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Problem with 555 timer

electrowhiz

Apr 9, 2017
1
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Apr 9, 2017
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I planned to operate 555 timer in monostable mode. I gave the connections correctly.
Pin 8:Vcc
pin1: gnd
pin 5: 0.1 nf cap to gnd
pin 8 to 7:47kohm
pin 7 to 6:just a wire
pin 6 to gnd: 100 microfarad
pin 2 to Vcc through a resistor.
pin4: to Vcc
toggle switch is used to alter between gnd and Vcc for triggering the pin2
pin 3 to gnd: resistor in series with led.
when i gave a trigger, the led started to glow continuously. Why this happens? actually i set it to operate only for 5s.
The Led turned off only when the supply is removed.What should i do to rectify this problem
 

AnalogKid

Jun 10, 2015
2,665
Joined
Jun 10, 2015
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2,665
First, since you are a whiz, post a schematic. Be sure to have a reference designator for each component so we can discuss them clearly.

ak
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
Discharging the 100uF capacitor through the discharge pin could easily kill the transistor. Check you don't have continuity between pin 1 and 7 now.
 
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