Questions tagged [monostable]

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1answer
45 views

Why am I getting an "invalid expression" for output voltage and not for other voltages?

I have designed this monostable (one-shot) vibrator using the 555 timer, yet I am getting this type of error on Pspice for the output voltage only. Where have I gone wrong?
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1answer
68 views

555 timer monostable → simulation is not working

I would like to build a simple circuit with a 555 timer, in monostable mode (monoflop). I looked at these two diagrams for this purpose. http://www.learningaboutelectronics.com/Articles/555-timer-...
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1answer
52 views

How to connect the output of the 555 in monostable mode to an optocoupler?

I currently have the following schematic for my circuit: Link to the simulation. On the simulation everything is working pretty good. The output of the 555 which is in monostable mode is giving ...
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2answers
79 views

555 PWM Checker/Filter

I need to design "PWM Checker" or filter - that will check that the input signal is at specific frequency (let's say 1 kHz) and specific duty cycle (let's say 33%) and the design has to use ...
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1answer
94 views

OUTPUT pin is not going LOW in 555 timer IC

I was working on a simple monostable IC project and I came acroos this problem. When the switch is closed which triggers the pin 2 and sets pin 2 on low logic OUTPUT goes HIGH. As per my settings of C ...
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2answers
93 views

555 timer won't trigger monostable mode unless I add a switch between R12 and ground?

I have this setup which is a part of a bigger circuit to control motors. This is supposed to be a timer in monostable mode with about a minute of hi output when triggered. The lines going down are to ...
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3answers
94 views

Usage of 555/556 Timer as a One shot timer

Im using two 555 timers / one 556 timer IC for a project. I've used it a couple of times before but never in monostable mode. Basically I need to activate a DC Motor in one direction for a set amount ...
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0answers
54 views

Toggling between astable and monostable input to dual 555 timer pulse generator

Hi there, I am looking to build a simple analog circuit to generate adjustable pulses for a medical device. The current circuit utilises 2x LMC555 timers - one in an astable configuration to generate ...
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1answer
57 views

555 timer IC unexpected pulse wave width problem in monostable mode

I was trying to make a monostable timer for a specific project which should trigger output high for around 5 seconds. For that, I have chosen a capacitor of 4700uf and a resistor of 1K. According to ...
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3answers
1k views

How to build an arbitrary (one-shot) pulse generator?

I need a circuit/IC that can generate a single pulse with a variable pulse width (I would want a minimum of 50 ns but if that is not possible the next minimum can be 1 μs, and even if that is not ...
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1answer
57 views

My NE555 circuit triggers falsely when connected to the mains using a 5V adapter

I have designed a laser security system using an NE555 in monostable mode with a potentiometer to adjust the pulse length. Another NE555 (U2) ciruit is used for delaying power on the monostable ...
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0answers
22 views

Recovery time of an monostable circuit using op amps

I'm having troubles deducting this T(charging). The waveform and corresponding circuit are below. I saw similar deductions, on this circuit, and on other circuits, and I understand we need to use the ...
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0answers
37 views

Tacho signal for led fan monitoring

I am struggling with this problem: I have a fan whose output tacho signal is a square wave when it is running properly. If the fan stops the signal remains at its last value (either high or low). I ...
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0answers
44 views

What is equation for the 555 timer control voltage in monostable

How do i get the 555 timer in monostable output frequency when there is voltage apply at control voltage. I only able to find the formula for astable which is Orignal post:- What is the equation for ...
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1answer
190 views

Reset and trigger 555 timer with one push button

I want to turn on a LED with a single push button. When the button is pressed, the LED has to be turned on for an X amount of time. But what I also want, is to turn of the LED with the same push ...
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0answers
90 views

How does the loopback on a non-retriggerable monostable work?

I understand how to connect a monstable multivibrator to be in the non-retriggerable mode. Just loopback the /Q to the falling edge input or the Q to the rising edge output) as in the following ...
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2answers
110 views

How to bypass continuous input on Trigger pin of 555 IC after some time working in Mono-Stable/ One shot version?

I configured the 555 IC such that it gives the output pulse for 3 Seconds (Approx.) as soon as there is input on trigger pin, but my project requirement is; even if there is input continuously on ...
3
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1answer
182 views

What is this circuit called?

This is a circuit I made to create a high signal when a switch is opened and closed. The duration of the signal can be adjusted by changing the capacitors and resistors. It is also low powered when ...
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1answer
282 views

555 timer not working in monostable mode

I am a newbie electronics learner and trying my hands on 555 timer to get it running in the monostable mode. Am trying the circuit as in the attached diagram. I am just unable to get the LED blink. I ...
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1answer
26 views

Switching circuit based on clock

I have attached the timing diagram. I want something similar to monostable multivibrator but with so additional features. don't know how the circuit will be. Case 1: I want the output to go high at ...
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1answer
47 views

How to find the exact value of K for SN54LS123

I have a circuit containing SN54LS123 (Datasheet) IC. I want to know the output pulse width but unable to figure out the value of K. The formula is PW = K * R * C. The values of K is given in the ...
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2answers
230 views

Replacing an NE555 with a 74HC123D

I want to replace an NE555 with a 74HC123D in a battery powered device. It is used to clock a CD4017, for which I need a pulsed signal of 46Hz. I read that a 74HC123D needs less power than a 555. How ...
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2answers
84 views

Can we trigger a mono-stable multi-vibrator( using 555 IC ) using mono audio signal?

I'm working on a project where, a certain low frequency audio spike should trigger the mono-stable multi-vibrator. If we can trigger a mono-stable multi-vibrator using a mono audio signal, how much is ...
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1answer
261 views

How to stretch 1ns pulse into a 5ns pulse?

We have a time-tagger device that records the arrival of a LVTTL signal with 0.5ns resolution. Currently the 5ns LVTTL signal is generated by a separate commercial Avalanche Photon Diode but I would ...
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0answers
62 views

555 Monostable delay circuit misbehaving

I have designed a basic application of a 555 in a monostable configuration to delay the LOW/off state of an output signal. (The output drives some power electronics through an optocoupler). As per my ...
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1answer
267 views

555 timer that does not output low when reset

I'm trying to design a circuit with the following goals: When not active, output can be either Vcc or floating When triggered by pressing a button, output pulses several times to GND at some ...
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2answers
126 views

555 Timer with controllable reset

I have a 555 monostable set up which is triggered when an output from another circuit goes low. This then remains on for 10s. This all works almost perfectly. My issue is that when the output from ...
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2answers
113 views

Trouble with engineering project - 555 timers

I'm currently finishing my GCSE engineering project and I am attempting to use a dual 555 timer circuit as a timer. I am using a schematic I copied off Kitronik Alarm Project Kit, but when simulating ...
2
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1answer
620 views

Can an electrolytic capacitor be charged reversed bias by a small voltage? [duplicate]

In this monostable circuit the C1 capacitor is reverse biased. When T1 is closed and C1 is discharged what will happen on the right side of C1? Will it charge up to 0.6 volts so that T2 can be ...
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1answer
153 views

Capacitor charging voltage showing ripples on scope. Origin?

I have an RC circuit delivering a square signal via a standard 555 timer set in monostable. I am powering the 555 with 4.88V DC directly from the Arduino, which itself is taking its power from the ...
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1answer
70 views

monostable 555 timer - buzzer motor and pulsing

I need this circuit to pulse an LED while running a buzzer motor for an adjustable period RV1 and C1 should give me 1 - 5s of pulse, while RV2 and C2 should adjust the LED ramp times The LED will be ...
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2answers
84 views

Comparison of 1G123 to 4538

I am designing the edge detection circuit with predefined output pulse duration. Pulse width will be 18.33 ms, supply power is 5V. Error tolerable is +-1 ms. There're a number of designs already ...
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1answer
142 views

IC 555 as monostable multivibrator

How is the output of a monostable multivibrator affected if the trigger pin is kept at a negative voltage (0V)? The upper voltage reference comparator will change its output to logic 1, while the ...
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1answer
93 views

Speed of monostable circuit

i need to find a time between rising edge of input signal and generating new output state. I dont have a scope so i cant measure Does someone have imagine how fast it is and how the edges looks like?
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1answer
79 views

Can I use the oscillation frequency equation for this circuit?

I'm not really sure if this is a question that can be answered so I'm sorry in advance if it isn't. I've just started doing electronics on a breadboard and I'm making a "Mini Strobe Light" from Jaycar'...
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1answer
82 views

monostable Eccles - Jordan multivibrator, theory

I’ve a few problems and questions to the principle of monostable multivibrator’s work. Basic schematic is as below: What is the reason for D1, C1, R3 elements at input? Why I can’t just tie a ...
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1answer
223 views

Why is the potentiometer setup in this configuration in this 555 circuit

I just started learning about chips and signals using the book Make: Electronics, in one of the circuits, used to generate a pulse in Monostable mode a potentiometer is used to vary the pulse length....
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2answers
2k views

One-shot Monostable 555 with long trigger

I am building a one-shot monostable oscillator using 555 Timer. Trigger pulse is controlled by a pushbutton, and thus can be long. I don't want output pulse to stay high for that long (simulated by V2 ...
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1answer
296 views

Expected behavior of 555 timer in monostable mode

While assembling the 555 timer based circuit below I noticed that 1) the intended delay on pin 3 only works if the switch on pin 2 is closed before attaching the circuit to the 9V power supply. ...
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2answers
1k views

Using Timer 555 to obtain a frequency multiplier

How can I use a timer 555 IC to obtain a frequency multiplier? I made a frequency divider by using a timer in monostable mode but a multiplier looked difficult. Can somebody tell how can I design a ...
0
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1answer
155 views

Keep Blowing out 2STN1550 Transistor [closed]

I'm (Trying) to build a trigger timer for an air cannon to launch ham radio antennas. This is an attempt to only allow the valve to stay open by a consistent interval to get max distance without ...
2
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2answers
220 views

How does this TLC556 work?

I'm having trouble understanding what the upper part of an electronic metronome depicted in the below schematic does. I already asked about the lower op-amp part in another topic, but I also can't ...
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2answers
990 views

Designing an Over-Current Protection Circuit with Delayed Reset

As part of a larger design I am trying to monitor current through a wire and cut it off if it exceeds a threshold. After the current has been turned off it should remain off for a minimum time period ...
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0answers
624 views

A monostable multivibrator using two NPN transistors works as desired in LTSpice, but in reality is very different

I designed a simple monostable multivibrator to extend a pulse of width \$\approx\$ \$1{\mu}s\$, to \$8ms\$ (to illuminate an LED when something happens on a bus). This is the circuit here, and the ...
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1answer
127 views

Monoshot false triggering and latchup problem

I use a monoshot to extend the duration of a short duration pulse (few microseonds) to 150 milliseconds. The issue is that the monoshot undergoes false triggering in the absence of valid input: The ...
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1answer
3k views

Why does this Edge Trigger Work on input of 555 monostable config?

I recently wired up a 555 timer in a mono stable configuration and found that when the trigger was held low for longer than the configured output pulse width, the output would stay high. After ...
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0answers
309 views

Holding Reset State Low longer with hardware 555 Timer

I have a 555 one shot timer circuit in which the Trigger and Reset pins are tied together in attempt to reset the timer every time the timer is triggered so that the one shot really extends for the ...
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1answer
270 views

Interfacing retriggerable oneshot with optocoupler

I'm trying to interface 74HC123 monostable with 6N137 optocoupler. Signal from optocoupler will turn on MOSFET driver. Monostable outputs correct signal when optocoupler is not connected - 200 ns ...
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1answer
210 views

SN74LVC1G123 Monostable Multivibrator IC

Good afternoon, I was hoping someone could help me understand some of the terminology in this data sheet and how I translate that into a basic one-shot multivibrator that is retriggerable. http://...
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2answers
1k views

Question about comparator and 555 timer circuit

I'm designing my first circuit for a university project. This circuit will check the voltage of two sensors. If both are over a reference voltage and persist as such for more than one second, a relay ...