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Old Aug 6, 2005, 11:40 AM   #21
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I would forget about delving inside a flashgun.There are very high voltages in there . and there is not much spare space.
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Old Aug 6, 2005, 11:44 AM   #22
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tilgates wrote:
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1. can we use power from the flash battery pack

depends how it is connected regarding the flash circuit, and what voltage.

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2. i tkink 2.5mm side goes to camera and 3.5mm for the flash trigger
Yes, in geriatric schematic, the 2.5 mm (left side) is the input , from the camera hotshoe

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3. i also thought of a foolish circuit im attaching it please look at it and complete it
My comments:
In general, a transistor will work to trigger the flash, but:

1- How the battery is connected versus the trigger terminals? Is the trigger (-) the battery (-) ? what is the battery voltage?
2- What the led's for ? anyway, a current to bias a transistor will be far under the led glow up current, so you can't see anything, not to count that the contact is very brief.
3- What transistor do you use? Transistor are like tires, there are tires for bicycles and tires for heavy load truck. First, you need a transistor which can withstand 60-100 volts , and you have to knowit's curent gain.
4 – How do you determine the 100 ohm value? That value is too much too low and may blow the transistor since E is tied to ground and not allowed to follow the base voltage.
You need to know the transistor specs to determine this value.







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Old Aug 6, 2005, 12:00 PM   #23
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geriatric wrote:
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I would forget about delving inside a flashgun.There are very high voltages in there . and there is not much spare space.



I agree. If you are not comfortable with electronics parts manipulation, you may scrap your flash .
Another option: if the preflash can be disabled on your camera, use a simple slave cell to trigger your flash.

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Old Aug 6, 2005, 10:24 PM   #24
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thanx,

a. The flash run on 4AA so the battery voltage would be 4.8-5v

b. rest im new to electronics thats why i was asking you to complete the circuit, like which resistance to use and what other components to use.

c. i justedited the trigger.jpg to build mine circuit so the R and Led are from that circuit.

d. im going to use the geriatric circuit.

e. mine circuit was only to chk .
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Old Aug 6, 2005, 10:56 PM   #25
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Tilgates,

OK, if you want to use thebattery power of the flash, an important info is where is the "ground". check with an ohmmeter to see if the battery (-) is one of the trigger pin? like: is the battery (-)and the trigger(-) connected?

Also, what do you have as transistor in your "junk box" ? many will do the trick , but a low signal transistor will blow out at 55 v:?

If you don't know your transistor data, just try it (if you don't care it blows). the circuit can't harm the flash itself.
If in fact the the battery (-)and the trigger(-) areconnected, then just replace the resistance and the led with a resistance only, arround 5k ~ 20 k , it should work depending on the transistor curent gain .

good luck and keep us updated
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Old Aug 28, 2005, 7:39 AM   #26
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i have a working circuit, i used a TIP41C transistor and 2 rechargable AA.

i used different Resistance at the base with different results

10K- nothing worked

4.8K - nothing worked

2K - nothing worked

1K - worked partialy

0k - worked fine

check the circuit


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Old Aug 28, 2005, 11:10 AM   #27
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Tilgates,

Glad it work for you, but I am intrigued ... the TIP41C is an NPN, so the flash + should be connected to the collector (center pin and radiator) instead of the #3 as shown (current flows from C to E) :?
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Old Aug 29, 2005, 4:17 AM   #28
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i also thought so but when i connected the Flash(+) to the collector it didnt worked

i think u should try it by yourself. thanks a lot for ur support , i will keep u updated.
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