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.

Filter by
Sorted by
Tagged with
17
votes
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
votes
1answer
266 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, ...
1
vote
3answers
460 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 ...
0
votes
3answers
2k views

What is the typical frequency drift of an astable 555 circuit over its lifetime?

I am involved in qualifying a sine wave generator that is using a first order LPF and a 555 timer in astable configuration to generate a sine wave(-ish) output. I would have designed it differently, ...
0
votes
1answer
251 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 ...
-4
votes
2answers
252 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.
-3
votes
1answer
135 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
vote
2answers
259 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 ...
1
vote
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
964 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 ...
0
votes
2answers
354 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
votes
2answers
271 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
votes
1answer
161 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 ...
0
votes
2answers
4k views

555 Timer Monostable Mode Self Triggering

I'm working on a simple project with 555 timer. I'm trying to generate a high-state output for 10s when Vcc is applied to the circuit(It is initially off). However, I have not managed to operate the ...
3
votes
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
votes
1answer
760 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
votes
1answer
819 views

Servo control without micro controller

I am trying to create a circuit that will control a servo. I need the servo arm to move from 0 to 90 degrees when the power is turned on, and then from 90 back to 0 degrees when the power is turned ...
1
vote
1answer
229 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 ...
5
votes
1answer
5k views

Difference between NE555P and 555CN?

I'm working on a circuit that uses two 555 timers. At the electronics store, they gave me a handful of 555 chips, I only noticed the difference when I finished my circuit: the R1 value is shorted out, ...
2
votes
1answer
98 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 ...
2
votes
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
votes
2answers
692 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
votes
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
0
votes
2answers
775 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 ...
0
votes
1answer
174 views

Astable timer: Halve frequency while maintaining the same “up” pulse width?

Disclaimer: I am not an electrical engineer, but an environmental science student. I'm trying my best here. I have a basic astable 555 timing circuit with the following components: \$R_1 = 10k\...
2
votes
2answers
468 views

555 astable operation not getting stable frequency

I needed a 38 kHz wave no matter the shape. So I started off with a 555 timer to produce a 38 kHz rectangular wave using its astable mode. Here's the circuit: For that I used R1=9.8kohm, R2=17....
1
vote
1answer
810 views

A stable negative supply for an op-amp (using 555)

I need a differential amplifier circuit for my design and I am using the LM358 op-amp. The problem is of negative supply. I need to give negative power voltage to my op-amp(-Vcc). and I only have a 9v ...
1
vote
1answer
462 views

Making an 8-bit register using an 74LS377

I am trying to build a an 8-bit register using 74LS377 IC (It's from Motorola and the complete part name is 74LS377NDS but I haven't been able to find out what the extra letters mean, here is a ...
0
votes
1answer
66 views

Use 555 timer to output same interval as user presses a button

I was curious if such a circuit already exists tentatively using 555 timer chip (I know I can do this with a micro controller so please don't suggest that). Basically I need following functionality: - ...
0
votes
0answers
75 views

Implementing non-linear time delay

I have a feedback system including an OP-amp in comparator mode and a transistor, in present time it acts like a regulator, constantly limiting the current through the transistor to a certain value. ...
-2
votes
2answers
196 views

555 Astable Period Incorrect [closed]

I set up an astable 555 timer with the output connected to an LED. C1 = 1000 uF, 16V. R1 = 68000 Ohm. R2 = 33000 Ohm. Vcc = 6.5V. By my calculations, the total period should be roughly 93 seconds. But,...
1
vote
4answers
203 views

Overtones Produced From Speaker Load on Asymmetric Square Wave

What I am doing I built a circuit using a 555 timing chip in astable mode which produces a square wave. There is a potentiometer which allows me to adjust the frequency produced. One aspect of this ...
0
votes
3answers
95 views

Control Output Shock From Cockroft-Walton Doubler

so I'm building a device that charges a capacitor bank to between 1kV and 2kV. The goal here is to use a 555 timer to control a shock pulse from the capacitor bank. I can touch the ouputs of the bank, ...
1
vote
0answers
197 views

How to vary the range of a potentiometer…is this even possible?

I am a total noob so apologize if this doesn't belong here but I haven't had any luck finding an answer to this... I have a simple circuit with two 555 timers...similar to an Atari Punk Console. I ...
0
votes
2answers
490 views

Astable 555 timer [closed]

The circuit diagram is above R1,4,6,7:1K R2,5:10K R3:100 ohms C1: 0.047 uF C2,3 :100uF C4:69uF C5:0.1uF And we finished building the circuit and connected the battery onto it. But the LEDs stayed on ...
0
votes
2answers
748 views

555 Timer Monostable Circuit Triggered When Circuit is Powerd

My monostable 555 timer circuit (like the one seen below from Electronic Tutorials) behaves as it should in a steady a steady-state environment. However, the 555 timer is also undesirably triggered ...
0
votes
0answers
250 views

Holding Reset State Low longer with hardware 555 Timer

I have a 555 one shot timer circuit in which the Trigger and Reset pins are tied together in attempt to reset the timer every time the timer is triggered so that the one shot really extends for the ...
1
vote
2answers
271 views

7490 Counting But a Little bit Buggy

I followed a video (Click Here) to make the 0-9 Counter. The counter does work but its a little bit buggy. For the first 0 - 9 cycle it works fine but then it starts to follow this sequence: Where ...
1
vote
2answers
751 views

Having an issue connecting two 4-bit Synchronous Up Down counters

That's a Traffic Light circuit I designed on Multisim. I used 2 74LS191 Counters, 2 74LS47 Decoders, 2 Seven Segment Displays, a 555 timer and a J-K flip-flop as you see. It should count from 29 down ...
-2
votes
2answers
158 views

Simple 555 on/off oscillator [closed]

I have heard many people talking about how useful and simple the 555 timer chip is, yet I still cannot find a simple, easy method of creating a circuit that oscillates on and off every hour or so ...
2
votes
4answers
1k 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 ...
2
votes
3answers
356 views

Anyway to avoid the startup delay on square wave generator (e.g. 555 astable) circuit?

In the classic 555 astable circuit the external capacitor charges to 2/3 of the Vcc (through R1 and R2) and then is discharged to 1/3 of Vcc (through R2) and then it continues to oscillate between 1/3 ...
0
votes
3answers
381 views

74LS90N Is not counting!

So basically Im working on a counter from 0-9 and I have made a simulation and it works completely fine but when I implement it on the breadboard it does not count. I have implemented it more than 4 ...
0
votes
3answers
3k views

TIP 120 replacement [closed]

Although I read the article advising against using TIP120: http://sensitiveresearch.com/elec/DoNotTIP/index.html I only have couple of other transistors on my hand: ...
0
votes
1answer
131 views

Pausing sawtooth generator given an input

I created the following sawtooth generator to go between 5v and 10v. I need a way to keep the output at 5v given a while a certain input signal is high. I've tried various combinations of MOSFETs and ...
0
votes
1answer
302 views

Photoresistor with NE555

I would like to build a circuit with two blinking LEDs using a NE555 timer and a photoresistor. In the schematic below the blinking frequency becomes higher when more light shines on the photoresistor ...
1
vote
5answers
2k views

Does a 555 astable dissipate more power at higher frequencies?

I'm planning on running a circuit on a 9V battery and it uses a 555 in the astable mode to generate pulses. I want this circuit to be as efficient as possible, and not have to replace the battery ...
0
votes
0answers
131 views

What is the 555 doing in this circuit?

I'm trying to understand, from a functional standpoint, how the 555 timer plays a role in this circuit? What I understand: Astable at f = 7.142kHz It's supply is the 150VDC. It's floating on R6. ...
1
vote
1answer
114 views

Can a 555 be used to control the charging and discharging of a capacitor to provide bursts of current?

I have a solar cell that charges a capacitor. I want to switch on a motor when a voltage level is reached and then switch off again at a lower voltage or when the capacitor is discharged. I modelled ...