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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35 views

Capacitor Timer Circuit [on hold]

I understand that you can charge a capacitor in a certain amount of time depending on the resistor value you put in parallel with it. I am also told that capacitors are used in timer circuits and ...
2
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1answer
59 views

STM32: Timer interrupt works immediately

This is code for timer in my project on STM32F429: ...
0
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3answers
41 views

Delay function using timer/counter 1

i have made a function called _MY_Delay() which use 16bit timer/counter1 in ATMEGA16 , and used this function to blink a LED . the problem is i didn't work and i don't know the reason , here is my ...
0
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1answer
26 views

Time delay relay

I am having trouble figuring out what kind of time delayed relay I need for this circuit or if anything will work even. It is used to keep a dome light on for a few seconds in a vehicle after the ...
1
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0answers
27 views

PIC12F simulator: Why isn't the oscillator running?

I have written firmware for a PIC12LF1572 that I am testing in the MPLAB X simulator. The program runs and correctly responds to stimuli, except when it needs to wait for a timer interrupt. After a ...
0
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1answer
54 views

How do I build a DC time out circuit that stays off until power is toggled?

My girlfriend bought an LED faucet that is actuated when you turn the water on and is powered by a battery pack of 4 AA batteries (2 wire out). However, when the water is turned off, the slope of ...
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0answers
61 views

Using Pic18F timer for external pulse count assembly code

I am new to using a Pic18f2550 micro-controller. I have been searching for examples on how to setup and use the 16 bit timer Tmr1 and Tmr2 to count the number of pulses from an external motor opto. ...
0
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1answer
18 views

STM32F051R8: PWM timers don't work?

I'm working with MB1034B discovery board and STM32F051R8 microprocessor. I'm trying to output some PWM pulses using hardware timers. I use this tutorial (for STM32F4xx): ...
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18 views

Measuring time using an STM32F407VGT6 microcontroller

I'm using a custom board for charging and testing batteries. Its 'brain' is an STM32F407VGT6 microcontroller. I'm developing in Ubuntu (14.04.2 LTS), using ChibiStudio (ChibiOS/RT 3.0 development ...
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0answers
16 views

program stops in non maskable interrupt when initializing time interrupt

I am using RX62N microcontroller and am new to it. In this i was trying to blink the led using interrupt(compare match timer) but after the initialization it always goes to the non maskable interrupt ...
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1answer
43 views

PIC18f4550 Timer setup for 1sec Interrupt

I want to generate Interrupt(on PIC18f4550 using TIMER0) every 1 sec but by using the following code interrupt is generated after every 6 secs. ...
1
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2answers
62 views

Turn a METAL HALIDE BULB On/Off in 1 minute Intervals?

OK, let me 1st give you some background information. I need to generate 40,000 lux of light in an indoor environment (in a area of around 5 feet by 3 feet) and I need the ability to turn the light ...
3
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3answers
74 views

Help Trobleshooting my first solderless circuit on a breadboard

I'm working on my first project from the book "Electronics All in One for dummies", chapter 6, book 1. I work through all the instruction but I cannot make the LED blinks. The circuit diagram is: ...
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0answers
21 views

arduino - millis() [migrated]

I copy from http://arduino.cc/en/Reference/Millis Tip: Note that the parameter for millis is an unsigned long, errors may be generated if a programmer tries to do math with other datatypes such as ...
0
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3answers
116 views

How to turn a switch on/off repeatedly in 1 minute intervals?

I have a light bulb plugged into an outlet and I need to be able to turn it on and off again and again in 1 minute intervals for a period of 10 hours per day (a total of around 600 on/off events per ...
2
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2answers
45 views

On STM32F4xx: Can I trigger a timer by itself so it goes through a list of periods updated from an array?

I need things to happen at precise (down to the clock, ~5.5ns at 180MHz) periods of time based on a list; let's say 5 periods of 444444, 555555, 666666, 777777 and 888888 timer clocks (obviously a ...
1
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0answers
26 views

program resets after ISR for TIMER 2 on pic24F

I am trying to configure the timer2, but every time that an interrupt occurs, the microcontroller goes to the ISR and then starts the main() function again. This are the functions: ...
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1answer
68 views

PIC18F25K80 4 > 20 returns true. How is this possible?

I'm using such code on PIC18F25K80 compiled with xc8 compiler: ...
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votes
1answer
87 views

flow meter that displays litres per hour [closed]

for the past 2 week iv just started my first ever project to make a c program on the software called mikroc where i would get pulses in from the flow meter and calculate the flow rate of how much ...
4
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1answer
78 views

AVR: Timer overflow flag in TIFR [duplicate]

I have a little question about the TOVn flag located in the TIFRn register. The datasheet says, if the ...
0
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1answer
31 views

Frequency of the CTC mode in the atmega328

I am trying to understand the expression for the waveform frequency of the CTC mode (p. 99 of the datasheet). Assuming that the prescaler is 1 and that \$OCR0A\$ is a constant value, in ...
0
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0answers
30 views

Low power, low duty cycle, full speed dc motor timer

I need to drive a 12v dc motor drawing 300ma under load. It only needs to run about 4-5 seconds per min. But the run and idle times need to be adjustable with some degree of accuracy. Once ...
0
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3answers
158 views

Reversing polarity of motor with timer

I have a timer that allows me to preset times and run a motor for a predetermined amount of seconds. I need this to reverse polarity as soon as this predetermined time has expired. The timer is a ...
0
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2answers
87 views

Using TMR0 to time an event

i'm trying to use TMR0 on a PIC18F2420 to time the opening of a device and display the percentage it is opened. the issue i'm having is that it has frozen up pretty much all other operations. i'm not ...
6
votes
2answers
156 views

Turn a mains light on slowly

I've been looking at creating a simple circuit to slowly turn a halogen daylight bulb on over about 30 minutes as soon as power is supplied to simulate dawn. I've got a 240VAC 42W halogen bulb that ...
0
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3answers
125 views

wiring 555 to disconnect itself from electricity

i had idea for a circuit with 555 and here is the IDEA: circuit is stationary somewhere, it is in "passive state" meaning its drawing no current from battery and pin 3 is set low, then someone comes ...
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0answers
30 views

Fan needs full power to spin up; would then like to have to run off a speed control

Fan in question: http://www.amazon.com/Active-Air-inch-In-Line-Fan/dp/B002JQ4N92 Fan speed control: http://www.amazon.com/Lutron-DVWFSQ-FH-WH-Single-Pole-3-Way-Control/dp/B000MAVHTG The lowest ...
2
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2answers
95 views

Design of a Five Second Kill Switch

I think I have a challenge for you smart souls on here, who donate your time by answering all of my terrible questions. I have to design a switch that completely shuts off a system when it is ...
0
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1answer
33 views

Timed Selection Between AC Power Sources

I would like to be able to run a freezer from AC power line A in the daytime and AC power line B at night. Right now, I am manually unplugging the freezer from power line A and plugging it into power ...
1
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1answer
63 views

Switch to power pump with relay [closed]

I couldn't find this question anywhere else. I have a pump, a 12v battery and a switch and can purchase any relays etc that may be required. I want it so that when a switch is triggered and kept on ...
1
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3answers
303 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 ...
0
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2answers
130 views

Circuit Requirements for a 30 min continuous on off cycle

I would like to build a circuit (preferably using components from old common electronics like a VCR or whatever) that continuously cycles on/off in ~ 30 min intervals. Input voltage is from a 12v ...
1
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0answers
41 views

RC compare in capture mode - Timers SAM3X

So I am using an Atmel SAM3X8E micro together with a temperature sensor over a one-wire interface. The short version is: I give the chip a sequence of setup and start pulses, and the chip responds. ...
0
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1answer
69 views

Where do I connect earth wire?

I'm trying to use this delay timer to control an exhaust fan. I have a 3 pin connection (with earthing wire) powering this fan and it works fine. If I have to insert this delay timer module in ...
0
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0answers
34 views

NTP offset error

we are having problems getting our time synchronized in an embedded processor system using a NTP server and a FPGA based hardware RTC. Our offset calculation says that the time error is 0, but our ...
1
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0answers
88 views

STM32F4xx WFI unable to sleep due to SysTick Interrupt

I am trying to add some power conservation to our STM32F4xx powered device using its WFI sleep function. However, whenever I call the WFI function, the system is not being put to sleep (or rather, it ...
0
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2answers
83 views

Can you set up a monostable 555 timer so it reverses the output?

I would like to make an alarm that goes off about 1 minute after it has been triggered. To do this, I want to delay the circuit using a 555 timer in monostable, but I can't do this as they turn it on ...
0
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2answers
187 views

PIC16F877A Timer0 delay problem?

To get min 5ms square wave. I chosen prescalar as 1:32 (The internal clock given 4Mhz), what will be the TMR0 register value? Is it 0x64 or 0x63 !!
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0answers
44 views

Circuit that takes input signal and controls led

I am trying to design a circuit that compares a recorded signal to a stock signal. If they are not similar it then inputs a signal into a circuit which will change the pulse of the led to stimulate a ...
0
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1answer
47 views

Timing Delay Error

I am new to embedded system programming. I am working on clock using 8051 timer and interrupt.The delay is perfectly of 1s but when I run my clock with computer clock I loses 3-5s in 10min.I have try ...
0
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2answers
219 views

555 Timer Monostable Mode Self Triggering

I'm working on a simple project with 555 timer. I'm trying to generate a high-state output for 10s when Vcc is applied to the circuit(It is initially off). However, I have not managed to operate the ...
1
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2answers
116 views

STM8L Timer 1 unexpectedly low overflow frequency

I'm running the MCU off the high speed (16MHz, confirmed) internal oscillator and I've configured timer 1 to overflow with maximum overflow frequency: ...
0
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1answer
120 views

using one 555 timer to control the pulse of another

tried making something like this Limit Number Of Pulses From 555 Or Similar but it doesn't work. I'm not sure what it needs. I'm trying to make the first timer put out voltage to the second one for ...
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0answers
135 views

555 timing formula when the diode forward voltage drop is not neglected

(Image Sources) In this modified astable multivibrator circuit the forward voltage drop of the diode D1 is always ignored, and the timing formulas are given as $$ t_1 = \ln(2)R_1C_1, \quad t_2 = ...
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0answers
63 views

Light-dependent timer circuit design

I am a relative newbie in electronics and would like to build a circuit that controls a light or small array of lights (2 - 5W LEDs). The system will be powered by a car battery (12V) with a solar ...
0
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1answer
248 views

AVR TIMER0 treating with prescaler and without to blink a led

I am playing with ATMEGA168A's TIMER0. CPU is running at 20MHz and there are two treatments. a) Blink a LED at 20ms frequency by using a 1024 prescaler. In that case i count the the times that an ...
0
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1answer
49 views

3 second fogger

hello I'm new here and I have a question. I'm no electronics expert but what I'm trying to do I thought would be rather simple but I'm having trouble with one part hopefully somebody can help me. I'm ...
2
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0answers
197 views

STM32 - Multiple channel PWM input

I am using an STM32F405 based board , (OpenPilot revo ) to receive PWM signals from a joystick receiver . i have to xapture 5 PWM signals using only two timers , the timer 8 and the timer 12 . I've ...
0
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3answers
112 views

Designing a simple pulse generator

I read in many tutorials that the inner clock in a micro controller are less accurate (%10) than the external crystal clock. When I generate variable frequency pulses by using a micro controller does ...
2
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3answers
105 views

How are timers adjusted in a micro-controller?

In a 555 Timer the resistors and capacitors determine the frequency and the duration of the timer pulses. How is this actualized in case of a micro-controller timer?