slave flash trigger

[simple&cheap]

I would like to build a slave flash trigger for a carmers I have looked a few drawing on the internet some using photodiodes and some using phototransistors. Not sure which is the best to uses or if it matters.
any ideals?. Also I can not find the photodiode or Phototransistor locally
Digikey did not show them eather. any help ?
thanks :?:

 

[Rolf]

Digital Slave Flash for DC's

Hope you are talking about digital cameras. The simple old photo-opto slaves do not work because most DC's have a (or more) pre-flash(s) to adjust the cameras white balance and the exposure. Only the more expensive ones allow you to turn the pre-flash OFF. Note: this is not the same as red eye elimination.
So what is needed is what is called a digital slave to make the slave flash ignore the pre-flash(s). There are commercials units but they rather overpriced, I think. Have been searching the internet for a good simple circuit, for some time. Found none that were simple. Most are counter type that you have to set for one, two or three pre-flashes with a selector switch. This is not practical in my opinion.
I am now working on a circuit that works on a different principal and uses only two 14pin IC's and a few components. Have not got to make the prototype yet.

Rolf

PS. Just noticed this was an old post (stupid me), will not delete yet as I am hoping for some comments.

 

[1Steveo]

Rolf, Have You seen This Remote Slave Trigger? It looks simple enoff. He dose have the "hex" code on his site, but not the source code. As I realy like to add a Daylight sensor to this.

 

[Rolf]

Have not seen this design.
Steve, micro controllers became popular after my retirement and I know little about them. Don't quite understand what you mean by a daylight sensor.
Are there more information on how this design works. By that I mean does it count pulses or what? Did you try to contact the designer, I see his email addr. on the schematic.
Would like to discuss this in more detail, do you Skype?
Rolf

 

[1Steveo]

I should have posted the link. Sorry, But here it is **broken link removed**
As far ast the daylight sensor, It is something that I was wanting to add so I can use it with a "Trail Camera" to take pics of wild anamils.
Sorry I do not Use Skype. But I will be happy to awanser any questions Just leave me a private msg.

Steve

 

[Rolf]

Thanks for the link. So it counts pulses. This is what I am trying to get around; after we did some testing and found our two cameras fired different number of pre-flashes under very similar circumstances.
Seems like you would adjust the slave flash to accommodate your camera and leave it ON. The problem would be to design an interface from the remote movement sensor to your camera. Quite a few problems would have to be addressed. Like, is your camera fast enough to be woken up and take the picture before the game despairs from view. Or are you going to going to keep the camera alive by preventing it from shutting down. I would think it could be solved and I think I have seen some information on the net.

Rolf

 

[1Steveo]

So I assume that you are looking for a Slave that will flash in sync with the Pre flashes than the Main Flash?
I Thought that a slave flash purpose was to give extra lighting! If it flashes with the "white balance / red eye " The pictures will be Darker as you camera as your camera will adjust for the extra light from the slave flash.

 

[Rolf]

No, what I want is for the slave to fire when the cameras main flash goes off (the last flash). Then the cameras setup will be unaffected by the slave. It will be used mainly for filling in background when taking pictures in large rooms. Or when taking portraits, as the main flash, when the camera flash will be used in the bounce mode. Used this way, the exposure should be OK.
This could be achieved with a time delay that blocks any triggering for about 50mS (I think all pre-flashes occur in this period), when this delay times out the cameras main flash (last flash) would trigger the slave. After about 300mS the unit should reset.

 

[Rolf]

Problem solved..................

No, what I want is for the slave to fire when the cameras main flash goes off (the last flash). Then the cameras setup will be unaffected by the slave. It will be used mainly for filling in background when taking pictures in large rooms. Or when taking portraits, as the main flash, when the camera flash will be used in the bounce mode. Used this way, the exposure should be OK.
QUOTE]

Here is what I made:
https://www.pbase.com/sinoline/digital_slave_trigger

 

[Rolf]

No, what I want is for the slave to fire when the cameras main flash goes off (the last flash). Then the cameras setup will be unaffected by the slave. It will be used mainly for filling in background when taking pictures in large rooms. Or when taking portraits, as the main flash, when the camera flash will be used in the bounce mode. Used this way, the exposure should be OK.
QUOTE]

Here is what I made:
https://www.pbase.com/sinoline/digital_slave_trigger

**broken link removed**
This output circuit works fine, with my Vivitar 2000, that have a trigger voltage of about 102v. The SCR (MCR100-6) is rated at 400v and the gate resistor is 10 K. But some commercial strobe units have trigger voltages well above 300v and that makes me a little nervous. I don't have a HV variable power supply to test this and I don't have a lot of room on the PCB for an optical isolator circuit.
The IC is a 4011 operated on a 3v supply.
Any ideas?

 

[jankop]

Why optoisolator?
1. All flashguns have very high voltage internaly on flash capacitor!
2. Thyristor MCR100-8 has Vdrm = 600V

 

[Rolf]

Why optoisolator?
> Don't really know, thought maybe there was need for some additional safety to the CMOS circuit.
>1. All flash guns have very high voltage internal on flash capacitor!
I am not sure voltage on the capacitor is necessarly the same as the trigger voltage. So I don't think this has to be factored in.
>2. Thyristor MCR100-8 has Vdrm = 600V
So you would feel save with my circuit at trigger voltages up to 400v? Like I stated I have not found any unit with a trigger voltage over 380v.

 

[Nigel Goodwin]

The high voltage is ONLY across the SCR (anode to cathode), not anywhere else in the circuit, so it's not a concern.

 

[Rolf]

Thanks Nigel, I wasent sure, maybe I was worried about a catastrofic failure of the SCR.
Do you know anyone who would write some code for 12F675 PIC? It seems like a dounting task to learn programming at my age just for a few lines of code..(timing function) Buying Pic Basic Pro for a one time project dosent make sense ither. Anyone interested please email me.

 

[mister_e]

you could use the DEMO version. It will provide you more than enough to do the whole thing.

 

[Rolf]

you could use the DEMO version. It will provide you more than enough to do the whole thing.

I have now buildt the PIC slave flash trigger described at this link:
**broken link removed**

It works great! Have not got it put in a box yet.
https://www.pbase.com/sinoline/pic_slave_flash

 

[Rolf]

you could use the DEMO version. It will provide you more than enough to do the whole thing.

I have now learned to burn PIC's thanks to 1Stevo who have helped me, by communicating with me on Skype. But learning the programming aspect of PICs has not been successful.
1Stevo brought my attention to Povel Jenko's PIC slave flash trigger (see his post) and it works great. His (DIY) design (noting for sale) but the schematic and HEX code is poster here:
https://www.fancon.cz/slave-flash-trigger/slave-flash-en.html
One problem, I need to modify a flash gun's output drastically. I would like to have some input on how to squelch the discharge capacitors voltage to the flash tube. How to interrupt the flash at some predetermined point is the objective.
Or can you lower the voltage? And how much before the flash tube refuses to fire.

 

[Rolf]

Slave Flash Trigger, using a PIC ........

No, what I want is for the slave to fire when the cameras main flash goes off (the last flash). Then the cameras setup will be unaffected by the slave. It will be used mainly for filling in background when taking pictures in large rooms. Or when taking portraits, as the main flash, when the camera flash will be used in the bounce mode. Used this way, the exposure should be OK.
QUOTE]

Here is what I made:
https://www.pbase.com/sinoline/digital_slave_trigger

This is what I ended up with by using a PIC and a much simpler circuit: https://www.pbase.com/sinoline/pic_ii

 

[Azaruk]

I used the design from Pavel Janko (the image included in one of the posts already), but changed the photodiode to a phototransistor.

The unit works exceptionally well, with the ability to "learn" the pricipal camera's flash pattern, and only triggering the slave flash on the main (shutter-opening) flash.

As far as photographing wildlife is concerned, this unit has also worked very well indeed (I am a wildlife photographer), and has markedly reduced eye reflections in night shots. Just for information:- wild animals are more concerned with "alien" noises rather than light. Flashes of the type we're discussing here are assumed to be natural (i.e. lightning) by animals and they often continue with whatever they are doing when the flashes go off. This behaviour, of course, is heavily exploited by me to produce some fine images.

If you require any info regarding my particular set-up, get in touch.

 

[ventureglen]

Hello i am looking for information for a very sensitive high quality slave flash design, willing to pay if necessary