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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555 timer charge pump with feedback

In the circuit I am working on there is a requirement to create 30V DC source for a very light load (couple of mA max). I am aware that there a specialized ICs that can do that but I would like to ...
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132 views

Cheapest way to detect low voltage of a battery

I have 29V battery which drops to 24V at about 30% capacity. I want to detect when the battery goes lower than 24V and generate a 12V signal. (I have 12V auxiliary supply for lights etc) Since I'm ...
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Is this current reading of my power supply correct?

I have built this simple ignition coil driver to test old ignition coils I have. I added R7 to match the drain to source resistance of the mosfet in my real circuit which is a p10nk70zfp. The drain to ...
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2 answers
58 views

Detecting activity on CANbus

I would like to ask for help designing a circuit to turn on a relay when there is CANbus activity in a vehicle. (sounds like other questions but with CAN) What I have so far is a SPST bistable ...
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5 answers
129 views

Effective way to generate low frequency square wave

My goal is to generate a 40Hz square wave in a reasonably cheap and effective manner with a precision around 1%. I considered two approaches: 555 chip: There it seems that they are themselves around ...
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Turn signal detector

I'm trying to figure out the simplest design possible. I want a video camera to activate on my truck when I activate either left or right turn signal. Each side mirror has its own camera. So basically ...
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1 vote
0 answers
37 views

Raspberry Pi RS422-485 HAT

I am trying to design a RS422-RS485 HAT with the schematic design that I found here: http://electroshed.com/wordpress/isolated-rs422485-for-the-raspberry-pi/ However, I would prefer the data-rate (...
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41 views

Different input voltages for IR LED and TSOP

I'm designing a circuit where I need to detect an obstacle in the front efficiently in ambient light at a distance not more than 3-4 cm. For that I'm planning to use IR sensor system, IR LED as ...
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4 votes
2 answers
126 views

Increasing the forward voltage required of the PNP transistor?

I am a newbie and was reading about the uses of a 555 TIMER. I came across a project to create 40 LED Bicycle Light in Led Circuits. I can understand the diagram and most of the explanation except ...
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3 answers
79 views

Is this two-tone oscillator a smart design?

I am fiddling a bit with building some kind of programmable sound generator using simple components. I got something more or less working now as a proof of concept: Here, the 555 is wired as an ...
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1 answer
36 views

AC Motor Control circuit not working in Proteus

I am new to 555 Timers, Triacs and Proteus and I need help to fix a circuit I have built. The intended function of the circuit is as follows. Two 555 Timers are used to produce variable duty cycle 0-...
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2 votes
2 answers
79 views

Voltage controlled 555 bistable operation

[Updated with working schematic!!!] I have a circuit which I tried to adapt from the 555 bistable configuration to have the 555 states controlled by input A and B; B always goes high before A. I am ...
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1 answer
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An over- and under-voltage protection system

How can the block diagram below operate as an over and under voltage protection system? I thought it will work as follows: A step-down transformer is used to bring down the alternating current supply ...
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-1 votes
1 answer
68 views

555 flyback - question about efficiency

How can I improve this scheme to reduce consumption? MOSFET is 4N0403
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555 FlyBack low power

I want to build a 555 converter with which to get 3 V AC ~ 100 mA, I stopped at the diagram below. I need help to increase the efficiency of the circuit. Load is VFD display (for filament drive), so I ...
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1 vote
2 answers
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Limit 12VDC motor to momentary run time

My latest project involves running a 12VDC motor very, very briefly via a momentary DPDT switch that I have wired to reverse polarity depending on which direction the switch is thrown. In the end I ...
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2 answers
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How to design an analog circuit that turns on a dripping irrigation systems? [closed]

...
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1 answer
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Triple-555 timer circuit not working in Proteus

I am new to 555 Timers and Proteus and I need help to fix a circuit I have built. The intended function of the circuit is as follows. The logic is controlled by an external circuit but it is ...
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1 vote
2 answers
85 views

Momentary switch to activate 555 timer

I am very new to circuits and I've tried everything online but nothing seems to be working. I am making this circuit for a class. I am trying to emulate this circuit diagram from this youtube video ...
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1 vote
3 answers
107 views

What causes the output of the flip-flop to be LOW in 555 timer monostable circuit?

Before pressing the button, the external capacitor isn't charging because of the short circuit applied across it, but the short circuit is happening because discharge transistor is ON because the \$\...
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1 vote
1 answer
80 views

How to compute component values for current-controlled 555-based oscillator?

I am building a project where I plan to have a current controlled oscillator based on a 555. The oscillator is controlled using current source I1 (a current mirror) charging capacitor C2 in lieu of ...
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TLC555 Timer very Low or No Output

I am trying to simulate TLC555. Simulation results don't show any issue except that the out is almost negligible.
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0 answers
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Advice on SIPO FIFO clock, as well as 555 timer usage

I've made a circuit which involves me entering inputs, and the result being displayed in a seven segment LED. The LED must flash on and off and display the input number at least two times in two ...
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2 answers
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Fixed pulse width with 555 Timer

new here. I have a question regarding sending a PWM signal to a brushless motor ESC using a 555 timer. I'm using an Arduino Uno to control it currently, but I'd like to simplify my setup. I have an ...
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0 votes
1 answer
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Create a rapidly varying frequency ckt with 555 timer

I'd like to create a rapidly varying, and repeating, frequency ckt (with a 555 timer if possible), in the audio range, that will drive points of constructive interference up the inside of a tube, by ...
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0 votes
1 answer
63 views

Filtering Frequency Peaks of Sound File

I'm looking into using a 7 second long .wav sound file, and turning on an LED for 0.5s once a 500 Hz peak is detected. I have looked into several methods on how to achieve this. My main idea was to ...
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0 votes
2 answers
47 views

555 timer based cyclic LED fading circuit problem

I have the below circuit with... R1 100 Ohm R2 10k Ohm potentiometer R3 10k Ohm potentiometer R4 100k Ohm R5 4.7k Ohm R6 47 Ohm C1 470 uF D1 1N4148 D2 1N4148 T1 BC337 NPN T2 2N2222 NPN IC1 555 timer ...
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0 votes
1 answer
142 views

What is faster than a relay?

I need to find something that is faster than a relay. What I'm trying to build is an electrosurgical generator for acollege project. I want to accomplish something like this: This was the reference I ...
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1 answer
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Minimum time pulse for the NE555

I want to know if the pulse period of the monostable multivibrator using NE555 can go down to around 200ns. I don't have necessary equipment to test it and I'm afraid the timer can't work with that ...
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1 vote
0 answers
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I am making a theremin-like circuit using a 555 timer and an LM386 amplifier chip. It’s currently not outputting any sound. Why is it not working?

This is the 555 timer circuit that I am using: This is the LM386 circuit I am using: I have connected the output of the 555 timer to the 10k potentiometer. If I connect the 555 timer part of the ...
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3 answers
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Does the 555 timer 50% duty cycle capacitor discharge not affect the output voltage?

I'm new to the 555 timer and I'm trying to understand the configuration shown in the image below. The tutorial mentions that the capacitor C1 now charges and discharges through the resistor R2. The ...
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3 votes
2 answers
881 views

555 monostable configuration: why shorting a charged capacitor is not a concern?

In the typical monostable configuration, 555 timers are shown with the discharge pin (7) connected directly to the capacitor. The idea is that, when the output pin (3) goes low, both sides of the ...
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1 answer
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I'm looking for a traffic light circuit which includes a pedestrian crossing using a 555 timer IC [closed]

I'm looking for a basic traffic light circuit to make a toy crossing. There will be 1 traffic light using the typical lighting sequence. A button for the pedestrian to request crossing red/green ...
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-3 votes
2 answers
103 views

Can a 555 amplify another 555? [closed]

I read an article that claimed it is possible for one 555 to amplify another when they are placed in cascade (serially). We always use transistors for amplification; why would we place a 555 in that ...
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0 votes
2 answers
159 views

How to 'retrigger' 555 timer, when already triggered/high?

I wanted to ask for some help regarding the setup of a 555 timer. I'm using it in the standard monostable mode, running at 5 V, basically as a 1 min timer, using a simple momentary pushbutton to ...
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2 answers
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Need help driving IRFP460 using 555 IC

I have put together a variable pulsed dc signal using 555 timer ic. I wan't to control a IRFP460 mosfet so that i can drive high current loads. I have found a circuit of mosfet driver on one of ...
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0 votes
0 answers
93 views

555 timer emits tone regardless of reset value

I made a microcontroller circuit on a PCB and I attached a typical timer circuit to it. The IC of the timer is an 8-pin DIP texas instruments NE555 Resistors are 5% tolerance. Output capacitor is ...
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2 answers
70 views

Adding a buzzer to an existing LED

I have a set top box. It has a 3 mm green LED (on the front panel) that lights up when I connect the dish coax cable (signal LED). I measured the voltage across the LED. It has 0 V when the dish cable ...
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1 vote
3 answers
95 views

What is the purpose of the diode in this peak detector?

I was reading about a capacitive soil moisture sensor circuit today, and came across the following diagram: (Diagram taken from the Cave Pearl Project, https://thecavepearlproject.org/2020/10/27/...
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2 votes
4 answers
408 views

How to turn a normally-closed temperature control circuit into a normally-open one?

I've designed a very simple heating circuit that runs a heater until a certain temperature has been reached (as measured by an NTC thermistor) at which point the heater turns off. The circuit diagram ...
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0 votes
3 answers
69 views

Function of timer's output buffer

What's the function of the timer's output buffer?
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1 vote
1 answer
90 views

Astable multivibrator frequency mismatch

I made an astable multivibrator using an NE555p and a transistor. I checked the frequency and found it to be 220 kHz, but it should be 481 kHz. I used a resistor of 1 kΩ for both R1 and R2. The ...
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2 votes
1 answer
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Does this circuit work to switch a load with a microcontroller?

I want to create a circuit to switch loads (e.g.: led lights). Following requirements have to be met: the load should keep it's state when the microcontroller goes to sleep/powers off the load could ...
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2 votes
2 answers
164 views

555 Timer with 50% duty cycle

I've seen below 555 circuit which produces a square wave of 50% duty cycle. I am quite new to electronics and I saw Ben eater's 555 timer tutorial where he used discharge pin for capacitor discharging....
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1 vote
4 answers
194 views

Pulse a 555 astable oscillator every second without an additional IC

I am developing a ranging device to help people with blindness. I need to pulse a 38 kHz Infrared LED every 1 second. A 555 timer in astable mode generates the 38 kHz modulation. I'm currently using ...
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6 votes
2 answers
702 views

555 Astable : Separate charge and discharge resistors?

The 555 astable oscillator seems to be usually implemented with one common resistor between the charging and discharging paths of the capacitor. Is there something wrong with putting one resistor for ...
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-3 votes
1 answer
96 views

How to make a 555/556-based one-shot timer on a breadboard? [closed]

How can I implement the circuit as described below on a breadboard? The Monostable or “One Shot” Refer to the datasheet for the NE555 https://www.ti.com/lit/ds/symlink/ne555.pdf Find and read the ...
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0 votes
0 answers
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Timer 555 AC square wave

Im currently trying to build a square wave circuit using the 555 Timer (see picture). Currently it is producing a square wave between 0 to 5V, duty cycle is about 50% and a frequency of about 50kHz. (...
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0 votes
4 answers
182 views

Making a simple 555 sawtooth VCO stable?

I have figured out how to make a sawtooth VCO using a 555 IC , by using a current mirror. The issues I am having is I can't make it stable at all. Its having random issues like it randomly changes ...
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0 votes
0 answers
32 views

How to stabilize this CV triggered toggle (555 timer latching switch) when fed with two gates?

I created the prototype for a modular synthesizer module. The project goal is an AND gate that is fed with two control voltage inputs (A and B with an Vpp around 5V). There will be two outputs: the ...
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