Help with a timer 555

Jrohg

New Member

• Apr 6, 2017

• #1

hello i would like some help with a circuit i'm trying to make, here is what i want the circuit to do.
The Input 12v
And i want the Out put 12v
Once power is applied to a 555 timer, I want an 12vLED to be on for 5 seconds, and cut off (NO FLASHING). Once power is taken off, and applied again, this "system" will restart.

Thanks i really appreciate any help

 

AnalogKid

Well-Known Member

Most Helpful Member

• Apr 6, 2017

• #2

**broken link removed**



Circuit #1. Replace the two diodes and relay with an LED and resistor.

ak

 

crutschow

Well-Known Member

Most Helpful Member

• Apr 7, 2017

• #3

Here's the LTspice simulation of the circuit AK posted with RC values to get a 5s pulse, and the suggested output modification:

 

Attachments

• 555 one-shot on Pwr Up 2.asc

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Last edited: Apr 7, 2017

Jrohg

New Member

• Apr 7, 2017

• #4

First thanks for helping. I tried the circuits but they didn't do what i need, i put power turns led on but it doesn't turn off the led because i don't take out the power.
That's my problem that the circuit has to turn off the led Without taking the power from the trigger

 

Last edited: Apr 7, 2017

Jrohg

New Member

• Apr 7, 2017

• #5

maybe it's not possible what I'm trying to do

 

AnalogKid

Well-Known Member

Most Helpful Member

• Apr 7, 2017

• #6

The circuit does what is described in post #1. Try to explain again the sequence of events that you need. List them as a number of steps in a sequence.

ak

 

crutschow

Well-Known Member

Most Helpful Member

• Apr 7, 2017

• #7

Jrohg said:

First thanks for helping. I tried the circuits but they didn't do what i need, i put power turns led on but it doesn't turn off the led because i don't take out the power.

Click to expand...

Then it would appear that there's an error in the circuit you built.
The simulation shows the output turning off after 5 seconds with the power continuously applied.