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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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How can I turn off automatically, say after a fixed number of cycles, a 555 in astable mode?

I looked at the answer to "How to turn a 555 in astable mode into a decaying square wave" but this is really for an input to a speaker. I want the input to go into a counter to count the number of ...
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35 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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32 views

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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33 views

Generating a delayed pulse of 0,5sec with one 555 timer upon powering up the circuit [duplicate]

In the link below, this circuit I found is what I needed. Only the length of the pulse and the delay are not what I want. When I want just 0.5sec before pin 3 is up and the pulse duration I want is ...
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73 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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74 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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58 views

555 as slow PWM driver

I would like a slow PWM output, driving a relay turning an AC heating element on and off. I desire a period time of around 10s. What is a realistic upper period time limit for a PWM circuit like the ...
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44 views

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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125 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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73 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
42 views

How can I use the component CD4538 or a 555 timer on Multisim?

How can I use the component CD4538 or a 555 timer on Multisim for a delay of 1 second ? I want both of the nor gates to be 1 for roughly 1 second when the output of the op-amps is either 01 or 10.
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78 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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32 views

Delay timer for car bar light to stop mode cycling

I just brought a bar light for my vehicle. My problem is the light has 4 modes (white, white flashing , yellow, yellow flashing) and the modes are triggered by turning the light off then on in less ...
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1answer
63 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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2answers
64 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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43 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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2answers
47 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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45 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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66 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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39 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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63 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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44 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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65 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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81 views

555 Astable Timer produces incorrect period/frequency

I am building a 555 astable timer circuit for a course which must match the BPM of a song. The song has a BPM of 104, which requires a timer frequency of roughly 1.733 Hz. The circuit looks as ...
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192 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
100 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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73 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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1answer
72 views

Reset circuit loops forever on-off

I've designed the following circuit: This is a "self-reset" circuit, VCC_IN es 12V from source, VCC_OUT powers the entire board, including a PIC microcontroller. The idea behind this is whenever the ...
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1answer
283 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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1answer
92 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
146 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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88 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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1answer
92 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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77 views

How does the capacitor charge and discharge in this configuration?

I wanted to build a metal detector using 555 timer and I found this circuit online along with a video of the working model. It says that the timer works in astable mode. But since the capacitor is not ...
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86 views

Retriggering 3V PIR sensor with 555 timer circuit and LEDS

Hi y'all I'm putting together a PIR sensor circuit that will trigger a 555 timer in monostable and run a set of LEDS for about 5 sec all on a 3v cr2032 button cell battery and than reset until next ...
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2answers
60 views

Hold Pushbutton for soft latch after X seconds

What I'm trying to achieve is have a momentary push button that must be held for say 5 seconds before latching on permanently. But the button must be held for entire duration or else timer will reset....
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198 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
117 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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82 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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62 views

Safety of an Inverter Circuit

I built this circuit for an EL driver/inverter I found on this website: https://dcroy.blogspot.com/2011/02/ The transistor is a TIP122 Darlington transistor and I used this transformer in the circuit....
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1answer
112 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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2answers
171 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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1answer
395 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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3answers
124 views

Can I use a mosfet as a switch to power arduino?

I have a project in which I intend to use a NE555 timer to turn the arduino on/off on specific intervals. I don't want to use the ne555 output directly because of the current limitations of the chip. ...
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1answer
109 views

Why Arduino does not suit the to trigger a Spark plug but 555 timer can?

To trigger a spark plug and to control it using an Arduino, I tried following this really well-written guide. Basically, a MOSFET(IRF540N in my case) controls the closing and opening of the primary ...
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1answer
72 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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1answer
70 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 ...
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2answers
55 views

Electronic bell for lecture [closed]

please help me about this project. I want to make electronic bell. Which duration time is like 10.45 AM to 11.45 AM ..1st lecture 11.45 AM to 12.45 PM .. 2nd lecture 12.45 PM to 1.30 PM lunch break ...
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2answers
234 views

Chicken coop door opener circuit

I'm designing a circuit that will open a chicken coop when the sun comes up. I've attached a bungee cord to the door which opens the door when a pin is released. This pin is released by a car door ...
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2answers
137 views

Can someone explain how this circuit works? I have an idea but I dont know if its correct

What circuit does is turns the lights on sequentialy like on this gif. What I think is happening is that the capacitor thats connected between ground and the output pin through that 4k7 res is slowly ...