Skip to main content
Electrical Engineering

Questions tagged [555]

Ask Question

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 low price and ubiquity. The 556 timer is simply two 555 timers in a single package.

1,261 questions
Newest Active Bountied Unanswered
Filter by
Sorted by
Tagged with
1 vote
1 answer
47 views

I am currently designing a 2-digit BCD counter circuit using an IC 555 as the clock (Astable mode) connected to two IC 4033 (BCD Counter/Decoder) and Seven Segment Displays. I need expert verification ...
Maulana Alvisheva Widyatmaka's user avatar
  • 11
6 votes
1 answer
340 views

I build a simple LED chaser that will be powered from a 9 volt battery and will start with a simple slide switch. I have simulated the design in TinkerCAD and it worked the way I wanted. However when ...
BalP's user avatar
  • 63
1 vote
2 answers
167 views

I see multiple internal diagrams for the 555 timer IC. If I consider the following schematic, is the text below correct? (Also is this the correct diagram for the IC?) Author: EEGuide.com. Link: https:...
Deagle's user avatar
  • 41
0 votes
1 answer
68 views

I'm trying to send PWM signal to MOSFET gate to control 12VDC 2A motor. The NE555 circuit is built as shown in this article (https://www.build-electronic-circuits.com/555-pwm-circuit/) with the same ...
steve d.'s user avatar
  • 177
1 vote
2 answers
101 views

I'm building a circuit in Multisim and I can't get the oscillator to run at 1 kHz. Honestly, it doesn't work at all. I built the circuit but can't figure out what I did wrong. In the finished version,...
Foma Loktionov's user avatar
  • 19
1 vote
2 answers
122 views

I want to simulate a push button with a little circuit. I'm using an IC 555 as a timer. The button is in another circuit (different device), pin A has 2.4 V and pin B is GND, it does activate if I ...
Panamanian's user avatar
  • 409
1 vote
3 answers
160 views

Is it possible to simplify the circuit by removing the logical NOTs while maintaining the identical output response to the input signal?
Arseniy's user avatar
  • 2,315
8 votes
5 answers
869 views

I am designing a circuit that uses a 555 timer to output a 10% duty cycle pulse train. I don't want to get into the details of what this is used on, as it is not relevant, but long story short I need ...
Engineer1's user avatar
  • 305
7 votes
3 answers
967 views

http://electronic-projects.50webs.com/555-based-siren-circuit.htm the source online, but who knows the original designer. U2 is configured to have a much higher frequency than U1. U2 provides the ...
qwr's user avatar
  • 449
1 vote
2 answers
128 views

I have a device which has a part of that functions as a power failure alarm. This means, if my SMPS is not delivering power to my circuit then an audible alarm will sound off. This circuit is powered ...
Engineer1's user avatar
  • 305
1 vote
1 answer
185 views

A long time ago I put together a 555 tone generator from Radioshack parts. The circuit was similar to this: This is the source: http://electronic-projects.50webs.com/variable-frequency-tone-generator....
qwr's user avatar
  • 449
2 votes
3 answers
165 views

I am trying to implement a power-on delay circuit using a 555 timer. I referred to the circuit shown below: In my application: A switch is used to apply power. When the switch is closed, the input ...
zoghii's user avatar
  • 323
2 votes
2 answers
113 views

This is for a variation on my 9 y.o. grandson's brushless motor project, and my aim is to have the minimum component count in order for it not to look too complicated (I want to demonstrate the speed ...
chackers's user avatar
  • 21
1 vote
2 answers
146 views

So here is my schematic: TLDR; Basically it is a boundary wire detector transmitter, pushing a 50 kHz 150 mA current into a wire, Q1 and Q2 are used to detect wire interruption, if wire is ...
Felice Pollano's user avatar
  • 1,163
0 votes
1 answer
59 views

I am using the design below for a capacitance meter project: simulate this circuit – Schematic created using CircuitLab The charge/discharge waveform is relatively stable, so I feel that there's ...
Eigenvlad's user avatar
  • 131
3 votes
3 answers
713 views

I'm attempting to create a 555 timer oscillator circuit, in which the rising and falling delays of the generated clock signal are independently controlled by two analog input signals. As an initial ...
Runsva's user avatar
  • 587
2 votes
2 answers
484 views

I am trying to create a circuit that I can make as a PCB that will take inputs from buttons, the 3 timed inputs on the left, and generate a pulse using 555 timers that will then be sent to a MOSFET ...
CNCs's user avatar
  • 59
3 votes
2 answers
239 views

I am looking at this schematic from Nuts and Volts of a semi-auto ranging capacitance meter, which I will eventually hook up to an Arduino or some other microcontroller. Its range is 0.1F–0.01µF, but ...
Eigenvlad's user avatar
  • 131
1 vote
2 answers
163 views

I'm attempting to match the frequencies of two 555 timer oscillators, by using digital potentiometers to fine-tune the charging & discharging resistors on one of the oscillators to match it's ...
Runsva's user avatar
  • 587
1 vote
3 answers
242 views

I'm attempting to make a 555 timer circuit with the capability of pausing the timer in a continous time-space. I'm doing this by disconnecting the timing capacitor from the circuit every time I want ...
Runsva's user avatar
  • 587
1 vote
1 answer
107 views

I am working on an LED driver board with 3 SMD LEDs. It consists of two parts: one is the LED driver itself, while the other one is a NE555 timer to generate a PWM signal for dimming. The schematic ...
FloTec09's user avatar
  • 51
0 votes
4 answers
114 views

I am building a square wave generator with a ne555. The datasheet in section 6.3.2 Astable Operations has an example circuit that is essentially the same as my practice circuit but with a 1k pullup ...
Zeno of Elea's user avatar
  • 21
0 votes
0 answers
139 views

I've built a basic 555 astable circuit - I've done this in the past without issue but this time, the output isn't right (scope trace attached). It's only swinging ~0.5v on a 12v supply with huge ...
Brydon Gibson's user avatar
  • 241
3 votes
1 answer
159 views

I am building this capacitance measurement device for educational purposes and I am trying to understand how it functions given that the unknown capacitor does not have a path to ground. The schematic ...
bobthechemist's user avatar
  • 261
2 votes
1 answer
311 views

Context: looking to generate a 1.5MHz square wave. In the MIC1555/7 datasheet there is an example astable oscillator circuit on page 2, which lists the output signal frequency as 8kHz for R=1k and C=0....
InBedded16's user avatar
  • 1,592
0 votes
1 answer
67 views

Since reset pin 4 is held high and threshold pin 6 is initially low, how can output pin 3 be low?
Richard Rosborough's user avatar
  • 11
1 vote
3 answers
150 views

I try to construct a ON delay circuit using 555 timer IC, that charges a electrolytic capacitor. I want to measure how much voltage retain in capacitor, at a single trigger. But there appears a very ...
Rajesh R's user avatar
  • 485
2 votes
2 answers
543 views

I've been trying to get this 4017 and 555 timer LED chaser to work. Specifically I was building Moritz Klein's 5-step sequencer and realized I needed a clock for the 4017 to work and build the 555 in ...
Giuseppe Lisi's user avatar
  • 21
0 votes
0 answers
74 views

I'm using microcontroller input (pin1) by classic switch to control relay on (pin2) manually. The input (pin1) can change the status when it pulled down by press of button, but the problem is that the ...
Badr Al-moraggab's user avatar
  • 11
2 votes
2 answers
516 views

I am new to circuit/electronics design so please forgive me if this is very simple. I have a project that involves RS232 and I would like to provide a visual indicator that data is being transmitted. ...
WattIsThis's user avatar
  • 21
1 vote
2 answers
168 views

I created a circuit and made the schematic in EAGLE. The idea is I have an LED (and a relay also) that turn on via a NOR Gate (which I built out of 4 NAND Gates). If both the input from my comparator ...
Erik Vincent's user avatar
  • 168
0 votes
0 answers
79 views

I was trying to design a three step (phase) LEDs chaser circuit using the 555 timer. This is based on existing designs from the Internet. I drew the circuit using KiCAD and tried to simulate it but ...
Limyx826's user avatar
  • 1
5 votes
3 answers
604 views

I'm looking to put together a 555 timer on a PCB as a learning aid (that is, put three 5k resistors, a couple comparators, a flip-flop, transistor, and an inverter on a PCB to represent the internal ...
Trevor's user avatar
  • 61
0 votes
1 answer
93 views

I am new to electronics. I need to turn on COB LEDs that use 4V when motion is detected by a PIR sensor, which provides a 3.3V output. I saw a circuit using an NE555P IC as a gate driver, but the ...
Ben000001's user avatar
  • 21
4 votes
3 answers
310 views

This is my first post here and I'm new to electronics. I am trying to delay a motor start up, when user pushes a button. I came up with something like this for now: I have two 555 timer IC (actually ...
Den's user avatar
  • 43
-1 votes
1 answer
69 views

I'm trying to design a circuit that would detect an AC signal from my old analog intercom ringer and create a 1second pulse upon detection and feed it towards a relay and/or a GPIO on ESP32 or similar....
von_saiko's user avatar
  • 109
2 votes
3 answers
152 views

It works well in Proteus (Simulation), but when I implement it, it doesn't work. I'm sure that the hardware connections are correct. Also, the 7-segment doesn't display, for example, the number 2 ...
Mahmoud Elkomy's user avatar
  • 47
0 votes
0 answers
82 views

I'm using Proteus to test a circuit before implementing it practically, but it doesn't work. I'm supposed to build a counter that is displayed in a 7 segment display, using a 555 timer. The counter is ...
Mahmoud Elkomy's user avatar
  • 47
0 votes
0 answers
111 views

I need to make a relay drive board which is triggered by the enabling of 2 signals that can be either 12V or 24V. The board will also need to allow for 12V or 24V supply (They will never be present at ...
Matt's user avatar
  • 65
2 votes
2 answers
109 views

What configuration of 555 is this. How is this circuit flashing green led 2 times (with 100 ms gap) and after 400 ms delay flashes red light 2 times. Timings are approximate. Runs on 3 V. IC number is ...
Hars's user avatar
  • 49
0 votes
0 answers
61 views

I'm currently doing a project in Multisim and I've come across a weird behavior in my 555 timers. When I have the monostable (the output should be high for 11 seconds) and the astable timers on the ...
Abril Calatayud's user avatar
  • 21
0 votes
1 answer
95 views

I have made a breadboard prototype for this capacitive soil moisture sensor: https://thecavepearlproject.org/2020/10/27/hacking-a-capacitive-soil-moisture-sensor-for-frequency-output/ (I'm using ...
Milos's user avatar
  • 213
0 votes
1 answer
175 views

Please see the attached; it is a simple LM3915 LED indicator. I want to add a beep generator so that it produces beep (buzzer) if the first LED turned on (or pin 1 of 3915 is activated). Is it ...
HFAR's user avatar
  • 9
0 votes
2 answers
175 views

Will this circuit work? It didn't flash for me, just on all the time. Initially it flashed few times, now not working. Using 7555 ( not 555), and not using pin 7. Pin 3 connected to pin 2, 6 via 33 kΩ....
Hars's user avatar
  • 49
1 vote
5 answers
256 views

Following the content of this article: PNP Transistor as Switch I built the circuit shown below. The 555 timer is configured in astable mode with an output period of approximately 1.5 seconds and a ...
RickyBoy's user avatar
  • 445
1 vote
1 answer
62 views

I am troubleshooting a circuit I have designed and have come to a major road block. I am using a current sense amplifier to determine if there is a drop in current. I know that the output of this ...
Engineer1's user avatar
  • 305
2 votes
5 answers
389 views

I assembled this circuit on a breadboard. As is well known, the oscillation frequency changes with the duty cycle. I've used a couple of different capacitor values and resistors. Some work better, but ...
Willian Gaspar's user avatar
  • 141
-1 votes
3 answers
226 views

Here's what I try to do: There is these common soft latching circuits using BJTs or MOSFETs or a 555 timer I made those circuits and they're working very well. The buttons used are always Normally-...
gowb0w's user avatar
  • 39
0 votes
2 answers
310 views

Source is https://youtu.be/_uReSadp-KA?si=OydlMA-SuNtQQxYi Yes, the circuit is working with added 0.01 µF capacitor at pin 5. After observing carefully, if I touch/tap the positive or negative side of ...
Tb Jem's user avatar
  • 11
0 votes
2 answers
105 views

I'm hoping someone could help me out here. I need the name of a circuit I can google or a schematic, that when a button is pushed; there is a 3 second delay, then a LED turns on for 5 seconds then ...
Alan Toline's user avatar
  • 1

1
2 3 4 5
…
26