BD649 DATASHEET PDF

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BD649 Datasheet

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. When I shine a torch on the datasjeet resistor, it saturates and the LEDs light up bright, but when I try to activate the system with the flash, the LEDs don’t seem to work.

Nov 30, 18, 9, Mar 5, 1, Does anyone have any suggestions? Yes, my password is: I’m working datasgeet the idea that when the built-in flash is blocked by a large macro lens at close range, the LED ring will compensate, and the camera will calculate from whatever it ‘sees’ through the lens.

The opto-transistor can only allow. And it looks like they should work. Hypatia’s Protege likes this. And the tailing off from the phosphorous in the white LEDs may become darasheet problem at fast moving objects. Generally a good job for an SCR. Lets try 30 ua in ambient light. Jul 22, 9. First measure the current through the opto transistor in ambient lighting conditions to find the off leakage current. You suggested xatasheet 22k in series with the trim pot meter, and none in series with the opto-transistor.

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So, yes I guess the IR filter might help, but the dtaasheet pair is perhaps excessive? Just playing devil’s advocate here. Mar 1, 3, 2, I think there should be one in series with the opto-transistor, so I can adjust the voltage at the point to the darlington to be 0v datassheet ambient light. Then the adjustment leg is designed to develop less than 1 volt at that current, and some adjustability to compensate for ambient light.

That’s not going to blow out anything.

BD649-S – NPN SILICON POWER DARLINGTONS 8 A, 60 V, NPN, Si, POWER TRANSISTOR, TO-220

Now, putting the opto-transistor right in front of the built-in flash? Solving for two resistor values in a resistor-divider network Posted by jerseyguy in forum: I’m trying to make a flash slave as in the attached diagram.

When a light flash happens the opto will suddenly allow a lot more current. Jul 23, No, create an account now. Quote of the day.

It either emits nearly invisible preflashes and analyses results to adjust flash output. OK thank you all for your thoughts on this. But if it’s in series with the opto-transitor, it’s multifunctional. I’ve learned quite a bit here, but I can put this project at rest and tidy up now and focus on other things again. Jul 22, 6.

Transistor Substitute. – Datasheet/Parts requests – Community

Jul 21, 7 0. If datwsheet could build your dream bench, what datasueet you put on it? Sep 24, 2, You size R3 to limit the total opto current to 0. Discussion in ‘ General Electronics Chat ‘ started by roukeDatasheeet 21, You get the power in the capacitor and you can’t stop the light until the capacitor is empty.

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Really don’t think you are going to get that circuit to respond fast enough. Nov 13, LEDs and Solar Cells Combine into Devices that Emit and Absorb Light Researchers have developed double-heterojunction nanorods which can be biased to both send and receive light—in other words, a device that is both an LED and solar cell, capable of emitting and absorbing light.

Suppose the PT is 5 mS and the darlington is 20 mS.

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The datasheet says the gain is aboutbut you seem to have a different data sheet with different gain values for different mA and volt values. Jul 21, 5. 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. The unit works well, although not as bright as flash tube, but good for macro photography.

But yes, speed matters. That’s what an SCR and a capacitor will do. Jul 22, 8. 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, dump that cap into the LEDs. Posted by striplar in forum: One-Time Programmable Memory in Action: I want it to be triggered by the camera’s built in flash, but I can’t get it to work satisfactorily.

But that’s something I can olny find out when the electronics work.