Questions tagged [multivibrator]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
1 vote
1 answer
179 views

How can I build a current controlled 50% duty cycle oscillator from two CMOS inverters?

I am in need of a current controlled audio range (output around 1000 Hz) oscillator/multivibrator circuit. To make the result sound nice, I want to oscillator to have a 50% or near 50% duty cycle. ...
user avatar
  • 490
0 votes
1 answer
31 views

What happens if we give a negative trigger pulse before a monostable multivibrator reaches it's stable state

Monostable Multivibrator using Op Amp, from this link, Obviously there is a certain amount of time that the capacitor takes to charge again from -Vcc*β to VD (0.7v) and therefore during this period a ...
user avatar
3 votes
4 answers
266 views

Low amplitude output in Opamp square wave generator

I have made a square wave generator using an OPamp in positive feedback. The generator was designed to output a frequency of above 200KHz, so I chose the values of 200ohm and 0.01uF for the RC circuit ...
user avatar
0 votes
4 answers
178 views

CD4047 only has OCS output when operated in astable mode

I'm trying to build a simple astable multivibrator using a CD4047. I try to demonstrate using 3 LEDs on the OSC, Q, and Q` pins. Following is the circuit I built (copied diagram): The only difference ...
user avatar
  • 61
1 vote
1 answer
107 views

Newb trying to understand astable multivibrator

I've been trying to understand one thing about the astable multivibrator below. According to https://www.build-electronic-circuits.com/astable-multivibrator/, at the very beginning of the operation, ...
user avatar
  • 11
1 vote
1 answer
84 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 ...
user avatar
  • 39
0 votes
3 answers
112 views

Why does the astable multivibrator using transistor not work when I use the same value of resistance for the collector of both the transistors?

The circuit shown in the figure does not run even in proteus. But when I change the collector resistance above 1.43k of one of the transistor, the circuit starts working. What's the reason behind such ...
user avatar
  • 39
0 votes
1 answer
111 views

I made an astable multivibrator, connected it to a transformer, and I really don't know what's going on

I tried to drive some H-bridges with the multivibrator circuit to drive a small 1:25 SMD transformer to make hv for geiger tubes. My results were slightly underwhelming, so I started to do random ...
user avatar
4 votes
4 answers
586 views

BJT astable multivibrator frequency increasing with voltage

I'm trying to get a 27V 120Hz square-wave, so I tried this circuit : I get a decent 128Hz signal with 9V, which is close enough. However, if I increase the input voltage past a certain point, the ...
user avatar
  • 144
1 vote
2 answers
146 views

PNP Astable Multivibrator Variation

I am trying to learn astable multivibrator circuits and I found one in an EL wire driver. I have noticed it has a 100nF ceramic capacitor connected between the transistor bases and additional 22R ...
user avatar
  • 11
-3 votes
1 answer
106 views

precise 50 Hz oscillator [closed]

I need an astable multi-vibrator at exactly 50 or 100 Hz with exactly 50% duty cycle. using circuits like 555 can't give me that with the common well-known values of components R and C , let alone the ...
user avatar
0 votes
1 answer
69 views

Why is my Multivib piezo atomizer/transducer driver not working?

I'm tying to drive a "Moisturizing Transducer Mist Maker Atomizer Film Plate" using a simple astable multivibrator circuit like this: I can't make it work. No reaction from the atomizer. I ...
user avatar
0 votes
1 answer
82 views

BJT twin transistor astable multivibrator always outputs high

Noob here (again). I have made this schematic of an astable multivibrator and a Raspberry Pi. I want it to produce a square wave, but it just outputs high constantly. I use the Raspberry Pi as a ...
user avatar
0 votes
1 answer
74 views

Astable Multivibrator using BC549s not oscillating

I just recently started learning about electrical engineering stuff, and since my final goal of building a Z80 Computer seems a bit far away, for now, I decided I'd make a simple clock I could ...
user avatar
2 votes
3 answers
512 views

How to skip the first pulse triggering for this circuit?

Following my previous question, I came up with the following circuit using 74HC123 for simulation and in practice planning to use this IC. The circuit out should be ON when it waits for a rising edge ...
user avatar
  • 1,097
1 vote
2 answers
121 views

Astable multivibrator malfunctioning on circuit board

Here is the circuit that I've built on my project board (GL-12) Here is a schematic: Note: I'm using BC107B transistors instead of BC547 as they are quite similar. To test the circuit, I added two ...
user avatar
0 votes
1 answer
81 views

Using a DSO138 digital oscilloscope to probe a circuit

I'm new to using a DSO138 to probe my circuit. In order to get the square waveform on my DSO for an astable multivibrator, do I need to connect a jumper wire from the collector of a transistor of the ...
user avatar
0 votes
0 answers
46 views

Figuring out the importance of components in a circuit-2

This is a follow-up question for this qs which I asked earlier Here is the full specifications- The simulation gives me a current of 6.5 mA through D1 and 833 micro-A through D2. Also, I get the ...
user avatar
0 votes
2 answers
137 views

How to actually calculate the rise time for a square wave generated by an Astable Multivibrator?

If I have an astable multivibrator like the one shown in the picture, how do I actually calculate the rise time for the output square wave? I know that it's the time required to change from the low ...
user avatar
  • 121
0 votes
2 answers
129 views

What actually causes the distortion in the output wave due to an Astable Multivibrator?

I've witnessed that the output square wave from an astable multivibrator using two BJTs has its edges rounded during the rise up time(just as it is seen in fig. 1). Across resources, I've come to know ...
user avatar
  • 121
0 votes
1 answer
37 views

Connecting a RC circuit to the output channel of an astable multivibrator (follow up question)

This is a question which I had asked earlier. Tinkering around, I found out that if I connect a capacitor to the load resistor, i.e. if I pass the output through a RC circuit, the voltage retains it ...
user avatar
1 vote
2 answers
124 views

Playing around with an astable multivibrator

I had a doubt regarding the astable multivibrators using BJTs. This is a typical astable multivibrator. I have been told that if I connect a capacitor to the output channel, there would be no ...
user avatar
1 vote
1 answer
125 views

Astable multivibrator not producing a square output wave, using two BJTs

I've been trying to build an astable multivibrator circuit using two BC547B NPN transistors. I know how to build one using a 555 timer, but I'm having some problems using transistors. I should've ...
user avatar
  • 121
0 votes
0 answers
27 views

Window comparator with transient detection

I need some advice with over range circuitry I my design. In summary, I need to probe two nodes in my circuit and raise an alarm if any of them raises above approx. 2V peak (in both polarities). The ...
user avatar
0 votes
0 answers
33 views

PVT indepedent CMOS multi-vibrator design

I am doing a process, voltage, temperature (PVT) analysis of an RC-based multi-vibrator. Simulations under varying temperature (0-100 C) and process corners (FF, FS, SF, SS) show signal delay in the ...
user avatar
1 vote
1 answer
123 views

Unstable astable multivibrator

I'm trying to do an ngspice simulation of a 1KHz astable multi-vibrator. While I can achieve oscillations the output is very erratic and all over the place. [edit: two good responses below who said ...
user avatar
  • 13
1 vote
3 answers
316 views

How to read a schematic with capacitors

I've tried many times to read electronic schematics. I always struggle to understand how to read it in order to understand how the circuit works. The most important problem I have is trying to figure ...
user avatar
1 vote
1 answer
161 views

What is wrong with my circuit and how can I fix it?

This circuit used to work before I soldered it. When I initially soldered it, I used a 6V battery and it was oscillating, but the speaker was very quiet. I went with a 9V battery and I re-soldered ...
user avatar
1 vote
1 answer
194 views

I don't understand the working principle of this metal detector circuit?

The circuit below is a metal detector circuit. The inductor serves as a "sensor" to detect metal. The tone of the speaker changes when a metal is detected. However, I don't know anything ...
user avatar
0 votes
2 answers
282 views

How do I make an edge triggered T flip flop using integrated injection logic (I2L)?

I have been searching everywhere online on how to make this circuit. I found out I can make NAND gates using I2L and connect them together to make a T flip flop , but this is very impractical since I ...
user avatar
2 votes
1 answer
140 views

Why is the input trigger pulse in a monostable multivibrator fed to the base of the transistors through a capacitor and not an inductor or resistor?

In a monostable multivibrator, one of the transistors will be fed with a trigger pulse using a capacitor. I have heard about capacitor coupled circuits like stagger tuned amplifier where one single ...
user avatar
4 votes
2 answers
250 views

In an astable multivibrator, why doesn't negative feedback prevent the output from ever saturating?

What I understand of an astable multivibrator so far is this: The output saturates to one of two extremes, which drives the capacitor in the negative feedback loop to either charge or discharge. Once ...
user avatar
0 votes
0 answers
52 views

Very high current frequency on transistor collector

simulate this circuit – Schematic created using CircuitLab I am designing astable multivibrator for homework and I have calculated values for resistors and capacitors (hopefully right) but I ...
user avatar
3 votes
2 answers
517 views

Astable multivibrator using op amps - why does it start?

I'm new to electronics and I'm learning some circuits with op amps. Now I have been shown this astable multivibrator. I understand how it works. The op amp is saturated at one side or the other ...
user avatar
1 vote
1 answer
59 views

Current direction in a multivibrator

I have been studying multivibrators lately, but I have hit a wall right now. I have attached a sketch for an astable multivibrator. I know the basic stuff. When Vout is high then Vin will rise as CT1 ...
user avatar
  • 11
0 votes
1 answer
119 views

Analysis of a multivibrator circuit

I have trouble understanding the operation of the following circuit: This is the given description of the schematic: "This is a voltage controlled multivibrator that is used as an acoustic volt ...
user avatar
3 votes
3 answers
2k views

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 ...
user avatar
  • 314
0 votes
1 answer
73 views

What would be the main advantages of constructing an astable multivibrator with two CMOS inverters?

What would be the main advantages of constructing an astable multivibrator with two CMOS inverters? Can these semiconductor devices be declared to introduce small parasitic capacitances to the circuit?...
user avatar
3 votes
1 answer
373 views

Astable multivibrator: what starts the first cycle

I think I understand how the astable multivibrator works once the LEDs are blinking (cf. below), but I don't understand how the first cycle begins. I can see that at first, the 2 LEDs are on (based ...
user avatar
  • 251
1 vote
1 answer
50 views

Does the Ebers-Moll BJT model support multivibrators?

I'm developing a circuit simulator and tried to create an ideal astable multivibrator (I set some values not to be completely symmetric for the correct startup). The simulation usually stuck in ...
user avatar
1 vote
0 answers
82 views

How can I produce continuous signal from short one?

Can somebody explain, please. How can I produce continuous signal from short one?
user avatar
  • 11
2 votes
1 answer
80 views

Which ground plane shape is more appropriate in my application?

I've been working on re-making the two PCBs in the HP 211A square-wave generator from 1955, as the traces on the one I own are starting to peel off. Focusing on one board, the multivibrator, for the ...
user avatar
1 vote
3 answers
894 views

Is this D Flip Flop positive edge triggered or negative edge triggered?

It is an edge triggered D flip flop where X is input, Y is clock, Q is output. Is this D Flip Flop positive edge triggered or negative edge triggered? ADD (copied from a comment): Actually I am trying ...
user avatar
2 votes
1 answer
96 views

I'd like to know whether my attempt to increase duty cycle will work

I've been looking for a solution to make an astable multivibrator give me a 90% duty cycle or a duty cycle above 50%. This is what I came up with. I have very limited resources and means of testing, ...
user avatar
0 votes
3 answers
170 views

Convert astable multivibrator square output waveform to sawtooth

I designed an astable multivibrator by using BJT (necessary) to produce a square waveform. How I convert the output signal from a square to a ramp waveform?
user avatar
3 votes
1 answer
196 views

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 ...
user avatar
0 votes
0 answers
81 views

Simulation problem for a multivibrator IC in Proteus

I have the following circuit in Proteus, and I try to simulate the functionality of the 74HC423 multivibrator IC: The problem is whenever I change the values for Rx or Cx, the output's pulse width ...
user avatar
2 votes
2 answers
711 views

Bypass capacitor in 555ic

What will happen if we don't bypass capacitor at pin 5 of 555 ic as an astable multivibrator.Will voltage/current changes in line affect on pulse width?will capacitor at pin 1 discharge late?
user avatar
1 vote
1 answer
150 views

What's the purpose of the capacitor in this circuit?

If this trigger pulse is starting the process of sweep generation, seems to me like it would be going directly to the base of the transistor (Q701) to switch it on and off, so the series of multiple ...
user avatar
0 votes
1 answer
83 views

Some confusions on a basic CMOS multivibrator question

This is a previous exam question, so I do have a solution already, I am not trying to make you solve my homework etc. Few questions in my mind regarding this question above, There is not a given ...
user avatar
  • 1,966