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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2answers
67 views

How to generate clock in 7555 timer?

I am trying to simulate ICM7555 timer on proteus schematics. However, after following the datasheet for Astable operation, I don't see any results on the analog analyzer. Can anyone tell me what I am ...
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36 views

555 timer delay circuit: resume after supply outage

I have created a 555 delay circuit where output goes down after a delay of T minutes. The 555 IC is in astable mode and is triggered automatically upon turning on the supply, Vcc. After turning on ...
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1answer
29 views

The best way to power LEDs [duplicate]

I have device with one PCB with 6 parallel LEDs (30mA and 3.8V forward voltage each). This very small PCB is connected via 2 vires to main PCB where 555 timer is generating PWM signal based on voltage ...
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58 views

How to make a Ramp generator with a NE555 from 0V to 2/3VCC?

Hi Ladies and Gentlemen, It is related to an existing post here from early 2019. Voltage to PWM Circuit, need to understand frequency I am trying to make a simple 0-10V to PWM converter (idealy ...
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1answer
49 views

How to pull a normally floating pin to ground for 500ms when circuit powered on and circuit powered off

I need some help designing a circuit to pull a floating pin to ground for approx 500ms when the circuit is first powered on, then pulling it to ground again for another 500ms when powered is lost. The ...
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Is the NE555 the IC I need, and if not, what do I replace it with?

I've noticed that whilst I have a well-known solution using an NE555, that IC doesn't fulfill my needs perfectly. Others have told me that the NE555 is very rarely an appropriate solution to one of ...
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1answer
48 views

555 timer operating voltage

I am trying to build a bistable multivibrator using NE555 timer. The datasheet says the operating voltage should be in the range 4.5V-17V, but during testing I have observed that my circuit works even ...
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2answers
66 views

Voltage protection with 555 timer not working

Briefing I am using Multisim to simulate a circuit before building it. The voltage protection circuit with a regulator works fine and the timer circuit works fine as well separately. When I try ...
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2answers
46 views

How to adjust duty cycle of an existing square-wave, based on light level

I am making a wall-powered, battery-backed, BCD alarm clock with discrete logic. I'd like to adjust the brightness of the LEDs based on light level, as this clock will be used on a nightstand. So ...
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34 views

Signal modulation at 38kHz using a 16-1 mux w/ 4bit counter

A little back story to what I am trying to achieve: I want to be able to control the bit pattern using DIP switches to send a controlled IR signal at 38kHz. I want to create a "game" where each IR ...
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41 views

Why can a capacitor connected to ground in a 555 astable circuit change pin 2s output?

beginner here. Basically my question is exactly as it says in the title. I was watching a video ( https://youtu.be/qfWIjb48mjE ) about 555 timers and was wondering how the capacitor can change the ...
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1answer
47 views

Feedback on astable 555 timer circuit to control MAC valve for turbo control

I have some questions and wanted to get feedback on this circuit I have put together. Basically to see if there is something I missed or obvious that I should change or should have designed ...
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1answer
56 views

3 Way flip flop between LEDs with 555 timer

I'm a beginner working on a project which requires flashing high power LEDs, they will be supplied by a battery and flash at a frequency with a 555 timer. However, because I would like the battery to ...
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2answers
112 views

Removing voltage spikes and overshoots using power MOSFET as switch and 555 timer as pulse generator

I'm trying to turn on a power LED using LM555 timer as input signal of IRF630N N-channel power MOSFET as Fig1. Fig1. pulse generator and switching circuit. Here is the output of LM555 Timer (Not ...
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1answer
90 views

Toggle 555 timer IC both with switch and arduino

I want to use 555 timer IC (NE55P) as a latching toggle switch. I successfully did it using a switch as described in this toggle 555 schematics except, I am using 5V power with led as output ...
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2answers
56 views

Beginner - unable to use AND gate with buzzer and flashing light circuit

I have a circuit which needs to turn on the buzzer and flashing lights when both my switches (switch 1 and 2 left side of the circuit) are on. I was trying to do this with a AND gate but couldn't get ...
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59 views

How to protect my 555 timer against DC motor noise?

I have this circuit: (Sorry for such a bad schematic.) As you can see, there is a DC motor that gets power from 12V source, using a NPN transistor controlled by a 0-5V signal. Please note that ...
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2answers
116 views

How might I increase incircuit voltage from 2.5 DCV to 3 DCV

I'll cut to the chase, an about me is at the bottom of this post... I have a standard NE555P fader circuit powered via a 1.2V battery boosted by a QX5252 with 220µH axial inductor (which according to ...
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4answers
70 views

Using a 555 timer and 14-stage binary divider for 2 hour timing circuit

I am researching how to design a timing circuit that will activate a relay with a push button and deactivate the relay after two hours. My understanding is that I can feed the output of a 555 timer to ...
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1answer
59 views

how to design a low pass filter for square waveform

I have square wave signal of 100KHz with few high frequency ringing from 555 timer.when i tried to use a 100KHz first order rc low pass filter,i got a sawtooth waveform because the 100KHz square will ...
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2answers
107 views

Can I add two LEDs to this circuit?

I am working on a diorama. I found this circuit online and it's what I want. (I'm NOT making a railroad diorama.) I want to add two more LEDs to this circuit to have 4 flashing LEDs. Like this: ...
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1answer
52 views

555 NOISE BUTTON/ OP AMP

I have this circuit from the image below that I am designing myself. part of this circuit is cut so 2 78xx is present. This circuit is being designed and tested in parts. This part of the circuit has ...
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1answer
158 views

Power Latching Relay off/on in response to 12V ignition and 1 second ground pulse

I have the following sample schematic of a 12 volt automotive circuit to trigger about 60 seconds of power output to a latching relay on output pin 3 of the 555 Timer chip. The schematic below is a ...
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2answers
85 views

Wake up circuit - keep the circuit off when not in use

Goal: As the power supply is a battery, I want to shut down the circuit when it is not in use. Circuit description: Basic 555 timer circuit. By pressing the switch, the light turns on. What I have ...
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4answers
153 views

What type of capacitor is most stable for use in 555 timer circuit?

I am building a 555 timer circuit with a frequency of 15, 30 and 60 Hertz. I will most likely use a 1µF capacitor but I was wondering what kind of capacitor would be best for keeping a stable value ...
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3answers
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555 timer frequency is way off

I'm currently designing a 555 timer to provide a 38kHz square wave to drive an IR LED as part of a beam interrupt detection system. This beam interrupt is a part of an embedded product where we ...
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2answers
235 views

Using high resistance resistor greater than 10M possibly does not work with 555 Timer

I am trying to create a 20 minute timer for 20-20-20 Rule with some bunch of resistors and capacitors available with me. I am using a 10M reistor here in place of R1 and some 10K/20K in place of R2. ...
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65 views

Monostable and astable on breadboard

I am trying to fit all three modes on of 555 timer on a breadboard. But no matter what I do I am not able to get it to work on a single breadboard. When I move the circuits on different breadboards ...
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1answer
79 views

555 Timer Output Always V+ or Ground?

If the output of the 555 timer is not trigger to high, is it ground? Or is the output left floating?
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58 views

Small ripple in 555 timer output when connected with a 2nd 555 timer chip

I have two 555 timer chips. The 1st is used to create a transition every .1 seconds while the 2nd is used in a monostable configuration to debounce a button. When using my DLA to look at the output ...
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3answers
115 views

Why won't this 555 timer flashing circuit work?

The circuit which I made shows the following behavior, when power is given to the circuit: Sometimes it lights up, sometimes it doesn't. When it does light up, it flashes properly for a few seconds ...
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60 views

PWM with 555 timer IC

I am trying to build a PWM signal with 555 timer. I am following this website to build my circuit. simulate this circuit – Schematic created using CircuitLab I have placed my components in my ...
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2answers
148 views

Boost converter based on 555 timer not working

I tried to make a simple boost converter circuit for driving an LED using 555 timer IC, but somehow the output voltage is not increased at all. I suppose that the problem is the inductor I used, since ...
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1answer
151 views

Designing a circuit with a “short-lived” switch with 555 IC

i am very new to electrical engineering and designing circuits and there is a particular project that i am working on that involves using a switch and a 555IC timer. So basically my desired output ...
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31 views

Total Power Cutoff circuit

I'm designing a battery controlled circuit using a 555 timer to control a mosfet to provide power to a load. The problem I'm trying to solve is to reduce the current draw while the circuit is not ...
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0answers
48 views

Wireless power transfer circuit to attain ~5W of power on the receiving end

I am designing a WPT system to run a ws1812 based pixel chain. The ws2812 pixel chain runs on 5v and consumes 500-800ma of power, means 2.5w-4w. The system I made is not able to transfer adequate ...
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1answer
52 views

Backup PWM signal for DC fans

Currently, I have a board that powers 4 DC fans. A PWM signal is received from an external microcontroller to control the fan speeds. Unfortunately, the microcontroller sometimes fails to send the PWM ...
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1answer
88 views

Using the same potentiometer for two 555 timers

simulate this circuit – Schematic created using CircuitLab I have two 555 timers hooked up and I want them their duty cycle to be controlled by the same potentiometer. The second one has twice ...
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0answers
56 views

555 timed power at high to low edge in battery powered circuit

I have a lovely Atmel touch sensor whose output is high only as long as it's touched. I want both off-on and on-off edges of its output to initiate two 3 sec pulses (and the time between edges is > 3 ...
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51 views

Comparing the results of two electronic dice

I made two electronic circuits each consisting of a 555 Timer, a CD4017 and 7 leds in the shape of what you'd find on a dice. They work great and all, but I want to "compare" the results of both and ...
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1answer
36 views

Time step Error In Multisim Using 555 timer

I am trying to simulate a circuit in multisim and I keep running into the following error. (new to multisim) I attached a picture of the circuit and error. Any advice on how to fix this? The purpose ...
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62 views

Back EMF protection

I made an ignition coil driver circuit which is nothing special - they are everywhere on the internet. What's really bothering me is the back EMF that would fry the 555IC. If I put a rectifying ...
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6answers
5k views

Where do overtones in a 555 generated square wave come from?

I have built a 555 oscillator and connected it to a speaker. Using an oscilloscope I adjusted the 555 to generate a 2.5kHz square wave. I then held a microphone up to the speaker and fed the input ...
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2answers
59 views

Getting trigger signal for 555 timer from elevator button

I want to turn a load like light on for a certain time when one of elevator buttons pressed say button 1 and while the button pressed the load should be on. In the figure below circuit 1 describe how ...
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2answers
115 views

555 PWM motor driver controlled by external analog signal

I used the below 555 timer PWM circuit to control the speed of a dc motor, and it works like a charm :) now i have a requirement to change the PWM speed externally from another module, that module ...
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2answers
64 views

2-Bit timer with 1 ms period

I am trying to find a simple hardware solution to implement a 2-bit timer that gives out 2-bits continuously repeating data 00, 01, 10, 11, 00, 01.... whose time period is approx 1ms. The accuracy and ...
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1answer
49 views

Why should we charge the capacitor halfway in 555 timer circuit(as given in datasheet)?

In the Texas Instruments datasheet for LM555 IC, at Page 11 below Figure 15, the calculations for charging and discharging of the capacitor are given. In those calculations, the capacitor is made to ...
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1answer
63 views

Cascade of 555 timer with Control Voltage not triggering

Hi I'm currently working on a cascade 555 circuit, both operating in the monostable mode. I also want to be able to control the pulse width with a voltage so am using applying 0-5v to the ctrl pin (...
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2answers
87 views

555 Timer - How to quickly discharge RC capacitor

I'm using a 555 timer to turn off an LED with delay. Here is the circuit. All I want to implement is, to get the input voltage changes in output with a constant delay. When I close the switch, the ...
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1answer
54 views

Capacitor Discharge Pin 7 555 Timer

I am very new to electric engineering, so bear with me ;) Before building the circuit IRL, I wanted to try to build a simple 555 timer with a simulator following ...

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