Questions tagged [555]

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator applications. The part is still in widespread use, thanks to its low price and ubiquity. The 556 timer is simply two 555 timers in a single package.

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Configuring an astable 555 timer to milliseconds

I am working on a Tinkercad project to make a computer. I am trying to configure an astable 555 timer for every millisecond (or something close). I don't know how to do it, can one of you show me?
some human's user avatar
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2 answers
47 views

Making a timer on delay and off delay without microcontroller

I am new and want to make a compact circuit without a microcontroller. The idea is when you push the button/switch, it will delay the timer for at least 6 hours. After that, it will activate the motor ...
Spacing99's user avatar
2 votes
1 answer
117 views

NE555 slows down - bad capacitor?

I'm trying to follow Ben Eaters clock module design using the NE555 timer in astable configuration - basically right now to only flash an LED. I think the design is basically what is shown also in the ...
schneida's user avatar
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3 votes
2 answers
150 views

How can I simulate a (simple) 555 circuit in KiCad?

I want to simulate a 555 circuit in KiCad, but quite failing to do so. I found a SPICE model here and included it in my model like this: My circuit looks like this: The transient simulation works. ...
Bart Friederichs's user avatar
4 votes
3 answers
114 views

When I measure VM1 at the output pin 3 of NE555 U1 in the schematic below, it differs from VM2 at the control pin 5 at NE555 U2 - why?

I temporarily replaced C1 with a 100uF electrolytic capacitor so that the oscillations in pitch from high to low were slow enough to allow me to take voltage readings at VM1 and VM2. For IC 555 U1 at ...
J R's user avatar
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3 answers
125 views

How to get megahertz frequency with a 555?

I need to produce a 1.7 MHz signal. Up to around 200 kHz the 555 IC and my simple astable circuit are working just fine as expected, but when I decrease R1 and R2 to less than 100 Ω the frequency ...
Vahid Heidary's user avatar
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0 answers
77 views

555 timer blink circuit not working

I received my 555 timers in the mail today, and I wanted to make a simple blinking circuit, but no matter what I do, the LED just stays on, it does not flash. Even stranger is that this exact circuit ...
benji bon's user avatar
0 votes
1 answer
54 views

NE555 Delay On Off Timer Schematic

I'm trying to make a timer that turns on at a certain time and turns off after 3 seconds, i found a circuit in youtube and made it in proteus, but the output is not the same. Is there a problem with ...
Noobielectrix's user avatar
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2 answers
70 views

Adding on and off state in a 555 timer clock circuit

I'm making a clock signal for my circuits, and I'm utilizing the 555 timer for this. I made this circuit below which outputs a clock signal. And now I'm trying to figure out how can I add on and off ...
Noobielectrix's user avatar
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0 answers
120 views

Designing a DC motor speed control circuit using PWM

I am designing a DC motor speed control circuit. I am using a centre-tapped transformer to get a dual voltage of 12v. The problem is both the 555 timer and the motor need a positive supply and ...
Tolu's user avatar
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2 votes
2 answers
209 views

How can I generate square pulses of the format shown in picture? The positive part should have smaller time scale

How can I generate pulses of this format? I need to generate a single pulse of 20V as a trigger pulse for performing a microscopy experiment( I couldn't manage to get a programmable function generator ...
Gan's user avatar
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2 votes
3 answers
216 views

A circuit that temporarily keeps the toy on after pressing the button

I'm working on a project to add a time delay to the button, so that when pressed, the toy plays for, say, 15 seconds and turns off. The toy is intended for children with disabilities and sometimes ...
JSK's user avatar
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0 votes
2 answers
140 views

555 timer producing 3x expected frequency in astable mode [closed]

I’ve just started experimenting with electronics, and for my first project I made an oscillator with a 555 in astable mode. I used two 56k resistors and a 0.1 uF capacitor for the C1. I also included ...
Chickenguy5's user avatar
0 votes
1 answer
40 views

CV(0-9v) controlled 555 pwm duty cycle

I'm working on a motor control project using the DRV11873 which is controlled by PWM duty cycle. Based on the DRV11873 dev board I have a working circuit using a 555 for variable duty cycle using a ...
Niles Fromm's user avatar
0 votes
2 answers
119 views

15 minute timer between battery and main switch [closed]

I am making a 15 minute timer between battery and main switch such that it doesn't run unnecessarily. I want such that if we press the switch in between it resets to 15 minutes again. I tried using ...
Gaurav Kumar's user avatar
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1 answer
102 views

The astable 555 timer broke down after a few hours. Why?

Eager to put my new Geiger-Müller tube to the test, I embarked on the journey of crafting a custom circuit for the purpose. This is my circuit: Getting straight to the point, my circuit successfully ...
Doobalo's user avatar
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1 answer
81 views

555 Timer Delay on Trigger

I am trying to build a circuit which will have an IR sensor. The type of IR sensor is active high. I need to connect the output of the IR sensor to a circuit which will give low output when the sensor ...
kailash kumaravel's user avatar
1 vote
0 answers
66 views

Triggering a signal on the falling edge of an input, and not re-triggering when it stays low

I have a 555 in monostable mode that will generate a signal from the transition to low from one of it's inputs (as they do). The issue I have is that the trigger will out last the signal by an order ...
QueueHammer's user avatar
0 votes
0 answers
34 views

NE555 pulse extender for PIN photodiode radiation detector is it fast enough? And more

I've designed a circuit using a PIN photodiode for a radiation detector aimed at identifying radium in an old watch. However, I'm uncertain about its effectiveness, particularly regarding the speed of ...
Doobalo's user avatar
4 votes
2 answers
664 views

How can prevent the source voltage from dropping when using a 555 timer

I am trying to use a 555 timer in my circuit to produce a signal (rather generally) above 100kHz. I have been successful with this goal, but have had an issue where the voltage measured on my positive ...
Alex Heinle's user avatar
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1 answer
72 views

555 circuit with high input and pulse adjustable output

I found a 555 timer that works with a pulsed input and gives an adjustable single pulse output. (see below). I need the same circuit to work with a constant high input. 8ms input high 4ms output high ...
Energy Hack's user avatar
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2 answers
114 views

Designing a power supply circuit for a DC motor speed control circuit

I am designing a a power supply circuit for a DC motor speed control circuit. I am using Proteus to simulate it but it is not working. I am using a step down transformer to take 230V to 16V then ...
Tolu's user avatar
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0 votes
1 answer
43 views

Time delay circuit to reverse the rotation of DC motor when input is high

I am trying to design a circuit to use to control a DC motor according to the output of a capacitive proximity detector. The circuit should turn ON the DC motor in forward direction when the hand ...
Shamooooot's user avatar
3 votes
1 answer
81 views

Sign Modulator - Class Project [closed]

I need to simulate a specific circuit, and I'm running out of time, so please someone can tell me what I am doing wrong? I think I have this part correct: Here starts the problems, I don't know how ...
MARMOTO's user avatar
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2 votes
3 answers
668 views

NE555 + CD4017 Airplane Strobe Light with LDR

Engineers! I have built a simple airplane strobe light using NE555 and CD4017 in order to flash two LED in a different pattern. I have added an LDR resistor with a transistor in order to switch OFF ...
Svet GEoff's user avatar
1 vote
1 answer
102 views

Motor Driver Project using 555 Timer PWM + 4N25 + 2N7000

I need to build a circuit that controls the speed of DC Motor using external potentiometer, here are the requirements of the project: Power source: two 12V dc, 450mA power supplies Motor: R140 Micro ...
Saif 's user avatar
  • 11
0 votes
1 answer
152 views

How to boost the output voltage of my 555 timer design?

I'm fairly new to the world of electronic design. I'm building an astable 555 timer with the limitation being I can only drive it with a 3v coin cell battery (design has to be lightweight). I've been ...
Eric D's user avatar
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0 votes
1 answer
75 views

555 delay timer before powering PCB with 5 V [closed]

I am wanting to know if the circuit below looks correct for using a 555 delay timer to take ~5 secs before applying 5 V to the rest of the board? I'm not sure if I have the correct wiring for it to ...
StealthRT's user avatar
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3 votes
2 answers
208 views

555 Timer Astable Multivibrator Circuit Analysis

I was looking at a dead Molex "Suitcase" terminal applicators and found on its controller board this 555 circuit. It appears to be an astable multivibrator, but not the typical kind. It ...
Erik Vincent's user avatar
1 vote
3 answers
103 views

NE555 monoflop only trigger once on power

I'm struggling more than I probably should with this simple sounding task: The bell should be triggered once for about a half or 1 second when 12 VDC are applied. I tried to solve this with a monoflop ...
Nic's user avatar
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0 votes
2 answers
94 views

Combining two RC time delay circuits to generate both LOW and HIGH pulses with two push buttons

I have come up with the following circuit that can be used to momentarily generate either a LOW or HIGH pulse based on what push button is pressed. Can you please tell me if there is any issues with ...
David Refoua's user avatar
1 vote
2 answers
131 views

Monostable mode of ne555 is not working

I am trying to connect a 555 timer in the monostable mode. Although it is a very simple circuit, I still for some reason can't make it work. I would appreciate it very much for your help in this ...
minhaz ahmed's user avatar
0 votes
2 answers
217 views

Monostable "One shot" 555. Longer trigger than T (output pulse width) eliminator

It seemed to me that a classical "one shot" output will go low after a determined period set by T (Output Pulse Width), even if push button is held down. What I want to happen is, when the ...
Domenico's user avatar
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0 votes
0 answers
98 views

Clock logic for 8-bit computer

I have been in the process of remaking Ben Eater's 8-bit-computer, and have a few questions. I got to the part where the clock, which consists of 3x 555 timer, is connected with logic gates. However, ...
lukasm06's user avatar
0 votes
1 answer
136 views

A 555 timer changes time when you touch it?

I designed a simple 555 astable 50% duty cycle square wave generator, assembled in China on SMT PCB. It works well: Except when you touch it, or even put your fingers near it, the timing changes ...
SRobertJames's user avatar
1 vote
1 answer
55 views

which mode is 555 timer in this case

This particular timer is made to turn off the load, after KEY1 is pressed long enough. I am not sure if it is in astable or monostable mode.
Domenico's user avatar
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1 vote
1 answer
74 views

Measuring capacitance with NE555 in astable mode

I have one problem with my project. I trying to measure capacitance with NE555, but i have problem with protection. In this schemeatic instead of a capacitor, I have put connection socket 01x02 for ...
Византија Исток's user avatar
0 votes
2 answers
79 views

Correcting error in 555 PWM circuit

I'm trying to design a 555 circuit that outputs a low frequency PWM signal (1-10 Hz) and is adjustable in both frequency and duty cycle (0-100%). I've come across this design and it seems to work ...
bdmcnamara's user avatar
0 votes
1 answer
147 views

Alternatively blinking two LEDs with 555 Timer

I tried to make a simple 555 timer circuit which turns on one LED when its output is HIGH and turns on another LED when its output is LOW. I tried connecting two LEDs with single 1k ohm resistor (...
Muhammad Nowfer's user avatar
0 votes
1 answer
152 views

Need 15 minute delay alarm [closed]

I need to use electronics to make a: 12v, ~60db, ~3second intermittent beep, ~15 minute delayed alarm, started by toggle switch, stopped by toggle switch. Analog or digital, whichever is smaller. Help ...
Rick DuRapau's user avatar
0 votes
1 answer
82 views

Turn on LED for fix time when box is closed

I have a box which is used to put PCB in it when we are not using PCB. I want to turn on a UV blue LED for 1 minute when box is closed to cleanout the inside of box. I cant use limit switch as I don't ...
Zunuran Nasrullah's user avatar
1 vote
4 answers
164 views

Blue UV LED Timer Circuit

I have designed a PCB for mouth guard device and also its enclosure is ready in which PCB will be placed when its not in use. I want to use a UV blue light for UV sterilization inside the box. Now the ...
Zunuran Nasrullah's user avatar
0 votes
4 answers
176 views

NE555, 50% duty cycle at 110kHz

I want to get an NE555 chip with a 50% duty cycle to 108-110kHz in output. I have already experimented with various online calculators and values. However, I never get the values that allow me to do ...
dessi's user avatar
  • 89
0 votes
0 answers
40 views

Help with using monostable one-shot multivibrator for limited time

Trying to develop a circuit that would know how to output a square wave with a duty cycle that would be controllable, and the duration would be between half a second and a second. Now I manage to make ...
Knowledge's user avatar
  • 401
0 votes
0 answers
149 views

LMC555 delay off timer, M20 motor drive, updated

The goal is to either just give a signal to the motor with momentary switch, or turn on the toggle switch, let 3.7V motor run for a couple of seconds before 440uF is fully charged, after which voltage ...
Domenico's user avatar
  • 147
0 votes
3 answers
231 views

How re-trigger NE555 timer in monostable mode while it is already triggered?

While using 555 timer in monostable mode, I want to extend the timer if trigger activates while output is active due to a previous trigger. For example if I have set the timer for 60 seconds and a ...
AKTanara's user avatar
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2 votes
0 answers
42 views

How can I make "50% duty pwm signal" + "flicker signal" circuit? [closed]

I'm new to electrical engineering. I want to make 50% duty pwm signal(adjustable frequency) + flicker signal as following picture. I think 50% duty pwm signal can be made using 555 timer like this ...
Jaeho Lee's user avatar
1 vote
1 answer
180 views

Two 555 Timers working in monostable mode, triggering each other [duplicate]

I'd like to generate a square wave signal with Ton Toff time length based on two analog voltages between 0-5V, went with the method that seems the simplest, two 555 timer ICs with their trigger and ...
fflori4n's user avatar
2 votes
1 answer
117 views

555 timer vs 556 timer

I'm currently working on a project for an internship where I need to reverse engineer a design for a vibration simulator, which use two 556 timers in order to generate four output signals. The final ...
Jack Recher's user avatar
0 votes
2 answers
125 views

Rising and Falling edge pulse alternative

I have a requirement to generate a 4 sec pulse when a switch is closed and another pulse when the switch is open with minimal (<10uA) to zero power consumption when the pulses are not being ...
Planestoner's user avatar

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