LED and Quench Pin

[tim10243]

Hi,
I hope that these are my last hardwarequestions now:
- Till is using a 3mm LED. Does it make any practical difference if I
´ll take a 5mm LED?
- In Tills circuit the three pins for fire, quench and ground which
are going to the flash are coming from the two optocouplers. I guess
the pin which comes from both optocouplers is ground. But which one is
fire and which one is quench?
and finaly:
- The two pins which comes from the shutter; does it matters which one
is coming from camera ground and which one is coming from camera fire?
thanks
tim

[Till Seyfarth]

Hi,

 

- if I remember correctly I chose the smaller LEDs because of power requirements. I had the impression that 3 Volts limited my choice but electronics is not really my area of expertise. I just looked into a few datasheets.

 

- the OC connected to the D0 pin is fire, the one connected to D1 is quench - this is only visible in the source code and not very obvious there, sorry.

- polarity of the shutter: I think it does matter. I was rather unafraid to simply try this out with my camera because it's only 3V - but my risk assessment could be totally wrong. This should also be the same for all hot shoes because on this level most flashes seem to be compatible.

 

Cheers

Till

[Mathe]

3 or 5mm LED's don't make a difference regarding power requirements.
Just take the LED size of your choice and search for a 'low current'
version.
Those types emit plenty of light at low currents (2-5mA) instead of
the 20mA that 'normal' LED's require.
When using an LC type all you need to do is raise the resistor value
to 470 or 560 Ohms for appropriate current limiting.

Marc

> > tim- Tekst uit oorspronkelijk bericht niet weergeven -
>
> - Tekst uit oorspronkelijk bericht weergeven -

[tim10243]

hi marc,
the LED I would like to use is:
LED 5mcd / 10mA 60´
so they have 10mA - do I have to change a resistor or not?
if so, which resistor i should take?
if the only difference would be, that the battery is running low a
little faster, it wont make any difference to me as longs as the
battery hold for half a day shooting - I use to recharge my batteries
after each shooting anyway.
tim

[Mathe]

Hi Tim,

It's depending on the Vf of the LED.
When assuming it's 1,8V the resistor should be 120-150 Ohm

btw, I don't consider 10mA really low current.
I use the Osram LO T67K (orange and PLCC2 package) which specs at
least 11mcd @ 2mA.

Marc

> > > - Tekst uit oorspronkelijk bericht weergeven -- Tekst uit oorspronkelijk bericht niet weergeven -

[tim10243]

hi marc,

thanks again. looks like these details are a little more complicated
than i thought.
this is the LED i got (Kingbright L-53HD):
http://pdf1.alldatasheet.com/datasheet-pdf/view/166116/KINGBRIGHT/L53HD.html
Maybe its not the moste efficient one, but as i said before: as long
as don´t suck the battery empty within a half day shooting i don´t
care.

tim

[Mathe]

Hi Tim,

According to the specs in the datasheet the resistor should be 120
Ohm.

On 11 sep, 23:18, tim10243 <t...@brakemeier.info> wrote:
> hi marc,
>

> thanks again. looks like these details are a little more complicated
> than i thought.

> this is the LED i got (Kingbright L-53HD):http://pdf1.alldatasheet.com/datasheet-pdf/view/166116/KINGBRIGHT/L53...

[tim10243]

thank you so much !