I need some help with an external DIY flash


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endycool

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Oct 8, 2009
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Hi everybody. I'm new here, so if the thread it's not in the right place, i'm sorry.
A few days ago i found some old cameras and now i'm recicling them. I was able to build an optical slave flash that works great, and now I want to transform the other camera into an external flash. In other words, a flash that can be triggered from the hot shoe of my camera. I dismantled the old camera, and now i have two cables that when they touch they trigger the flash. I thought that simply "connecting" one cable to the center of the hot shoe, and the other one to the lateral it will trigger, but it doesn't. I suppoused that profesional flash worked that way, but it seems that i'm wrong...
The question is. Can I trigger this flash from my camera using the camera hot shoe? How should i connect the cables? I don't want to open my digital camera, simply place the cables as if they were a standard external flash.
Thanks
(sorry if my english it's not completely right, it's not my original languaje)

EDIT: I just tried with an old Reflex Camera and it works great, simply connecting one cable to the center and the other one to the lateral. But it still doesn't work on my digital camera. The hot shoe of this last one has another 4 circles. I red that those circles are for another options, but i wonder if i should connect the flash to one of them...
 

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karnage

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Feb 26, 2005
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#2
I think you should not connect your old flash to your new digital camera. Depending on how old, the trigger voltage of the flash may be too high for digital cameras, which usually take about 6-9V. Perhaps you should let it remain on your Reflex or other older film cameras, and get a proper, digital-compatible flash for your digital camera.
 

catchlights

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#3
old camera does not have any circle board, don't have to worry about fried the camera with high trigger voltage.

suggest you better not try this only your DSLR, else your DSLR will RIP very soon.
 

Octarine

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#4
Google for 'flash trigger voltage' - saw some very detailed lists with lots of tips.
 

endycool

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Oct 8, 2009
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Thank you all for your answers. A few thing the i want to mention:
* What i ment to say with the circle, is the middle circle of the hot shoe, the bigger one.
* The old flash that i'm talking about is a built-in flash from a 35mm compact camera that i disassemble, and now i have two wires that when you make them touch the flash trigger.

I already try to connect it to my digital camera (by the way is a Canon S5 IS, i don't have a DSLR yet :cry:) and nothing happens. The camera is still working (thank GOD!:sweat:) although the flash didn't trigger neither. I'm new in all this photography thing.... I suppouse that the older flash only have 2 "contacts", the trigger and the ground, am I right?. A connection in the middle circle and the one from the laterals. Now, if hypothetically connect an old flash to my camera will it work? Because the camera doesn't seems to be triggering the flash unless it detects that have one already attach to it (I mean a ttl or a ettl, through the ready signal). Is this truth? If it doesn't detect a flash attached, the camera just doesn't trigger the flash, doesn't make the connection between trigger and ground like my old reflex do?
 

catchlights

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#6
Thank you all for your answers. A few thing the i want to mention:
* What i ment to say with the circle, is the middle circle of the hot shoe, the bigger one.
* The old flash that i'm talking about is a built-in flash from a 35mm compact camera that i disassemble, and now i have two wires that when you make them touch the flash trigger.

I already try to connect it to my digital camera (by the way is a Canon S5 IS, i don't have a DSLR yet :cry:) and nothing happens. The camera is still working (thank GOD!:sweat:) although the flash didn't trigger neither. I'm new in all this photography thing.... I suppouse that the older flash only have 2 "contacts", the trigger and the ground, am I right?. A connection in the middle circle and the one from the laterals. Now, if hypothetically connect an old flash to my camera will it work? Because the camera doesn't seems to be triggering the flash unless it detects that have one already attach to it (I mean a ttl or a ettl, through the ready signal). Is this truth? If it doesn't detect a flash attached, the camera just doesn't trigger the flash, doesn't make the connection between trigger and ground like my old reflex do?
if you go Youtube, you can find people show how to make stun gun from the flash component salvage from disposable camera, well, do you want to stun your digital camera??
 

endycool

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Oct 8, 2009
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#7
LOL!, i don't wanna stun my camera! But those stun guns looks nice....:think:
I want a simple (and cheap) external flash, and i know that i can create it with an old camera. Yes i know that it wont be the best quality flash, i'm just want to experiment with these old cameras and see what happen.
 

Octarine

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Two things to think and to find out:
- Charging voltage / method: Every flash needs charge, a capacitor element needs to collect a certain charge which gets released into the flash tube in an instant and causes the white flash. This charging is audible even on my old EOS5 when I switch it on and also on newer flashes, it's a thin, high-pitch noise. Which means that there is some sort of voltage conversion.
- Trigger voltage: the signal to the flash to release the charge and fire the flash. Old flashes have much higher trigger voltages. Google for that, even though your flash is not listed. Helps to get an idea.
Hope that shows that there is more than just two wires connecting to two contacts. I guess the capacitor element of your flash is somewhere in the camera and the flash is just the bulb.
 

endycool

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Oct 8, 2009
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#9
Two things to think and to find out:
- Charging voltage / method: Every flash needs charge, a capacitor element needs to collect a certain charge which gets released into the flash tube in an instant and causes the white flash. This charging is audible even on my old EOS5 when I switch it on and also on newer flashes, it's a thin, high-pitch noise. Which means that there is some sort of voltage conversion.
- Trigger voltage: the signal to the flash to release the charge and fire the flash. Old flashes have much higher trigger voltages. Google for that, even though your flash is not listed. Helps to get an idea.
Hope that shows that there is more than just two wires connecting to two contacts. I guess the capacitor element of your flash is somewhere in the camera and the flash is just the bulb.
Thanks a lot for your answer. The capacitor element it's inside the old camera, i can hear it, and i have seen it, it's a big cylinder, that actually have some numbers on it... "220uf 330v". Correct me if i'm wrong, but I should be able to measure the trigger voltaje that it's "emited" from the camera and the one needed to trigger the flash with a tester, right?. Then i could make some sort of circuit to adapt those values.... i should go and see a friend who knows about electronics.
I have already found out that it's more complex than just two wires and two contacts. I'm new in all this things, and i want to learn more, that's why i'm asking, and I really aprecciate your answers.
 

Octarine

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200µF is just the capacity of the capacitor element itself. But you see that the maximum voltage is 330V. There are similar capacitors for much lower voltages (below 12V) which are also much smaller - clear indication about the voltage conversion happening there. It's done in some other elements, not the capacitor. The conversion is necessary to 'collect' enough charge to fire the flash, the camera batteries can't do that alone.
But you see where catchlights' remark comes from: high voltages with high frequency and low current are used in stun guns as well, not only to charge flash lights. Be careful when playing with the capacitor and the conversion unit. Easy to get electric shock even minutes after removing the battery since capacitors can store the charge for quite some time. Not dangerous, but rather unpleasant (see stun gun).
 

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endycool

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Oct 8, 2009
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#11
200µF is just the capacity of the capacitor element itself. But you see that the maximum voltage is 330V. There are similar capacitors for much lower voltages (below 12V) which are also much smaller - clear indication about the voltage conversion happening there. It's done in some other elements, not the capacitor. The conversion is necessary to 'collect' enough charge to fire the flash, the camera batteries can't do that alone.
But you see where catchlights' remark comes from: high voltages with high frequency and low current are used in stun guns as well, not only to charge flash lights. Be careful when playing with the capacitor and the conversion unit. Easy to get electric shock even minutes after removing the battery since capacitors can store the charge for quite some time. Not dangerous, but rather unpleasant (see stun gun).
I've been following your advice and reading some more information about this. I read that some old flashes use up to 20V to trigger!, and digital camera supports no more than 6v... I'm pretty scary now. However it seems that old standard flashes should work on my camera, even if they don't have six pins. I will try tu measure the voltaje of both (the hot shoe of my camera when i shoot, and my flash) and see what i get.
 

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Edwin Francis

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Mar 24, 2006
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#12
Hi endycool, nice to meet another tinkerer here. But just a warning -- do get some advice from a friend who knows some electronics. Aside from the dangers of high trigger voltages (to you and your camera), do note that the main capacitor you're dealing with is an electrochemical device that is potentially explosive. I had one blow up almost in my face years ago. That was a tiny capacitor, smaller than the tip of your little finger, yet it blew a small hole in the formica top of my workbench (that's formica, not veneer!) before flying off somewhere.
Also do remember that even if you turn off the power, there may still be a dangerous charge stored in the capacitor.
 

endycool

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Oct 8, 2009
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#13
Hi endycool, nice to meet another tinkerer here. But just a warning -- do get some advice from a friend who knows some electronics. Aside from the dangers of high trigger voltages (to you and your camera), do note that the main capacitor you're dealing with is an electrochemical device that is potentially explosive. I had one blow up almost in my face years ago. That was a tiny capacitor, smaller than the tip of your little finger, yet it blew a small hole in the formica top of my workbench (that's formica, not veneer!) before flying off somewhere.
Also do remember that even if you turn off the power, there may still be a dangerous charge stored in the capacitor.

Hi Edwin, nice to meet you too. Are you talking seriously!?, the capacitor can really blow up?. WOW!, i'll be more carefull then. I always leave the flash uncharge, i have read that it's something that must be done, but i never really understand why. Thanks for your advice.
 

Edwin Francis

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Mar 24, 2006
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#14
Hi Edwin, nice to meet you too. Are you talking seriously!?, the capacitor can really blow up?. WOW!, i'll be more carefull then. I always leave the flash uncharge, i have read that it's something that must be done, but i never really understand why. Thanks for your advice.
It's not that easy -- they normally leak first, but if the gas buildup is quick enough the casing can be blown off with some force. Normally this only happens if you exceed voltage limits, or if the polarity is wrong.
 

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