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Vivitar 283



 
 
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  #11  
Old January 1st 09, 10:29 AM posted to rec.photo.equipment.35mm
Noons
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Posts: 3,245
Default Vivitar 283

Geoffrey S. Mendelson wrote,on my timestamp of 1/01/2009 8:19 PM:


Not really. If the flash uses direct triggering, high voltage will be
present on the sync contacts when the ready light is lit.


And how do you know beforehand the flash uses direct triggering?


If it stays low (3-6 volts), then there is some sort of triggering
circuit inbetween and it is safe.


Not necessarily. The triggering circuit may have a step
transformer that will zap the circuits with a high voltage spike.
In fact, if you take the care of reading the page I pointed
to in my original reply, you'll find lots of information there
and in other links.



One thing to keep in mind is that they way to find out is NOT!! to try it.


Exactly. That's why you need the correct instrument to measure
the effect, whatever it may be. And since you do NOT
know in advance what type of triggering the flash uses, you
better have the appropriate gear to measure it, like
I said.

And unless one understands the electric details behind
this, the best way of making sure is simply to NOT use
a flash that has been tested as the potential source
of problems.

Nitpicking aside, of course.
  #12  
Old January 1st 09, 07:20 PM posted to rec.photo.equipment.35mm
Ken Hart1
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Posts: 79
Default Vivitar 283


"pumper hinkle" wrote in message
...
Well, unfortunately I don't have the original box, just a vinyl case. I
had bought this unit used at a camera shop several years ago after my
original 283 had developed an incurable problem. The serial number of
this unit, if that is any sort of indicator, is 1948082.

How does one measure the voltage? A volt meter across the flash
terminals? This is something I've never considered before.

I would like to use the 283 but not if there is any possibility of
damaging the camera.

By the way, what is high voltage and low voltage considered to be?

Ralph


Generally, high voltage is fatal, low voltage is not. In this case, the
fatality is to the camera. I would hazard a guess that 5V is close to the
dividing line. Putting a voltmeter across the flash terminals might not show
any hazardous spikes. For that, you really should use an oscilliscope. But,
start with a voltmeter.

Another consideration is current. You can have low voltage with high
current. If you were, for example, firing off big flashbulbs with a six-volt
lead acid battery (automotive battery type), I'd bet that it's extremely
likely that many digital cameras would have their flash circuit fried.

There are "safe-sync" devices on the market. If you really want to be sure,
I'd go with one of those.


  #13  
Old January 1st 09, 08:30 PM posted to rec.photo.equipment.35mm
Alan Browne
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Default Vivitar 283

pumper hinkle wrote:
Well, unfortunately I don't have the original box, just a vinyl case.
I had bought this unit used at a camera shop several years ago after my
original 283 had developed an incurable problem. The serial number of
this unit, if that is any sort of indicator, is 1948082.

How does one measure the voltage? A volt meter across the flash
terminals? This is something I've never considered before.

I would like to use the 283 but not if there is any possibility of
damaging the camera.

By the way, what is high voltage and low voltage considered to be?


42V or 45V (can't remember which) is a safety threshold voltage for the
purpose of appliance certification. Eg: at some point above there you
can feel the voltage as pain.

42V, not coincidently, is becoming the standard voltage for automobiles.
Eventually the 12V battery will disappear. (Some cars already have
dual voltage systems, 12 and 42). The reason being that there are so
many subsystems on cars needing electrical power that there is a
significant saving in wire weight and bulk by increasing the voltage.
Higher voltage is also better for cold cranking.

I hope that systems like steering and brakes will become electrically
boosted this way as well removing the continuous hydraulic load from the
engine. (eg: the hydraulic load is always present even if not doing
anything. Electrically boosted steering and braking would be on demand,
seriously reducing energy consumption). Such would need at least a dual
channel actuator and dual batteries. But well worth it for energy savings.


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  #14  
Old January 2nd 09, 01:19 AM posted to rec.photo.equipment.35mm
Noons
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Default Vivitar 283

Ken Hart1 wrote,on my timestamp of 2/01/2009 5:20 AM:


Generally, high voltage is fatal, low voltage is not. In this case, the
fatality is to the camera. I would hazard a guess that 5V is close to the
dividing line.


And that is indeed a very safe value. Canon claims around 6V max,
Nikon 12. I know nikon speedlites do not exceed 6V, so 5V is
indeed a safe target to shoot for.

Putting a voltmeter across the flash terminals might not show
any hazardous spikes. For that, you really should use an oscilliscope. But,
start with a voltmeter.


Exactly. There are sampling voltmeters in the market, which
take the max reading over a preset period. But most of the
ones you get at Tandy and such do not do so.
  #15  
Old January 5th 09, 02:58 AM posted to rec.photo.equipment.35mm
Peter Chant[_2_]
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Posts: 203
Default Vivitar 283

Alan Browne wrote:

I hope that systems like steering and brakes will become electrically
boosted this way as well removing the continuous hydraulic load from the
engine. (eg: the hydraulic load is always present even if not doing
anything. Electrically boosted steering and braking would be on demand,
seriously reducing energy consumption). Such would need at least a dual
channel actuator and dual batteries. But well worth it for energy
savings.


Interestingly my car has power steering, it is hydraulic but the hydraulic
pump is powered by an electric motor rather than directly from the engine.

Pete

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