Questions tagged [timer]

Circuit to generate a signal a specific time after a trigger event. The timing can be defined by an RC time constant, or by clock pulses from an oscillator.

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37
votes
4answers
11k views

How to synchronize two microcontrollers to micro-second accuracy?

I need to synchronize two micro-controllers so that they can measure the speed of propagating waves. The time delay measurements need have microsecond accuracy (error less that 1/2 of a microsecond). ...
-1
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2answers
465 views

Ideas on building a water sensor power switch

I would like to build a water sensor power switch. A device which completes the circuit of an outlet adapter when the water sensor has detected water. I have a very simple idea about this little ...
4
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5answers
3k views

Maximum attainable delay with Micro controller

I am designing a microcontroller based delay circuit to implement delays of 2 hours, 1 hour, 45 minutes, and 30 minutes. The circuit will automatically turn on off a relay after this time period has ...
5
votes
3answers
31k views

How to calculate the time of one single tick on microcontroller

I have been in Embedded system for 8 months. I have worked application part more compare with low level. I have basic questions on systems ticks, How to calculate the system tick of Timer, if I am ...
3
votes
4answers
1k views

Delayed power supply startup

I would like to make a circuit that turns on a power supply to a microcontroller after holding down a button for a period of time (say 2 seconds). To make matters slightly more complicated, if ...
0
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1answer
2k views

How to generate a 555 fixed time delay even if trigger button is held on? [closed]

Can any one help me how to make it when the switch is presed for long time but it will not affect the time delay
10
votes
4answers
12k views

555 timer: how to set values to take an hour

I'm new (and novice) in electronics. I came to seek your knowledge to see if someone can help me with a very basic circuit. It is a 555 chip, which should light a LED (for about 1/2 second) every ...
5
votes
4answers
55k views

0-10 second on-time with a potentiometer

I would like to make a simple circuit, where the a potentiometer controls a 0 - 10 second on-time. If the potentiometer is set to min, the on time should be 0 seconds. If the potentiometer is maxed ...
4
votes
2answers
4k views

Is there a way to control the PWM duty cycle of a 555 timer without using a variable resistor?

I need to control the duty cycle of a Pulse Width Modulation (PWM) circuit from a DC voltage input. To do this, I've been looking into 555-timer circuits - but every circuit I've come across involves ...
2
votes
2answers
713 views

Timer1 remap cause debug crash on STM32F103

I build a Keil project for my STM32F103 MCU with STM32CubeMx. My goal is use the TIM1 channel 2 for control a Buzzer. I want to generate a PWM at 4KHz through TIM1 channel 2. I configured, with ...
1
vote
1answer
517 views

How do I extend the output (high) time of my circuit (retriggerable)?

I need help with the design of a timer delay circuit for the output of a sensor circuit which can keep the output HIGH for an adjustable time range (about 1 to 10 min), after the digital output of the ...
1
vote
1answer
499 views

Holding voltage high, for monostable 555 timer pulse

I want to know if there is a simple (and cheap) way to make a momentary button (for which we cannot control the time it holds when pressed!) press to virtually hold for about 1-2 seconds. More ...
1
vote
2answers
474 views

How can i trigger this watering timer manually

I have a automatic watering timer that I purchase from the internet. I'm attempting to hack it into something that I can either trigger from a micro-controller, or sense when the solenoid has been ...
1
vote
2answers
1k views

Need single-shot 1 minute delay-off LED circuit

What I would like to do is have an LED turn off 1 minute after the power is turned off. The LED would be on all the time when power is on. Thus: Turn power on: LED comes on immediately. Turn power ...
3
votes
2answers
6k views

Use PWM and ISR at same time on AVR

Is it possible to use AVR PWM outputs and ISR interrupts at the same time? I've got a project I'm trying to do on an ATMega328P and I need 3 PWM outputs but ALSO need to be able to use ISR interrupts ...
2
votes
4answers
439 views

I need help designing a very simple timer

I'm designing a very simple led light timer based on the Pomodoro time management technique. For those of you unfamiliar, you work for a set amount of time, take a short break, and repeat. My end ...
1
vote
5answers
2k views

Limit Number Of Pulses From 555 Or Similar

I need as small a circuit as possible that can produce 2 pulses (say maybe 200 milliseconds long and apart) when I press a button. My thought was to use a 555 timer and set it up for my desired pulse ...
1
vote
0answers
191 views

STM32F4 OC Clock Jitter

I am using STM32CubeMX to configure an STM32F4 to output a clock signal using Timer 3, Channel 4 on PC9. I have read in the datasheet PLL section that jitter shouldn't be more than 15ps RMS but I am ...
0
votes
2answers
131 views

Synchronize Clocks

I need to develop a system where there are 4 sensor boxes powered by USB and they have their internal clock. Each of these boxes are connected to a Linux pc and all these PCs are linked with WiFi. API ...
0
votes
2answers
2k views

Building a 12 hour timer

So, i want to make a timer that will turn on/off a circuit. I want to turn on the connected device at 08:00 and stop it at 20:00, so the interval is 12 hours. Correct me if i'm wrong but i can't use ...
-3
votes
3answers
471 views

Discrete one-shot lamp timer circuit

I'd like to use a momentary switch with a simple circuit (like the one below), that will illuminate two lamps for a short period (i.e. 10-20 seconds) with a single push. Obviously 555 timers are ...
30
votes
4answers
7k views

Why would a modern digital clock rely on mains frequency?

I am in the military, stationed in Djibouti, Africa. We generate 240V/50Hz power on base, but some buildings also have 120V outlets, which I assume is transformed somewhere else on base, probably at ...
3
votes
3answers
13k views

High resolution system timer in STM32

I have some software running on an STM32F103 (I'd also like to be able to use the F4) where I'd like to be able to 'timestamp' events (such as interrupts on external pins) to the nearest microsecond (...
3
votes
1answer
5k views

555 Temperature Controlled PWM

I am trying to build a temperature controlled 555 circuit to drive a cpu fan (used for cooling my entertainment center) I built this using slightly different diodes and MOSFET, and it works great (...
2
votes
2answers
13k views

STM32F4 TIM2 timer, getting to 1 second

I'm learning a bit about general purpose timers on my STM32F4Discovery board, and would like to know how I can configure the timer to invoke a timer interrupt each second, or at least have the auto-...
17
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4answers
4k views

Why are 555 timers so prevalent? [closed]

I've noticed is that 555 ICs seem to be extremely common. Why is the 555 so prevalent, or ubiquitous; what about it so useful?
10
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4answers
10k views

Can I achieve a one shot button without a 555?

I have a complex circuit, but my problem only relates to one small part. I have a relay, which is energised by pulling the low side low using an NPN. I would like a pushbutton to operate the ...
8
votes
3answers
4k views

Suggest a timer chip

I need to take voltage measurements separated by long delays (couple of hours) and beep a buzzer when voltage level is met. Power consumption is important. What I want is a simple timer chip like ...
7
votes
3answers
6k views

purpose of diode in this 555 timer application

I'm a newbie in electronics. I need to make a 555 timer base circuit(Refer to the schematic below) such that O/P pin of 555 is held LOW by default at power on, and the I/P pin is held initially at ...
6
votes
5answers
7k views

Random time timer

I'm constructing a simple circuit that beeps a beeper on a given time interval, using a 555 timer. Is there any simple way to randomize the time on the 555 timer between two given intervals, say, any ...
2
votes
1answer
3k views

Dinamically change PWM frequency with interrupt with STM32

i'm using an stm32f4 to control a stepper motor. I'm not sure if i need PWM mode or OC Mode or OnePulse Mode. I can generate a fixed frequency PWM wave but since i need a particular acceleration/...
1
vote
9answers
3k views

How do I produce a 1Hz clock output using a 555 timer IC? Are there better ways other than a 555 timer IC?

I've been messing up with timer ICs, looked up on how they work and now I want to design a simple digital clock using a 1Hz pulse generator. Is a 555 timer IC sufficient enough to make accurate 1Hz ...
8
votes
3answers
2k views

Which of these approaches for a watchdog timer?

I recently learned about watchdog timers, and am trying to implement one for my circuit for the purpose of resetting my (AVR) microcontroller if it hangs (i.e., doesn't respond to the watchdog). ...
4
votes
3answers
6k views

555 timer one-shot 30 second light LED strip, TOTALLY CONFUSED!

I'm working on a personal project and I am at my absolute whits end here. I have a configurable N.O. or N.C. switch (nteinc Magnetic Alarm Reed Switch) so I'm not too concerned with which way I use it....
4
votes
4answers
8k views

How can I make a 15 minute egg timer circuit?

I want to make a 15 minute timer for a game. I would like it to count down 3 x 5 minute segments of time, and then ring a bell when the 15 minutes is up. To do this, I want to push a button to ...
3
votes
6answers
1k views

General directions for a timer circuit which will not use microcontroller and which can measure several hours needed

Some background info first: In my country, price of electricity depends among other things on the time of the day when energy is used. Because of that, many people tend to turn on big energy consumers ...
0
votes
3answers
115 views

Minimal components for timer relay

A 5V LED should run for a predefined time period once a button is pressed. The LED should be illuminated for the same duration as the button is pressed, but only once the button is released and ...
0
votes
3answers
2k views

how to calculate time for timer relay

In the below circuit of Timer Relay, how I can calculate the time for C1 to be fully charged? please don't use regulator, transistor or any other device I just want to use Resistance and want to ...
8
votes
6answers
3k views

6 Month Countdown Timer Circuit

I need to design a timing circuit. After a duration of 6 months a LED must come on. The LED can then be turned off at the press of a button and the 6 month count-down must begin again. Anyone have ...
8
votes
1answer
13k views

arduino : delaymicroseconds()

How does the delayMicroseconds() function works. From what I understood the prescaler of timer0 is set to 64. For a 16MHz clock gives 4.0uS per count. I am a bit confused on the math to get to 1uS ...
6
votes
2answers
11k views

Problem with 555 timer and 4017 counter

simulate this circuit – Schematic created using CircuitLab I'm attempting to make a circuit that flashes each LED sequentially. So far my 555 timer works just fine and gives me a pulse about 3x/...
5
votes
4answers
18k views

Delay function in ARM programming

I have just started programming on ARM, I had some experience on AVR but not that much. The question is probably too trivial but the material about ARM is too little on the net... sorry anyways. I ...
4
votes
3answers
7k views

DIY small motor that turns for x seconds every y seconds

I'm a civil engineer, hiker, and hobby photographer. I am trying to build a little device that gently turns a small motor on every x seconds, keep it on for y seconds, and stop it for z seconds. For ...
3
votes
3answers
1k views

Use USB as an on-off switch

I'm looking for a way to build a zero(ish) cost intervalometer for my Canon SLR using only stuff that I have or can get very cheaply (my budget is about $4). I've already managed to "build" a wired ...
3
votes
2answers
316 views

Best way to sync LED's to light NES figures on a wall clock?

Advice & Ideas needed... Working on a project - a custom wall clock with perler bead NES sprites in the place of the numbers. The figures are mounted to a wood board with cutouts underneath, and ...
3
votes
1answer
10k views

What is the purpose resistors and capacitor in this 555 circuit?

What is the purpose of the capacitor , the resistor , and the variable resistor ? Do they work like clock pulses for the 555 timer?
2
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3answers
1k views

Does this timer circuit make sense?

I want to make a timer that counts down from 15 minutes, in 5 minute intervals. It should use 3 LEDs, and behavious should be such that when it is switched on, all 3 LEDs are lit. Then after 5 mins ...
2
votes
1answer
288 views

atmega32u4 use Timer as souce for a counter

I started to play around with an atmega32u4 and came across a question I wasn't able to solve right now (may be I just missed the right page in the 500 pages datasheet). I was able to create a ...
1
vote
0answers
49 views

CircuitLab simulation of 555 timer - OUT HIGH always delivering 5V irrespective of Vcc?

I've scratched together a design for a 555 timer based driver for an IR540 MOSFET. But in CircuitLab the simulator shows the 555's OUT voltage is always 5V when high, for Vcc ranges 3.3V through 24V. ...
1
vote
3answers
2k views

Momentary-Pushbutton Latch Switch with off delay?

I am trying to construct a latching circuit with a 1-2 minute shutdown delay so I can soft start/stop a 240V-5V power supply. I am looking for a momentary push latching (on-off) circuit to switch the ...