Collector-base voltage (IE = 0). BD BD BD BD The device characteristics and parameters in this data sheet can and do vary. BD Transistor Datasheet pdf, BD Equivalent. Parameters and Characteristics. BD Bourns Darlington Transistors W NPN Silicon datasheet, inventory, & pricing.

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I guess it’ll always be 3 volt, and in my case. Now, putting the opto-transistor right in front of the built-in flash? Really don’t think you are going to get that circuit to respond fast enough.

The opto-transistor can only allow. Hypatia’s Protege likes this. That’s what an SCR and a capacitor will do.

Suppose the PT is 5 mS and the darlington is 20 mS. Jul 21, 4. Quote of the day. Jul 22, 6. You can not get dahasheet zero volts and you don’t need to. That’s not going to blow out anything. I’m working on the idea that when the built-in flash is blocked datasueet a large macro lens at close range, the LED ring will compensate, and the camera will calculate from whatever it ‘sees’ through the lens. Are you referring to R3?

You suggested a 22k in series with the trim pot meter, and none in series with the opto-transistor.

How are you with mosfets? But I think that’s what you’re saying albeit in other words ;- However, if R1 and R2 are high enough, the current through the base of the darlington would also be limited to a safe level. dahasheet


Determining resistor values in a mesh. Have I got that right?

Jul 22, 8. Without it the current through the opto-transistor at ambient light is sufficient to saturate the base of the darlington, and the LEDs are always on. R1 is k and R3 is 50k. Mar 5, 1, Nov 13, One-Time Programmable Memory in Action: Be649 learned quite a bit here, but I can put this project at rest and tidy up now and focus on other things again.

Resistor values in flash slave

And it looks like they should work. See where I’m going with this?

Measure the current through the opto-transistor in ambient light. Jul 21, 2. First measure the current through the opto transistor in ambient lighting conditions to find the off leakage current.

I would start by re-designing this. R1 datashee only be necessary if the adjustment leg will eat too much current when the flash fires. That’s going to be 25 mS delay in the flash of the LED’s.


Yes, my password is: You size R3 to limit adtasheet total opto current to bd469. And the tailing off from the phosphorous in the white LEDs may become a problem at fast moving objects. And using the hot accessory shoe would be an option, but I like the challenge of wireless, and so far I’m not yet convinced that using the hot shoe would solve the problems I’m encountering here.

As you could see from my pictures, the unit is a rectangular circuit board that slides in a Cokin filter holder with the LEDS facing forward and the opto-transistor mounted on the reverse side of the circuit board, facing the built-in flash. It either emits nearly invisible preflashes and analyses results to adjust flash output.


You route that to the base of the transistor. When a light flash happens the opto will suddenly allow a lot more current.


But if it’s in series with the opto-transitor, it’s multifunctional. Do you realize how short that flash datazheet the camera really is? Jul 21, 7 0. If the current assumption is that it receives too much light and we have to reduce it with the IR filter. OK thank you all for your thoughts on this. You May Also Like: What you want to do is allow the input power source to charge up a capacitor, and then when your light sensor senses the external flash, datashest that cap into the LEDs.

BD 데이터시트(PDF) – Comset Semiconductor

So I guess my main question is, how do I calculate the size of R1 and R2 so it protects both the opto-transistor and the base of the darlington at 0. I’m trying to make a flash slave as in the attached diagram. Posted by striplar in forum: Jul 21, datasehet. Do you already have an account? Set R2 to allow that current to create not more than one volt.