductance and only considering the resistance of the inductor) with a multimeter. Now since the power consumption can vary across a program's duration I wanted to measure this using an oscilloscope.

For this I connected the probe and the ground across the inductor (L18 inductor in the schematic given below) and measured the voltage. Though the idle voltage did not match the multimeter readings, the dynamic change in voltage when a program runs on the processor matched the value given by the multimeter.

But I later read in many posts that the correct way to measure the voltage across a resistor is to use two probes and the math function or use a differential probe.
Later I used a differential probe to measure the voltage drop and here also I found that the idle value differs from the multimeter but the dynamic change matches the multimeter readings.

What errors are there in the measurement I made by connecting the oscilloscope probe and ground across the inductor?
Why didn't this cause a short and cause all the current from the voltage supply to go to the ground of the oscilloscope?
Why did the dynamic change in voltage match the multimeter readings?
Why are the idle voltage values different when measured by the oscilloscope (when using differential or passive probes) and the multimeter?

I was using a Tektronix MS04104 Mixed Signal Oscilloscope and the board was a pandaboard.


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I would like to ask why the switching component of this circuit (Q1 with the condenser electret mic) works? From what I understand, the mic has to be supplied a voltage for it to operate.  Hence, there is a DC voltage across it whether it receives a sound or not.  When it is connected that way, wouldn't it always turn Q1 on - thereby triggering a high on the 555 - regardless of the mic detecting a sound? However, I saw the demonstration video and it works as it should - clap on and clap off to toggle the LED D1 (of course having a time in between the claps).

Here's a link to the video: https://www.youtube.com/watch?v=xVAMNR_zIQE

Note: The circuit and the video aren't mine.  It is from circuit digest.


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I'm looking for a good schematic capture checklist to use when reviewing schematics.  This is for the usual issues such as check that you don't have similar but different nets (e.g. GND and GROUND) that are separate and style/readability issues (e.g. no 4-way ties).  Either your list or a link to an external one would help.

For what it's worth, I'm using DX Designer, so if you have specific checks you run, let me know about that too.


texts: Basic equipment for getting started in digital electronics/microprocessors

texts: What equipment would you recommend for getting started with micro controllers. I guess I need a programmer, but what else do I need? What are the essential tools for debugging?


texts: Simple switching between clocks using oscillator disable pins

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I am working on a circuit where I need to use different clock sources. I am using two HCMOS oscillators. Both oscillators have an disable pin. When disabled, the clock output buffer is placed in tri-state.

Can I safely connect both lock outputs with each other and use the disable pins so that only one oscillator is enabled at a time? The following image shows what I mean.

NOTE: Glitch-free switching between clock signals in not required.


texts: How on earth shall I design the ground planes for mixed signal circuits, split or not?

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Our circuit is like following:

There are four layers, including top, power, ground and bottom.
My way of grounding:
I follow the instruction by Maxim: https://www.maximintegrated.com/en/app-notes/index.mvp/id/5450
As it introduces, there is no need for a cut in ground plane. Since the return currents from analog circuits will not overlap with the return currents of digital circuits. And the high frequency currents will be absorbed by the small capacitors.
However, we recently hired a very professional consultant company to help us design a newer version. They design in a different way.
The consultant way
They cut the ground plane into two: analog and digital. And connect the two planes with 0 Ohm resistors when necessary. They are very professional, so I start to think in their ways.
What I think their way could be good: Without cutting, the digital return currents still have the chance going into the analog ground.
What I think may be bad: There could be several connections between the analog ground and digital ground. There would be ground loops and become antenna.
Could I have comments here?