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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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
104 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
48 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
67 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
57 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
85 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
441 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
93 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
37 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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2answers
129 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
217 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
73 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 ...
2
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2answers
77 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
34 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
34 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
133 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 ...
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9answers
289 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 ...
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1answer
96 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
126 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 ...
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1answer
110 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 ...
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1answer
57 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 ...
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1answer
58 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
76 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
102 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 ...
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4answers
87 views

Unstable input to trigger LED after 10-15 seconds (12 V)

I have a small excavator that, when fuel levels get low, the warning light flashes irregularly (due to movement of the machine) until it stays on as fuel level gets really low. It's very annoying and ...
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2answers
45 views

Discrete Logic with Seven Segment Displays Problem

As a small project, I decided to make this circuit from Gadgetronix. However after wiring it, the display is stuck on 20 and when I activate the pushbutton, the 0 (display of IC2) just dims, and when ...
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1answer
44 views

Having trouble with light activated circuit.

R1 = 10K 1/4W Resistor R2 = Photoresistor (any type) R3 = 2M2 1/4W Resistor R4 = 1M 1/4W Resistor C1= 10µF 25V Electrolytic Capacitor C2 = 100nF 63V Polyester Capacitor D1 = 1N4148 75V 150mA ...
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2answers
66 views

Lower resistance resistor in place of a higher resistance one

I drew this small circuit from a design a friend gave me to blink an LED, but I am missing a certain component. I am missing a 12KΩ resistor. Can I get away with a 10KΩ resistor in its place?
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1answer
40 views

Monostable IC 555 with 12 volts output voltage

i know that in the 555 IC you can feed it using 5 volts to 15 volts, i need a Monostable circuit using a 555 with output voltage, i can use a transistor in the output, does anyone has a diagram like ...
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1answer
76 views

is a 555 timer flyback driver lethal?

i have always heard on websites that the 555 timer flyback driver is not lethal. i know that the common ZVS driver is lethal but would the 555 flyback driver be able to deliver a deliver a lethal ...
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0answers
46 views

NE555 Timer working only with B20 Buzzer

I have been new to electronics and was working with NE555 Timer. I connected the circuit as the image below: Resistor on pin 8 is 220 Ohms Resistor on Pin 6-7 is 1000 Ohms Capacitor on Pin 6 is ...
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2answers
130 views

4060 Timer Calculation

I am working on an analog timer using a 4060, 4017 & 555 IC to create a circuit. I need a timer which is 48 hours OFF.. 12 minutes ON.. to control a standard relay. So far I have got the ...
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1answer
108 views

Advantages on using a function generator against a multi-pulse generator by using a 555

I have designed a noise and interference reduction block. When I was going to test it by mounting the system in the lab, my professor told me that I could test it by creating a source of 50Hz by using ...
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1answer
56 views

Momentary switch with IR receiver and transmitter

I want to make a momentary switch with help of IR receiver and transmitter. I need only a pulse near about 2 seconds and I chose this circuit http://www.meedtech.com/touch-free-timer-switch-circuit/ ...
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1answer
37 views

What is the difference between a precision timer and LinCMOS timer?

I'm busy with a certain project that needs a 555 timer chip. But there are different kind of timer chips and I don't know what the differences are. What are the differences between a precision timer ...
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1answer
113 views

555 Timer @1MHz

i am very new to electrical engineering and super unsure what to buy, because this is my first practical project... The task: I want to implement a hardware timer ...
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2answers
82 views

Triggering a 555 timer IC

I need to trigger a 555 timer IC in astable mode as soon as it has power. It CAN NOT be done manually through a negative pulse like it usually is. The solution must be compact as space in my project ...
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2answers
83 views

what type of switch would this be?

what type of switch will normally be off/ open but when activated and held in the on/ closed position will then go back to the off/ open and rest when the switch is released? I am wanting a to make a ...
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1answer
61 views

555 timer output current

I'm designing a 555 timer circuit where I want to control the brightness of an LED array. There is a minimum lux requirement for the array so I need to know the output current when I have a 4.8 V ...
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1answer
526 views

Build DC/DC (Buck) Converter using 555 timer

I saw a design for a 12V DC to 5V DC buck converter using a 555 timer on http://www.simple-electronics.com/2011/10/12v-to-5v-converter-555ic-mosfet.html. Is this a good design to use towards my smps? ...
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4answers
291 views

DC motor speed control -> motor heating up too much

I have 90V brushed DC motor which I try to make to turn 100-500rpm with PWM controller (555 based, 100Hz). Otherwise it works but the motor heats up so much that I can not touch it with hand. I think ...
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3answers
122 views

555 AM transmitter

I looked on instructables and I found an interesting(at least for me) AM transmitter made with a 555 timer which acts as the oscillator:http://www.instructables.com/id/555-AM-Transmitter/ Is this ...
0
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4answers
117 views

NE555 output voltage is too low

I'm trying to make a simple astable circuit. It should be one of the easiest ones in history of electronics, but I can't figure out what's wrong with my design: simulate this circuit – ...
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0answers
102 views

555 to debounce comparator output for PIR circuit

I'm trying to create a circuit that takes an input from a PIR and outputs a high signal when movement is detected. My circuit currently looks like the schematic below (VCC is 5V). The circuit works ...
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2answers
85 views

How to use 555 timers to control 2 relays [closed]

I'm looking for a way to do the following: Once triggered, the circuit will close the first relay (R1) for 10 seconds, then open then close the second relay (R2) for 10 seconds, then open have a ...
2
votes
2answers
96 views

555 timer circuit error

I have recently built a circuit with a 555 set in monostable mode which was supposed to turn on three bright LEDs for 51 seconds when a button was pressed.The button was connected with some long ...
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1answer
86 views

How to drive NPN transistor based on this circuit?

I just built a fan speed controller, using the following schematic: Now if you connect 12V from 555 and connect pin 7 to the blue CPU fan wire, it controls the speed, but whenever the PWM signal is ...
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0answers
112 views

Which are the reasons to burn/bust 555 timer IC ? How to prevent?

I am using NE555 in inverter circuit & VCC voltage is regulated 16VDC from LM317. But issue is that NE555 IC bust after 3-4 month on site. I try to simulate same condition in my lab but couldn't ...
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2answers
50 views

Deactivating NE555P with a latch

I wish to use a two gate latch to control a 555 timer.The goal is to turn off the output by shutting down the IC.Will this happen if I disconnect the positive supply or the ground so there will be no ...
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1answer
40 views

Controlling valves the efficient way

I am working on a Project that require something very simple. Is actually so simple that I’m more worried about getting it the most efficient way (less price with better solution). The project ...