555 used as a delayed pulse generator?

T

Tristar

Guest
I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.

Circuit is started with a momentary contact switch. After 10 seconds (exact time
isn't critical here +, - a second or two is fine) the circuit momentarily
outputs a pulse. I thought I'd feed the pulse into a switching transistor to
make it operate as a momentary contact switch.


Thanks in advance!

Lawrence
 
On Tue, 23 Aug 2005 14:12:18 GMT, Tristar <admin@nospam.com> wrote:

I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.

Circuit is started with a momentary contact switch. After 10 seconds (exact time
isn't critical here +, - a second or two is fine) the circuit momentarily
outputs a pulse. I thought I'd feed the pulse into a switching transistor to
make it operate as a momentary contact switch.


Thanks in advance!

Lawrence
___
Click to expand...

Here's one that gives about 1 second delay, 1 second pulse. Could
also use one 556 instead of 2 555s. Delay/pulse is 1.1RC where R is
the 22K resistors and C is the 47 uF capacitors.
"Sic hoc legere scis nimium eruditionis habes."
(If you can read this, you're overeducated.)
 
Tristar <admin@nospam.com> wrote:

I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.

Circuit is started with a momentary contact switch. After 10 seconds (exact time
isn't critical here +, - a second or two is fine) the circuit momentarily
outputs a pulse. I thought I'd feed the pulse into a switching transistor to
make it operate as a momentary contact switch.


Thanks in advance!

Lawrence
Click to expand...
This does what I think you want:
http://www.terrypin.dial.pipex.com/Images/10sMono+Pulse.gif

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
This looks easy Terry, I tried Johns circuit on a breadboard last night. I'll
give this a try too.

Thanks, Lawrence

BTW, nice website you have there.



In article <jtiog1t55kcang4enh52kdhtjhqhshrlqb@4ax.com>,
terrypinDELETE@THESEdial.pipex.com says...
Tristar <admin@nospam.com> wrote:

I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary
pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.

Circuit is started with a momentary contact switch. After 10 seconds (exact
time
isn't critical here +, - a second or two is fine) the circuit momentarily
outputs a pulse. I thought I'd feed the pulse into a switching transistor to
make it operate as a momentary contact switch.


Thanks in advance!

Lawrence

This does what I think you want:
http://www.terrypin.dial.pipex.com/Images/10sMono+Pulse.gif

--
Terry Pinnell
Hobbyist, West Sussex, UK
Click to expand...
 
In article <69GOe.31777$ll3.404429@twister.southeast.rr.com>, Tristar wrote:

I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.
Click to expand...
set up the 555 as a monostable and use a capicitor in series with the output
to pulse the transistor's base when the output changes state after the 10
seconds have elapsed. (there'll bve a pulse to the transistor when it starts
too but it'll be the wrong polarity and the transistor will ignore it)

--

Bye.
Jasen
 
Jasen Betts <jasen-b@free.net.nospam.nz> wrote:

In article <69GOe.31777$ll3.404429@twister.southeast.rr.com>, Tristar wrote:

I'm looking to set us a simple way to turn something on after 10 seconds. The
resulting output after the end of the 10 seconds needs to be a momentary pulse
and not stay in a closed position.

-----------------------------------------------------------------------^-

Like this.


set up the 555 as a monostable and use a capicitor in series with the output
to pulse the transistor's base when the output changes state after the 10
seconds have elapsed. (there'll bve a pulse to the transistor when it starts
too but it'll be the wrong polarity and the transistor will ignore it)
Click to expand...
That's what my circuit does.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Hi Terry, It's probably me but I couldn't get it to work, I used a pnp 2N3906.
I tried various combinations of caps and resistors but no luck.

Any ideas?

In
 
Tristar <admin@nospam.com> wrote:

Hi Terry, It's probably me but I couldn't get it to work, I used a pnp 2N3906.
I tried various combinations of caps and resistors but no luck.

Any ideas?

In
Click to expand...
Without more information, not really. Best guess would be that you've
made a wiring error. As you see from the simulation - the circuit does
what it's supposed to do.

How are you testing it? 'Scope, DMM...?

Is the mono working? If not, then obviously the brief pulse won't be
generated.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
Hi Terry, I gave it another try and Success this time!

Thanks again,

Lawrence

In article <u43sg191u0r2i1tj27qgv6ubhll3asrjbp@4ax.com>,
terrypinDELETE@THESEdial.pipex.com says...
Tristar <admin@nospam.com> wrote:

Hi Terry, It's probably me but I couldn't get it to work, I used a pnp
2N3906.
I tried various combinations of caps and resistors but no luck.

Any ideas?

In

Without more information, not really. Best guess would be that you've
made a wiring error. As you see from the simulation - the circuit does
what it's supposed to do.

How are you testing it? 'Scope, DMM...?

Is the mono working? If not, then obviously the brief pulse won't be
generated.

--
Terry Pinnell
Hobbyist, West Sussex, UK
Click to expand...
 
Tristar <admin@nospam.com> wrote:

Hi Terry, I gave it another try and Success this time!

Thanks again,

Lawrence

In article <u43sg191u0r2i1tj27qgv6ubhll3asrjbp@4ax.com>,
terrypinDELETE@THESEdial.pipex.com says...


Tristar <admin@nospam.com> wrote:

Hi Terry, It's probably me but I couldn't get it to work, I used a pnp
2N3906.
I tried various combinations of caps and resistors but no luck.

Any ideas?

In

Without more information, not really. Best guess would be that you've
made a wiring error. As you see from the simulation - the circuit does
what it's supposed to do.

How are you testing it? 'Scope, DMM...?

Is the mono working? If not, then obviously the brief pulse won't be
generated.

--
Terry Pinnell
Hobbyist, West Sussex, UK
Click to expand...
Good - thanks for letting us know.

BTW, *bottom* posting is the favoured standard here.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
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