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.
Questions tagged [time]
207 questions
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What does the "proportional symbol" (∝) mean when used as a time unit prefix?
In several datasheets for electronic components, I have seen a ∝ symbol used as a prefix for a time unit, usually seconds, writing as ∝s. As far as I know ∝ is not a valid SI prefix, so what does it mean? What unit is ∝s?
Comparing different…
Pep
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Very accurate time measurement
I'm going to measure very short times as accurately as possible. The device will get first one pulse and within 150 microseconds six more, each on their own wires. The time between first signal and each of the six other signals must be measured as…
Kestis
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Cheapest way to synchronise date and time for standalone system?
If you have a device connected to a network, the answer is obvious - use NTP.
If you don't have a network connection, I can think of 3 ways to get the current date and time:
Radio signal, i.e. WWV or WWVH in the US.
GPS.
Cell phone signal.
I don't…
Mark Ransom
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What do I need to close an electrical circuit for a certain amount of time
I need something that closes an electrical circuit for a certain amount of time when it receives an electrical pulse.
In my case, two wires touch, even for a second, the device I need will supply power for 30 seconds to another device.
Someonation
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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 resistor values were carefully chosen to try to avoid…
Kevin
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Why wavelength is not measured with a unit of time?
While learning Fourier transforms, I have this little doubt about wavelength.
Why is that wavelength for a sine wave, or any other wave, is measured with a unit of distance?
If it travels w.r.t. time, why is it not measured as a unit of time?
I…
Zaid Khan
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Is there any real time clock (RTC) which provides time resolution in microseconds?
I've been searching for high precision RTCs on Google but almost all RTCs like DS12C887, DS1307 provide time resolution in seconds which is ok for general use. Are there any RTC ICs which can provide finer resolution like in milliseconds and…
Osaid
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9
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Measuring the activation time of a solenoid
I'm trying to measure the activation time of a pull-type solenoid.
When the solenoid doesn't have a load connected to it, you can measure its activation time through the current it consumes.
At first, the solenoid will consume current until the…
Florian Humblot
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Is my phone battery better / more capacitative than my laptop battery?
When we go out and look for phones, the first thing I do I always look at the battery capacity, usually 2000 mAh, 3000, up to 10000 mAh for a (external?) battery.
Looking at laptop batteries, they are much much larger and have only afraction of…
Gizmo
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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.
I guess it is possible to use an offline receiver as a very precise clock.
If so, is it possible to flood this offline receiver with…
Akita
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Time of flight difference in hardware
I have an ultrasonic emitter, and two ultrasonic receivers. When the emitter emits a pulse, the receivers get the signal at different times. I am only interested in the difference between the two reception times.
At first, I was thinking of using a…
Randomblue
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How does GPS calculate time
How can a GPS device give exact timing even when the number of available satellites are zero?
I'm monitoring GPS data using VisualGPS.
Anubis
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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 consumption of 5 mA. According to this formula I have to divide battery…
daviddgz
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"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 a GSM/CDMA module without establishing a…
iter
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Bipolar stepper motor: What should the sequence timing be?
What I mean is, how long should a coil be energized before it's de-energized. Also how long should the coil stay de-energized before I power it in the reverse direction. Where can I find this timing information for stepper motors. I've been having…
user3657