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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Capacitive proximity sensor

Is it possibel to make a Capacitive proximity sensor using 555 timer of using an OPamp. I wish to construct a set up( MAde of plastic 6mm thickness) I will be palcing the sensor inside the setup to ...
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35 views

help with 555 timer to dim led driver

I am trying to build some DIY LED fixtures to light my saltwater aquarium. They need to be dimmable, and I want to dim them with Pots for convenience versus a controller. It will probably be clear by ...
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29 views

Inconsistent behaviour from SA555

So I was "hacking" (I'm not really in a level to call what I'm doing "hacking") a small device and it just can't help but produce a small voltage spike when power is first turned on; registering at ...
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1answer
54 views

555 Timer Zapper

I want to make a simple bug zapper. I was planning to make a cockroach zapper but I want it to be a small DC application and dont have any transformers on hand so I may have to settle for a zapper the ...
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2answers
60 views

How delay or phase shift a signal?

I'm using a 555 to create a throbbing effect on a LED, like in this project. Is there a simple way to delay the signal for a second (then third, then forth...) LED to have them fade in and out at ...
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29 views

Confirm my suspicions about astable 555 “always on”, dumb mistake?

got a astable 555 timer schematic here, worked fine with a through hole NE555P when I didn't add the switch to pin 4. Now, in my SMD NE555PSR, the pulse is simply always 'high' or always 'low'. Am ...
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1answer
62 views

555 timer as FM transmitter vs. Tank Circuit

This site seems to suggest the use of the 555 timer in astable mode to generate frequency modulation from a source. The typical transmitter uses a tank circuit with an inductor and trimmer capacitor ...
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2answers
35 views

555 timer control voltage

I'm trying connect the 555 timer as a pulse wave modulator. Notice from the diagram below, the - input of Comp1 is internally connected to \$2/3V_{CC}\$. The control voltage is applied at pin 5. The ...
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1answer
51 views

Damped RLC Circuit Equation

I'm trying to measure the inductance of a toroid with the use of a 555 in astable mode. Hopefully, by putting the toroid in parallel with a known capacitor and driving the circuit with a low duty ...
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1answer
115 views

Problem in Basic 555 Timer Circuit

I am trying to build a simple LED flasher circuit using 555 timer IC. Tried building it on breadboard and simulators several times but that is not working. As I am a beginner I think I am making some ...
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48 views

DC Motor Speed Control With 555

Can you please explain why this circut is not working in simulation. I get GMIN Stepping failed, too many iterations errors. Is there something wrong with the design?
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35 views

555 trigger with small voltage

I'm trying to determine the right kind of circuit for this situation. I've got a small sensor that goes high whenever a fin passes by a small light and blocks the light. The frequency is about 10 Hz ...
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3answers
85 views

Any way to create a 3 LED chaser with only a 555 IC?

I've seen single and dual blinking circuits, but wanted to know if there was some easy way to squeeze in a third? I don't have a 4017 IC at the moment, unfortunately.
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4answers
590 views

Multiplexing a Circuit

Frankly, I'm overwhelmed with this circuit that I have to start building in lab tomorrow. Last week we built an octal decoder that takes a 3-bit binary input from 000 to 111 and displays a unique ...
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1answer
69 views

Solar Charge Controller Function Details

I am planning to make this controller: I would like to understand the way the components work to switch from charging to dumping and vice versa at set points. Note that the 555 timer is not being ...
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3answers
54 views

Identifying the “Preset” Component in this 555 Monostable Timer PCB

I have a PCB for a 555 monostable timer circuit as shown below: For the most part, the components are clearly labeled (I think the round circle with a + inside denotes a capacitor, but please ...
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2answers
105 views

Difference between NE555 and NE555xx

I'm going to order the NE555 chip from Texas Instruments (Link) to build a circuit, but they only have NE555P, NE555DR etc. Can I use the NE555xx instead of NE555? What is the difference between them? ...
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5answers
433 views

Can someone check over my schematic?

This is the first schematic I have made that was not a simple LED. I want to know if it seems good before I go and build it (and buy the parts). Here is the schematic: Here are a few of my ...
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1answer
75 views

555 and output amplifer with different Vcc supplies

I want to increase the power of the push-pull amplifier in this circuit. The left 555 generates a square wave and the righthand 555 is triggered by it, and the output of both is amplified by the pairs ...
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3answers
768 views

555 timer boost converter doesn't meet spec

I've been messing around with nixie tubes lately which requires a high voltage source (~150V-200V) to turn on. I searched around for a simple high voltage generator and found this circuit which uses ...
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1answer
83 views

Driving 555 control voltage with DAC

I have build a stepped tone generator (aka Atari Punk console) which are 2 555 timers connected together (one 555 is configured as a astable oscillator and drives the second configured as a monostable ...
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3answers
82 views

555 Astable Multivibrator Voltage Spikes

I built a 12V LED dimmer based on (modified from) the circuit below. Essentially I used a TIP31C instead of the Darlington pair, and provide power to 555 with 7805. An oscilloscope gave me the ...
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1answer
173 views

Floating charge pump for high side N-channel MOSFET bias

This question is derived from this one. I'd like to keep gate on for an indefinite period of time (100% Duty cycle) and for that I'd like to use charge pump since idea with relay is not attractive. ...
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2answers
356 views

Is this 12 volt LED circuit correct?

I found this "Plant Grow LED light" circuit on the Internet and I wanted to know if: (Please don't feel pressured to answer all my questions. You can just answer a few only if you like.) this is ...
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3answers
128 views

wiring 555 to disconnect itself from electricity

i had idea for a circuit with 555 and here is the IDEA: circuit is stationary somewhere, it is in "passive state" meaning its drawing no current from battery and pin 3 is set low, then someone comes ...
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3answers
121 views

Slightly weird astable oscillator in a 555, where does this capacitor discharge to?

In the 555 datasheet, the cap is usually connected to pin 7 (discharge), but in this circuit, it's not: When the capacitor voltage is >2/3Vcc, output will turn off and current will have no where to ...
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324 views

Modifications to 555 LED Fade Circuit

I was looking for a circuit to fade an LED on and off using no microcontrollers, and found this nice circuit: http://www.555-timer-circuits.com/up-down-fading-led.html it seems like exactly what I ...
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2answers
103 views

Boost converter simulation keeps getting fried

In my project I want to use a couple of old russian VFDs. To drive them, I need 28V from a 12V power supply. The plan is to use a DC-DC boost converter as calculated here and here. I've ported the ...
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1answer
69 views

NE555 Timer Problem

I need help using an NE555 timer to flash an LED. Here is my current set up: All resistors are 220 Ohms and LED is link The capacitor is 10uf and same result happens with 1uf. I am using a 9V ...
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3answers
343 views

555 timer one-shot 30 second light LED strip, TOTALLY CONFUSED!

I'm working on a personal project and I am at my absolute whits end here. I have a configurable N.O. or N.C. switch (nteinc Magnetic Alarm Reed Switch) so I'm not too concerned with which way I use ...
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1answer
61 views

I need help in starting this 7segment from 0

I am making a control system as my project. Here i have used 2 555 timers one in monostable and the other sin astable. The monostable outputs when process one button is pushed and this also triggers ...
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1answer
47 views

Running a 12VDC motor for adjustable interval

I want to set up a timer circuit that will run a high-torque, low RPM 12VDC motor (max 200mA) for an adjustable amount of time. This motor drives an auger in a home designed pet feeder and I need to ...
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3answers
119 views

555 timer ciruit errors

I have set up a 555 Timer circuit on my breadboard following this diagram. These are the values I use: R1: 1k R2: 1k C: 0.1uf Vcc: 9V The only problem is, on pin 5, I have a 0.001uf capacitor. ...
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4answers
129 views

Any reason I cannot just switch a transformer from a 555 to generate high voltages?

I had an idea to finally start using my nixie tubes and thought why not just switch a mosfet which switches a transformer to generate required high voltages for nixie tubes from a low voltage supply. ...
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2answers
92 views

How is 555 astable timing affected by a resistor on Vcc

I am trying to build a circuit that will plug in to a cell phone and let me read the value of a thermistor by generating a tone to the microphone, where the frequency is a function of the thermistor's ...
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2answers
90 views

Choosing resistor values for a 555 timer

I have to design a frequency counter using a 555 timer as a pulse generator. I included a schematic for part of the circuit, but this is my first time using a 555, so I also included the original ...
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2answers
85 views

Can you set up a monostable 555 timer so it reverses the output?

I would like to make an alarm that goes off about 1 minute after it has been triggered. To do this, I want to delay the circuit using a 555 timer in monostable, but I can't do this as they turn it on ...
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3answers
1k views

Why 555 timer IC has three 5k resistances and not any other values?

Why does 555 timer IC has three 5k resistors and not other values, like 10k-10k-10k or something else?
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2answers
288 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 ...
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1answer
130 views

using one 555 timer to control the pulse of another

tried making something like this Limit Number Of Pulses From 555 Or Similar but it doesn't work. I'm not sure what it needs. I'm trying to make the first timer put out voltage to the second one for ...
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1answer
132 views

Can I make a step up transformer using these components?

I have a step down transformer that converts from 220 volt to 15 volt. I want to connect the secondary coil of this transformer to the output of 555 IC that produces ( 5 volt / 100 KHz ). Is there ...
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1answer
114 views

Where does the current in a Dickson Charge Pump come from? Does the oscillator/PWM pin of a microcontroller also source current?

Well, I am making a small circuit which looks like this: When simulated, the load current gets up to about 200-280 mA no problem, so I want to implement this circuit in real life. My only problem ...
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165 views

555 timing formula when the diode forward voltage drop is not neglected

(Image Sources) In this modified astable multivibrator circuit the forward voltage drop of the diode D1 is always ignored, and the timing formulas are given as $$ t_1 = \ln(2)R_1C_1, \quad t_2 = ...
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0answers
56 views

monostable 555 current is bleeding, battery dies

This is likely an obvious question to an electrical expert, but I am only doing my best. My monostable 555 project is currently working: when triggered, an LED gets 5V and stays on for 5 minutes. ...
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0answers
81 views

I guarantee this one will be fun - Need help putting several circuits together into one

So I did my best to annotate the schematic with what I'm trying to do. Where I'm really running into trouble is past the output of the 555. This is basically a control circuit for a camera's ...
8
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4answers
2k views

555 timer: how to set values to take an hour

I'm new (and novice) in electronics. I came to seek your knowledge to see if someone can help me with a very basic circuit. It is a 555 chip, which should light a LED (for about 1/2 second) every ...
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2answers
350 views

Why does this circuit keep killing my 555 timers?

I have a 555 timer set up in a standard monostable oscillator configuration. Nothing fancy, no modifications whatsoever. I'm driving it with about 12V. If I trigger the 555 with the ground directly, ...
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1answer
80 views

Analog PWM generator from 0%

I have to prepare easy analog PWM regulator which can operate from 0% (0V). I know that one 555 can't do that... Do you know any circuit that can handle that?
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1answer
304 views

Generate PWM signal based on 555 for Meanwell LDD driver

I am using a Meanwell Led Driver LDD-1000H. It has a single pin for PWM input for dimming. I have seen many sketches using the 555 to dim a LED but in these cases the LED was part of the circuit. How ...
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3answers
162 views

Need help with an LED flash circuit

I joined just because I'm having sort of a dilemma. I need to design a flash circuit for a tiny SMD based project, and I have a way of doing it, but I want to see if I can make it better and I haven't ...