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Questions tagged [multivibrator]

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48
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5answers
6k views

Why does music synthesizer built from chain of astable multivibrator circuits get “out-of-tune” after a few hours?

I built a prototype keyboard/sound synthesizer using a chain of 13 astable multivibrator circuits whose outputs are connected to an audio amplifier chip (LM386) and speaker, all powered off a 9V DC ...
-1
votes
2answers
57 views

BJT Astable Multivibrator - What is the max. oscillation frequency?

What is the max. oscillation frequency of this Astable Multivibrator circuit? Is it directly related to transition frequency of the transistor? I plan on using it with BC547B transistor. The hardwired ...
1
vote
0answers
37 views

Upgraded flipflop square wave generator - did I do good?

I've drawn up a simple multi-frequency square wave generator, based on a astable multivibrator circut, with frequency trimmed by the two ganged pots (both 100k) and the range set by a DPDT switch, ...
0
votes
1answer
35 views

IC 555 as monostable multivibrator

How is the output of a monostable multivibrator affected if the trigger pin is kept at a negative voltage (0V)? The upper voltage reference comparator will change its output to logic 1, while the ...
0
votes
1answer
32 views

What is the purpose of higher-resistance resistors in Astable Multivibrator circuit?

The astable multivibrator circuit has two higher-resistance resistors (47k on the pic). What are they there for? Wouldn't it work without? And what is exactly their function? I spent a lot of time ...
-4
votes
1answer
75 views

Bistable Multivibrator using transistors [closed]

how does the pull up resistor work in bistable multivibrators, does transistor's base voltage drop below zero voltage as they do in astable multivibrators to drive off the transistors
1
vote
2answers
60 views

Philicorda phase shifter vibrato circuit doesnt work

I have built this circuit in the online editor, but it doesn't seem to oscillate. My philicorda vibrato broke down and i want to repair it. It should convert 21V DC into a sine wave when i understand ...
1
vote
0answers
33 views

Astable multivibrator

I found an Astable multivibrator schematic online and the transistor they used was a NPN 2n2222 and I didn't have one so I was just wondering if it's a must to use a specific NPN or PNP for ...
0
votes
1answer
48 views

monostable Eccles - Jordan multivibrator, theory

I’ve a few problems and questions to the principle of monostable multivibrator’s work. Basic schematic is as below: What is the reason for D1, C1, R3 elements at input? Why I can’t just tie a ...
0
votes
0answers
58 views

Circuits that take advantage of tolerances in components

Bit of a wordy question title... I was trying to simulate an astable multivibrator the other night and the simulation refused to run. I eventually realised that because the simulation assumes perfect ...
1
vote
2answers
66 views

Analog Bistable Memory

I am looking for a device which I do not know exists. I would like to store the state of a number of analog switches, perhaps driven by a D Type Flip Flop. I'd like to drive the flip flop and set ...
0
votes
2answers
36 views

Should analogue multivibrator and comparator pullup circuit have separate supplies?

I have managed to produce a design within the falstad circuit simulator for an analogue "LED chaser" using an analogue multivibrator and 3 comparators inspecting the voltage of one side of the ...
-3
votes
1answer
121 views

Astable 555 not oscillating [closed]

I've been struggling with building a 555 timer for a project. I get the expected voltage at pin 3 (output), but the problem is that it's not oscillating. The Vout is constantly 8.4V, while I expected ...
2
votes
3answers
161 views

CMOS frequency of oscillation

How to find the frequency of oscillations in this circuit CMOS circuit: simulate this circuit – Schematic created using CircuitLab Assuming the ideal CMOS gate with the threshold at 0.5Vdd. ...
0
votes
0answers
30 views

What is the maximum output pulse width of this multivibrator?

I have an IC which is this multivibrator. And it is the model CD74HC123EE. But I actually noticed on the receipt there was an indication as "short". I also saw two folders in a folder called ...
0
votes
1answer
48 views

A question about circuit design with a multivibrator

I want to implement a pulse extender with a retriggerable multivibrator IC called CD74HC123EE4. Here is the datasheet. The input will be a 32Hz pulse train with a 5 µsec duty cycle; and at the output ...
0
votes
1answer
70 views

Monostable multivibrator problem

As you see in the picture above, diode voltage drop is 0V, and the monostable multivibrator is made in CMOS technology with protection diodes. I have problem finding the output of this circuit in some ...
1
vote
0answers
125 views

A monostable multivibrator using two NPN transistors works as desired in LTSpice, but in reality is very different

I designed a simple monostable multivibrator to extend a pulse of width \$\approx\$ \$1{\mu}s\$, to \$8ms\$ (to illuminate an LED when something happens on a bus). This is the circuit here, and the ...
0
votes
2answers
155 views

nand gate astable vibrator do not work at 400kHz

I want to build a 400kHz square wave oscillator with NAND GATE using the CD4011BE circuit. Unfortunately, it does not work as expected when I use R2 and C values according this schematic: ...
0
votes
0answers
75 views

Astable multivibrator with capacitor on output

Can someone explain how does the capacitor on the collector of Q2 impact the output voltage from Q2's collector. I would like if someone could draw the signal output voltage in Q2's collector when Q2 ...
6
votes
2answers
1k views

Astable multivibrator using transistor

I have started learning transistors few weeks ago and I hit a roadblock (again). I have been following this tutorial on Sparkfun -https://learn.sparkfun.com/tutorials/transistors Now I have moved to ...
1
vote
2answers
254 views

Controlling which transistor turns on first in a multivibrator

I've managed to adapt a basic multivibrator circuit to contain 3 LEDs that blink in sequence, but I want to be able to control which LED lights first when it's turned on, so the same LED lights first ...
3
votes
2answers
146 views

Naive VCXO design - runs at 3rd harmonic, I need the base freq. Corrections welcome

Dear (ladies and) gentlemen, consider this a hobby question. (How do you call a hobby project on the fringe of your nominal work? A skunkworks job?) I mean to say that I'm not an EE design pro = ...
3
votes
2answers
650 views

Bistable Multivibrator using discrete transistors

I am trying to understand this circuit but as of yet I still have a number of gaps in my reasoning. So far I have deduced: (assuming TR1 is ON and TR2 is OFF) left hand side capacitor charges ...
3
votes
3answers
725 views

How to determine the saturation level when an opamp schmitt trigger starts worknig?

The Opamp inverting schmitt trigger is constructed as shown. The output signal is So I ask why is the output at the start of operation saturated to positive? Also, if the input voltage is moved ...
1
vote
2answers
486 views

Replacing push button by transistor in 555 circuit

TL;DR: I need to replace the button S1 by a circuit/component that could close the circuit which the button is closing by applying a 5V signal (with 0.5s duration) in the new circuit/component. Well, ...
1
vote
1answer
261 views

Opamp Astable Multivibrator - initial delay

I'm trying to build a low frequency oscillator (think about 0.01Hz - 5Hz) using a TL072 as an astable multivibrator. Here's the circuit in LTspice: And here's the simulated output: Where does the 2....
0
votes
1answer
311 views

Is this an astable multivibrator?

In this circuit the LED flashes on and off, however could it be classified as an astable multivibrator?
1
vote
1answer
84 views

BJT Bitonal Astable Multivibrator, can someone explain me how this circuit works?

I've been analyzing this circuit and so far I think it divides in two separate oscillators, but I still don't have a clear idea on how this two work together. I'm leaving a picture of the circuit, ...
1
vote
1answer
198 views

Why Op-amp pulse generator circuit do not providing any output?

I'm trying to design a clock with 1.8V CMOS. I've designed the Op-amp and individually it works fine (simulated with up to 10MHz pulse input) . But when I use this opamp to draw the feedback circuit ,...
0
votes
1answer
149 views

What does this circuit do?

If someone could explain how does this circuit operate it would be appreciated. As far as I can see the "trigger" is a rising edge which is low pass filtered by R10 & C4. I'm not 100% sure about ...
1
vote
1answer
663 views

Why does this Edge Trigger Work on input of 555 monostable config?

I recently wired up a 555 timer in a mono stable configuration and found that when the trigger was held low for longer than the configured output pulse width, the output would stay high. After ...
1
vote
2answers
224 views

Why cannot circuits like astable multivibrator, RC phase shift oscillator and wien bridge oscillators be used as inverters?

I have been having this doubt for quite a while. An inverter basically is a power electronic equipment that converts DC voltage in AC voltage for powering loads that work on AC supply.So this means ...
0
votes
1answer
108 views

PWM signal is affected when motor is connected

I am working on a fun side project where I am creating a PWM waveform using the LM324 and a small solar panel. I am using the LM324 for the astable multivibrator, integrator, and comparator. The ...
1
vote
2answers
202 views

Compact way to generate a square wave with double pulse (like a heartbeat)?

I'd like to drive a small vibrating motor to produce a heartbeat-like effect by feeding it a square wave such as the one below. Times t1 and ...
0
votes
1answer
161 views

SN74LVC1G123 Monostable Multivibrator IC

Good afternoon, I was hoping someone could help me understand some of the terminology in this data sheet and how I translate that into a basic one-shot multivibrator that is retriggerable. http://...
0
votes
1answer
66 views

What type of monostable multivibrator is this?

In the circuit description it said 4538b, but after googling the diagram of this IC, it seems there is no schmitt trigger on the input as it shows on the photo. Does CD14538BE work for this ...
0
votes
3answers
2k views

When does the capacitor charges and discharges in an astable multivibrator circuit?

I was reading this and couldn't figure out at what point and how are the capacitors getting discharged?
0
votes
2answers
4k views

The input frequency of a servo

If the speed of the motor speed depends on the duty cycle how frequent should that pulse be passed to the motor. I know that there is some minimum frequency such as 33Hz but I am not sure, and I am ...
0
votes
1answer
486 views

turn level-based input to edge-triggered input [duplicate]

I'm trying to figure out with the most minimal part count how to convert an input of a digital IC to an edge-triggered input. I am using the 82C55 IC and the input on it I want to make negative edge-...
1
vote
2answers
428 views

Astable Multivibrator not oscilating

I am pretty new with this stuff, just learning. I wanted to make a simple PCB, and as this was my first project, I decided to go with astable multivibrator circuit, to oscillate 2 LED's using ...
0
votes
2answers
386 views

Period for this astable multivibrator (nor gates with limiting diodes)

I was able to find the period without the diodes which was T=2RCln(3) But I am unable to find the expression when we connect the two diodes. (Our course says it is : T= RCln( (VDD+Vd) /vt). I am ...
0
votes
1answer
1k views

IC Timer 555 Astable Multivibrator 50% Duty cycle

I'm given this configuration to solve for a IC-Timer 555 in astable mode to get a 50% duty cycle however I'm having some difficulties in the calculations. The circuit is modified a bit as shown. ...
1
vote
0answers
255 views

Dark detector with 555 timer and output pin has a LED

I am a complete novice and I had done it in a hurry with my kiddo around. I have redrawn it, with the values I used. The circuit works. Also between pins 6 and 7, if I use a 100 K/10 K it works. ...
3
votes
1answer
2k views

triangular and square wave generator

the circuit below is a triangular and square wave generator. With the first stage (the integrator) I can generate a triangular wave, and with the second stage (comparator) I can generate a triangular ...
-1
votes
2answers
113 views

Generation of Digital modulated waves using 555 [closed]

I am confused why there is ppm and digital modulated wave occur at 555 output, when 5th pin is given a triangular signal, instead of connecting it to 0.01uF capacitor. Please tell me which wave (PPM ...
0
votes
2answers
138 views

Retrigerable Monostable Multivibrator that fires on both rising and falling edge.

I have a need to generate an active low pulse when a switch is depressed AND when it is released and keep the component count and PCB real estate as low as possible (while still allowing me to ...
0
votes
1answer
208 views

Monostable Multivibrator

I am doing an experiment on Monostable Multivibrator using IC 555. But, I need to generate a trigger source (which goes into pin 2). I have a 5V supply and IC 555 timer. I have used R1 as 100K and ...
0
votes
2answers
407 views

DC to AC conversion and filter wave shaping

My question refers to checking concepts.It's a scientific one,so I am not looking for a way to make a DC to AC power supply for a device because its charger broke or something similar. The goal is to ...
0
votes
1answer
169 views

How to vary amplitude of my custom pulse generator?

I'm attempting to build a custom pulse generator that I can trigger with a digital I/O pulse. So far I've used a TI SN74LS123N Retriggerable One-Shot Multivibrator in combination with a 22 pF cap and ...