Your browser is incompatible with Multisim Live. Use the Chrome™ browser to best experience Multisim Live.

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

3

Favorite

61

Copy

18906

Views

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Circuit Description

This is an adjustable frequency , 50% duty cycle astable multivibrator using the 555 timer IC. An approximately 50% duty cycle is achieved by using a single timing resistor. In contrast to the conventional 555 astable circuit, which uses a discharge resistor to the discharge pin and additional resistor to Vcc for charging, this circuit has almost symmetrical charge and discharge periods. To obtain this balance, the circuit around the open-collector DISCHARGE terminal is modified by adding external BJT and diode. When the discharge transistor is off, the BJT in emitter follower configuration drives the timing resistor high to charge the timing capacitor. The voltage level at the emitter of the transistor is about one diode drop less than the power supply voltage. To match this voltage loss, a silicon diode is employed between the timing resistor and the discharge pin. When the discharge transistor is on the timing resistor discharges the timing capacitor through the diode to the discharge terminal. The voltage level at the anode of the diode is just a little higher than one diode drop. Hence, symmetry and consequently 50% duty cycle can be achieved. To make the frequency adjustable, the timing resistor is split into a fixed and variable resistor. The variable resistor provides frequency adjustment. The fixed resistor can serve to limit the maximum frequency allowed. It can also serve as a current limiter, useful when large capacitor is used in the circuit.

There are currently no comments

Kithu

15 favorites

Skagra

1 favorites

livefreest

4 favorites

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

stickys

Frequency Comparator 555 Timer

baykalsarioglu

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

hussainyakub

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

novatronica

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

mahesh1264

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

pranavm193

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

ashraf1979

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

bpjl

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Lucas.Bonilha

Astable Multivibrator Using 555 Timer

gauravpandey

Muj tone generator

Krokoush

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

noeldodd

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

YasaAli

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

revanth1998

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Paolosfo

555 Timer 5-3000Hz

ccsys

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Giachicoro

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

leventates

555 Timer one of two1

Joefraser2020

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

jmb0088

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Mashhoor

555_Timer_Multivibrator

Agila2021

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

hellgoku

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Mashhoor

Генератор на правоъгълни импулси

mtomov

555 inverted astable timer

rosyrazo

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

jluis.lopez

duty cycle variabile 555

jasonzan02

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Dominique89

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Imad28

Simulación Pr5(2)

Attorrente

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

NLHunter

PAM con 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Guido_Humberto

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Jigar213

miniproject 555 timer hibban nippori

ManabBud1n

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

jmsoares

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Riz22

555 TIMER

alekss

555 Timer 50% delovni cikel Tadej Kemperle

tadejkem

EX_11_Astable

18_017

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

jmsoares

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

karla2021

Modding public 555 timer circuit

Skagra

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Brunoparedez

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

zfish

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

mrma

15

Radmir00070

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

V_J

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

syafiqroy00

ere

timurlitisachery

Astable Multivibrator

chenyang01

apchi88

apchi

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Lalocura55

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Adam2022

copied project not mine

Pozzibrossyo12

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

DayaneCordeiro

555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

Júlioczar

Copy of 555 Timer Adjustable Frequency, 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)

quintin3

Private Copy

Private Copy

Private Copy

Creator

GGoodwin

1116 Circuits

Date Created

7 years, 8 months ago

Last Modified

6 years, 11 months ago

Tags

circuit fundamentals
555 timer circuits
555 oscillator
555 astable multivibrator
50% duty cycle
555 square wave generator
555 timer applications
555 adjustable frequency
555 variable frequency

Circuit Copied From

555 50% Duty Cycle Astable Multivibrator (Charge By BJT Pull-Up)