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 ease of use, low price and good stability. The 556 timer is simply two 555 timers in a single package.

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137 views

Pausing a clock signal generated by 555 timer

I am planning to make a simple integer adder/multiplier which needs a variable frequency, comparatively slow clock (around 1 to 200 Hz) for demonstration purposes. I used the following generic 555 ...
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128 views

555 Timer Giving Unexpected Output (Astable Multivibrator)

I am using this design with the only exception that C2 is 150nF to change timing slightly. When I plug in the circuit and attach an LED across GND and pin 3 output the LED is static on. However, on ...
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Inverted 555 Monostable Timer With a Sustained Input

I am using a 555 Timer to control a motor for a science team project. I have to make a Rube Goldberg-like machine and I am not allowed to use Arduinos or Raspberry Pis. However I need to trigger the ...
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Generating a delayed pulse with one 555 timer upon powering up the circuit

This is a very beginner's question - I apologize if this is some trivial extension of a known practice. Can I use one 555 timer without any extra transistors/IC to generate a delayed pulse as shown ...
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135 views

Swapping two 500kohm pots with one MCP42010 10k ohm digital pot

What additional elements do I need in my circuit to compensate for changing a pair of manual 500k ohm pots to a pair of digital 10 ohms? I'm a beginner implementing an Atari Punk Console on Raspberry ...
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556 circuit not working

I just got my 556 timers and I wired it up just like the 555 but now: it flashes one HighTime and stays off then... I used this calculator and basic diagram: http://www.ohmslawcalculator.com/555-...
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1answer
185 views

555 Timer Stops working after a few seconds

I'm building a LED dimmer using a 555 timer (yeah, lame I know). I'm using it to produce photographic flat frames which require perfect illuminated fields even with shutter speeds as low as 1/1000 of ...
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2answers
684 views

Baby 10 step sequencer help!

I'm a beginner in electronics and am working on a Baby10 step sequencer for a project. It consists of a 555 timer for a clock signal, a CD4017 decade counter and 2 more 555s for an Atari Punk Console ...
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79 views

Self cancelling indicator project. Help needed

I am embarking on a new project to design a circuit for an automatic vehicle signal actuator. Outline of the project is this: The problem: I have a car that has indicators operating on a standard ...
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1answer
3k views

74HC595 LED sign [closed]

I'm new to electronics so I'm sorry if this sounds stupid. I recently created an LED sign consisting of 97 LED's on a piece of wood that all light up at the same time when I supply it with 3v. I have ...
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359 views

Astable 555 timer circuit that resets on a heartbeat

I'm trying to design a circuit that will reset my ESP8266 when it crashes/hangs. It does this by sending a heartbeat to a 555 timer every minute which resets the 555 timer. The 555 timer is configured ...
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853 views

What is the best oscillator to be used in a capacitive soil moisture sensor?

I am working on this project where I am going to make a soil moisture sensor. The principal that I'm going to use is the change of capacitance of the soil with moisture. What I'm going to do is make a ...
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153 views

What is the purpose of the resistor between the Vcc and discharge pins in the astable 555 timer?

In a standard astable configuration of the 555 timer, we have two resistors R1 and R2. The capacitor charges through both resistors but only discharges through R2, consequently, the high interval is ...
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How do I use pin5 to control duty cycle of a 555 based PWM?

I have built a simple PWM using a 555 IC to drive a motor for an optical chopper and I want to be able to use the output of the chopper signal as a speed correction feedback for the PWM. I think I ...
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109 views

IRFZ34N doesn´t switch on when a NE555 timer pulse is applied

simulate this circuit – Schematic created using CircuitLab I have the above circuit in my breadboard. The problem in a nutshell is that when the NE555 timer is switching at 50kHz in astable ...
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108 views

Shift register led display not working?

I am very new to circuitry and have attempted to make a circuit (only using IC's) which displays 0's and 1's from the shift register as LED's either on or off, and through the use of a 555 timer shift ...
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96 views

Bistable and astable 555 IC interfere with each other

I am currently toying around with electronics and read Make:Electronics which is a very fun book. In one experiment (19) I came to a deviation in behaviour of my circuit compared to the expected ...
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506 views

Driving LED with 555 timer and BC639 transistor

I am trying to produce an LED dimmer circuit using a 555 timer circuit and a BC639 NPN transistor. I know there are better transistors that would suit the task better, but the BC639 is what I have to ...
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106 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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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 ...
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847 views

Detecting sparks at the output of a high voltage flyback transformer

I was trying to generate plasma inside a cylinder for a hobby project, so I decided to use a flyback transformer from an old TV and drive it with a 555 timer as shown in the schematics. It solves my ...
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1answer
354 views

How can I use a voltage to control the pulse width of a 555?

I have a variable PWM signal at 13.2 kHz. I want to control a servo with this signal, but the servo needs a much lower frequency, at most 80 Hz. My first idea was to use two binary counters, a NOT ...
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207 views

How to turn off 555 Timer for a period of time after Vout signal passes through

I have a single-shot 555 Timer. After triggering, output goes high for a period of time. What I would like to do now: After Vout goes high and then low again, I want to disable the 555 timer for a ...
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77 views

Multiple sensor circuits connecting to one counter and a 555 timer IC [closed]

I have to use a 555 timer in a context where I have multiple sensor circuits connecting to one counter circuit. The idea is that the counter should indicate how many activated sensor circuits are ...
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3answers
1k views

Controlling spotwelder timer with 555

I want to use the 555 time to control the timing on the power pulse of a spot-welder using a foot switch. I have seen a few 555 mono-stable circuits, but am having trouble finding the values of the ...
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555-timer circuit supposed to give 50% duty cycle square wave doesn't

I wanted to build a circuit that gives 50%-duty-cycle square wave. I built the circuit of figure 4.4.6 from this link which is shown below: I used the NE555 chip, and used a potentiometer instead of ...
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564 views

The 555 regulator that won't regulate

I made a 170V step up converter using a 555 timer for my Nixi project. At first I tried to run it using 5v but could not reach a 170v output, so I opted for a 12V supply and put in an LM7809 ...
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2answers
601 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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165 views

555 Timer circuit analysis

I am trying to analyse a 555 based timer circuit: My current understanding of the circuit is that the output is changed by the voltage at pins 2/6 (let's call it V). If V drops below 1/3 Vcc, output ...
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4answers
3k views

Ultra low power 555 timer circuit

I am trying to design a circuit involving an LMC555 CMOS timer operating as a monostable multivibrator. Essentially, I want a momentary switch to turn on a set of LEDs for ~20 seconds and then turn ...
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4answers
29k views

555 timer boost converter doesn't meet spec

I've been messing around with nixie tubes lately which requires a high voltage source (~150V-200V) to turn on. I searched around for a simple high voltage generator and found this circuit which uses ...
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2k views

555 Timer IC Simulation in Eagle

I am currently designing a circuit in Autodesk Eagle which requires a 555 timer IC. The timer may be any 555 chip, such as an ne555, tlc555, or lm555, or even one of their 556 variants, but the lm555 ...
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180 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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496 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 ...
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7k views

555 timer with output voltage equal to 5V?

I am (still) learning about electronic and want to get a 555 timer. From a datasheet (page 5) it looks like when the input voltage is 5V, then the output voltage is only 3.3V. Is that correct? If ...
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98 views

Is there such 555 timer circuit?

I was wondering if there is a simple 555 Timer circuit, or even simple transistors circuit, that has a HIGH output for 1sec, 2sec, or more seconds when I trigger the input switch and will remain HIGH ...
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99 views

How to avoid this voltage when I turn on the circuit?

What I want to do is an Delay ON, but when I press the switch this voltage pass for a brief moment and turns the led on for a moment. How can I avoid this? Should I put the switch somewhere else? ...
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3answers
369 views

PWM dimmer for off-the-shelf 12v LED bulbs

I am building a PWM dimmer for loads of up to 10 off-the-shelf 12v LED bulbs. Here is my current circuit. I'll describe a fundamental problem and I ask if I'm missing something here. The driver (...
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1answer
136 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 ...
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2answers
5k views

555 timer circuit power consumption

My goal is to have an LED flash (rather than stay on all of the time) in order to conserve battery life. So, I learned how to modify a 555 timer circuit so that the LED flashes for about 0.1Hz and ...
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2answers
2k views

IR Emitter/Detector with 555 timer alarm

I have this circuit that detects when a tube is empty and pulses a piezo buzzer in .5 second intervals. I have it working with 5v on a breadboard, but I need to move it to 12v from a wall wart. ...
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2answers
8k views

Functional difference between various astable 555 circuits

Looking through some 555 square-wave-generator circuits (possibly with variable duty cycle for 4-wire PWM fan control) I've found three different circuits: From the Wikipedia 555 article, a "standard ...
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9answers
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Astable 555 timing circuit (0.5 Hz and 50% duty cycle)

I am trying to build a timing circuit to generate a 0.5 Hz 50% duty cycle signal. In other words 1 second on, 1 second off, and so on... I have searched a few places and found the following ...
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1answer
207 views

Astable 555 not oscillating [closed]

I've been struggling with building a 555 timer for a project. I get the expected voltage at pin 3 (output), but the problem is that it's not oscillating. The Vout is constantly 8.4V, while I expected ...
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1answer
86 views

Doubt about a NE555 [closed]

I created this circuit a few days ago, but I'm a beginner in electronics, so I do not know if it's well done This circuit causes the LED to turn on after 5 seconds and to keep it on Could someone ...
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2answers
522 views

Changing frequency of 555 timer with varicap or capacitor

I have created a 555 oscillator circuit where the output is set to have flashing LED light. Now I have a problem when I change the voltage of the potentiometer, the output frequency does not change. ...
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1k views

What all do I need for a simple speaker circuit?

I'm trying to use a 555 timer in astable mode to play a square wave sound out of a small speaker, but I'm having trouble understanding all the components I should use. I think I need something like ...
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4answers
1k views

Arduino watchdog with 555 Timer and a MOSFET

I want to protect an Arduino from stop running using a 555 timer. I saw some projects that use the Arduino RESET pin to do that but there are cases that my Arduino project still stop working even when ...
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1answer
86 views

Can a 555 output be made to pull to ground?

I have design in Multisim with a 555 timer that I want to pull to ground when the signal changes. It's a missing pulse detector for resetting an mcu. Is there anyway I can achieve this with say a ...
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116 views

NE555 Circuit stops working after random time

i finished my NE555 circuit and created some pcbs. After a few attempts i could get the circuit working, and tested it successfully. I placed my circuit between a 12V 1.5Hz square wave signal and a ...