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How to use 555 to start some circut in delay?

JakubPrazmowski — Wed, 02 Apr 2025 07:34:00 GMT

Ok. I got monostable mode. I am pressing my little button and timer starts rolling. I getting HIGH on output 3 and it last some time. I wonder why how to connect it with some other circut to start rolling just after state from pin 3 will go back to LOW?

I am new in electronic so any help is very welcome. Thank you very much for help.

Jakub

Analysis of a 555 circuit design, will it work, maybe there is a better way

colporteur — Fri, 20 Sep 2024 15:58:11 GMT

I'm looking to build an End of Train (EOT) circuit. The model railroad folks I hang out with, just purchased a commercial unit. After gagging at the price, I figured why not build one.

My search found this resource https://techlib.com/area_50/Readers/Lennie/End%20of%20Train-1.pdf complete with PCB. Unfortunately all the links are dead so I had to generate a schematic from the PCB layout.

Question: Will the circuit work? Are there any reasons for the design?

Instead of bread boarding the design I figured the folks that hang out here are great and offering solutions. Tapping into the experience of the members surely helps. Nothing like experience to find a solution fast.

I have some concerns with the circuit. I couldn't found a 555 circuit that uses pin 7 as an output. I took a look through Cabe Force Essential 555 IC book (Cabe hangs out here:) and found nothing like this beast.

I'm not sure of the design. It looks like nothing I have found.

I'm thinking it would have been easier to just start from scratch.

Feedback on 555 timer Schmidt Trigger design

colporteur — Thu, 13 Jul 2023 22:47:23 GMT

Can I get members insight into using a 555 timer as a schmidt-trigger design that I pulled from the Internet?

I found this schmidt-trigger design using a 555 timer. I would like to use it to condition the output of a photo-resistor. The 555 timer output will feed the input to a Arduino Mega. I'm in the process of bench testing the setup to finalize component values. While testing I figured I would throw it out to some more enlightened minds than mine for feedback.

I'm using the 555 only because I have a stock of them. I don't have any readily available smidth-trigger IC's so I figured I would go with what I have and build from scratch. Building from scratch especially using Internet designs comes with risk. I was hoping to mitigate the risk by getting community feedback.

If inquiring minds suggest you don't want to do this, that is a good thing.

555 timer bistable

Psin545 — Tue, 31 Jan 2023 23:51:24 GMT

I have a question regarding some behaviour of a 555 timer circuit in bistable mode. I attached a photo I found off the internet that is the one I’m using, the output goes to a 440 ohm resistor and then to a red LED also I’m using 10k pull up resistors. I noticed when I push the trigger pin switch and the light comes on, that sometimes when my hand is hovering over the circuit the LED goes out. I got curious and made sure not to bang into anything or touch anything and I would slowly bring my hand near the circuit, and almost half or more of the time the LED would turn off. Being more curious now I took the breadboard set up like a “bridge” (basically I have two small bins and I had the breadboard laying across so each end of the breadboard is resting on those bins and there’s nothing touching the bottom of the breadboard) I noticed that if I put my hand under the breadboard (without touching it at all!) the LED light on the output pin goes out. Getting more curious I held the breadboard by the sides so there was minimal contact and the light would work perfectly fine until I ran my hand close to (but still not touching) the breadboard. I tried this on different surfaces such as plastic bins, slabs of wood, the floor (lol) and on a glass table. It did it the least amount of times when laying on the plastic bin. I’m not using a anti static wrist strap but I’m curious if this is an environment issue or like a workstation issue? Or a simple fix with a anti static strap? It was kind of neat to play around with it like that but now I wonder about the last 2 years and all the heart ache from circuits not working properly even though I was CERTAIN I had built them exactly as per the diagrams. Also I tried 5 different 555 chips and 5 different breadboards with the same results. Any ideas or suggestions?

Delay off timer

Naresh_155 — Wed, 26 Oct 2022 07:37:37 GMT

I want without pushbutton delay off timer with 555 ic

555 timer and beyond

Limster10 — Wed, 24 Aug 2022 13:46:52 GMT

I've been studying the 555 Timer and I need to learn more then LED lighting: A stable, mono Stable and bi stable mode with IC's

My configuration: push button --> to 555 Timer--> Mini Solenoid and press the solenoid triggers. (what resistor if needed for solenoid)

Bounce Servo with 555 timer

Eric — Thu, 16 Dec 2021 04:45:17 GMT

I want to toggle a servo with the push(and release) of a button. I then want the servo to return to original position after x seconds. I think I'm close by enlisting a 555 timer. I have it successfully powering an LED for 1 second. (hold your applause)

Is this at least possible with this same circuit? This is just a hobby project and I was trying to avoid grabbing an Arduino and coding something.

When I tried to connect my servo to pin 3, positive, and negative....it moved slightly once out of 10 attempts. The LED is dimmer and shorter lived while the servo is attached.

I should check back in here at least once a day until I get this working (and will report so) or smash the thing with a bat.

-EP

Some details...may be garbage. THANKS IN ADVANCE!

Power = old 9v battery (8v)
Resistors = 10k
Cap = 100uf

How to slow the charging and discharging of a 555 timer without changing the frequency.

63stratman — Sun, 28 Mar 2021 04:14:36 GMT

Imagine driving at night and seeing a radio tower in the distance. At the top, a red light appears to brighten and dim instead of just blinking on and off. How can this effect be accomplished with a 555 timer? I assume the charging and discharging times must be increased, but I don't want to change the on/off frequency of around 1hz.

Long Timing with a 555 IC

paddler47 — Tue, 26 Jan 2021 11:20:03 GMT

I am not an engineer. I am an old retiree who took up woodworking as a hobby and recently took an interest in making whirligigs. My third whirligig had a nautical theme, with a sailboat and a buoy which rocks when the wind blows. This time I decided to put a blinking LED on the buoy and started watching videos on YouTube to learn about LED's and solar charging circuits. I soon had a steadily blinking LED on my buoy, but wanted it to have an on-off-off-off-on-off-off-off, etc. pattern, so soon found Karen's videos on the 555 IC, and now have the desired blink pattern on my buoy. Now I want sound.

I picked up a few of those greeting card type MP3 player circuits and have gathered some suitable nautical sound files ranging in length of from about five seconds to about a minute. The MP3 players are triggered by a momentary push button switch, which I want to replace with a pulse timed to play the file, wait a while, and play it again. I need a circuit to generate those pulses.

The 555 IC claims "timing from microseconds through hours", but I've only seen demonstrations of fast blinking or flashing LED's, and I've seen the formulas and the nomograph in the data sheet, but just can't figure out where or how to start to get the necessary time delays. Do I start with a capacitor and the desired delay in microseconds and figure the R values from there? I'm really lost. Am I on the right track at all?

I'm very new on this site, and this is my first post. I hope it's appropriate and in the right place. This is a very busy web site, and I get confused easily.

Message was edited by: John O'Neil Sorry for the long delay in getting back to this, but we had a major wind and rain storm the beginning of the week and the electricity has been off since Tuesday night. I'm going to have to start over reading the replies and studying the new information, and I have some catching up to do with other things, so it will be another day or so before I get back again. I think I should have mentioned that I'm talking about the astable mode of the 555, so my specific issues are the values of the two resistors and the capacitor, frequency, and the duty cycle. Thanks again!

Understanding 555 timer in astable mode but stuck on capacitors

opalko — Thu, 24 Sep 2020 18:10:50 GMT

So I am still plowing my way through Platt's Make: Electronics and into chapter 4 working with the 555 timer IC. The astable mode of the timer is giving me trouble as I don't understand how

When C1 acquires 2/3 of the positive voltage powering the circuit, the 555 reverses its output on Pin 3 from positive to negative and forces C1 to discharge itself through R2.

(This last sentence is actually from Make Magazine issue 10 where Platt is explaining the same thing as in chapter 4 of his book - see image below)

What I am confused about is the discharging through R2. I am obviously stuck on what is going on with C1. As I understand it, it first gains a positive charge on what I will call the top plate in the picture above, and a negative charge on the bottom plate (next to where the label C1 is). Maybe I have read too many analogies of water with electricity but I think of the capacitor as a balloon (in fact there are many analogies in Platt's book like this). So how is the balloon releasing the pressure in what seems like a reverse direction back through R2? Here is a similar circuit I found on circuitlab albeit the pins arranged differently and it shows that reversing of "flow":

Is there not +5V into R2 from R1 at the same time C1 is discharging??

Finally here is Platt's "internal" view of the 555 timer in astable mode. I assume pin 7 gets grounded to pin 3 but I am still confused about the seemingly reversal of flow through R2.

I've read through this many times and still stuck. Any additional help is appreciated!

Cheers

Message was edited by: Robert Opalko same day