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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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3
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2answers
456 views

How does this circuit work to fade an LED in and out?

I'm new to electronics. I'm trying to figure out how this circuit works to fade the LED light in and out: This is how I think it works (of course, I'm wrong): When you initially connect the circuit, ...
4
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3answers
1k views

On— off— on— off timer circuit

I want to make a circuit to do something that is relatively simple but I need to find the optimal way to do it in order to take as little current as possible. Here is what I want to do: When a ...
5
votes
3answers
2k views

Creating positive and negative voltages from a battery

I have a circuit that is usually powered by +9V and -9V (uses two 9 volt batteries), but I am trying to power this from a rechargeable 3.7 V battery. The circuit does not draw much power (can be ...
1
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2answers
695 views

Replacing push button by transistor in 555 circuit

TL;DR: I need to replace the button S1 by a circuit/component that could close the circuit which the button is closing by applying a 5V signal (with 0.5s duration) in the new circuit/component. Well, ...
1
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1answer
563 views

Very Basic 555 Timer oscillator not working

I've been trying to make an LED blink. My first approaches were without the 555 timer, and they were unsuccessful. I decided to make an Astable multivibrator circuit. I'm using an NE555, and I'm using ...
2
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2answers
164 views

Low power delayed off circuit

I am running into problems creating a circuit that once a button is pressed ( clicked ) will latch and run for a few seconds and then turn it self off. This would be trivial with a MCU but now I am ...
0
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3answers
383 views

How to check for quick oscillations without an oscilloscope

I'm working on a 555 timer oscillator circuit, and I'm trying to get an LED to blink. The LED turns on, but I'm not sure if it's blinking. I do not own an oscilloscope I've tried a few things, such as ...
1
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2answers
299 views

With a 555 + 4017, how do I light 7 LEDs, then 6, then 5… then 1 then 0?

I'm in the process of turning a Raspberry Pi project into a simpler circuit board powered with 555 and 4017 chips. I want to be able to start by showing 7 LEDs, then go to 6 then to 5 and so on until ...
0
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1answer
378 views

How to drive a 555 timer with pwm input?

I'd like to create a square wave generator with variable frequency that is determined by the presence of a 0-5 volt input signal. I have a very sketchy understanding of electronics - but I know what ...
0
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1answer
166 views

555 - HIGH then long delay [duplicate]

I trying to create a circuit with only one 555 to send HIGH on output(3) for very short time, like 200ms, then set LOW for something like 20~30 seconds. Then I'm just need turn on circuit, then: a) ...
0
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0answers
193 views

Transistor for 38kHz IR pulse amplification

I am trying to build a timer circuit in which I will send a modulated 38kHz (almost) signal to an IR Receiver (TSOP38238 in Arduino Nano) and I want to amplify the square wave to the IR Led to ...
0
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1answer
428 views

Creating stepper motor driver using only TTL ICs [closed]

I am trying to drive a 5-wire unipolar stepper motor WITHOUT a microcontroller or driver ic, just using logic gates and JK flip flops (74LS107N's). The motor shaft needs to rotate a certain number of ...
0
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1answer
44 views

Timer with fixed input [duplicate]

I'm using a lm555 IC in monostable mode. When my input varies from 5v to 0v the output goes from 0v to 5v. But this only happens perfectly if it happens just a pulse at the entrance, in case my input ...
0
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1answer
428 views

How do I drive pin 2 on my 555 IC low so the one-shot timer will fire, using an IR sensor in place of my pushbutton switch?

I have a basic one-shot timer circuit (shown below in schematic). If I press the button, it brings pin 2 low and triggers the timer one time for a period which with my cap is about 5 seconds. Use IR ...
-1
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1answer
122 views

Relay sending too many signals.

I have a 555 timer clk output going to the coil of a relay. 5volts going throw the contact. The 5volts is then going to the clock bit of a CD4026 then to a 7 segment display, Seems the relay is ...
1
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1answer
80 views

Keeping a PIR on all the time

I've just moved to a student accommodation,and they are using sensors to keep the lights in the room on(I'm almost sure that they are PIR). The problem is that they turn off way too quickly and it's ...
-2
votes
2answers
646 views

How to stop a 555 timer [closed]

I have a 555 timer set up so each cycle it will count up a 7 segment display. clock output of 555 goes to a CD4026B clock input , this feeds the 7 seg display. I would like when the 7-segment ...
1
vote
1answer
306 views

Power & Reset in momentary switch in analog circuit

So I am designing a circuit and wanted to implement both power and reset in one momentary switch. What I mean is, if the switch is pressed, it sends a reset signal (4.5v), but if it is held for x ...
3
votes
1answer
242 views

12V variable-speed fan as a function of temperature using 555 timer

I would like to turn the car fan into a variable-speed fan using a the analog temperature sensor of the car, and a 555 timer. While temperature decreases, resistance (of the sensor) increases. Can I ...
1
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0answers
135 views

Can I control the charge of a Cell-Phone with a 555 Timer and a Transistor?

I want to charge my phone in a controllable manner, using a 555 and a Mosfet transistor. The 555 is a countdown timer that gives an output (pin 3) of 5V for 1 minute, and then remains at 0V until an ...
0
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1answer
305 views

Q: Can I use the LM3914 voltage indicator IC as a low-voltage cutoff device?

I came across these two circuits, and tried them out successfully: LM3914 Battery Monitor, drives 10 LEDs in a linear relation to the input voltage. NE555 Low-Voltage Cutoff, uses a 555 timer to ...
0
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1answer
185 views

Can Pulsed DC be used in a radio transmitter?

I'm building a small radio transmitter based on a 555 timer. In my circuit a 555 timer in astable mode is used as an oscillator. kind off like : http://www.instructables.com/id/555-AM-Transmitter/ ...
1
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2answers
3k views

independent control of frequency and duty cycle in 555 timer (formulas)

I want to control frequency and duty cycle of output pulse of 555 timer. I searched and find this schematic in a post in SOV but I don't know how calculate frequency and duty cycle in the circuit. ...
0
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2answers
198 views

IR Barrier with a 555 [closed]

I'm trying to build an IR Barrier with an 555, a sfh4547 and a tssp58038. Here are the datasheets: http://www.ti.com/lit/ds/symlink/ne555.pdf https://www.osram-os.com/Graphics/XPic0/00209793_0.pdf/...
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2answers
607 views

What is the simplest possible monostable 555 timer circuit?

Say for instance, the goal is to light an incandescent bulb for x amount of seconds (let's say 20). What is the simplest configuration possible? Of course, simple timer circuits aren't rare, and can ...
1
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1answer
1k views

555 positive and negative edge detector?

Is there a circuit using the 555 (without additional logic gates) that creates a positive pulse when it detects a rising or falling edge? The goal is to have a circuit that detects when a signal goes ...
0
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1answer
248 views

How can I separate/isolate two parallel circuits running on the same battery?

I am mixing audio tones from two 555s. simulate this circuit – Schematic created using CircuitLab The basic circuit is working fine so I have not shown all the little capacitors and resistors, ...
17
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4answers
4k views

Why are 555 timers so prevalent? [closed]

I've noticed is that 555 ICs seem to be extremely common. Why is the 555 so prevalent, or ubiquitous; what about it so useful?
0
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1answer
245 views

Can I use a 555 to ignore short DC pulses in simple switch circuit? Not same as usual debouncing [duplicate]

I have a reversing camera in my car that I wish to: switch on whenever the reverse lights come on turn off when reverse lights go off. Problem is, my car's computer will periodically send these ...
-3
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1answer
133 views

Can a MicroSD card work at 144 kHz or lower?

Can a MicroSD memory card work at a 144 kHz or lower frequency? I want to read a text file that has a syntax that would be filtered and matched to a speaker. I would like to get data from the MicroSD ...
1
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1answer
1k views

Why does this Edge Trigger Work on input of 555 monostable config?

I recently wired up a 555 timer in a mono stable configuration and found that when the trigger was held low for longer than the configured output pulse width, the output would stay high. After ...
-1
votes
1answer
931 views

Simplest (cheapest) adjustable PWM oscillator? [closed]

I'm trying to make an oscillator where I can adjust the frequency and the duty cycle independently, but I'm not having much luck. What I want is a frequency range from 1Hz to 1MHz; and the ability to ...
1
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2answers
247 views

How can I decouple two 555s from each other?

I have two 555s in astable mode producing two audio tones that are sent to a speaker. The idea is to mix the tones. The power source is a single 9V battery. The problem is that the two 555s interfere ...
7
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3answers
826 views

Detecting sparks at the output of a high voltage flyback transformer

I was trying to generate plasma inside a cylinder for a hobby project, so I decided to use a flyback transformer from an old TV and drive it with a 555 timer as shown in the schematics. It solves my ...
-4
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2answers
247 views

Hi Can we have delay timer with one Shot ON/OFF?

Need a Timer circuit like, for 20 sec it should be on then completely off. generally RC timer gets off gradually so the buzzer sounds for long. Thanks in Advance.
0
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2answers
338 views

Timer of 12 seconds using hardware circuit

In my design, say there are 2 pins A and B. Now I want to implement circuit in such a way that B is initially high , but when A goes low, after 12 seconds B will go low for short duration and again ...
2
votes
3answers
75 views

Varying frequency by percentage, rather than with linear resistance?

I'm using a 555 timer to generate musical tones, and employing resistors to get various pitches. Instead of resistance by linear amounts (ie. 1KOhm) , is there a way to apply resistance by percentage?...
0
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2answers
249 views

Small Slope On Square Wave Generator Output

I have made a square wave generator using 555, however there is a small slope on the high level of the square wave as you can see below. How can i overcome and obtain a straight high level of signal? ...
0
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1answer
153 views

False Triggering of when Intergration of TI SE555 with Maxim MAX6866 IC

I am using Maxim MAX 6866UK28D3L+T in my Design with TI SE555 Timer IC , and having some problem of Flase Triggering. Circuit Explain:- WDI_IO is Drive from Micro controller , which Continuous toggle ...
1
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3answers
442 views

How are multiple frequencies played through a speaker/buzzer without distorting eachother?

I have an idea for an Arudino project which is essentially a piezo buzzer music machine that I will be able to program sheet music into. It would consist of individual 555 oscillator circuits at ...
3
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2answers
1k views

NE555 above 100kHz frequency problem

At first I searched this problem and could not find anything with this specific. I am using NE555 to generate frequencies. I'm using the calculations of this website. I am using 10nf as it says. My ...
0
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1answer
745 views

555 Timer in monostable mode with reset on the same momentary button

I've been researching this problem for a few days. I have a 555 timer for controlling a car heated windshield, and I'd like to have a single button controlling it, and use that same button to cancel ...
1
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2answers
677 views

Baby 10 step sequencer help!

I'm a beginner in electronics and am working on a Baby10 step sequencer for a project. It consists of a 555 timer for a clock signal, a CD4017 decade counter and 2 more 555s for an Atari Punk Console ...
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1answer
255 views

will this voltage tripler circuit work?

I need power supply for my opamp as i only have 5 volt supply. I need at least 14 volt power supply so that i can power my opamp. I recently got this circuit of voltage tripler using 555 IC. Will it ...
1
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1answer
219 views

Why doesn't my 555 + MOSFET setup drive my motor?

I have a 3v motor driven by a MOSFET that gets its input off an inverter circuit that comes off the output of a 555: The idea is that when you press the button, it waits for about 20 seconds and then ...
2
votes
1answer
96 views

Where does my negative input voltage come from? [closed]

I'm a bit confused about the concept of an input ground for an op Amp. Let's say I'm amplifying the output from a 555 timer ic. I assume the output pin from the 555 is my positive input but what is a ...
0
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2answers
668 views

555 auto-off timer circuit validity

I was hoping someone with experience with these types of 555 timer circuits would look this over and just see if I made any basic fundamental mistakes. I did a ton of research and believe I used all ...
0
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1answer
2k views

How to generate a 555 fixed time delay even if trigger button is held on? [closed]

Can any one help me how to make it when the switch is presed for long time but it will not affect the time delay
1
vote
3answers
2k views

Obtaining a triangle wave from a square wave using a LM324N op-amp

I am generating a square wave with a 555 timer chip and I am trying to obtain a triangle wave from the 555's output by using an op-amp (LM324N) as an integrator. The op-amp is in single power supply ...
0
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2answers
743 views

Alternate design for an astable 555 circuit

I was looking at how to get a sign wave from a 555 chip and found this article. It seems to say it's using an astable 555 circuit outputting to an LC resonant circuit. However, the circuit diagram ...