555 timers?

I was wondering if there is a difference between a ne555p timer chip and a ne555d timer chip, and if there is then what is it? if there is a difference between them, then where can i buy a ne555p timer in australia? :)

Question by jcolefran   |  last reply


555 oscillator?

How can I make a simple variable oscillator out of a 555 timer, loudspeaker, capacitors, transistor, potentiometer, and resistors? (and anything else I may need). I would ideally like it to go from about 10Hz-20KHz.

Topic by andy70707   |  last reply


help with a 555?

Hi, to make a long story short i don't want to have to go into the cupboard and turn on my amp every time i plug it in, it has a button on it that needs to be pressed about 5 secs after power is turned on and then left like that, could i take a feed off the power supply, connect it to the 555 or another ic and make it activate a transistor 5 secs after power was applied? i only need it to do this once every startup, i don't want it pulsing on and off and it needs to be as simple as. thanks, luke

Question by ljarrald   |  last reply


555 timing circuit?

Question by gadget01   |  last reply


555 working backwards?

Hey, so i wired up my 555, with a trigger button, and because i only had small resistors at the time, I used one to give a really quick period. however when i put in a brand new 800 KOhm resistor (that should have raised the period to 8 seconds) instead of lengthening the period it put a time limit on the trigger. so now i have an output that stays high for a faction of a second and then the chip can't be re-triggered for 8 seconds. i know people don't have an encyclopedic knowledge of 555, but does anyone more experienced have any ideas why this might have happened. thanks in advance.

Question by DrVonTrap   |  last reply


555 timeout troubles?

Evening all,  This is most likely a very basic problem but for the life of me I can't find the solution. The project: auto folding wing mirrors (see below) http://www.lexusownersclub.co.uk/forum/index.php?app=core&module;=attach&section;=attach&attach;_id=6108 The problem: for some reason my alarm logic is the opposite way round, most likely due to the removal of my motion sensor due to it tripping my alarm when locked. Now I have modified the circuit shown in the PDF to remove TR2 and R4 so the I/P to the 555 is kept high by the 12v alarm signal. I have a pot between pin 2 and ground so I can adjust the pull down point as the alarm signal only drops to 9.7V and, obviously, the 555 needs logic high or low. So, having adjusted the pull down point, I find that the 5 second timeout, which worked when I first built the circuit as per the PDF, no longer switches the O/P off.  So so what am I doing wrong or is it just best to us a picaxe to do all of this as I code write up the code in half an hour or so. thanks

Question by LED Maestro   |  last reply


555 timer cicuit

Hello guys I have a minor problem, I built a 555 timer circuit and it runs off of 6v. My plan is to use a 9v battery. Will the project be OK or will I need to drop the voltage and how would I go about that? Would I connect a resistor to the positive of the battery then to my project's input? Thanks, 

Topic by HavocRC   |  last reply


555 Timer Calculator

Hi everyone, I was looking around on the internet a while ago for a calculator for 555 timer circuits and couldn't find one that worked very well. Then I set about making my own in a Excel spreadsheet to calculate the frequency and duty cycle for me. I have decided to share it with everyone to help others. It is quite simple. Enter your vaules into the yellow boxes and get your frequency and/or duty cycle from the blue boxes.

Topic by qwertyboy   |  last reply


555 monostable sensitivity?

Has anyone built a 555 monostable circuit that was extremely sensitive for no apparent reason? I'm trying to use one in a rube-goldburg machine, and for some reason it's extremely sensitive to any sort of touch! The circuit sometimes comes on for no apparent reason, other times it will stay on for longer than the expected duration after the button is pushed. I'm using non-CMOS 555 on about 5 volts to run a small LED. The capacitor I used was a 0.01 uF on pin 1 to 5, and a 1 uF electrolytic on pin 1 to 6. I used a 1M resistor on pin 7 to 8.  I'm simply baffled by it. I've tried using different breadboards, different PSUs, brand new components, and correct gauge wire, but despite everything being seemingly fine, it's still shows the sensitivity. Anyone have any advice?

Question by tylervitale   |  last reply


Running a 555 timer? Answered

So, I have this program that I got online that simulates a 555-timer. Basically, if you want it to put out X Hz in Astable mode, it'll tell you which capacitors to use and stuff. It'll also show you how you can modify the duty cycle.  I'm wondering if anyone can explain something to me: When I run the program in astable mode, the duty cycle must be above 50%. I want to power an LED that flashes very briefly, but has a relatively large interval of being off until if flashes again. Something more along the lines of a duty cycle of maybe 5%-20%.  First, could you explain why the program constrains the value like this? Is it because the 555 can't run at a duty cycle that isn't greater than 50%? If that is the case, why can't it? Second, if I can't run it like that, what would you propose I do to power the LED in the manner I described? btw, if you want the program follow this link: http://clarkson-uk.com/555-timer/ It's actually a pretty cool program! :D

Question by tylervitale   |  last reply


555 monostable timer

I've no idea what I'm talking about here but can only explain what im looking for which is help. I'm basically looking for a relay or multifunction relay not really sure but here's the plan. When my smart plug is turned on (at certain programmed times through the smart plug app) to provide power to a 12v 6amp pump (I have 240v ac to 12v DC transformer pluged into smart plug I'm in uk) I would like for this pump to turn itself back off after 10 or 15 seconds. I cannot for the life of me find an analogue or digital timer that can do seconds. The smart plug can work down to minutes and not seconds. So basically smart plug on = pump run for 15 seconds cuts itself off and then the smart plug turns off once the minute is up and when plug is on again at next programmed interval it does same thing. Any help would be great as I've no idea what I can buy or try to make thanks When trying to research I hear about 555 monostable circuit but I don't know how to wire something up or what to buy to make this work.

Topic by croyf85   |  last reply


555 timer output hight and low? Answered

I just soldered up a 555 monostable circuit following an internet tutorial and for some reason the output seems to be both low and high. it can power a LED connected to the 0V & pin 3 and the 9V & pin 3. any ideas what might have happened?

Question by DrVonTrap   |  last reply


Simple 12v battery level LED indicator w/ A single 555 IC, none on the net. (555 is for looks) is it possible?

Well im somewhat novice and I was wanting to make a circuit to monitor the level of a 12v car battery with 3 LEDS (although more is cool) Yellow for low, Green for good and red for overcharge. Ive looked all over and cannot find a circuit that uses a single 555 ic to do this easy task.

Question by Sky Graham   |  last reply


how are the pins on a ic numbered?

I have been trying to make cylon light bar thing. http://www.evilmadscientist.com/article.php/CylonOLantern but it isn't working, all the wires an connections are done according to what is said and i asked my neighbour to have a look he is a electrician and he was surprised it didn't go as well. its the NE555  i put it togther. looking down on the plastic.     ______ 1-| o  U    |-8 2-|            |-7 3-|            |-6 4-|_____|-5 was that the wrong way? i have seen other circuit diagrams and the pin numbers where not like that. thank you oh and also is some solder non-conductive? and can you burn wires and make them useless? i don't think i could have fried the chip i getting pro at quick soldering.

Question by Scotty3000   |  last reply


555 frequency control another 555 controlling a servo motor.? Answered

Hey guys, I have another question. I'm in the planning stages of a project, It's basically supposed to be an astable 555 sending out a frequency that's supposed to control the mark space ratio of another 555 that's going to send a signal to a servo motor, causing it to oscillate back and forth. Tl;dr, I want to make a servo wiggle around with two 555s. I have used the output of a 555 to modulate another one before, but I understand that using a 555 to control a servo is slightly different than just audio output. So is there anything I should be aware of? Is there anything I can read or look at to point me in the right direction? Thanks. EDIT: I just had an idea. What if I took the output of the first 555 (thus forth referred to as IC1) and used it to turn on a transistor, which connects a resistor in parallel to some part of the IC2 which decreases mark space and turns the servo. https://www.instructables.com/id/Simple-Servo-Tester/ This one uses some pots to control rotation, if a resistor is connected in parallel using a transistor... something will happen. It moves.

Question by mrmerino   |  last reply


Pushbutton Servo Control with a 555

I've found numerous write-ups on getting a servo working with a 555 IC but it's not quite the functionality that I'm looking for. What I'm trying to do is have two buttons go to a predetermined position but the write-ups have two buttons that just go clockwise or counterclockwise. I know this can be done with an Arduino but I'm trying to avoid that route so I can keep the footprint as small as possible. I've attached a picture of the schematic I was working from.

Topic by XAlliedYouthX   |  last reply


555 timer circuit question

Hi everybody! I need to make a small pcb which will be able to turn on/off a switch about 10/sec, whenever I turn it on. I understand that 555 timer is the easiest way to go.Even better it would be if it was fully customizable like I could set it to open/close the other circuit from 1 to10 times/sec per manual switch on and also set the duration that the 555 will be keeping the other circuit on each time . I am able to do the soldering needed but I don't know the parts needed and how to properly connect the the pcb.Thanks (sorry for my poor English)

Question by c_fish   |  last reply


555 timer and servo help? Answered

Hello, I just finished building this instructable: https://www.instructables.com/id/The-Most-Useless-Machine/step6/Original-Design-Using-555-Timer/ However, I have run into a couple of problems with the 555 timer and the servo. As suggested by someone in the comments section of that instructable, when the server turns on it is consuming enough current to drop the voltage enough to mess with the 555 timer's PWM output (I do not have an oscilloscope, so I can't really prove this). Whenever the servo starts, it works properly for a couple of seconds, then it starts acting very strange, stuttering, going the wrong direction, ect... I'm thinking if I add a capacitor the the power source, it will help stabilize the voltage, but i'm not sure if this will work. Any help and/or suggestions would be greatly appreciated. Circuit is running at 6v (4AA cells) Servo runs at minimum 4.8v to max 7.2v

Question by psp3601   |  last reply


555 pwm AND frequency controllable? Answered

Hello, I've been breaking my head on this for a while now, and still couldn't find a correct solution for this. I want to be able to adjust the duty cycle (pulse width) with one potentiometer, and the frequency with another potentiometer, using a 555 timer. Adjusting the frequency shouldn't change the duty cycle! (which is the problem in All of the circuits I find online). This is an example of a circuit I find online, many of the circuits look just like this one (see picture) Now, the problem is that when you increase the resistance of the potentiometer for adjusting the frequency, that makes sure you can never get 0% or 100% duty cycle anymore! or not even close to that. It's because increasing that resistance, also decreases the 'discharging current' of the capacitor, so it will also increase the discharging time when that's not wanted. Without R2 it works perfectly, from 0% to 100% duty-cycle; but with the frequency potentiometer it all gets messed up. It's a little difficult to explain, I'll try it with another example :) To get 0% duty-cycle (or something close to that, like 10%), you'll need to make sure the path for Discharging the capacitor goes near 0Ohm. Increasing the potentiometer for the frequency makes that impossible because it's in series with the capacitor's charging and discharging circuit. So that would also increase the discharging time while I don't want that. When the resistance of the frequency potentiometer increases, the duty-cycle gets variable between just something like 45% and 55% (example) so that's not good. Is there any way do do this? :/ Thanks in advance, Elecotrials

Question by DELETED_Electorials   |  last reply


555 TImer/Chip Help

I need your help people of Insturctables. I am working on an project, and I need to make a circuit whit a 555 timer/chip so that it makes,for example, an LED light up in every 2 second. I mean when it turns on, it needs to be on for 2seconds than off for 2 second...loop. ON(2 seconds)___OFF(2 seconds)___ON(2 seconds)___OFF(2 seconds)___LOOP I need the output to be 12V. Actually I need it for a fan to turn on and off(the fan runs on 12 volts) Can you help me make a circuit for this, what value of the resistors and capacitors do I need... It would be grate if some one could make a schematic of the circuit in Eagle, or so... If I make an Instructables about my project I will surely mention who helped me realize my idea! Thank you all! -Stanislav

Topic by comodore   |  last reply


Switch a relay with a 555 timer?

I have a clap activated relay which I want to use to switch on my computer but when you leave the switch on my PC in the "on" position it just keeps rebooting. Would it be possible to use the relay to activate a 555 timer circuit or similar to the switch off the relay after 2 or 3 seconds?

Question by cheesemarathon   |  last reply


Push button to toggle servo direction - monostable 555 circuit? Answered

I would like to build a circuit where I push a button once and a servo moves 180 degrees and stays there.  If I push the button again it should move back to the start position. A switch is good alternative, whichever would be easier. I've been looking at circuits to do with 555 timers and servos and have found these two which seem useful: http://www.555-timer-circuits.com/servo-controller.html http://www.dummies.com/how-to/content/electronics-components-555-timer-chip-in-monostabl.html Is that second circuit what I need?  How would I change the direction of the servo each time it runs? I looked into flip-flops such as the 4013 which came up as a suggestion instead of a 555 but quickly got out of my depth.  I'm happy tinkering around with electronics but unfortunately don't know too much of the theory...

Question by Sparrowhawk   |  last reply


Is there a way that I could use a 555 chip to give 5 pulses then stop?

Or any other easy way to create a certain number of pulses? The amount of time this happens in doesn't really matter. The o/p of this pulse generator must have enough voltage/ current to power the clock of a 4024 7 bit counter

Question by hrimiller   |  last reply



I want to use a 555 timer to be off for 1 minute, give a brief pulse (about 0.5 seconds).

The circuit is to provide a pulse to a 4017B decade counter to count up to 5 minutes

Question by ralph4ed   |  last reply


I'm trying to use a 555 timer to flash a LED but I want to be able to adjust the speed of the flashing Answered

I'm trying to build a simple circuit using a 555 timer chip Ideally a low power one so I can power it off 2 AAs to flash a LED at a variable speed from rapid flashing to once every few seconds. any help would be appreciated.

Question by joeAMERICA   |  last reply


i would like to build a small simple synthesizer using 555 chips if possible. any oe haeve ideas or help?

I have a few 555 timers and  have always wanted to build a sythesizer but i just don't know where to start. i have seen the optical theremin and  the 555 metronome. i could add a pot instead of the photo transistor, and maybe connect the out put from the theremin to the metronome  i would like some thing more like this ,http://hackaday.com/2009/08/28/xr-noise-box/ . i would like to kow if it is possible with 555 timers.

Question by zs   |  last reply


panic alarm data?

 i request to get data about panic alarm.

Question by nelson ndegwa   |  last reply


I just bought 7 555ic timers, all of them are faulty?

I bought 7    555ic timer. i tried to blink an led but the output always stays high. when i swapped the 555 by a 556 it then worked. first i thought that my circuit was wrong. i've verified it countless times all seemed to be good but the pin 3 output was always high. when i used the 556 timer with same components it worked. is the 555 timer at fault or i am missing something?

Question by ARJOON   |  last reply


Hey Guys,I need some help making a project for school

It needs to have at least 1 555 Timer within it. I was thinking of building a jacobs ladder with a 555 timer or if i could get it working perhaps a sonic pulse generator. Want something interesting and that won't take more then 7 weeks to build. Would it be possible to make a Cree Light and mod it to turn off after X amount of time? I'm just struggling to find idea's as our projects must be able to run off a 12V Battery or less and we cannot make anything dangerous. IE Rocket Launch Controller etc.... Thanks

Question by bcurko   |  last reply


What value resistor do I need for a transistor base? Answered

Hello, I am trying to work out what resistor I need to use on the base of a 2n3904 base. I am using a 555 timer to flash some leds all powered by a 12v power supply. There are 4 leds in series each with a forward voltage of 2.1v and they require 50ma. I have found that I need a 82 ohm resistor to protect the leds using a online calculator. Pin 3 is driving the transistor base and the transistor controls the leds but I do not know what resistor I need on the base. Any help is appreciated! Edit: here is the finished circuit. http://vimeo.com/33513619

Question by Alex1M6   |  last reply


Need suggestion for clap "push Button" instead of a clap switch.?

Well I want to make a circuit that send out a "high" pulse instead of being "high" continuously and getting "low" after next clap,just like pressing a push button and not like toggling a switch a circuit that turns toggle switch signal to a single pulse

Question by Suraj Grewal   |  last reply


How to increase NE555 output amplitude?

Hi, I have the following circuit: http://s17.postimg.org/86bus6rm7/Sawtoot_Gen.png which is able to generate a nice sawtooth waveform. When I provide 13.12 volt as power supply, the max peak of the sawtooth will be near to 8.7 volt. There is a viable way to increase this value at least to the same value of the power supply (13.12 volt)? And can someone provide me a schematic based on my circuit? I suspect that this would be viable using a transistor or an op amp on the output, am I right? If i had to implement  an op amp, I prefer to use a "single power supply" op amp, and a common IC (eg an LM358?) Kind regards.

Question by akopelumenuscu   |  last reply



555 Am Transmitter Circuit Diagrams?

I have two ICM7555 CMOS 555 timers, and I was wondering if anyone has any good am radio transmitter circuits that incorporate two (or one!) 555 timers.?

Question by BurningSandman   |  last reply


That I project can I make with an integrated 555?

That I project can I make with an integrated 555? i have a protoboard

Question by mr.mister   |  last reply


Will this 555 circuit for 8 leds flashing work? Answered

Will this 555 timer work and make these 8 leds flash with this circuit I drew up.

Question by mykiscool   |  last reply



led display using 555 timer? Answered

Can anyone help me with a design , i would like to make a 5 letter display using leds that spells my daughters name "TRULY" lighting up each letters one at a time then having them all light up at once then repeat? i am new  and this will be one of my first rojects not out of a kit. any suggestions?

Question by vince26   |  last reply


7805 and 555 timer circuit heat.

Hi all! I made a test led blink circuit with a 555 timer on a bread board. Just a basic two led blink circuit you can find all over the place. I used a 7805 for a supply regulator with power from a 9v batt. The circuit functioned fine (to my knowledge), but the 7805 got REALLY hot. I've used 7805 in opamp circuits with a 7.2v batt and no detectable heat. Is what I'm experiencing normal? Or do you believe something I did was wrong. If I remember correctly (I'm really tired as I write this) i was using 100nf caps on both ends. Thank you Nic

Topic by Mrlzeppelin   |  last reply


555 1 Hz pulse generator? Answered

Hi,I have a simple buzzer which I want to convert to an oscillating buzzer so as to obtain the sound similar to that of an automobile's reverse indicator.I've posted a schematic(borrowed from electroschematics.com) below.I intent to replace the LED with my buzzer and omit the resistor.I hope by building this circuit,to make my buzzer 'buzz'(or make noise) at an interval of 1 second(since its a 1 Hz pulse generator).Would the results be similar to my needs?

Question by Adarsh_tronix   |  last reply


How to make an LED blink using a 555 timer?

So im doing a school project and i need to figure out this whole circuit thing. my teacher recommended me this circuit (picture related) but i dont understand it. can anyone help me? i am trying to do this on a bread board (i think they're called that). i am making LEDs that are blinking using a 555 timer and a BD139 transistor. and some resistors that i dont know the resistance of.

Question by Gaudnarok   |  last reply


How do I add a delay start to my 555 chip in astable mode?

Hi all, My goal is to turn 3 bulbs on in a series. i.e. 0 min - B1 on 3 min - B1 still on, B2 on 5 min - B1 off, B2 on 7 min - B1 on, B2 off, B3 on I have decided to use 3 555 chips. May I know how can I add a delay such that their switching on and off are staggered? thanks!

Question by pantss   |  last reply


Why is my 555 timer metronome circuit so variable?

I constructed this metronome circuit using a IC555 timer chip (see image below) and it worked fine on the breadboard. I wanted 2 ticks a second (2Hz) so used a trimpot to set that but was getting wild fluctuations with either the tempo increasing or really fast ticks even with the trimpot at maximum resistance. So I changed out the trimpot to a 30KR resistor and that seemed to work, but after doing the circuit nine times, it has also proved highly variable and I don't know why. I'm running the circuit on 6V (2x CR2032) and my resistors are rated at 1% tolerance. Any help please?

Question by chiok   |  last reply


Ps3 Rapid fire?

I was thinking of using a 555 timer to make my ps3 controller rapid fire, what do you think?

Question by tom10122   |  last reply


2 Position Servo Controller

I need some help, I am trying to create a damper control using a servo and a 555 timer. Is there anyway that you can use a 555 timer to make a servo move back and forth between 2 positions (0 degrees and 90 degrees) with an with and on/off signal and not a pot? So when the thermostat sends power, the damper moves to 90 degrees, then when the thermostat shuts off the servo returns to 0 degrees? Thanks for the help in advance. -Ryan

Topic by WingmanSVT   |  last reply


How to control DC motor off and on cycles. Answered

I need to control the speed at which a pager motor is on or off. I don't need to control the motor speed, just the timing of off and on. What would be the easiest way to accomplish this? (I have some 555 timers and an Arduino Uno so either of these would be preferred methods). I've tried but failed with the 555 timer and a pot to do this.  Eventually I would like to have two pager motors cycling between off and on (pulsating effect). Thank you, -shortdiesel

Question by shortdiesel   |  last reply


i was wondering if anyone can look at my atari punk circuit and see if maybe im missing something.

I put together a apc on my bread board using 2 555 timer ic's, looking at the schematic is seems like i did everything right, but i cant get it to produce a sound. hopefully you guys can spot what i did wrong. 

Question by skatattookid   |  last reply


Creating a 10-15 second timer?

Hi All, Here's what I need to try and achieve: - I have a servo that I had modified and have removed the circuit board.  Now it just runs from 3 v - I want to reverse the servo once a momentary switch has been activated for 10-15 seconds - once time is up the servo reverses again I thought about using a 555 monostable circuit which would give me the amount of time, but I am unsure how to achieve everything above. I'd love not to have to use an arduino if possible. Any ideas? Thanks.

Question by lonesoulsurfer   |  last reply


First I'm still a newbie at electronics. I know there are schematics for the "annoying cricket" out there.

Is there a schematic or explanation telling me how to make the device give a double chirp then silent for a seond before another double chirp, turning off in the light and then back on in the dark?

Question by OnCrowsWings   |  last reply