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The Vivitar 283 electronic flash is the workhorse of people who don't use TTL or automatic lighting, like the so-called Strobists (http://www.flickr.com/groups/strobist) or more particular photographers, like http://www.photomacrography.net/forum/viewtopic.php?p=55625
This old model has one disadvantage: a high trigger voltage, more than 260 volts, some samples over 280. Such a high voltage is deadly for digital cameras that conform to ISO 10330 standard and withstand 24V. Let alone Canon cameras that ignore standards and don't accept more than 6V!
There are some solutions, like Wein Safe syncs, or photo-slaves, or DiY adapters (http://repairfaq.cis.upenn.edu/sam/strbfaq.htm#strbtoc). All of these solutions are external accessories, which makes them not so handy and let you with the risk of forgetting to use them.
The really safe solution is simply to include the (simple) protection circuit into the device itself, and lower the sync voltage to under 6V, be it on the shoe, the remote cable, or the Vivitar PC cord. This is important for people who had to replace a worn out or broken shoe with a metallic one. They are exposed, when touching the shoe off camera, to electric shocks, not really dangerous, but surely unpleasant.
This old model has one disadvantage: a high trigger voltage, more than 260 volts, some samples over 280. Such a high voltage is deadly for digital cameras that conform to ISO 10330 standard and withstand 24V. Let alone Canon cameras that ignore standards and don't accept more than 6V!
There are some solutions, like Wein Safe syncs, or photo-slaves, or DiY adapters (http://repairfaq.cis.upenn.edu/sam/strbfaq.htm#strbtoc). All of these solutions are external accessories, which makes them not so handy and let you with the risk of forgetting to use them.
The really safe solution is simply to include the (simple) protection circuit into the device itself, and lower the sync voltage to under 6V, be it on the shoe, the remote cable, or the Vivitar PC cord. This is important for people who had to replace a worn out or broken shoe with a metallic one. They are exposed, when touching the shoe off camera, to electric shocks, not really dangerous, but surely unpleasant.
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Signing UpStep 1Schematics
The principle of the adapter is explained here http://repairfaq.cis.upenn.edu/sam/strbfaq.htm#strbtoc and in French here http://gary.summers.free.fr/flash/adaptateur.html.
A pdf file is available here http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf , probably more legible than the poor jpeg hereafter.
A pdf file is available here http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf , probably more legible than the poor jpeg hereafter.
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Thanks.
Did you notice that the capacitance is 22 nanofarad (10^-9, nF), not 22 microfarad (10^-6, uF)?
The insulation voltage will always be sufficient, whatever the rated value: it just needs to be 6V (six) or more.
Haven't you got any other source than ebay for such ordinary components?
You could even easily salvage them from an old radio set or any discarded electronic device.
I don't see the point in further lowering the voltage. The minimal value is somewhere about 2V, you'll try by yourself.
the flash still works though!
Hello,
I won't search the web to see which components you grabbed. It would be useless since I can't see how you wired them.
There are several possible explanations for your measurement,
You could try and verify, from the least to the most likely:
- your flash is not working
- you don't measure between the right points
- your voltmeter doesn't have a sufficiently high impedance (resistance in our case)
- there is some error in the wiring, the most likeky here is that you reversed the polarity of the zener diode, which would be consistent with your 0.6V
Cheers
Z
If your capacitor is not internally shorted, it cannot be the culprit, whatever its capacitance.
Try and measure the voltage on the flash alone. If it happens to be much higher than your 116V, then you can conclude that your circuit draws a noticeable amount of current, which it should not..
Anyway, if you remove the zener (just unsolder one end), you should read a voltage equal to that on the flash alone. If not, and the capacitor is not shorted, it can be that the triac is defective.
If you don't know a better way of doing it (stabilized power supply with current limitation), check the zener (no voltage applied) with your multimeter in diode test position: you should measure a threshold somewhere betweeen 0.6V and 1V under one polarity, and an open circuit (infinite resistance) under the other polarity.
Should you measure a low threshold voltage under both polarities, then you can conclude that your zener is dead. Try another one.
Good luck
Z
If I am not mistaken the resistance would be as follows:
Schematic: Two 4.7 Mohm resistors connected in Series equals 9.4 Mohm.
"Assembling..." Four 1 Mohm resistors connected in Series equals 4 Mohm.
Which one is correct?
Thank you.
you're right as to the addition of resistances.
In fact, any value above 4 megohm wil work. The resistor's function is charging the capacitor. The resistance has to be high in order not take two much energy from the internal triggering capacitor of the flash. The capacitance in the adapter is very small, so the charging time is short, some milliseconds; 100 milliseconds or 200, it doesn't matter.
What does matter is the so-called dielectric strength, i.e. the ability to withstand a voltage. Ordinary through-hole 1/4W resistors withstand about 250V; 1206 type SMD resistors only 100V. So, if you want your adapter to work safely, with a margin, when connected to a 280V source, you need a series assembly of several resistors. The original circuit was made of two 1/4W resistors, hence the two 4.7M parts; the circuit presented here was wired with SMD devices, 100V each, so four of them were needed.
Then the answer to your question is: both values are correct, each with a given type of components. The important point is putting the right number of resistors in series to insure a sufficient dielectric strength. You could as well use two 1/4W through-hole 2.2M resistors.
If you are certain that your adapter will never see a voltage above 200V, for example, you can use one 1/4W 4.7M resistor. (I wouldn't play this way with safety.)
I did something similar a few years back.
I put the whole circuit in an adapter casing though, so it can be used for any flash, also it allows you to use the flash with a sync cord to allow indirect lighting.
http://www.instructables.com/id/Use-old-flashes-on-new-DSLR-cameras./
I like to encase the circuit in epoxy once I'm sure the whole thing works to avoid any shorts. The modern components will last the life of the flash I'd think.
K.
As to the danger with high voltage capacitors, I hope that the reader will take advantage of the Instructable I refer to in step 2:
http://www.instructables.com/id/How-to-disassemble-a-Vivitar-283/.
Its author gives all necessary BOLD warnings and how-to details for the reader who wants to disassemble his flash.