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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 low price and ubiquity. The 556 timer is simply two 555 timers in a single package.

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Analog pulse width detection [closed]

I have to make an analog circuit that the input is a pwm, when the pulse width is 1000ms the output must be 0 and when the pulse width is 750ms the output must be 1, i tried using an 555 with a ...
Rodrigo Vernizzi's user avatar
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1 answer
50 views

Can't get 4017 led walker to work

For days I've tried to create a simple led walker using a 555 and 4017 IC, with a 9v battery. My latest attempt was from the electronics for dummies book: I'm not using these exact values, instead of ...
Oli's user avatar
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1 answer
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555 timer automatic triggering in monostable mode

I have a 555 timer in monostable mode connected to a momentary push button. My goal is to power the circuit, and then press a button that will start the 555 timer for 10 seconds, then completely stop, ...
Michael's user avatar
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Dimmer circuit for LED brightness control

I have a circuit using 555 timer with 2 tact switches to increase and decrease the brightness of LED, but what I need is to store the last state of circuit whether it is on/ off and also automatically ...
Nan dv's user avatar
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0 answers
52 views

Problem with the triggering the 555 monostable trigger

I am currently making a dual speed dc motor circuit that is controlled by 555 timers. My goal is to have DC motor full speed below 2V and between 2-3V, the DC motor spins half-speed using PWM from 555 ...
Anson Chow's user avatar
8 votes
2 answers
2k views

How can the CMOS version of 555 timer have the output current tested at 2 mA while its maximum supply is 250 μA?

As per the Datasheet of LMC555, the maximum supply current is 250 μA @ 5 volt supply voltage. How come the output current reach 2 mA, I mean where did the IC get the extra (2*1000-250) μA? Maybe I ...
AbdAllah Talaat's user avatar
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1 answer
46 views

555 IC - Role of Resistor in Capacitor Discharge (Astable mode)

I can't grasp the role of resistor Ra in this circuit. I know that when the output from the SR latch is low, the transistor doesn't allow the capacitor to discharge. And when the output is high, ...
João Amaral's user avatar
1 vote
1 answer
79 views

How to implement a blinking led circuit that is dependent on its voltage input?

I am designing a circuit with two LEDs, where one LED will blink when the output voltage (Vout) is 5V and the other LED will blink when Vout is grounded. I am confident in the functionality of the ...
Ewheel's user avatar
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1 answer
90 views

Pulse generation with NE555S-13 (square wave)

I want generate a 5 volt, around 55 Hz(50-60) square wave with an NE555S-13. In the datasheet, I found the configuration for astable operation which I assume is what I want: screenshot from datasheet:...
George P.'s user avatar
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Home a servo motor after power shutdown

Background: I'm trying to setup a servo motor 1171MG with a 555 timer and finetune the position with a potentiometer as it depends on various project aspects. The circuit is driven by a small board &...
Squiffy's user avatar
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1 answer
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Astable 555 timer staying on

I've recently followed Ben Eater's tutorial on how to make an astable 555 timer with parts that were just hanging around my house, albeit with a NE555P instead of his HA17555. I did not have a 10kOhm ...
Stressed 's user avatar
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How to use a monostable 555 one shot circuit with a single dc rise at the trigger

In order to measure battery contact fidelity/degradation I am developing a "one shot" current measurement circuit. Basically, when a HV battery is plugged into a connector I will have a ...
wgthompson's user avatar
1 vote
2 answers
134 views

Having trouble with a 555 Astable timer outputting into NPN transistor switch that controls 741 Op-Amp

I have been building a circuit that takes the output of a 555 IC and outputs it into an NPN transistor that acts as a switch to toggle a 741 Op-Amp connected to an 8 ohm, 0.5 watt speaker. I'm new to ...
RetroBoltDev's user avatar
1 vote
1 answer
54 views

NE555 PWM Circuit Problem [closed]

I am using NE555 in a care-over project for generate PWM. But i have a problem. On this 12V input path, there is 4.2V on the R1 resistor, although it is expected to be 11.6V. What could be the reason ...
SpeedyGonzales's user avatar
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2 answers
120 views

what the electronic board is this

I have a few questions: First Does anyone know what the electronic board is this.... Or what electronic board this homemade electronic board is based on?
SergeyE's user avatar
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Troubleshooting a Positive Rising Edge Trigger Monostable Circuit with 555 IC

I've been working on designing a positive rising edge trigger monostable circuit using a 555 IC, aiming for a pulse duration of around 5 seconds. However, my simulation attempts have been unsuccessful ...
seccpur's user avatar
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2 answers
119 views

How to create a 38 kHz pulsating signal using two 555 timers

I need to create a circuit that will send out a 38 kHz, 50% duty cycle wave for 0.52 ms and then off for 0.39mS. I have searched various sites and I get conflicting information. Some sites state to ...
Rick's user avatar
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1 answer
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Output of TIP122 drops when connecting a load

I have built this circuit: (the components here are labeled wrong LM317LZ is LM317T and TIP122G is TIP122) When there is no load the output of TIP122 is 10V-20V (when adjusting potentiometer) which ...
Raudonkepuris's user avatar
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0 answers
37 views

Ne555 Dimmer using IRFZ44

Excuse me, i am trying to deal with my semi-conductor devices course's assignment of my first year. My topic is that using ne555 and irfz44 to drive a resistive and inductance load like Led or Motor. ...
CÔNG NGUYỄN DUY's user avatar
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1 answer
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Using a 555 Timer to Connect to An Asynchronous Counter in Proteus

I'm trying to drive a binary asynchronous counter via the following setup though usually if I see binary counters they are connected to a 'CLK' source of some sort. In an ordinary case, the circuit ...
MechatronicsStudent's user avatar
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LED dimmer driver board

I am all very new to the electrical stuff and perhaps this is an advanced project but hopefully someone can at least point me in the right direction. I am looking to create a PCB that will allow me to ...
Maciej Olborski's user avatar
-1 votes
1 answer
60 views

How do I flash LED with signal from 555 timer ONLY when button is pressed?

I am trying to make a circuit in which an LED is off until a button is pressed, and then it flashes with a 1Hz signal from a 555 timer. Currently, its default state is flashing with 1Hz and when the ...
Chandler Thornton's user avatar
1 vote
2 answers
82 views

Low power toggle switch

I have used a 555 to toggle output on/off from a push button pulse and was wondering to use something similar to TTP223 due to its low consume once with 555 have more than 10mA in standby, anyway ...
Daniel Pechmann's user avatar
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3 answers
94 views

555 Timer for Motor Direction Control

I am building a circuit to control the direction of a DC motor using two 555 timers. The circuit diagram is given below. There will be a potentiometer and when it is turned to the rightmost position, ...
Kailash Kumaravel's user avatar
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1 answer
116 views

555 Monostable Mode Press and Hold Trigger

So, I have a 555 Timer in Monostable Mode, like below. I used a 47uF cap and a 47K resistor for the C and R. I press the trigger switch button and let go, and the output goes high for roughly 2.5 ...
Erik Vincent's user avatar
0 votes
3 answers
45 views

Flashing an LED while Raspberry Pi boots, then illuminate constantly via GPIO

I would like to flash an LED when my 5V power supply is turned on to indicate my Raspberry Pi is booting. Then, when booted and my application is running, I'd like to make a GPIO high (or low) and ...
edlea's user avatar
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1 vote
1 answer
66 views

555 Circuit for Spark Gap Lighter Not Functioning Correctly

I have a circuit designed and fabricated with the following schematic: The specific 555 timer I'm using is a NE555DR. However, when under power the circuit doesn't appear to oscillate and no spark ...
Charles Dean Modrich's user avatar
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0 answers
45 views

Toggling a relay using a 555 timer

I seem to be experiencing errors when trying to toggle the relay using a 555 timer. I have used two different simulation software packages already.  They both seem to crash. There appears to be some ...
Zipho Lunika's user avatar
2 votes
2 answers
122 views

LTSpice model of a NE555 as linear ramp generator has wrong frequency

So I found the variant of using an NE555 to generate a sawtooth signal by charging the capacitor using a constant current source. The simulation is shown below. The lower treshold is 1/3 * VDD and the ...
Junius's user avatar
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-1 votes
2 answers
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Configuring an astable 555 timer to milliseconds

I am working on a Tinkercad project and I would like a 555 astable clock for it. I am trying to configure the astable 555 timer for every millisecond (or something close). I don't know how to do it, ...
some human's user avatar
0 votes
2 answers
102 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
135 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
351 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
126 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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0 votes
3 answers
188 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
96 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
181 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
0 votes
2 answers
92 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
0 votes
0 answers
134 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
  • 1
2 votes
2 answers
224 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
  • 31
2 votes
7 answers
428 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
151 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
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1 answer
62 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
127 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
107 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
0 votes
1 answer
108 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
109 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
45 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
694 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
0 votes
1 answer
113 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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