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 to balance between frequency and duty cycle in this circuit?

I have this astable circuit that generate square waves with independent control of frequency and duty cycle: For this circuit: $$t_H=0.759\,C\,(R_f+R_y)$$ $$t_L=0.759\,C\,R_x$$ $$period = ...
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1answer
33 views

Speed and direction control of motor by using IR & 555 on Proteus. (Circuit with errors is attached.)

I am trying to control motor direction & speed by using IR and 555 on Proteus. Circuit and errors images are attached. Please help me solving this quagmire.
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1answer
36 views

Why I am seeing a spike of 9V on output and capacitor in 555 timer

I would like to have high voltage at output initially for a period of time, then low and high ... . But in the following circuit, I see spikes on output (green) and capacitor (blue) for a short period ...
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2answers
41 views

Closing a switch for a fixed (but short! milliseconds) amount of time

I would like to create a circuit with a button. When this button is pressed, a circuit should be closed for a fixed amount of time. Right now, I have managed to get the desired effect using an ...
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0answers
15 views

Understanding how to use a counter and timer for a fixed number of counts

I'm going to generate pulses indefinitely with a 555 timer and use have a counter such as the below one count from 0 to 64 or another power of two and convert the output into an analog voltage to ...
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1answer
46 views

How to change the frequency of this sawtooth generator circuit?

I've found the circuit below in "The Art of Electronics" book. This circuit generates sawtooth signal. This is some of what is written about it: By using a current source to charge the timing ...
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1answer
35 views

Servo control with 555 timer

first of all this is for an assignment so I have certain limitations, mainly cost. The problem I'm having is I have run out of PWM inputs on my ATtiny45 but I still want to drive a servo. The two PWM ...
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3answers
298 views

555 ticks at different frequency than calculated

I'm trying to get a 250kHz signal with 58% duty cycle from an NE555, i'm using values calculated by an online calculator but the circuit clocks at 168kHz when viewed in an oscilloscope. I'm feeding ...
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0answers
14 views

Orcad PSPICE Temperature Sweep

I have built a multivibrator oscillator using an op amp circuit (similar to a 555 timer approach) in PSPICE. The output is correct so the entire circuit is functionally working. I am trying to see ...
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1answer
112 views

(schematic) Using a micro controller to drive Opto-coupler > 555 timer > MOSFET

I'm trying to use a micro-controller to activate an opto-coupler connected to 555 timer which is connected to a MOSFET. The circuit will drive a solenoid which draws 2amps at 12v. I'm new to circuit ...
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4answers
477 views

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 ...
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4answers
104 views

How can you wire a 555 timer to gradually decrease sound volume?

Say you are taking in an audio input from a headphone speaker and you would like the audio to gradually decrease until inaudible. Are there better, also very common chips that can do this more ...
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1answer
30 views

Automatic and manual clock managing. Errors with ring counter but not with 4-bit counter

I'm building an 8 bit computer and I've just developed the clock. I used a NE555 (datasheet) with some other integrated (74 series) to manage it. The operator could stop signal from 555 (with a ...
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1answer
88 views

How to build a circuit that generates a sine wave?

How can I build a circuit to generate sine waves? What I am working on is building a 555-timer circuit that gives 50% duty cycle square wave, then using a low-pass or band-pass filter tuned to the ...
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1answer
102 views

Power calculation of circuits

Please read on..... this looks long but is entry level and easy I have done many simple projects based on microcontrollers but have not considered power and required current(for circuit to work) ...
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1answer
36 views

Glowing two leds alternatively in a given ratio of time

I want to design a circuit for glowing two leds for alternate intervals for different input voltages. For example: Consider two LEDS Red and Green. When the input voltage to the circuit is 0-5Volts ...
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1answer
53 views

555 autostart counting

In a monostable configuration of the 555: http://circuitdigest.com/electronic-circuits/555-timer-monostable-circuit-diagram I have connected pin2 to the ground all the time. My goal is that once the ...
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1answer
55 views

TIP 120 replacement

Although I read the article advising against using TIP120: http://sensitiveresearch.com/DoNotTIP/ I only have couple of other transistors on my hand: ...
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1answer
54 views

555 timer digital clock

How would you go about connecting a 555 timer to a circuit with a 16x2 LCD display, which is already connected, to create a digital clock that counts the time? Do you have a sample of how this code ...
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1answer
38 views

555 delay circuit is unsatble

Hello I have built the 555 delay power off circuit by using these 2 guides: home.cogeco.ca/~rpaisley4/LM555.html#30 http://www.electroschematics.com/5963/adjustable-timer-1-10-minute/ I using a ...
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0answers
34 views

H Bridge 555 Timer Votlage Drop

I am building the circuit presented at 4:45 in this video https://www.youtube.com/watch?v=iYafyPZ15g8 The problem is the frequency of the output of the 555 timer changes depending on the whipper but ...
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1answer
60 views

555 VCO Circuit - Speaker to VCC?

Hello! I have a simple question concerning this circuit I have built: It is a 555 Voltage Controlled Oscillator I have built as a foundation for my signal generator circuit. The circuit works ...
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2answers
63 views

make motor ON and OFF for fixed interval of time

I am new to electronic, studied this subject long time back but now not able to recall anything out of it. I have requirement to ON the motor after fix interval of 4 hours and run it for 30 seconds ...
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2answers
90 views

What circuit should I study, to learn all the details of the 555 timer? [closed]

I understand OHM's Law, and have a conceptual grasp of RCL circuits, but am a little weak on the math. I am good at math, even a little calculus, just weak on RCL math. I am trying to understand the ...
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4answers
90 views

Variable Resistance

simulate this circuit – Schematic created using CircuitLab This is a pulse generator, outputting square pulses with about 8% duty cycle. Tuning R2 down to 120k will result in the same ...
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2answers
55 views

How does the internal circuit of the 555 works in terms of transistors

I saw many explanations of 555 internal design based on block diagrams. It's good for basic understanding, but I want to understand how those internal transistor circuits make those blocks. I can see ...
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2answers
46 views

I need some help calculating values for a variable 555 oscillator circuit

For the past few hours i have been strugling with a 555 timer. What i am trying to do is generate a square wave of variable frequency controlled by a potentiometer. At the time i have a 200KΩ ...
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3answers
160 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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3answers
123 views

Timer sequence with delayed off and long trigger pulse

Attached here below is the input and out put sequence that I am trying to achieve with a timing circuit. This looks like something that might be achieved with a few monostable 555 timers, but I am ...
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3answers
78 views

555 monostable/astable on one chip

Is there any way to use a single 555 chip which could be switched with a two-state switch between monostable mode (one-shot pulse of a certain width) and astable (continuous pulses of a certain ...
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2answers
79 views

Complicated photo-motion-timer switch design?

Here's my scenario: I have an array of 120V LED fixtures that need to be turned on for 10 minutes when the following conditions occur: It's dark out AND Someone walks in front of a motion sensor ...
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1answer
136 views

Circuit for automatic watch winder

Looking for some advice, completely new to electronics so please bear with me. I am currently working on a project to build an automatic watch winder, I have a 12v 10rpm motor which should be ...
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5answers
520 views

Handmade timer versus IC

Are there power consumption benefits between a discrete timer: astable multivibrator or some other; and an integrated circuit? I have a time dependent circuit in a project and I went looking for the ...
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3answers
100 views

Transistors hooked up to one another

I stumbled upon a very badly drawn circuit on the interent which must be good . I have not been able to figure out how a series of transistors work in this circuit. It is depicted below. ...
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1answer
48 views

Astable 555 Timer creates longer pulse when just turned on

I have a question regarding the behavior of a 555 timer circuit that I have made. It is depicted below. Now, here is some interesting behavior, I wrote a program on arduino that measures the ...
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4answers
200 views

How the pin2 of 555 timer triggers this simple circuit?

First of all, I will go through my concept which make the doubt. When we connect positive side of LED to a positive terminal of a battery and negative of LED to floor (not to -ve of battery), current ...
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2answers
223 views

Reset Power using 555 timer

I'm trying to cut the power for 5 seconds to my circuit every 30 minutes using a 555 timer. I've been trying to design my circuit using 555timer and NPN but im not having any luck with it has anyone ...
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1answer
77 views

Extending diode with a buzzer

Basic idea is to extend existing device with a buzzer: I want to make noise when one of the diodes lights up (DL12 on the attached picture). From the layout of the board I assume that U1 (M74HC595) is ...
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2answers
83 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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0answers
46 views

clarification on a particular 555 implementation for 4017 johnson counters

I'm trying to build a 13 count johnson ring counter (which flashes LEDs sequentially 1 thru 13 and then repeats), and I found this circuit which looks perfect: I assembled it with an extra LED on ...
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1answer
48 views

555 Timer in Bistable Mode - Unexpected Behavior When Removing Power

I have a question regarding a 555 timer (TLC555CP) in bistable mode. Here is the schematic for the circuit in question. Now, this circuit works as I expect, when I hit the push button attached to ...
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4answers
228 views

LED dimmer for high current applications

Hi Guys .. I am designing a few panels using LEDs for backlighting. Some of these panels have over 20 leds, using a 5v power source. So only one of these panels can draw around 500mA alone. I am ...
3
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9answers
475 views

How can I make a linearly tunable 50% duty astable multivibrator?

I want to make an astable multivibrator with a 50% duty cycle that can be tuned with a potentiometer for generating sound, so accuracy is desired. My first thought was to build the standard one with ...
2
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1answer
114 views

555 Input Impedance

I'm building an audio circuit and need a comparator. I've explored using an op amp for this purpose but my TL072 doesn't seem to have a high enough slew rate which resulted in latency. Instead, I've ...
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2answers
144 views

Why does the Green LED stay lit and Red LED stay off in this 555 circuit

This extends my previous question involving same circuit, information replicated here for convenience and independence of this question. The following circuit schematic: Has been connected as ...
0
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1answer
124 views

Why do the 9V batteries immediately deplete on connecting to this circuit?

My son put together this railroad flasher circuit on a breadboard. He (and I) tried 3 brand-new 9V batteries. On connecting them to the circuit, the batteries immediately deplete/discharge ...
0
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1answer
119 views

Add a timer LM555C on Qucs

Does anyone know how to add a timer on Qucs ? The component's navigation bar doesn't help at all, It confuses me, I can't find a timer. I wondering, perhaps It could be added through library. In this ...
0
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1answer
97 views

Help with using monostable one-shot multivibrator?

Above is the schematic I simulate in LTSpice. The input signal is a 8V pulse train with 100us ON time and 2250us period. The signal is fed as an input to the timer 555(NE555 in LTSPice). I'm trying ...
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1answer
93 views

Converting constant voltage to a pulse

Im trying to do research for something I can't even name. Basically it goes like this: It's kind of like a multi-vibrator, but I need it to give a short pulse on the output, while input is a ...
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3answers
122 views

Blinking LED at two speeds using 555 Timer

I'm trying to build a circuit that will blink a single LED twice a second for one second and then once a second for two seconds. I can get the individual frequencies with two different 555 timers but ...