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Last update : 2020/09/05

Adapting an old silver flash to be compatible with a digital SLR

An external flash has many advantages compared to a flash on your digital SLR
as, for example, a power much greater, the possibility of deporting the flash.
No have effect of crush the object or character that you take their picture.
Illuminate a background via a trigger cell or RF-602 YONGNUO trigger.
The speedlights compatible with digital SLRs are very expensive
(The Nikon SB400 flash is more expensive than 150 Dollards and is not the best,
the SB600 offers a much better power).

The use of an old silver flash that you stored in a closet, or bought a cheap
Ebay or Priceminster example (10-30 Dollards), is a much better compromise.
The only disadvantage of a flash relative to a recent speedlight is the loss of function TTL
(Function that allows the determination of light). It will therefore refer to table distance / focal length / ISO
often present on the back of the flash (see photo01) to correctly expose the picture (like the good old days).

By cons, BEWARE!
Never insert your old silver flash on your DSLR without prior verification
tension on the hoof. Some have a flash silver voltage in the order of 300 see 400 volts.
Doing so may permanently damage your SLR.
You must, above all, measure the voltage on the flash shoe with a voltmeter (or multimeter).
The voltage to be measured is present between the armature (red arrow photo02) and the central block of
the flash (the green arrow photo02). If this voltage is less than 6 volts, then no problem, it
work. Otherwise this article will interest you.
I changed two old flash (both present on photo01). One, at the left had a voltage of 180 volts,
the other, a voltage of 270 volts! And now I use them without problem.

For this operation, you will have buy electronic components (6 total) and use a soldering iron.
First he'll have to open the patient (photo03) to see if you can find a place
empty for the electronic assembly often near the location of batteries (photo04). This assembly has a volume
about 1 cm cube (1cm * 1cm * 1cm) with classical component, SMD component could do even better.
If you do not find any place in your flash, assembly will be external (in a small box or adapter
You must also identify the thread that connects the center stud of the shoe of your flash electronic
(photo05, the yellow wire in this example) because this circuit that I present will be connected between
the central stud and the place where the wire is soldered to the electronics of the flash.

Now you can watch the assembly diagram (photo06). Wow! it is not super complicated at all!
I told you, only six components: a 5.1 volt zener diode, a switching diode 1N4148,
10nF ceramic capacitor, two resistors of 4.7 Mhoms (0,25 Watt) and a Triac 600 Volt 0.8 A (a Z0107MA).
You can use another model of triac but the maximum switching current is 5 mA (gate current),
and the voltage is 400 Volts supported minimum.
The cost of this circuit is quite small because income is less than 3 Dollards by going to the store
the nearest electronics (or you can find on the internet at Conrad, GoTronic, ...).

The operating principle is quite simple.
A zener diode used to limit the voltage to a maximum value side reflex or trigger at 5.1 volts.
A capacitor is charged through the voltage of X volts delivered by your flash through
of two resistors (they used to lower the voltage). Warning! the use of two resistors
series is important, a carbon resistance can not withstand higher voltage to 250 volts
and as you can have up to 400 volts, this is the max 200 volts to bear for each resistance
therefore no risk of breakdown.
A switching diode 1N4148 to boot / defuse the triac.
And of course a triac (600 Volts, 0.8 amps) that bear no problem all the flashes.
A short circuit of the zener diode (side "command" of photo06) will render the triac from
which in turn will short circuit the flash (side flash on photo06) and thus trigger the flash.
In practice and by bar-side, "order", so the party goes to the label of your SLR, I measured 3.6 Volts,
a voltage well below that can accept your SLR. There is absolutely no danger to it.

On photo07, the schematic implantation of components (as seen from above).
On photo08, the necessary components and a small plate of epoxy pre drilled I used to weld
components, 3 by 4 tablets.
In the photos 09 and 10 you can appreciate the size of the final cut but I am sure some of you
will be even better. The epoxy plate is not required, you might as well weld the legs of components
each other to maximize the space in the flash to spread the components inside the hull of the flash if
you have no choice.
In the photos 11 and 12, the two mounts that I made and inserted into my two flashes
(Photo11 flash left photo01, photo12 the flash right-photo01).
As a reminder, you must insert the assembly between the central block of the flash and the flash circuit
(instead of wire) and Of course connecting the frame (the red arrow photo02) to mount as the mass.

I can assure you that it works perfectly. I have tested my reflex the raise without problem.
Personally, I rather like my two flash slave flash trigger through the trigger (RF-602 YONGNUO) for
make light background or as fill flash with umbrellas to lead the shadows.

To test your new flash amended, get your SLR in manual mode. Set as setting a focal length of 8
and a speed of 1 / 200. It will also, in the settings from the camera, move the flash in manual mode.
If you make a photo and that the flash fires, but that does not appear on the photo, is that your settings
are not correct. You can try other settings but I would advise you to start it.

Copyright 2010 ThierryD -
Last update 26/07/2010
Reproduction prohibited

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