Hi here are the two pictures.
Aarg,
I've switched the wiring multiple times, flipping the main terminal wires, etc. as I felt that may be it too, but will try some more.
Hi,
Might not be enough LED current.
If we go for 30mA.
The drop across the two LEDs = 1.6 + 1.5 = 3.1V
So series resistor = V/I = (5 - 3.1) / 0.03 = 63R,
Try 68R as your series resistor.
I = V / R = (5 - 3.1) / 68 = 0.027A or 27mA
Which is within the Max rating for Output pin Current, the LED and the opto LED.
The 330R fitted will give
(5 - 3.1) / 330 = 0.005A or 5mA
Tom.. 
Hi Tom,
I swapped in two resistors in line 69R, unfortunately the flash hasn't triggered yet, but I pulled two leads from the main terminal pins to check their resistence. There is definitely a jump on the other side of the switch when the signal is sent, so I'm wondering if it could be the length of the pulse that's specefic in order to ignite the flash circuit as you said before. I've tried multiple lengths from 1ms to 2seconds without luck and also tried without the LED. I think we're close. I've attached another picture. If you can think of any other ideas please let me know. I'm wondering if using a triac between the optotriac and flash would help. I'll give that a go.
Thanks!
B
Hi,
You are close, what you have done there is put a 22K in series with a 47R, that makes 22047 Ohms, not 69 Ohms.
Put 2 x 47 Ohm resistors in series and see what happens, 47 + 47 = 94R.
If you have a DMM, measure your series resistance before putting it in circuit.
Tom...
Aha! I didn't see that, thanks I pulled it from the wrong batch. I just repaced it with a second 47ohm, then with a 'real' 22ohm and the LED turns on but no firing of the light yet.
Hi,
With the LED OFF measure the voltage across pins 4 and 6 of the opto. That is the flash side, and should be high voltage.
With the LED ON measure it again. It should be close to zero.
Tom...
This circuit is not optimum for high speed flash photography. It will only give you a flash duration in the range of 1/1000. Most speedlights use quenching for power control, and so you can get much shorter flash durations like 1/10000 when the power is dialed down. An additional benefit is that you can't easily be electrocuted by the 400V on the capacitor.
Hi,
@aarg
The OP isn't trying for hi speed, he is at the moment just trying to get it to flash once.
The flash unit he has is basically what Kodak and some others used in their disposable cameras.
I agree they are not high speed units, just a cheap compromise to expose 35mm 100ASA colour film for happy snaps.
@birdhouse
The flash should occur on the closing of the "contacts" of the flash unit, so closed duration should not be a problem.
As you have found if you short the two "contact" leads together the flash should operate, just be careful of the high voltage that is across them.
Tom...
Hi Tom,
I measured 215V, over the two terminals 4 and 6 on the opto, when the LED is off and .8V when the LED is on, so it seems to be working. I'm wondering if has something to do with the design of the opto, if it can take the votage spike, but I'd think that it would at least work once before breaking. Do you think a SCR would make any difference, like the C106D?
Thanks!
Hi,
It would be worth a try.
Strange that the opto triac is not working, the only thing I can think of is it is limiting the current through it and so the mag field in the trigger transformer does not change quick enough.
The SCR should work, as that is what is used in automotive timing lights to trigger the flash, a timing light is just a glorified version of what you have, just being able to flash very quickly.
Tom....
Post a series of detailed pictures of the wiring including everything. Find a piece of paper and draw a schematic. Post a photo of that too.
Are you turning off the drive circuit long enough for the flash to recharge?
Hi Tom and Aarg,
The SCR works! Thank goodness, It must have been what you suggested, about the opto triac limiting the current. Thanks so much for your help. I will be using this to shoot some high speed photos. I have attached a drawing and photo of the circuit that is working.
Thanks!
B
There is no limit on the gate current (but some people consider this unimportant), and the Arduino is no longer electrically isolated. However, I am glad that it is working.
birdhouse:
Hi Tom and Aarg,The SCR works! Thank goodness, It must have been what you suggested, about the opto triac limiting the current.
Great that you have it working. However, many people including myself have used the opto triac with absolutely no problems. Your diagram is labeled 5V but the Due is a 3.3V board. Maybe the Due requires different resistor values to drive the opto triac properly.
Why is the SCR shoring the 230V and GND ?
I'm not getting how that is supposed to work.
Shouldn't the SCR be between the load and GND ?
raschemmel:
Why is the SCR shoring the 230V and GND ?
I'm not getting how that is supposed to work.
Shouldn't the SCR be between the load and GND ?
It's ambiguous but correct. There is a high potential on the trigger terminal. A system diagram showing the Due, the SCR, and the flash circuit would make this clearer.
How canbot be correct as shown ?
( the SCR will short the 230V to GND.
The scr should be in series with the load or power source. ( not in parallel)
raschemmel:
How canbot be correct as shown ?
( the SCR will short the 230V to GND.
The scr should be in series with the load or power source. ( not in parallel)
I think you will find that the 230Vdc is what the OP has measured on that wire, which is the trigger wire that has to be shorted to gnd.
The "flash contacts" in the schematic.
I think that not worrying about an opto will be okay, as the flash is battery powered, and its gnd is basically floating.
Your old metal cased pentax/nikon/cannon had its chassis at flash gnd potential when you plugged into the "hotshoe" socket.
Tom...