Taming the High Trigger Voltage of the Vivitar 283





Introduction: Taming the High Trigger Voltage of the Vivitar 283

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.

Step 1: Schematics

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.

Step 2: The Guts

We want to include the adapter inside the flash, so we'll have to open it. There is already a good instructable which shows us how to do so. You'l find it there:

How to disassemble a Vivitar 283


We'll also unscrew the photocell/remote socket and remove the battery compartment, to get some room for the soldering iron.

The upper (moving) part, the flash tube housing and the trigger circuit don't need to be disassembled and they can stay in place.

The adapter circuit will take place electrically between the remote socket and the trigger input, physically between the trigger circuit and the battery compartment.

Step 3: Wires to Cut

The high voltage from the trigger circuit is lead by the yellow wire (#1) to the socket for the Vivitar PC cord, on the side of the flash. It wil be unsoldered from the socket contact.

The blue wire (#2) is the "common", negative pole, leading to the center contact of the remote socket. We'll cut it, and later electrically connect the two ends together again

The remaining length (photo 2) of the wire from the remote socket is not sufficient to allow us, when reassembling the flash, to comfortably put back the two screws of the socket. We'll have to solder 3cm of wire, insulated with a piece of heat shrinkable sheath.

On the other side, we'll add a new wire, the pink one on the second picture.

Step 4: Assembling the Circuit

The schema is simple enough not to need a printed circuit board. It will be assembled on a small piece of perforated board.

The two pictures, components and solder sides, should be clear enough.
On the solder side, the four 1 megohm resistors are SMD (Surface Mounting Devices) 1206 types,

The diodes (one small signal, one Zener)  are SMD SOD80 types. The PMLL4148 (=1N4148, black ring) is soldered just between the Gate and Anode 1 pins of the triac (MAC97A8 or equivalent).

The pad under each resistor is removed with the tip of the hot soldering iron and a reasonably violent pressure.

Step 5: Connections Inside

The board is connected to the three wires.

The two ends of the blue one, common, are connected again together, as previously announced.
The part coming from the socket should be extended, which is not done on this picture

The pink wire now leads to the socket a reduced trigger voltage (<5V).
From the socket, when the PC cord is not plugged in, the trigger voltage is lead to the remote socket, and from there to the flash shoe, provided the sensor is plugged into the socket.

Before re-assemblig the flash, we'll turn the board with the component (insulated) side against the main PCB, to avoid any unintended (and possibly disastrous) contact.



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19 Discussions


2 years ago

Can't you also make a relay switch that closes the high voltage circuit between the terminals on the flash gun using an electromagnet powered by a 9v or AA battery on a circuit through the flash hot shoe?

I have bought a triac 600v 1a, a 22nf 250v capacitor, 2x 4.7 mOhms 1/4 w, 1n4148 100v 0.2 a and a 5.6 v 1.3 w z diode. Are those feasible for building the voltage reducing circuit? Im not really sure about the triac.

1 reply

The question about the Triac. There are one, two, three and four quadrant triggering types. Any one of those types would be fine because the circuit operates in the first quadrant which is covered by all types.

I did not know that about the voltage rating of a Cannon camera. Having said that I have used the flash successfully with Cannon AE-1 and Nikon EM which are 40 and 30 year old camera's now. They may have traditional electrical contacts.

The resistor's could be replaced by one single VR37 or VR25 high voltage resistor. A 200mW zenner diode would be fine, and a series resistor added in the gate lead to limit the gate current to the maximum rated should be added.

A BIG thank you for this tutorial !!!
It worked perfectly. My Vivitar 283 Auto thyristor had 270 Volts at the hot shoe, now I measure ~4V.
Best regards,

Okay, So I decided add this inside the flash like you did, my original was external connecting to the socket and then to a 3.5mm jack. Anyways, I think I did something wrong, I am not getting any voltage at the hotshoe or socket, and the flash doesn't sound the same, the beeping is not constant like it was before. I connected the yellow wire up to flash + and it comes out Hot shoe +, right? I think My problem is with the blue wire, I'm not sure if I connected them right. I was looking at your board and it doesn't look like you connected it to each negative side, Can you explain what you did different.


I'm look for the capacitor and I found some on ebay they are listed as 63v does the voltage matter? just as long as they are 22uf

4 replies

Hello Seshan,

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.

So I built it and it works great, but I want to make it smaller, does it matter if I use a ceramic capacitor? Also, is it possible to drop the trigger voltage even more?

Of course, you can use a ceramic capacitor, as their insulation voltage usually is 63V. Even surface mounted devices, with a lower insulation voltage, are usable. (However, you don't want to try SMD triacs, for safety reasons. Stick to the TO92 case. )

I don't see the point in further lowering the voltage. The minimal value is somewhere about 2V, you'll try by yourself.

Yes, uF was just a typo :P I'll dig in my bin of old electronics to see if I can find any, thanks! I just wasn't sure about the voltage.

Can someone please tell me where the green wire on the flash head is connected as it has come off and I dont know where it came from!!!
the flash still works though!

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


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


What am I missing? Why does the Schematic calls for Two 4.7 Mohm resistors (i.e. R1 & R2) and the "Assembling the Circuit" section is using Four 1 Mohm Resistors.

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.

1 reply

Hello BHverify,

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.)

Nice Instructable!
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.


Great instructable. Don't own one of these strobes, but have always wanted to. I label my flashes with the trigger voltage so I don't use the bad ones on my sophisticated cameras. This is a great way to get around that hassle.

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.

Thank you for this brilliant instructable! Would you mind putting some bold warnings at the beginning regarding the dangers of high voltage capacitor and components inside the unit?


1 reply