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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0
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3answers
58 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 ...
-5
votes
0answers
36 views

Delayed power to led [on hold]

I own a bunch of led lights and I would like to apply power and after 3 or 4 seconds the LEDs would flash once then stay off until the power is disconnected then reconnecting.
2
votes
2answers
37 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
vote
0answers
21 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: ...
-3
votes
1answer
65 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 ...
0
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0answers
4 views

Servo Buzz / millis() [migrated]

I am having a problem with Servo Buzz that I have ascertained is from the millis() function using too much time for Arduino to generate a steady pulse for the ...
4
votes
1answer
58 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
votes
1answer
24 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
26 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
votes
3answers
109 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
votes
2answers
74 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
141 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
votes
3answers
120 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 ...
1
vote
0answers
27 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
votes
2answers
92 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
votes
1answer
32 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
vote
1answer
58 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
vote
3answers
257 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
votes
2answers
105 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
vote
0answers
33 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
votes
1answer
65 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
votes
0answers
33 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
vote
0answers
65 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
votes
2answers
79 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
votes
2answers
145 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 !!
1
vote
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
votes
1answer
45 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
votes
2answers
150 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
vote
2answers
98 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
votes
1answer
114 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 ...
1
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0answers
113 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 = ...
0
votes
0answers
60 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
votes
1answer
198 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
votes
0answers
178 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
votes
3answers
103 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
votes
3answers
103 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?
0
votes
0answers
80 views

Power micro LED's from 5 Volt USB

simulate this circuit – Schematic created using CircuitLab I'm working with this set of LED's: Link here: 30 Ft Led wire I measured the draw for the entire string at about 170 ...
8
votes
4answers
1k 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 ...
1
vote
0answers
57 views

Not entering ISR for timer 4 in stm32f4

I have coded for Timer 4 in a STM32f407vg discovery board. But while debugging the control is not entering the ISR. Please find the code below and help: ...
1
vote
1answer
494 views

STM32F4 Timer accuracy

I'm working with an STM32F4 Discovery board and I've come across a bit of unusual behavior that I'm hoping someone can explain the cause of to me. My goal is to configure a timer to trigger an ...
2
votes
0answers
141 views

STM32F103: not working USB when I turn on the timer

In my project the USB works, if do not use the timer 2. As soon as I enable the timer, the USB is not defined on the computer with an error -71. I use libopencm3; debian; gcc arm; what is the ...
1
vote
2answers
302 views

555 as a Schmitt Trigger and an ON delay timer?

I've scoured the internet trying to find this out to no avail. I would like to use a 555 timer to produce a Schmitt trigger with an ON delay of 20-30 seconds. Is this possible? Or will I have to use ...
0
votes
0answers
103 views

MSP430 PWM Dead-Time

According to the internet, the MSP430 has no hardware implemented to maintain proper PWM dead-time as the PWM duty cycle is modified. Apparently (and also according to the internet) this feature can ...
2
votes
2answers
274 views

Is there difference between Timer vs Counter in ATmega328P?

Is there difference between Timer vs Counter in ATmega328P? Or is it the same thing?
0
votes
1answer
100 views

Clock / timer activated 2 second voltage timer for wiper motor project

Ok, I need a 12 volt voltage timer using clock or timer for a wiper motor. I am working on a project in my garage. Simply put, I am wanting to use a wiper motor that will open and close a spring held ...
2
votes
3answers
97 views

Crystal or Crystal Oscillator for time sensitive device

A device that I'm working on is controlled by ATmega328P microcontroller. This will be some sort of a watch, therefore I want it to be as precise as possible. For instance if left to run for a whole ...
1
vote
2answers
119 views

555 timer to work once per day for 30 minutes

I was wondering if I could use a 555 timer to turn on a PI once per day for about 30 minutes. I want to use the 555 because it will take power from a photovoltaic source.
0
votes
3answers
505 views

How to make 7-segment display count up ?

I've connect 7447 decoder and 74193 counter as shown in the picture but I have not used 555 timer yet. Is there any way to test the circuit before using 555 ? I've connected the pins (up and down) ...
1
vote
1answer
318 views

STM32F1 troubles with a timer

I'm having some troubles with setting up a 1 second timer on STM32F103 mcu. I have set Timer 2 to have a prescaler of 1099 and a period of 65514, so I'm expecting to have a 1 second interrupt rate: ...