[alijafary509]

Today, i conducted some experiments in my lab just to figure out how much damage high voltage can do with limited current capacity. For that i used the following equipment and components:

LED 3.5mm dome style with operating voltage 3V @ 30mA
Neon lamy with operating voltage 12V
Resistor 100k
Variable AC power supply
Programmable DC power supply
Fluke Digital multimeter

First, I restricted the DC power supply current to 200uA and set the voltage to 250V. Then i connected the LED in correct polarity to the DC power source. Nothing happened, So high voltage didn't even cause the LED to illuminate. Fixing the voltage at 250V I slighted increased the current and slowly brought it up to 2.5mA. At that point there was a dim light emitted by the LED. I started increasing the current and brought it up to its max current capacity 30mA. Now LED was fully glowing without any damage so far. I kept the LED glowing at this point for 15 minutes. Nothing bad happened to the LED. Now, one thing is very clear that high voltage alone are not sufficient to cause a damage to any electronic component.

Then I directly connected the neon lamp to main power supply adding 100k resistor in series. LED was glowing very dim and was not damaged by the 220V at all. This was current was restricted to 2.5mA by the series resistor.

Now my Philips flash 25CB injects 130uA current maximum into my camera hot shoe to ground with a hot shoe contact voltage 150V. I don't think it can cause any damage to my camera electronic circuitry inside. I am quite confident now.

[IchabodCrane]

Today, i conducted some experiments in my lab just to figure out how much damage high voltage can do with limited current capacity. For that i used the following equipment and components:

LED 3.5mm dome style with operating voltage 3V @ 30mA
Neon lamy with operating voltage 12V
Resistor 100k
Variable AC power supply
Programmable DC power supply
Fluke Digital multimeter

First, I restricted the DC power supply current to 200uA and set the voltage to 250V. Then i connected the LED in correct polarity to the DC power source. Nothing happened, So high voltage didn't even cause the LED to illuminate. Fixing the voltage at 250V I slighted increased the current and slowly brought it up to 2.5mA. At that point there was a dim light emitted by the LED. I started increasing the current and brought it up to its max current capacity 30mA. Now LED was fully glowing without any damage so far. I kept the LED glowing at this point for 15 minutes. Nothing bad happened to the LED. Now, one thing is very clear that high voltage alone are not sufficient to cause a damage to any electronic component.

Then I directly connected the neon lamp to main power supply adding 100k resistor in series. LED was glowing very dim and was not damaged by the 220V at all. This was current was restricted to 2.5mA by the series resistor.

Now my Philips flash 25CB injects 130uA current maximum into my camera hot shoe to ground with a hot shoe contact voltage 150V. I don't think it can cause any damage to my camera electronic circuitry inside. I am quite confident now.

If "money doesn't grow on trees", why do you even consider risking your camera's health when the alternatives are potentially so inexpensive?

[Not a Number]

Now my Philips flash 25CB injects 130uA current maximum into my camera hot shoe to ground with a hot shoe contact voltage 150V. I don't think it can cause any damage to my camera electronic circuitry inside. I am quite confident now.

Ok, so the next logical step is to hook up the power supply to the hot shoe of you camera and do the same tests. Don't forget to trigger the shutter.

Then you should "test to destruction" and find out what the practical current rating is for the hot shoe and connected circuitry.

[alijafary509]

If "money doesn't grow on trees", why do you even consider risking your camera's health when the alternatives are potentially so inexpensive?

If I can make my flash work without spending any extra penny then why should i waste my money just to make them wealthy without a reason?? Why shouldn't I do some charity for the strive to death people of the rest of the world???? This is my thought may be I am wrong.

[alijafary509]

Ok, so the next logical step is to hook up the power supply to the hot shoe of you camera and do the same tests. Don't forget to trigger the shutter.

Then you should "test to destruction" and find out what the practical current rating is for the hot shoe and connected circuitry.

Your logic is FALSE in digital term. I can figure out that easily without any destruction but in a constructive way just by knowing what components are being used for switching purpose in side the camera. Every thing will be clear then.

[IchabodCrane]

If I can make my flash work without spending any extra penny then why should i waste my money just to make them wealthy without a reason?? Why shouldn't I do some charity for the strive to death people of the rest of the world???? This is my thought may be I am wrong.

That's an excellent reason for you to have not bought an external flash in the first place and have just continued using the built-in flash.

[GibbyTheMole]

I've heard it said that 25-30v is the maximum safe trigger voltage for most Pentax DSLRs. Personally, I would stick to a flash with 12v or less just to err on the side of caution.

Your K-r is worth at least 10 times what your flash is worth. I personally would just buy a flash that was safe for the camera, and not risk it.

[Macario]

Thanks for the testing, I have myself always wondered how a camera could be fried with high voltage. Especially as the camera makers never made any comments on the amps, which cuases the trouble with electronics.

For all the critics here, think about the situation at home. We have fuses to prevent our electronics of frying in case of a shortcircuit. But they are all based on current, not on voltage. So why should your camera fry with a high voltage and low current passing through it? it makes no sense.

and on the static electricity, you will not even feel anything below 3000V. So if you feel it, it is way above 3000V. And I have my camera in my hand while receiving a shock from staic electricity, and camera is still working fine.

[Tanzer]

That's a little different. Most assembled electronic goods are designed so that their components are isolated from damage by external static electricity.

When it comes to anything electrical, insulating parts are damaged by voltage, whereas conducting parts are damaged by current. Semiconductors both insulate and conduct, under changing conditions, so the behavior is more complex.

Here are links to two schematics for a circuit that should work. Uses a triac to adapt the high voltage to lower voltage. This can't cost much at all.
Notes on the Troubleshooting and Repair of Electronic Flash Units and Strobe Lights and Design Guidelines, Useful Circuits, and Schematics
http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf

If your camera has an electronic component like this (which is explicitly designed to handle these voltages), then you are in good shape. Sorry, most of us are not willing to take our cameras apart, but if the OP wants to take his apart, then by all means, this will be useful information to the community. After opening up your camera though, you might see a lot of very small surface-mount components which aren't labelled. Please let us know the outcome.

[SOldBear]

Here are links to two schematics for a circuit that should work. Uses a triac to adapt the high voltage to lower voltage. This can't cost much at all.
Notes on the Troubleshooting and Repair of Electronic Flash Units and Strobe Lights and Design Guidelines, Useful Circuits, and Schematics
http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf

Based on the second schematic, I built voltage-reducer circuits for a Sunpak 622, 2 Sunpak 522, and 2 Metz 45CT-1 units.

This post

[Digitalis]

I have my camera in my hand while receiving a shock from staic electricity, and camera is still working fine.

Static electricity is well known for destroying computer components, motherboards, ram modules and videocards - these components are all vulnerable to damage from static discharge from careless handling.

Most assembled electronic goods are designed so that their components are isolated from damage by external static electricity.

Indeed they are, especially cameras because there are flash capacitors inside them that hold a potentially lethal shock.

[alijafary509]

That's a little different. Most assembled electronic goods are designed so that their components are isolated from damage by external static electricity.

When it comes to anything electrical, insulating parts are damaged by voltage, whereas conducting parts are damaged by current. Semiconductors both insulate and conduct, under changing conditions, so the behavior is more complex.

Here are links to two schematics for a circuit that should work. Uses a triac to adapt the high voltage to lower voltage. This can't cost much at all.
Notes on the Troubleshooting and Repair of Electronic Flash Units and Strobe Lights and Design Guidelines, Useful Circuits, and Schematics
http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf

If your camera has an electronic component like this (which is explicitly designed to handle these voltages), then you are in good shape. Sorry, most of us are not willing to take our cameras apart, but if the OP wants to take his apart, then by all means, this will be useful information to the community. After opening up your camera though, you might see a lot of very small surface-mount components which aren't labelled. Please let us know the outcome.

Tanzer, relay a very interesting post you shared. I must give it a try. Thank you.

[alijafary509]

Based on the second schematic, I built voltage-reducer circuits for a Sunpak 622, 2 Sunpak 522, and 2 Metz 45CT-1 units.

This post

Very informative and helpful article.

[alijafary509]

Today i completed 2000 shots using my Philips 25CB flash with high trigger voltages (150VDC) on Pentax K-r DSLR. Everything is working great!

[electricnerve]

So refreshing to see someone thinking outside the box and actually putting this superstitious dogma to the test, rather than simply parroting the conventional wisdom.

Yes, you will find a list of 'safe' flash voltages on the web. What that list demonstrates is one thing: The propensity for photographers to collect things - in this case, trigger voltages.
You will find no logical rationale on how or why a high voltage could fry a camera circuit. Even a cheap $1 circuit is safe from these voltages. It's current that causes damage, and as the OP rightly points out, the current across the hotshoe terminals is negligible.

There are plenty of reasons why a modern digital camera is safe to use with high trigger voltages:

• Similar electronic circuitry is used in remote flash triggers, and these work fine with high voltages;
• Fuji and Nikon have declared their cameras to be safe with voltages up to ~400V, so why shouldn't other cameras be the same?
• Some people have actually done the practical testing with their camera and flash and found it works just fine.

And now here we have even more extensive lab tests commendably carried out by the OP, along with a rationale of why it is so.
On the other hand, there is a very powerful economic reason why camera and flash manufacturers want photographers not to use older flash guns (which still do the job very well):

• They want you to buy the new ones.

Further proof that these old flashes work with digital cameras is right here in front of your nose on these forums.
Unsuspecting consumers attach old flashes to their digital cameras with monotonous regularity. If high trigger voltages fried camera circuits, we would be seeing innumerable posts of the type:
"Hey, I just put this old flash on my new digital and it blew up my flash circuit! Wtf?"

But we don't. Instead, we see lots of posts of the form:
"Hey, I just put this old flash on my new digital and it works fine!"
"Don't do that! I've heard it could fry your camera!"

Really?

I'm calling Emperor's New Clothes on this one. I've used a range of old flash units on a range of new digital cameras without any problems whatsoever.
Yet I still find it entertaining to read the views of photographers who have never tried this, and never will - but will nonetheless try to shoot down in flames anyone who has.
For example, by insisting that they have to "test their camera to destruction".
Well, I've been doing that for the past ten years. I'll let you know when it happens.