Slave flash trigger circuit

vman

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Well I found this circuit and was thinking it might be worth a try.  If it works I guess you could buy a cheaper and smaller slave flash for the digitals.  I'm trying to figure out the schematic now.  Well what ya all think.. http://misty.com/people/don//slave.html
 

Archilochus

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Hi vman,

That circuit is a bit over-complex for a basic slave flash trigger. Check this one on my web-site:

http://archilochus.netfirms.com/images/slvflash.gif

The real problem with the slave flash for digitals is not triggering the flash (you can buy / build a simple slave flash trigger really cheap!). The main issues are power consumption of the slave flash itself and sync-ing of the slave flash to the 'master' flash.

If left ON constantly, a typical slave flash unit will draw down its batts quickly - so some scheme is required to cycle the power on/off as needed when a pic is ready to be taken (Brian worked this out with some of his digitals).

The other major problem is that many digitals use a dual flash pulse - the first pulse either for red-eye reduction or to help the cam make adjustments based on the effect of the first flash pulse. So your slave would need to discriminate between these pulses - ignoring the first one and only triggering on the second.

I don't know the specs for the 99$$ digital cam slave unit - but I'm guessing that it takes care of the power / timing problems automatically (thus the higher cost). I'd like to hear more on the workings of those slave units from any users out there.

Archilochus
 

Brian

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Hey Arch,

Do you have a source for the CR02AM?  I am working on a simple slave flash circuit with a delay.  I have found several types of delays but they are all custom to a particular slave or flash unit.  I would like to build my own.  I have taken several slaves apart and they all pretty much follow your schematic.  I want to build in a delay and go from there.  May be hard to do but I plan on trying it out anyway.

Thanks
 

Archilochus

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Hi Brian,
I don't find that specific part in my catalogs, but the 519-TCR22-8 from Mouser looks like a good cross.  Some specs for that part  look even better than the CR02AM.

Do your digital cams use the dual flash pulse??

Arch
 

Brian

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Only the D-370(I don't have one yet) and the EZ have the dual flash.  The AOL I have doesn't use it.  Neither does the S100 or S200.

I wanted to make one for the D-370 and the EZ.

I have crossed it with a Digi-key part number too.

Thanks
 

vman

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Thanks guys.  Well I will let the experts run with this.
 

Brian

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Sorry Vman,

I didn't mean to leave you out. I just had looked at this while trying to get a way to build in a delay for the EZ and thought Arch might have a source for the CR02AM.  If I get it to work I will post the results for sure.

I am trying to keep it simple but effective.
 

vman

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No problem.  Found this on ebay take a look.  slave flash  Seems to cheap to work.  I may get one just to see.
 

coyotebandit

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Vman,

Don't think that will work with the digitals that use a pre-flash system. But I have been wrong before... It looks like you have to spend some major money($100+) for a unit that will work with the pre-flash digitals.

CB


(Edited by coyotebandit at 11:44 am on July 2, 2002)
 

vman

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Coyotebandit,
That What I thought to.  Somewhere in all that garbage on the ebay item I saw something where it said it worked with digitals.  Anyway I'm sure that just a scam.  
 

coyotebandit

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Vman,
Some say they work with digitals, but they don't say if they work with all digitals, or if they work with digitals that use dual, or pre-flash systems.

I don't think you can turn off the pre-flash on the EZ-Digital or on the D-370.

There is a good explaination Here about how Digital Flash systems work. Looks like their base model that works with pre-flash cameras is $99. This must be the one DBworld has been using.

(Edited by coyotebandit at 11:44 am on July 2, 2002)
 

Hill Hopper

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You can NOT turn off the double flash. This is also a component of the white balance metering.
 

Dbworld

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There is a slave flash out there somewhere that is supposed to have a 200 millisecond delay.   I can't find the !#$!@#$ link anywhere.  It cost about $30.  Not sure if that is sufficient for the digitals with two flash sequence or not?
 

vman

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I have been looking all over the net for one.  Haven't had any luck yet though.
 

apittet

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Hello there,

Returning from a week in the woods, I try to catch up with the posting; that’s just to explain the delay…

Brian, I am a bit confused about the purpose of the delay for a digital slave flash.
If I get it right, some digicams send out two flashes, the second one being used for the actual picture capture. From my limited experience, the two flashes come within a fraction of a second. To trigger a slave flash for such camera, we need to sync on the second flash. I am not clear why you would like to make it through a delay as it looks more logical to have a dual state circuit that will take notice of the first flash and trigger in sync with the second one. This way you need not worry about any variation in the delay between flashes. It would also work for any dual flash cam. But I may be missing a point …

Cheers.

André
 

Hill Hopper

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Andre, thats what most of the schematics I've found do. Most use a photo transistor which triggers the slave. The delay from the transistor recognizing the flash to triggering the slave is usually about right from what I've read. I have not tried one yet, but at some point probibly will.
 

gizz

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I don't have much to add here except that I've been seeing these on Ebay.
They are advertised to work with the D-370 among others. Anyone ever try one?
They were selling for around $40 or so.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1364721605

I'd like to try one from a store like Wal-Mart in case it doesn't really work or make a difference in the pics so can take it back.

*** Here's a link to a product that is user selectable to flash on the 1st or 2nd flash depending on your camera. Of course it's $100 :cry-blue:
http://www.d-store.com/d-store/Digi-Slave/...igital_came.htm

This one's supposed to be compatable with the Olympus Cameras although i can't find any specific information on the MFG website. Here's a linke to where it's sold for $50.
I plan on trying to contact the MFG to see if it'll work with the D-370.
http://shop.store.yahoo.com/jandr/sup-2000dz.html

(Edited by gizz at 9:41 am on July 7, 2002)
 

Jon5ja

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Hi apittet and everyone,

I built a circuit last week that does just what you described -- it detects the first flash, sets a flip-flop that starts a timer which (after a few milliseconds) enables a synchronous circuit to drive the slave flash.

I have a D-370 ordered that should be here Tuesday, and after I verify its performance with the actual camera, I'll post my results.  See the "Digital Night Pictures" thread where I posted about this also.

Jon
 

davered1

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Guys,

I bought the flash in gizz's post off of EBAY. I'll let you know how it works when it shows.It claims 75' distance so I figure if I get half the distance I will be a happy man!!:dancinred:
 

Brian

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apittet,

This is what the circuit does.  It detects the first flash and inhibits the trigger until the second flash.  It is kind of a delay until trigger.

Just like ****** says.

Jon5ja,

How do you get around the 218 volts from the slave for activation.  Each slave is different on the voltage to the hot shoe slave but most I have give a high voltage and if you hook up a digital circuit like the flip flop without some isolation you will fry your electronics.  Your slave may actually give a 6 volt supply to the slave but mine doesn't.  I thought of changing slave flashes to one that does but I wanted to build a universal one first.  Some hot shoe slaves have a 6 volt signal source out of the side of the hot shoe but they sell for about $40 bucks.  I have several designs that work but none that interface with the higher voltages.

Just curious.  I took my hot shoe slave apart the other day and the design would be simple to change but the higher voltages will have to be isolated.  If you have this done I would be interesed in seeing it.  I haven't had a chance to work on it lately and this would save me some time.
Thanks
 
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