Questions tagged [astable]
The astable tag has no usage guidance.
88
questions
0
votes
2answers
34 views
555 timer Theremin - capacitor choice, and question about mixing signals
I'm trying to create 555-timer based Theremin, but I have a few questions that I don't quite understand. For now, I'm building it on a breadboard (yes, I know it's not the best option), but I don't ...
0
votes
2answers
43 views
NE555 - astable flashing alternative LED circuit
NE 555 help - astable alternate flashing LED circuit
"In the circuit, the LED1 lights when the output pin has a HIGH state and LED2 lights when the output is in a LOW state." - I couldn't ...
0
votes
1answer
42 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?...
0
votes
0answers
36 views
Circuit question for LM358 and NE555
I have made an IR proximity sensor which works fine when an LED is connected.
Figure 1: This is the IR receiver and emitter part of the circuit. The white LED is connected to ground via a 270 ohm ...
3
votes
1answer
272 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 ...
0
votes
0answers
45 views
555 Timer Astable Mode
Just to clear things up. This is NOT a homework question, but it is lecture notes used as a practice exam.
I am trying to understand the 555 timer in oscillation (Astable) mode particularly the ...
0
votes
0answers
14 views
A light dependent current astable multivibrator
i have basic knowledge about multivibrators and how a photodiode is operated but i'm having trouble trying to combine them into one circuit. Suppose if i am to operate the photodiode on the circuit as ...
1
vote
1answer
60 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, ...
0
votes
0answers
72 views
I've built dead bug (on steroids) boost converter
I know it looks sloppy but this is my very own homemade boost converter! It outputs 6watts of power from a 3.7v battery(phone battery)...
It's switched by an astable multivibrator, and the switch is ...
2
votes
2answers
547 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?
0
votes
0answers
43 views
How does a boost converter power the oscillating circuit and load at the same time?
so I've put together a boost converter circuit of my own and I have a problem, I want my boost converter to output reasonably high current but whenever I connect a high current load - the astable ...
9
votes
4answers
7k views
How does this astable multivibrator circuit with FETs work?
I am having trouble understanding this schematic. I do understand that it is pretty simple, but I just can't seem to get my head around part of it.
The schematic is a more complicated version of an ...
0
votes
1answer
48 views
CMOS astable circuit
I have made the following astable circuit in Multisim:
However, it didn't work (oscilloscope reads 0V as an output.)
I think the problem is because of VDD and GND pins which are hidden in Multisim.
...
0
votes
1answer
67 views
Feedback on astable 555 timer circuit to control MAC valve for turbo control
I have some questions and wanted to get feedback on this circuit I have put together. Basically to see if there is something I missed or obvious that I should change or should have designed ...
0
votes
1answer
125 views
Two questions about astable multivibrators and transformers
Here's something that confuses me: The output on an astable multivibrator will be shown on a multimeter as half the input voltage (for example we have 9V-0V-9V-0V...and the multimeter averages it out ...
-1
votes
2answers
158 views
Gating an astable 555 output signal in a way that oscilation always starts with a Low to High transition
simply, the circuit is a 38KHz signal generator for an IR remote project. the output signal should be gated by an MCU according to IR timing intervals recorded earlier. the design with the 4148 diode ...
22
votes
5answers
2k views
Astable 555 circuit not oscillating
I'm a complete beginner to electronics, but I'm trying to follow Ben Eaters video series "Building an 8-bit computer". I tried to do the first part of an astable 555 timer, but the LED does not ...
3
votes
1answer
174 views
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 ...
1
vote
2answers
155 views
Astable multivibrator not working
I was wondering if you can help me to know why my circuit is not working. I have tried with different pre-existing circuit values to make sure the circuit was working properly before I put my ...
1
vote
0answers
76 views
Astable multivibrator inverter
I'm new to electronics and trying to make an astable multivibrator oscillator. The PSpice simulation doesn't work (it says netlist error when I place a mosfet or a diode) and I get a really low ...
1
vote
2answers
45 views
Explain how this astable chain(?) circuit works
The circuit below fades on and off a cascading series of leds in an alternating fashion.
I tried reproducing it on a breadboard with 5 leds to try to understand it how it works, and got all sorts of ...
2
votes
2answers
461 views
BJT astable multivibrator generate triangle wave
In this circuit there is a bjt astable multivibrator. It generates a square wave. And according to the description, at the output of the opamp it generates a triangle wave from this square wave.
I've ...
1
vote
1answer
70 views
Op-Amp Astable Multivibrator - Effect of bypass Switch
For your consideration, I have this Astable-multivibrator via a classic Op-Amp Schmitt Trigger delivering a square signal (here 1.82Hz).
I am fine with the circuit with SW1 open as C2 is basically in ...
0
votes
1answer
59 views
Electric astable circuit not working
For school I have to build a astable circuit that stays on for 5 seconds and then turns off for 1 second. However my circuit isn't working I am do not know why here is my circuit on a bread board. The ...
7
votes
3answers
916 views
Adding Diodes to Transistor Astable Multivibrator; 1N5818 Schottky diodes work but 1N4148 diodes don't; can't figure out why
I am an avid electronics hobbyist, not an electronics engineer.
I built a transistor-based astable multivibrator circuit and then fed its output to an op amp buffer amplifier which then drove an 8 ...
0
votes
1answer
736 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 ...
0
votes
1answer
83 views
Why does the first pulse have a different duration than the other pulses?
Why does the triggered astable in the next figure have the duration of the logical component "0" of the first pulse lasting 2 times the logical component "0" duration of the next pulses (see the ...
0
votes
1answer
172 views
555 Timer Giving Unexpected Output (Astable Multivibrator)
I am using this design
with the only exception that C2 is 150nF to change timing slightly. When I plug in the circuit and attach an LED across GND and pin 3 output the LED is static on. However, on ...
2
votes
1answer
881 views
Astable 555 timer circuit that resets on a heartbeat
I'm trying to design a circuit that will reset my ESP8266 when it crashes/hangs. It does this by sending a heartbeat to a 555 timer every minute which resets the 555 timer. The 555 timer is configured ...
5
votes
2answers
227 views
555 Astable Timer produces incorrect period/frequency
I am building a 555 astable timer circuit for a course which must match the BPM of a song. The song has a BPM of 104, which requires a timer frequency of roughly 1.733 Hz.
The circuit looks as ...
1
vote
0answers
64 views
Variable frequency of an astable
I have to make the frequency variable of an square waveform generator built with the help of an astable. I modified a circuit a found on the internet and everything seems good with only one exception: ...
-3
votes
1answer
445 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
347 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.
...
2
votes
2answers
197 views
How does this TLC556 work?
I'm having trouble understanding what the upper part of an electronic metronome depicted in the below schematic does.
I already asked about the lower op-amp part in another topic, but I also can't ...
1
vote
1answer
346 views
555 stepper motor controller
I need to make a square wave generator to control a stepper motor driver.
It needs to be controlled with a potentiometer and get an output range from 40 Hz to 4 kHz.
I don't know a heck of a lot ...
1
vote
2answers
416 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
2answers
208 views
555 astable - frequency not linear with discharge resistor for smaller resistor values
I'm trying to use a 555 timer to create a variable frequency from a resistance, the output frequency should be about 1 kHz up to 300 kHz. I'm using a TS555CN CMOS version, which can oscillate up to 2....
-2
votes
1answer
236 views
What is the diode for in the astable IC 555
I am trying to get my head into electronics, so my teacher challenged me to find out what this diode does. I have done a ton of experiments and i just cant put my finger on it... Everything from ...
4
votes
2answers
267 views
Naive VCXO design - runs at 3rd harmonic, I need the base freq
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.
I'd appreciate your opinion about ...
1
vote
1answer
95 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, ...
0
votes
0answers
384 views
How to design a low voltage astable multivirator
I am currently trying to design a solar powered energy harvester. It requires a DC to DC boost converter to increase the output voltage and keep it regulated. I found that this can be achieved using ...
0
votes
1answer
178 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 ...
0
votes
2answers
981 views
Alternate design for an astable 555 circuit
I was looking at how to get a sign wave from a 555 chip and found this article.
It seems to say it's using an astable 555 circuit outputting to an LC resonant circuit.
However, the circuit diagram ...
0
votes
1answer
187 views
Astable timer: Halve frequency while maintaining the same “up” pulse width?
Disclaimer: I am not an electrical engineer, but an environmental science student. I'm trying my best here.
I have a basic astable 555 timing circuit with the following components:
\$R_1 = 10k\...
1
vote
1answer
982 views
A stable negative supply for an op-amp (using 555)
I need a differential amplifier circuit for my design and I am using the LM358 op-amp. The problem is of negative supply. I need to give negative power voltage to my op-amp(-Vcc). and I only have a 9v ...
4
votes
1answer
1k views
astable multivibrator: capacitor polarization
Looking at this circuit, I'm wondering if the capacitor polarization "+" is correctly draw. Assuming T2 is in cut, T1 is on, left capacitor will have a 0.7v in its right side (connected to T1 emitter) ...
0
votes
2answers
512 views
Astable 555 timer [closed]
The circuit diagram is above
R1,4,6,7:1K
R2,5:10K
R3:100 ohms
C1: 0.047 uF
C2,3 :100uF
C4:69uF
C5:0.1uF
And we finished building the circuit and connected the battery onto it. But the LEDs stayed on ...
-1
votes
2answers
172 views
555 Astable Timer: Why do these two circuits simulate differently?
I've modeled up the following two circuits in LTSpice:
simulate this circuit – Schematic created using CircuitLab
and...
simulate this circuit
(I've left out the other connections for ...
2
votes
2answers
8k views
Why is a common LED failure mode to flicker astably or oscillate? [closed]
There are many cases of LED lights failing by beginning to flicker intermittently. I am not talking about the intentional duty-cycle modulation utilized in many driver circuits. I am referring to ...
1
vote
5answers
2k views
Does a 555 astable dissipate more power at higher frequencies?
I'm planning on running a circuit on a 9V battery and it uses a 555 in the astable mode to generate pulses.
I want this circuit to be as efficient as possible, and not have to replace the battery ...
