555 timer DSLR time lapse shutter release

[Dave]

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

Thanks in advance, Dave.
<http://www.henniker.org.uk> 3000 photos especially
Edinburgh & Scotland. + 3D rendered art, old ads etc.
Délété david for email; watch the spam filters.

 

[John Fields]

On Wed, 21 Feb 2007 18:37:19 +0000, Dave <dave@dŞvĄdhenniker.org.uk>
wrote:

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

---
I'm not sure that's such a good way to do it because it won't
unshort the contacts in the same sequence the manual cable release
would. The way I'd do it would be to use a window comparator and
drive it with an RC which would be driven by a 7555. That way, the
last comparator that turned on would be the first to turn off and
the 7555 would supply the charge and discharge path though its
totem-pole output.

If you like I can draw you a schematic, but I'll need to know:

1. What's your supply voltage.
2. What are you using to trigger the 555
3. How long is the entire shutter release sequence?


--
JF

 

[ehsjr]

Dave wrote:

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

Thanks in advance, Dave.
http://www.henniker.org.uk> 3000 photos especially
Edinburgh & Scotland. + 3D rendered art, old ads etc.
Délété david for email; watch the spam filters.

I'm not sure what your velleman kit does. Presumably this:
------------
| |
------- --------- (autofocus etc)
T0 T1 T2

And you need this?

------------
| |
------- --------- (autofocus etc)
T0 T1 ---- T2
| |
----------- ------ (shutter)
T0 T1a T1b T2

In the absence of any specs, and if you have
a bunch of relays, you could try this:

Vellman
Relay
n/o Contact RY1-1 n/o RY1-2 n/o
|>| |>| |>|
+12 ---o o----+---o o---+-----+ +---o o---> auto-
| | | | focus
+-----+ [RY2] [D2] |
| | | |a |
[D1] [RY1] +-----+ +---------> Camera
a| | + | | | common
+-----+ [470uF] [10K] |
| | | |
Gnd ----------+---------+-----+ +---o o---> shutter
|>|
RY2-1 n/o

When the Velleman relay transfers, it energizes RY1,
which takes a few mS to transfer. When transferred,
it energizes autofocus, and energizes RY2 through
the charging current of the 470 uF cap. RY2 takes a
few mS to transfer, which provides the delay between
autofocus and shutter. When transferred, it activates
the shutter. RY2 drops out when the 470 uF cap is
charged and stops drawing current through RY2. The
10K will discharge the cap when RY1 drops out.

The circuit doesn't have a lot to recommend it,
except that it will give you a few mS delay, and
is "spec-less". It might work. You can try it
until you develop specs for what is really needed
for the timing.

Ideally, it would be nice to have a circuit with adjustable
times for T1 to T1a, T1a to T1b and T1 to T2 and
that can be designed if we know the specs.

Ed

 

[Lionel]

On Wed, 21 Feb 2007 18:37:19 +0000, Dave <dave@dŞvĄdhenniker.org.uk>
wrote:

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

Have you tried simply shorting both the center & tip to ground at the
same time? Your shot will probably be delayed by however long it takes
the AF system to achieve focus, but that'd be true with any other
system as well. Alternatively, you could use a positive output from
your 555 to drive the bases of 2 NPN transistors, with the collectors
connected directly to the tip & center connections, & both emittors
wired to ground.

 

[Dave]

On Wed, 21 Feb 2007 14:55:37 -0600, John Fields
<jfields@austininstruments.com> somehow managed to impart:

On Wed, 21 Feb 2007 18:37:19 +0000, Dave <dave@dŞvĄdhenniker.org.uk
wrote:

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

---
I'm not sure that's such a good way to do it because it won't
unshort the contacts in the same sequence the manual cable release
would. The way I'd do it would be to use a window comparator and
drive it with an RC which would be driven by a 7555. That way, the
last comparator that turned on would be the first to turn off and
the 7555 would supply the charge and discharge path though its
totem-pole output.

If you like I can draw you a schematic, but I'll need to know:

1. What's your supply voltage.
2. What are you using to trigger the 555
3. How long is the entire shutter release sequence?

I've copied the circuit diagram to:

<http://www.henniker.org.uk/images/555timer-circuit.jpg>

The supply voltage is 12 volts. There is no start button, just
applying power starts it. The length of the shutter release sequence
is probably roughly 1 second in manual use, whether using the cable
release or the button on the camera, i.e. press the button half way,
wait for autofocus / autoexposure to kick in, there's a beep to
confirm it's focussed then you press the button all the way to open
the shutter and take the photo.

Thanks to everyone for their suggestions. I reckon I'll dig out my old
'breadboard' and try a few things out...

Dave.
<http://www.henniker.org.uk> 3000 photos especially
Edinburgh & Scotland. + 3D rendered art, old ads etc.
Délété david for email; watch the spam filters.

 

[John Fields]

On Thu, 22 Feb 2007 09:32:08 +0000, Dave <dave@dŞvĄdhenniker.org.uk>
wrote:

On Wed, 21 Feb 2007 14:55:37 -0600, John Fields
jfields@austininstruments.com> somehow managed to impart:

On Wed, 21 Feb 2007 18:37:19 +0000, Dave <dave@dŞvĄdhenniker.org.uk
wrote:

I've tried to use a Velleman timer kit for time-lapse photography with
my Pentax DSLR camera but the single relay output isn't enough.

The Pentax-made *manual* cable release is terminated in a standard
2.5mm stereo jack plug. When the button is pressed, the centre contact
on the plug is shorted to the one nearest the body (triggering
autofocus etc) and when the button is pressed further in, these two
contacts remain shorted but the contact furthest from the plug's body
is then also shorted to trigger the shutter release.

What's needed for the 555 time-lapse circuit is second relay whose
Normally Open contacts close as well, a fraction of a second after the
first one. All 3 connections were shorted at this point when I checked
the manual cable release with a continuity tester.

I've considered adding a single transistor triggered by the 555's
output but with a simple RC time delay, e.g. its base taking a finite
time to reach a sufficiently high voltage to turn the transistor on,
and consequently activating the relay.

I'd be grateful for any suggestions to achieve this result. It's been
years since I've done much with a soldering iron and electronic
construction. Maybe I should be using a thyristor instead of a
transistor, or a Darlington or something. I want to keep it simple.

---
I'm not sure that's such a good way to do it because it won't
unshort the contacts in the same sequence the manual cable release
would. The way I'd do it would be to use a window comparator and
drive it with an RC which would be driven by a 7555. That way, the
last comparator that turned on would be the first to turn off and
the 7555 would supply the charge and discharge path though its
totem-pole output.

If you like I can draw you a schematic, but I'll need to know:

1. What's your supply voltage.
2. What are you using to trigger the 555
3. How long is the entire shutter release sequence?

I've copied the circuit diagram to:
http://www.henniker.org.uk/images/555timer-circuit.jpg

The supply voltage is 12 volts. There is no start button, just
applying power starts it. The length of the shutter release sequence
is probably roughly 1 second in manual use, whether using the cable
release or the button on the camera, i.e. press the button half way,
wait for autofocus / autoexposure to kick in, there's a beep to
confirm it's focussed then you press the button all the way to open
the shutter and take the photo.

Thanks to everyone for their suggestions. I reckon I'll dig out my old
'breadboard' and try a few things out...

---
Sorry, I forgot to ask how long it'll be between triggers.


--
JF

 

[Dave]

On Fri, 23 Feb 2007 11:29:26 -0600, John Fields
<jfields@austininstruments.com> somehow managed to impart:

On Thu, 22 Feb 2007 09:32:08 +0000, Dave <dave@dŞvĄdhenniker.org.uk
wrote:

On Wed, 21 Feb 2007 14:55:37 -0600, John Fields
jfields@austininstruments.com> somehow managed to impart:

[snip]
Thanks to everyone for their suggestions. I reckon I'll dig out my old
'breadboard' and try a few things out...


---
Sorry, I forgot to ask how long it'll be between triggers.


I think I'm on the way to a working circuit. The output of the 555

turns on the first relay and also turns on an NPN transistor with a
100K resistor as a collector load. This goes low and triggers another
555 in monostable mode. After a delay of say, between 500mS and 1S,
the second relay should close and fire the shutter.

I've got the trigger working - and I *did* have the monostable working
but I need to take a rest because of the need to keep changing my
spectacles as well as using a jeweller's eyeglass. The eyesight ain't
what it used to be. I'm glad I don't have to fix CRT monitors and
laptop mainboards any more!

Dave.
<http://www.henniker.org.uk> 3000 photos especially
Edinburgh & Scotland. + 3D rendered art, old ads etc.
Délété david for email; watch the spam filters.

 

[Big Tone]

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:QETHi.9826$924.8232@newssvr23.news.prodigy.net...



Two prong, potentially
ungrounded outlets were history in the early 1960's. Ground is always
present
unless some idiot disconnected the wire.


Not at all. Grounded outlets were required on all new installations from
the
'60s all right, but many houses are older than that. New work has to be

done to the new code, of course, but there's no requirement to upgrade
old
wiring just because it's old. Many houses in my area (Ventura Co., CA)
still
have the old two-pronged outlets.

I'm late with this but just in case someone with a similar question does a
search, for completeness I'd like to offer this...

http://en.wikipedia.org/wiki/PAT_Testing

Basically, what you have is a class 1 appliance, (as opposed to a class 2,
like a mobile/cell phone charger for example), and in the UK equipment has
to be routinely tested.

You may have noticed a small green label ‘Tested For Electrical Safety’
complete with a date and someone’s initials or signature on equipment used
at your workplace or out in the big world.

I have the qualification to do this and could go into more detail but if
you just Google ‘Portable Appliance Test’ you should find plenty of
information and resources to help.

Take care