Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [monostable]

85 questions
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2 answers

555 timer, one shot trigger

I'm trying to create a circuit that will pass a 12V pulse on the rising edge of a push button (it can be triggered by the entire input pulse but rising edge preffered). I've had some experience with microcontrollers but I'm very new to ICs. I…
Jordan Cartwright
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1 answer

Reset 555 timer when trigger switch is released

I have a simple 5 second Monostable 555 Timer circuit. Trigger Pin (#2) is connected to a momentary push switch. When it is pressed, the timer is started and LED stays on for 5 seconds. What I want is that if the tactile switch is released during…
Kashif
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3
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3 answers

Control timing of Monostable Multivibrator

Im having a hard time really understanding a Monostable Multivibrator. What I'm trying to achieve is being able to control the timing of the vibrator with a microcontroller of some kind. (arduino, pic, raspberry pi pico or the like) I know that Rx…
user1728582
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3
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3 answers

How to build an arbitrary (one-shot) pulse generator?

I need a circuit/IC that can generate a single pulse with a variable pulse width (I would want a minimum of 50 ns but if that is not possible the next minimum can be 1 μs, and even if that is not possible then the final minimum can be 5 μs,…
paulplusx
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3
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1 answer

What is this circuit called?

This is a circuit I made to create a high signal when a switch is opened and closed. The duration of the signal can be adjusted by changing the capacitors and resistors. It is also low powered when using a high resistance on R1 and R2. This is a…
John-Arvid
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3
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1 answer

555 timer that does not output low when reset

I'm trying to design a circuit with the following goals: When not active, output can be either Vcc or floating When triggered by pressing a button, output pulses several times to GND at some frequency F for a duration of N seconds After the N…
Ryan
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3
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2 answers

Question about comparator and 555 timer circuit

I'm designing my first circuit for a university project. This circuit will check the voltage of two sensors. If both are over a reference voltage and persist as such for more than one second, a relay will switch on. Until I switch off the entire…
Mattteo
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3
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1 answer

555 timer monostable operation not so stable

I'm experimenting with a bunch of Texas Instruments NE555P IC's that I bought recently from Amazon, I made a basic monostable operation circuit on a breadboard with the following schematics simulate this circuit – Schematic created using…
razzak
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3
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2 answers

Why does this dual monstable not function as such?

I have wired up a simple circuit here to test the cmos one-shot multivibrator. The top half of the chip seems to work but the bottom half does not. I even replaced the chip with a new one and I get the same results. R1 is 27K, R2 is 10K, and the…
user116345
3
votes
4 answers

555 monostable/astable on one chip

Is there any way to use a single 555 chip which could be switched with a two-state switch between monostable mode (one-shot pulse of a certain width) and astable (continuous pulses of a certain width)? Here's how I'd like it to work: I have a…
AlojzyBąbel
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2
votes
0 answers

Monostable multivibrator edge detector not working as expected

I have the following circuit that consists of a Monostable Multi-vibrator, SN74LVC1G123 configured to detect a falling edge upon button press and outputs a logic HIGH which in turn is inverted using the Open Drain Inverter SN74LVC1G06. The problem…
Adnan
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2
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3 answers

555 timer won't trigger monostable mode unless I add a switch between R12 and ground?

I have this setup which is a part of a bigger circuit to control motors. This is supposed to be a timer in monostable mode with about a minute of hi output when triggered. The lines going down are to give the Q2 base high and Q4 to turn the timer…
Swooperman
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2
votes
1 answer

Tacho signal for LED fan monitoring

I am struggling with this problem: I have a fan whose output tacho signal is a square wave when it is running properly. If the fan stops the signal remains at its last value (either high or low). I need to a simple circuit to light up a red LED if…
amsi
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2
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0 answers

How does the loopback on a non-retriggerable monostable work?

I understand how to connect a monstable multivibrator to be in the non-retriggerable mode. Just loopback the /Q to the falling edge input or the Q to the rising edge output) as in the following picture (taken from the MC14528B datasheet). Now I…
Francis Poirier
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2
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2 answers

Pulse output only from switch toggle on OR switch toggle off (not both)

I found this circuit here from a few years ago, posted thanks to tcrosley: Using the 74LS122 I found that it produces a short pulse both on latching the input high AND to low. The problem is I can't work out how to make the output pulse on just one…
Tim Higham
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