Testing trigger voltage

How can the trigger voltage on a flash be tested?
Old Bob

wrote in message
...
How can the trigger voltage on a flash be tested?
Old Bob


I made a flash gun once bought the tube and some huge capacitors, first time
i fired it the copper track on the circuit board disintegrated, repaired it
with some thick wire and it was OK.

As I remember the trigger voltage was taken off using a resisitor network to
bring it down to 12 to 18 volts, from about 500 I think.

The only way I can think of to measure the voltage of such a short pulse
would be to use an oscilloscope.

Jem

-------------------------------------
Birmingham Independent Photographers
http://bip.wikispaces.com/

wrote in message
...
How can the trigger voltage on a flash be tested?
Old Bob

http://www.botzilla.com/photo/g1strobe.html

On Sat, 25 Mar 2006 12:46:47 -0500, wrote:

How can the trigger voltage on a flash be tested?
Old Bob


Disconnect the flash from the camera. Turn it on, and wait for the
Ready light to illuminate.

Then, measure the voltage on the sync terminals (between the hot
shoe's center contact and the part that makes contact with the
camera's hot shoe rails) using a digital voltmeter.

For modern cameras, the sync voltage should be less than about 12
volts DC, with the positive side connected to the center terminal.

If your sync voltage is higher than 12 volts or so, you can obtain a
gizmo called a Safe Sync from B&H (or any good camera outfit) that
limits sync voltage to about 6 volts. If the polarity is reversed,
you need to get inside the flash and re-wire the sync wires to the
hot shoe.

Good luck!

Tom

I was just doing this before I looked at these posts.

One of the other posters and the site mentioned both suggest a DVM to
measure the voltage and that was my first choice.

However, I have discovered a problem. The problem is the readings on the
DVM's (two of them) do not agree with my AVO. For those who know, AVO's do
not lie. Both DVM's measure 94 volts on my Vivitar 283, while the AVO says
212 volts.

Update, using a third DVM, I now measure 257 volts. Obviously, the first two
DVM's have a low input impedance - less than the 20K/V of the AVO - while
the third DVM has a high impedance.

The first two are DVM's bought from an auto store and it looks like they are
different from the "normal" DVM.

You should be using a high impedance meter for measuring flash trigger
voltages.

Allan




wrote in message
...
How can the trigger voltage on a flash be tested?
Old Bob

In article ,
"Allan" wrote:

I was just doing this before I looked at these posts.

One of the other posters and the site mentioned both suggest a DVM to
measure the voltage and that was my first choice.

However, I have discovered a problem. The problem is the readings on the
DVM's (two of them) do not agree with my AVO. For those who know, AVO's do
not lie. Both DVM's measure 94 volts on my Vivitar 283, while the AVO says
212 volts.

I'm assuming DVM is Digital Volt Meter, but what's an AVO?

"Allan" wrote in message
.. .
I was just doing this before I looked at these posts.

One of the other posters and the site mentioned both suggest a DVM to
measure the voltage and that was my first choice.

However, I have discovered a problem. The problem is the readings on the
DVM's (two of them) do not agree with my AVO. For those who know, AVO's do
not lie. Both DVM's measure 94 volts on my Vivitar 283, while the AVO says
212 volts.

Update, using a third DVM, I now measure 257 volts. Obviously, the first
two
DVM's have a low input impedance - less than the 20K/V of the AVO - while
the third DVM has a high impedance.

The first two are DVM's bought from an auto store and it looks like they
are
different from the "normal" DVM.

You should be using a high impedance meter for measuring flash trigger
voltages.

Allan


Hi.

I tested the Trigger voltage on my 2 Vivitar 283s, and both of them were 280
Volts.

I have heard that some of the even older ones can be over 300Volts.

Roy G

Yes, DVM is Digital Volt Meter. AVO is the trade name of a British company
(AVO Megger) that makes high quality multimeters and other lab grade test
equipment - considered by many as the multimeter of choice.

Allan


"Roy Smith" wrote in message
...
In article ,
"Allan" wrote:

I was just doing this before I looked at these posts.

One of the other posters and the site mentioned both suggest a DVM to
measure the voltage and that was my first choice.

However, I have discovered a problem. The problem is the readings on the
DVM's (two of them) do not agree with my AVO. For those who know, AVO's
do
not lie. Both DVM's measure 94 volts on my Vivitar 283, while the AVO
says
212 volts.

I'm assuming DVM is Digital Volt Meter, but what's an AVO?

In article , Roy Smith
wrote:

I'm assuming DVM is Digital Volt Meter, but what's an AVO?

Roy-

It must be Analog Volt Ohmmeter, which explaines the reference to 20K Ohms
per volt.

The AVO (or is that VOA?) may not lie, but it can load down a
high-impedance circuit. Assuming a 300 volt range, the impedance would be
6 Megohms. This compares to some VTVMs and DVMs, but explains the
slightly higher reading of his third DVM.

Fred

(Fred McKenzie) wrote:
In article , Roy Smith
wrote:

I'm assuming DVM is Digital Volt Meter, but what's an AVO?

Roy-

It must be Analog Volt Ohmmeter, which explaines the reference to 20K Ohms
per volt.

Huh? You think 20K Ohm/Volt could not apply to a DVM?

It could just as easily...

The AVO (or is that VOA?) may not lie, but it can load down a
high-impedance circuit.

So can a DVM (or an oscilliscope or a VTVM).

Assuming a 300 volt range, the impedance would be
6 Megohms. This compares to some VTVMs and DVMs, but explains the
slightly higher reading of his third DVM.

Correct.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)