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Questions tagged [time]

Time cannot be created, but it can be measured by using common references. The oscillation of the cesium atom, or a pulsar, can be used in our lifespan, but neither one is steady forever. We can create 'instances' of time with tuning forks and electronic oscillators. By creating them we define them in terms of 'increments' of time. Those deemed to be laboratory grade become our reference devices for measuring time and frequency, the reciprocal of time.

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High precision timekeeping

Hey I'm looking for suggestions for implementing a very high precision timekeeping device. I need to record independent signals in multiple devices and then time match them to an accuracy of about ...
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20 views

Phototransistor and Photodiodes capacitances when some in an array sense light

I'm using phototransistors to sense low speed data (about 7 bits a second). With one phototransistor and a 300K resistor, I found my sweet spot and can transmit correct data with lazer. I find if the ...
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74 views

Detecting IR sensor at higher speed

I made a circuit which selects one of 4 sensors and determines if a valid data stream is present on that sensor and counts the number of times data is valid. I narrowed my problems to hardware. In ...
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STM32F4xx, How to use RTC correctly?

I'm trying to run RTC, but there are two problems. 1) It is impossible to write the security key in the WPR register. 2) It is impossible to set the time and date in the TR and DR registers. I tried ...
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36 views

Finding the time constant of an RL circuit

I've the following circuit: simulate this circuit – Schematic created using CircuitLab And I've to find the time-constant of the voltage across the inductor. I did the following: The voltage ...
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909 views

Discharge time of 12 V 8.4 Ah at 5 mA

I have a motorcycle battery rated as 8.4 Ah (20 HR). It also says 8 Ah (10 HR) and I am not sure what the difference is. Anyway, I have a GPS tracker fitted with a rated ...
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81 views

z-Transform Methods: Definition vs. Rectangular Rule or Tustin's Rule

The definition of the z-transform is defined as \$z = e^{sT}\$ where "s" is complex frequency for continuous-time systems and "T" is the sample period. Why are rules such as the forward rectangular ...
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74 views

how to calculate the tpdhl / tpdlh for any given circuit

i am struggling on calculating the tpdhl / tplh i dont know how to calculate is there any algorethim for the way we calculate the time propagation high to low etc.. several questions asking to take ...
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40 views

Byte-Banging 2 8051's using port addresses

Currently I have two microcontrollers setup in which entire ports are connected to each other (P1.1 connected to P1.1, P1.2 connected to P1.2, etc). I also have two pairs of extra GPIO pins connected ...
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122 views

“Leeching” clock information from cell towers

I understand that cell base stations transmit very accurate time signals among other things. Do you need a SIM card and an account to receive this information, or is it something you can "leech" with ...
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40 views

Programmatically determine the lowest waiting time for character LCD display

I made working code in an older microcontroller for a character based LCD that's based on the HD44780 chip. My code stops execution of everything else every 70uS to display one character from the ...
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183 views

RL circuit: How to determine the equivalent resistance of the circuit?

So I'm working on an RL circuit and the solution is stated to be that R1 and R3 are in series, but I didn't think that was the case because they don't have the same current through them. Given ...
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107 views

Activating a circuit based on change of resistance

I am looking to use a sensor, such as photoresistor, to activate a circuit only when there is a significant change in the input. Such as when the light incident on the photoresistor changes ...
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324 views

Are Civilian GPS signals cryptographically signed?

As far as I understand, receiving enough GPS signals at the same time enables to deduce the position and the time. So I guess it is possible to use an offline receiver as a very precise clock? If so,...
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122 views

How is rise/fall time definition

I understand that rise/fall time are related to RC charging/discharging waveforms. What I don't understand is how is the 0% and 100% points chosen? Do they have to be defined beforehand for a signal?...
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608 views

NPN transistor slow to turn off even when operated outside of saturation region

I am currently studying how transistors react and behave to simple signals. I have the following circuit: A square wave of approximately 83kHz is applied. The transistor used is a 2N5551. The ...
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83 views

Does the Epson RX8900 real time clock count the year “00” as a leap year?

The datasheets ambiguously say... A leap year is set whenever the year value is a multiple of four (such as 04, 08, 12, 88, 92, or 96). Is zero a multiple of four? This is more of a philosophical ...
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103 views

IEEE 1588 PTP phase and time synchronization

Why everywhere is said that PTP synchronize phase and time together? phase and time are totally separate concepts. does it mean after using PTP rising edge of slave and master clocks happen ...
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361 views

Voltage time graph integration

In a Voltage time graph , at constant current I= 170 amps, voltage=0 to 5,5 and time= 0 to 97 sec and voltage decreases from 5,5 at 0sec to 1,16 at 97 sec, now how can I find the total power ...
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293 views

Change a quartz clock timebase by changing the frequency of the quartz crystal oscillator?

I've been doing some research on rewiring clock circuits for a project, but I'm new to these types of pulse-counting circuits. My question at this point is: If I replace the existing quartz crystal ...
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2answers
124 views

PIC period measurement sometimes 1 overflow count wrong

Short info: I'm using a PIC18F4580 to measure the period time of two positive pulses using the CCP 1 on the MCU. And then writing the result to an LCD. When testing I sometimes get a result thats one ...
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53 views

Confusion about power in an RC circuit

Funny this is my third question in a row about RC circuits, but I wanted to figure out some stuff I'd been wondering for a while. What I was confused about the power while charging. Like say that ...
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92 views

Is it possible to speed up Battery simulations with power converters in Simulink?

I am facing a huge problem with real-time analysis of a PCS simulation. I want to simulate a power converter system, which can be used as a power converter. I have to do an accelerated simulation with ...
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Can someone please help me with this pipelining question

A pipelined implementation of the circuit shown below is to be designed. The delays of the building blocks are indicated inside circles. You are given buffers with a delay of 0.5 ns, and flip-flops ...
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234 views

Calculating R and C for schmitt trigger debouncer

I've been looking all over the internet to try to figure out the optimal values for R1, R2, and C but couldn't find info. I'm trying to ideally make a debouncer that will work with any button on the ...
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66 views

RC time constant in circuit with two caps with different potential

I'm trying to develop a model for the switching speed of a MOSFET. In reducing the equivalent diagram I have come up with this circuit with a resistor and two capacitors in parallel. The catch is ...
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2answers
50 views

Interpreting results when IC temperature fits all categories

I have recently downloaded a datasheet for one of the chips I am using in my project, the familiar 74HC164 shift register. The datsheet URL is here: https://assets.nexperia.com/documents/data-sheet/...
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1answer
117 views

DS1307 : Long term effects, time gets corrupted

I have designed a PCB which has ATMega328P and one DS1307, along with other sensors on the I2C line. The design is as follows : Y2 is 32.768KHz crystal, and BT1 is a standard 2032 3v3 coin cell. I ...
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48 views

Approximating dynamics in continuous-time with discrete-time

I'm not sure if this is the best place to ask this question, so please direct me to the appropriate community if this question seems out of place here. I am working on a project in which I'm trying ...
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3answers
163 views

Is a 0.01s time base really useful in a frequency counter?

I am currently designing a frequency counter based on the PIC16F628A. It is working as expected but I would like to add some useful features. According to the images found by googling, I noticed that ...
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2answers
649 views

How create a high precision clock in an FPGA?

FPGAs can easily run at 100 to 500 MHz and create time resolutions of 10 to 2 ns. That frequency can be used to create timestamp counters, which are in turn used to create very fine grained time ...
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65 views

Oscilloscope Trace Appear Delayed

I saw a thing on my GDS-1052-U oscilloscope: if I set the time base to 25mS/div there appear a delay of the signal on the screen. So, when I rotate the knob for the time base to 25mS/div, there is a ...
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118 views

Absolute minimum delay required to process data across shift registers

In an effort to make my serial data processing faster, I attempted to use serial mode 0 with a system clock speed of about 3.686Mhz. Its clock comes from the ALE output of an unprogrammed at89S52 that ...
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1answer
443 views

How to use TIMER 2 as simple counter in STM8S103F3?

I am new to STM8S and not yet that good at microcontroller programming in general. I am trying to learn about timers/counters in microcontrollers. I wrote following code to toggle an LED in each ...
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3answers
598 views

Making a radio-controlled clock work from a local time signal

Is it possible to modify radio-controlled clocks (so-called "atomic" clocks, like https://www.amazon.co.uk/Wall-Clocks-Radio-Controlled/s?ie=UTF8&page=1&rh=n%3A376322011%...
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501 views

Calculating Slew Rate from a time-constant

I have to choose an OP-AMP mainly based on slew rate. I am using the op-amp as a differential comparator with dynamic (time) hysteresis with a time-constant 3*tau=500µs. My upper threshold of the ...
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117 views

Mistake in calculating the last time of battery (Ampere hour problem)

I've a question about the mAh rating of batteries. At the Dutch Wiki page of Ampère-uur which is the Dutch word for Ampere hour, they say for example a \$100\$ Ah battery can supply 5 A for 20 hours ...
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101 views

What's the difference between measurement resolution and digits per second in time measuring devices

In time/frequency counters/analyzers in technical specifications you can almost always find resolution and digits per second values next to each other. What is the difference?
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Are there any transparent photoconductors? [closed]

Are there any transparent photoconductors? If so, can I know the timeframes of some examples of them where they reach full conductivity? I need one that reaches full(or approximately full) ...
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378 views

Extracting phase-shift and gain from a time series information

I have many files consisting input and output voltage signals for a linear filter circuit. For each file the input and output signal is at different constant frequency. All sampled for 2 sec duration ...
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1answer
160 views

Is there any real-time task set which includes WCET on both CPU and FPGA for every task?

As it has been proven, every task (application) we can run on a CPU we can also run on an FPGA (even if that is just by building a soft CPU). In addition, there is not any rule (or relationship) ...
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51 views

Form differential equation pair from discrete time system block diagram

I have a discrete time system block diagram. And my question is what is the output y(k) I managed to get what is V(k) $$V(k)=\frac{1}{2}*V(k-1) +U(k) $$ But now i can't form y(k) because ...
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79 views

How to test if a discrete system is causal or non-causual?

I know like this might seem like a trivial question but I am a bit confused with it. Take for example the the system y=x(n-10). Initially I thought this system was noncausal because n-10 means that ...
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1answer
149 views

My RC Time Const. Calculations are wrong. Circuit changes my input signal

I have a simple RC circuit of 22 ohms and 3.3uF My measured values put the resistor at 22.10 ohms and the cap at 3.15 which gives me a time constant of 68.5 uS The signal applied is a 100Hz Square ...
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265 views

Safety of current with duration [duplicate]

My question is about how dangerous a momentary amount of current is vs the duration. Like is there a reasonably consistent relationship between current duration through the body and relative danger? ...
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1answer
44 views

adjustable time delay, random output

I am looking to build a circuit that would control an output relay. This would be done in 12V and the sequence will be initiated by a manual switch. I will need an adjustable time delay (possibly ...
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2answers
237 views

Charge time capacitor in a BJT collector with a parallel resistor

Hello, Given that circuit that has a constant current(let's say 3mA), How do I determine the charge time of that capacitor? since in t=0 the capacitor would have all the current but later it will ...
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874 views

Capacitor with Current Source in parallel with a resistor

[![enter image description here][1]][1] I know that in a current source in series with just a capacitor (without the parallel resistor), it would charge until forever in an ideal case with the fomrula ...
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1answer
7k views

STM32F20x ADC sampling time/rate

I need to calculate the exact sampling time or sampling rate for my setup on a STM32F205. I have the ADC setup as follow: ...
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1answer
62 views

Use 555 timer to output same interval as user presses a button

I was curious if such a circuit already exists tentatively using 555 timer chip (I know I can do this with a micro controller so please don't suggest that). Basically I need following functionality: - ...