STROBIST - Home Made Triggers... UPDATE!!

i didn't mean to be abusive oldfella - I apologise for it

cheers who, this should be very helpful to the ttl guys that are trying to write codecs for different ttl systems
 
I've been subscribed to this thread since the beginning Jambo, any news for us from you and your Uncle? I'm one of the supporters by the way, not one of the detractors!

Pip
 
Steve Smith said:
Not really. The high voltage is at the flash end, not the camera end. The only bit which will connect to the flash will be (I assume) an opto triac.

The connection at the camera end will be a low voltage input stage pulled up by a large value resistor (I'm assuming again). Not much chance of causing any harm.


Steve.
Click to expand...
Agreed the high voltage is applied to the triac, but the popular American version that requires no external voltage is connected to this high voltage by a resistor and 5 volt zener diode. if this diode went open the full high voltage would be applied to the camera switch. :thumbsdown:
 
classcams said:
Agreed the high voltage is applied to the triac, but the popular American version that requires no external voltage is connected to this high voltage by a resistor and 5 volt zener diode. if this diode went open the full high voltage would be applied to the camera switch. :thumbsdown:
Click to expand...

But only to the receiver. There is no connection between the flash and the camera.


Steve.
 
Steve Smith said:
But only to the receiver. There is no connection between the flash and the camera.


Steve.
Click to expand...
please read my write up again. The R+ line goes to the hotshoe switch via a resistor with a zener diode to ground.
 
but its a wireless trigger? provided the tx on camera has a 6v or lower PS it can't blow the cam?

and surely the sync speed on a doorbell would be too slow?
 
classcams said:
please read my write up again. The R+ line goes to the hotshoe switch via a resistor with a zener diode to ground.
Click to expand...

Yes. The hotshoe of the flash, not the camera. It's the flash which has a high voltage from which you can derive a low voltage supply using a resistor and a zener.


Steve.
 
Steve Smith said:
Yes. The hotshoe of the flash, not the camera. It's the flash which has a high voltage from which you can derive a low voltage supply using a resistor and a zener.


Steve.
Click to expand...
Please look up the circuit on 'Sam`s Strobes" and you will see you are talking pooh:bang:
 
classcams wind it in please, a little thought about how you are communicating with others please?
 
Steve Smith said:
Can you give me a link so I can have a look? (I tried a search but can't find it).


Steve.
Click to expand...
Enter don`s, light lamp and strobe site
look down the list for sam g strobe faq

You will have to look down the list for the safe sync.
 
Sorry. Still can't find it.

But if it's labelled 'safe sync' then it's just an adaptor, not a radio link which is the subject of this thread.

If it's this one: http://repairfaq.cis.upenn.edu/sam/zpaofu1.pdf Then yes, if the zener goes open circuit, the full voltage is applied via the resistors to the hotshoe. However, look at the value of those resistors. 4.7M each so almost ten million ohms. The load resistance of the hotshoe connection would ensure that most of that voltage would be dropped across the resistors and not across the hotshoe teerminals.

Do some maths and you will see that with a 300 volt flash, the maximum current that you could put into the hotshoe would be 30 micro amps. This will not cause any damage.

If the zener does fail however, it is more likely to go short circuit which would put 0 volts onto the hotshoe.



Steve.
 
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