Tagged Questions

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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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
35 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
60 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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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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44 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
60 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
64 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
81 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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0answers
32 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
47 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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75 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 ...
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4answers
1k 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
203 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
51 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
83 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
116 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 ...
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1answer
101 views

Square Wave input into Transformer

Can a square wave generated using an astable NE555 be used as input of a transformer instead of AC? Say, I generate a square wave of 60Hz using NE555 and a 24V at 6A supply and feed it into a ...
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1answer
68 views

Control duty time and frequency with different potentiometers using one 555 timer

How can I regulate duty time and frequency of 555 timer output with 2 potentiometers?
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2answers
190 views

Use 555 for additional 40KHz PWM in Arduino

I need to transmit infra red signals using IR LED from my Arduino device. The IR signals consist of PWM 40 kHz periods and "silence" periods of various length (typical IR remote signals). I know ...
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1answer
86 views

Monostable and Astable 555 Timer

To begin with, I must say this is kind of a "homework" but I tried to do it on my own and I haven't succeed maybe someone can help me out with this matter. We're learning about digital systems, ...
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1answer
58 views

Count number of hours elapsed

It's been a long while since I played with circuits, I'd appreciate a sanity check of the following design; I'm trying to count the number of hours since the reset button was last pressed. Ideally ...
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1answer
113 views

555 timer as a humidity sensor

I want to use a 555 timer to measure humidity using a humidity dependent capacitor which goes from about 300-> 400 pF. This makes the frequency way to high for me to measure. Is there some similar ...
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2answers
170 views

555 as a Schmitt Trigger and an ON delay timer?

I've scoured the internet trying to find this out to no avail. I would like to use a 555 timer to produce a Schmitt trigger with an ON delay of 20-30 seconds. Is this possible? Or will I have to use ...
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1answer
115 views

555 timer flashing led circuit

I just have a question about this simple circuit or example: http://www.555-timer-circuits.com/flashing-led.html. I just don't get 1) why do they use 9V battery to power a single red LED light. 2) why ...
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4answers
311 views

I just fried a 555 timer IC and I'm trying to figure out how

I'm very new and just fried my first ic, trying to learn a lesson from it. Here's what I was building: (also here) on the 6v in I used 6 AA batteries that were reading about 7.5v on my meter, was ...
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4answers
328 views

Steering Diodes

What are the "steering diodes" next to the pot for? Source: http://www.youtube.com/watch?v=OXsu29K_Ap4
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3answers
290 views

How to make 7-segment display count up ?

I've connect 7447 decoder and 74193 counter as shown in the picture but I have not used 555 timer yet. Is there any way to test the circuit before using 555 ? I've connected the pins (up and down) ...
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1answer
59 views

How do I enable/disable a running 555 astable oscillator with a control signal?

I am going to control a fan using PWM signal. PWM is generated by a 555 IC. The duty cycle rate of the PWM is controlled by a PTC thermistor. And an NTC thermistor decides when to turn on and off the ...
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2answers
130 views

How can I turn pulsating DC (square wave) from a 555 IC timer into an ac square wave?

I am trying to create build a morse code transmitter. I know that morse code is sent at 500 KHZ so I set my 555 to spit out pulsating DC in a square wave with 9 volt peaks. But I am unsure wether ...
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1answer
99 views

Problem in creating one-shot impulse circuit

I am a student in university and I have a problem to be solved. I have to design a circuit that gives just one pulse (not periodic signal) when the 220V source is active. I will give 220V to the ...
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votes
4answers
773 views

How to get more current from 555 timer?

My power supply is filtered regulated 5 volt 500 mA . I am using a 555 in monostable mode to switch the motor on for a certain amount of time after the 555 is trigerred. (The 555 is being trigerred by ...
4
votes
2answers
247 views

CD4029 does not initialize at 0

I am attempting to build a very simple 4 bit counting machine using a CD4029 ic and a 555 timer. I have built my circuit on a breadboard and everything seems to be working perfectly, however on the ...
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1answer
504 views

How to build a blinking 12V indicator LED light

I attempt to build a blinking circuit using 12V truck light ( like this one: http://www.princessauto.com/pal/en/Tail-Lights/4-in-LED-Stop-Turn-Tail-Light/8126047.p). I have try to build a single LED ...
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0answers
87 views

How to combine a 555 timer and an MC34063

So, I've been at a project for a couple of weeks now, far too long in my opinion. I'm coming down to the final push and my last obstacle is to connect two circuits together to make a Piezo transducer ...
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2answers
63 views

555 delayed after threshold goes above control voltage

I am messing around with some 555s I bought a while back (NE555N from STMicroelectronics) and I'm getting some unexpected behavior. I have a capacitor hooked up to both the trigger and threshold pins ...
0
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1answer
53 views

555 servo controller “modulation input”?

Exactly as the question says. On the TI 555 Rev. C data sheet, what is the modulation input for the PWM circuit? Also, can I round the resistor and cap. to 10k and .022uf, respectively?
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2answers
667 views

Simple methods for switching a boost converter, to get a stable output voltage?

I've made a boost converter circuit, with a MOSFET as a switch, and a (7)555 timer operating as an astable oscillator, and it's output goes directly to the MOSFETs gate pin. The problem is that the ...
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2answers
162 views

How long will this low duty 555 LED blinker last on batteries?

I know there are many questions about LED blinkers, but I haven't yet found a clear answer for this. I have a 555 circuit blinking a blue led (or three in parallel). I has a low duty cycle (using a ...
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1answer
230 views

Difference between two 12V PWM signals/circuits (PIC and NE555)

I'm trying to understand the difference between two 12V PWM circuits I've build and tried. The PWM signal is intended to control the speed of a motor. Only not in the way you would expect. The motor ...
4
votes
3answers
212 views

Using timer to power on/off a high current circuit

I'm working on a Arduino project that takes measurements from the environment and sends them to a remote server over WiFi. The circuit should be battery powered and I've measured that what I have at ...
3
votes
1answer
109 views

What is the diode for in this 555 circuit?

Here is a schematic of a 555 setup to create a single shot voltage sawtooth pulse across the capacitor C2. It also outputs a square wave pulse on pin 3. A (reversed biased) Zener diode is used ...
0
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1answer
208 views

Flyback NE555N driver and mosfet overheat

I have built a small and very simple flyback SMPS based on NE555N IC. The circuit exactly I did built from is shown below: It works nicely for small loads. However I have some issues with it: ...
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4answers
593 views

Astable 555 timing circuit (0.5 Hz and 50% duty cycle)

I am trying to build a timing circuit to generate a 0.5 Hz 50% duty cycle signal. In other words 1 second on, 1 second off, and so on... I have searched a few places and found the following ...
0
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1answer
94 views

An adapter for disconnecting the current after a particular period of time

I want to prepare an adapter which will discontinue the power supply after a particular period of time. The time period will be provided manually using a switch. The time periods are: continuous ...
0
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2answers
179 views

IR proximity sensor

I have built an IR proximity sensor using a normal 940nm IR LED, Tsop 4856 kHz IR photodiode. I have used 555 timer to generate pulses to the IR led. the circuit is working correctly as far as I know. ...
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2answers
200 views

What do Capacitors do in a System with a Speaker?

I made a circuit based on a diagram from my physics teacher. The circuit has a 555 chip connected to seven wires that make up a circuit. The circuit includes a photocell resistor that acts as a ...
2
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1answer
114 views

Combine 2 circuits to get the best of both? Battery management system

I'm working on a battery management system for 2 12V batteries in series, totalling 24V, and I found this very good blog online with 2 circuits that got me very interested: This one, that got me for ...
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1answer
122 views

Digital Clock Circuit With A Buzzer

I developed a digital clock circuit that simply resembles the function of a stopwatch. The circuit works fine, but I decided to add an extra functionality: A buzz is produced each hour, but I seem to ...
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2answers
253 views

NE555 timer not working - how to identify the element at fault?

background Im a beginner in the field of electonics, and I have been trying to put together a IR remote control / laser tag system using Arduino Nano. I am using a TSOP4840 receiver and a TSAL6100 as ...
0
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1answer
142 views

Simple question (I guess): 555 timer

I want to know if it's possible to have a push button so that when it's activated, it turns on my 9 volts circuit for 10 minutes and then turn it off. Also, I don't want this circuit to consume ...