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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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1answer
66 views

Obtaining data from parallel port without the “phantom power” problem

After making failed circuits in the past, I learned that the cause is that the parallel port was producing "phantom power" (aka powering the circuit). This is because I plugged my circuit into the ...
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1answer
165 views

555 circuit problem.. could it be broken?

I've made a circuit that's connected to a 12V+5V power source (attached a gallery. last photo is the schematic) it is simply a 555 timer that goes off whenever one of the two input pins goes high (...
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2answers
180 views

How to minimize DC brushed motor arcing noise propagation from MOSFET drain to gate?

I designed a basic on/off control circuit using 555 timer for a 3v hobby dc motor as shown in below. Without the motor connected, the output off the 555 timer is as shown below. (the mosfet drain is ...
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2answers
306 views

Very weak LED dimming with combined PWM signals using 555 timers

First of all, here's the circuit: What I'm doing here is using 2 PWM signals generated by 555 timers to control the warmth of the LEDs and the brightness. The top 555 is the brightness control and ...
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2answers
135 views

How does this TLC556 work?

I'm having trouble understanding what the upper part of an electronic metronome depicted in the below schematic does. I already asked about the lower op-amp part in another topic, but I also can't ...
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2answers
207 views

Problem with dual led flasher 555

I have this schematic: which supposedly makes the two LED flash alternatively with a period of 1.5s The thing is that the one connected through the NPN transistor flashes, but in it's "off" state, ...
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1answer
1k views

PWM and PPM using 555 timer

I get what PWM is and how it can be done using a 555 astable circuit. However I feel I don't completely get what PPM is how its circuit works. I understand the VCO circuit, but I don't see how it can ...
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1answer
310 views

H-Bridge: forward and backward dc motor with ic 555 by esp8266 gpio

Searching on web for make h-bridge to forward and backward dc motor with ic 555 by microcontroller ESP8266 GPIO (PWM), i found some helps and i did this circuit: This circuit always stay with +3.95v (...
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3answers
75 views

555 timer oscillator schematic question

I found this schematic, which in theory alternates the LEDs like in railway crossing lights. First of all I was wondering if it works, and if it does, what frequency does it have, and what would I ...
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1answer
169 views

Can we use 555 timer in automotive electronic circuit? [closed]

Can we use 555 timer IC in autmotive electronics design? If not then please suggest an IC in order to create dealy at laod side.
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1answer
211 views

555 stepper motor controller

I need to make a square wave generator to control a stepper motor driver. It needs to be controlled with a potentiometer and get an output range from 40 Hz to 4 kHz. I don't know a heck of a lot ...
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1answer
133 views

Low cost PWM sweep

I have this project where I need to try and get a PWM duty sweep starting at around 30% up to 100%. The issue I have is that we don't have anything left in the design (BOM Cost). I would normally use ...
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0answers
79 views

NE555 monostable timer circuit restart timer when trigger grounded in between [duplicate]

I had made an NE555 timer IC based delay circuit (monostable mode) which keeps output HIGH for 10 seconds when trigger pin is connected to ground momentarily. But what I want is if I ground trigger ...
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1answer
153 views

Atari Punk Console with 7400 chips?

How would I create a stepped tone generator using 7400 logic? For the first part, it's easy to have same range generator, with an additional transistor. Is there any way to make the same range a ...
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2answers
304 views

Electronically adjustable PWM with 555 timer

I would like to create a PWM generator with a 555 timer (like suggested here), but I would like to be able to adjust the duty cycle with a microcontroller. I would simply use PWM from the ...
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2answers
819 views

What is the best oscillator to be used in a capacitive soil moisture sensor?

I am working on this project where I am going to make a soil moisture sensor. The principal that I'm going to use is the change of capacitance of the soil with moisture. What I'm going to do is make a ...
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1answer
323 views

Spice simulation of 555 flasher will not oscillate

I am hoping that this is a very simple question. I am trying to simulate the circuit in ngspice, but it seems that the oscillation will not initiate. I delayed the on pulse, but the expected 20Hz ...
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0answers
36 views

Switching timer delay, non accumulative

I am trying to build a 555-timer that delays the switch of an input signal, both ways. When input goes high there should be a delay before output goes high, when input goes low there should be a delay ...
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5answers
2k views

Simple Mosfet driver

I need to switch 8 IRF9540 (P-Channel Mosfets) with about 32kHz (so 1 MOSFET about 4kHz) so that only one is On at one time. I thought about using the decade counter 4017 for this, and the 555 Timer ...
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1answer
198 views

Ringing in the output of 555 timer

I am using a 555 IC to get 10KHz-50% square wave.Everything goes as expected Except for large ringing(About 2V above the normal 9V high voltage) during the rising Edges of output. I put 0.1uF and ...
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4answers
1k views

Arduino watchdog with 555 Timer and a MOSFET

I want to protect an Arduino from stop running using a 555 timer. I saw some projects that use the Arduino RESET pin to do that but there are cases that my Arduino project still stop working even when ...
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1answer
162 views

How can a flip flop alternate between two clocks, turning one off and the other on and repeating?

I am just experimenting with flip flops and am pretty confused about alternating between two clocks. Right, so I want a pulse to be sent to a flip flop first after 18 seconds and then after 2 seconds ...
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2answers
411 views

How does the NPN transistor in a 555 timer discharge the capacitor when the output is low?

I am new to electronics and I'm trying to understand how the 555 timer works based on the diagram below. I am following the tutorial/explanation at https://www.electronics-tutorials.ws/waveforms/...
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0answers
971 views

555 Monostable when switch is held for a period of time

I have a problem with the 555 delay before turned-off. The problem is that I want the time cycle to start after the switch is released if it was held for a period of time. I found this circuit at "...
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1answer
94 views

Resetting 555 via Transistor (optionally driven by Touchplate/Piezo)

Right now I am using a 555 circuit to generate a 1kHz square oscillation (not displayed below). Generally the reset is pulled down, but through a button I drive a transistor to output the square ...
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3answers
244 views

555 timer not switching at threshold voltage

This is a 555 timer circuit which is supposed to generate two short pulses, back to back, at a regular frequency. The top 555 is configured as astable to control the frequency. It feeds the first 555 ...
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1answer
1k views

How to get more efficiency out of 555 timer + MOSFET?

I needed to build a delay circuit so I'm following this guide: http://www.learningaboutelectronics.com/Articles/555-timer-delay-before-turn-on-circuit.php Using this circuit, I get a delay of about 5 ...
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5answers
1k views

What to make with hundreds of 555 chips [closed]

This is a little bit different question than normal.. Aliexpress is ruing my life, sometimes i order things i don't even need because it seems cool. A few time ago I ordered 500x 555 chips for just a ...
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2answers
157 views

555 astable - frequency not linear with discharge resistor for smaller resistor values

I'm trying to use a 555 timer to create a variable frequency from a resistance, the output frequency should be about 1 kHz up to 300 kHz. I'm using a TS555CN CMOS version, which can oscillate up to 2....
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1answer
224 views

Wireless charging

I am trying to make a circuit to transfer power from one coil to another I have tried difference frequencies here are the results Fun Fact: When I am producing frequencies between 20Hz and ...
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3answers
1k views

Controlling spotwelder timer with 555

I want to use the 555 time to control the timing on the power pulse of a spot-welder using a foot switch. I have seen a few 555 mono-stable circuits, but am having trouble finding the values of the ...
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2answers
307 views

How to block DC of triangle waveform from 555 powered by single supply?

I'm using a 555 timer to generate a triangle waveform with a DC offset. I would like to feed the waveform into a comparator along with an AC signal with zero offset to get a PWM signal, so I need the ...
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1answer
114 views

Is there anything wrong with this particular timer circuit utilizing 555?

I created following simple timer circuit for one shot operation. My expectation is it to give 5v as output (for D RELAY and SP RELAY) for certain number of seconds/minutes soon as it got powered-on. ...
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2answers
539 views

555 timer circuit with d type flip-flop

Found this circuit for a 555 timer. I can't understand the use of the d-type flip-flop. Please explain.. And is the variable resistor used to adjust the frequency?
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2answers
169 views

What is incorrect with my 555 LED flasher circuit?

I have built a circuit to flash an LED using a 555 timer IC, but it doesn't flash... the LED just stays on steadily. -- I carefully followed the instructions on a common tutorial, which is: http://...
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1answer
85 views

Replace button by a component/circuit in 555 diagram

I need your help im crazy with this, i already tried many ways to do it, i need to replace the push button in this circuit by a component or circuit to be activated for a signal of 5 v such as a ...
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1answer
200 views

What is the diode for in the astable IC 555

I am trying to get my head into electronics, so my teacher challenged me to find out what this diode does. I have done a ton of experiments and i just cant put my finger on it... Everything from ...
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2answers
3k views

555N vs. 555P? One works, the other does not!

I've implemented a water level indicator using a 555 timer. It works fine when I use 555N, but the output is always high when I replace it with 555P. I don't understand. I have tried four 555Ps to ...
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2answers
656 views

555 timing capacitor discharge via threshold input

The circuit below is the timing logic for the SC280 UV exposure unit. Based on my judgement the design of the circuit is poor - and I'm planning to replace it -, I'm posting my question only to learn ...
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2answers
217 views

how the calculate the specific resistor in a parallel led circuit?

This is a Sequential LED flasher circuit i found in you tube. He uses 11 leds in 5v power supply source and he connect them in parallel with a resistor 470ohms. I try figure out how he measure this ...
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1answer
414 views

7805 Voltage Regulator powering astable 555 Timer yields LOW voltage as input to timer circuit

Hello stack exchange, So, I have two batteries powering a circuit and I want to only use one. 12.7V comes from a lead acid battery, and the smaller one is a stack of 4xAA that yield around 6.4V. The ~...
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1answer
161 views

how can i add more leds to police light circuit?

This project uses a 555 timer and a 4017 decade to produce the flash police lights. This circuit has only 4 leds , 2 blue and 2 red. I want to connect in 16 leds ( 8 blue and 8 red ) is that ...
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1answer
255 views

Please critique my high-current voltage regulator [closed]

A project I'm working on requires a source of power which need to be both regulated (5.00V) and high current (~4A). An external power source may be any from 6V to 12V but it can be assumed that it can ...
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1answer
2k views

Delay turn ON circuit using 555

I want to set a delay of around 5s between power supply turning ON and my circuit getting power. Here is the circuit I have come up with: Datasheet of mosfet I am using a 555 timer to set the ...
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0answers
71 views

minimalistic digital 2-speed oscillator with 555

I'm trying to figure out how I can turn a schematic of a one-speed simple 555 astable multivibrator that's available everywhere on the internet to a digitally controlled astable multivibrator in which ...
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1answer
651 views

Does the Low State in NE555 go to GND?

Here is the first schematic that I created : . The Vcc is at 5.1V and I a self made using the LM317, Works Fine. When I checked the Output with the Multi-meter I use., I was getting a high state of ...
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1answer
127 views

LM555 timers for control of a secure door

I will explain existing hardware followed by my desired operation thereof. I have a security door the controller of which has failed. The door has four electronic deadbolts. -- A) Two open ...
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1answer
80 views

Discharge of capacitor bellow 0.5V

I have a conundrum that I am trying to solve and am afraid I am stuck. Could anyone share some insight please? My circuit is displayed on image above. 5V (5Vsw) and 3.3V (3V3sw) are used as supply ...
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3answers
116 views

Is the rise time of the output of a logic IC or optocoupler independent of the rise time of the input?

Is the rise time of the output of a logic IC (e.g. flip-flop or inverter) or optocoupler independent or dependent on the rise time of the input? If the answer is dependent, are there any other ...
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3answers
459 views

Installed 555 timer socket backwards - can I reverse the chip in the socket?

I installed the socket for a NE555 timer ic backwards on a PCB. Can I just reverse the chip in the socket to cure the mistake?