# Momentary pulse from constant 12v dc supply

Discussion in 'The Projects Forum' started by Taptotweet, Mar 5, 2013.

1. ### Taptotweet Thread Starter New Member

Mar 5, 2013
4
0
Hey all,
I currently have a project that requires a pulse to trigger an MP3 player. My problem is, the "trigger" signal is a constant 12 volt supply. In a nutshell, I need some way to create a short dc pulse from a constant 12 volt dc input.

Any help is much appreciated.

Cheers, Sam.

2. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
What voltage does the pulse need to be?
What duration is required for the pulse?
Does the pulse need to be repeated? If so, how often?
What is your skill level with electronic circuit assembly?

Finally, what is the airspeed of an unladen European Swallow?

3. ### MMH Member

Feb 8, 2013
143
4
You can use a 555 timer if you want. But What voltage does the pulse need to be, What duration is required for the pulse, Does the pulse need to be repeated? If so, how often? thatoneguy is right.

4. ### Taptotweet Thread Starter New Member

Mar 5, 2013
4
0
Thanks for the replies!

I guess I should have been more specific. I need either a 12vdc or 5vdc pulse for a second or so. The pulse doesn't need to be repeated.

Cheers, Sam

5. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
What starts the pulse?

6. ### Taptotweet Thread Starter New Member

Mar 5, 2013
4
0
The pulse would be started by a constant 12 volt signal.

Cheers, Sam.

7. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
So, the pulse starts when 12V is applied?

I guess if you explain the purpose, so many details wouldn't be needed.

There's another thread where I made a schematic for a timed pulse out at power on, it would just be a matter of changing two components to change duration of pulse.

Change the left 1M/15u to lower values for a shorter time at turn-on.

8. ### Taptotweet Thread Starter New Member

Mar 5, 2013
4
0
This is exactly what I need! Thanks heaps for your help.

Cheers, Sam