Hi all,
A couple of weeks ago I bumped into some LED panels (48 piranha LED) which were cheap enough to consider them for the following project. I was thinking to building a studio strip-light strobe; for whoever is not familiar with the term this is simply a photo-studio strobe but in a shape of a long strip not a square, triggered either by another flash (slave) or directly by a remote (master). I will not get into the details of why building it.
I used the attached schematic, which is fairly simple and so far the test results are ok. The logic behind it is to actually overload the panels with an impulse of max. 0,1s with 10% duty cycle. The panels are rated at 12V/300mA and yes, I know I might burn them, or one of them, by increasing the current, but I'd really like to build them. The characteristics I found on the Internet so far are saying about a ratio between 1/3 - max 1/10, between the rated current and the peak current. While I'm not sure I will peak the panels with 3A individually from the very beginning, I'd like to experiment with 1-2A peak.
0,1s is more than enough for studio shooting, most of the cameras go out of sync after 5ms so I can easily lower the duration of the impulse. The FT is not very sensitive, which is good, right now it can be triggered either by a very close LED flash-light or by the built-in camera flash. In the schematic, only one panel is shown, I will actually use 5 either in parallel or put more MOSFETs. I still have to tweak the MOSFET saturation and the panel currents, this is an ongoing work.
My questions so far are:
1. How can I reset the 555 timer in such a way that after 0,1s (T) is stays off? In other words, if the input impulse is longer than T, let's say 1 sec, then how can I make sure that the output is reset after 0,1s? By this, I would like to prevent burning the panels in case of an accident when there is a continuous and strong light in the FT. Also in other words, I would like the 555 to be triggered on the raising front of the IN-impulse and not to actually care about the duration of the IN-impulse.
2. Just as my regular strobes in the studio, I would like to have some sort of a modeling light. In the classical strobes, this is achieved by having 2 lamps in the head, one regular bulb and the strobe itself. The bulb is continuously lit and it is used not only to actually see what you shoot but also to have an idea about the shadows and help the camera to focus; when the camera is triggered then the strobe flashes.
I was thinking that maybe I can achieve this by having the LED panels normally powered and then trigger only a spike for actual shooting (mimicking the strobe). This idea is in the 2nd picture, in which just a "black-box" is shown; I need some sort of a circuit that can control the current going through the LED panels and in the same time to respond to the impulse given by 555.
I'm opened to suggestions.
Nedix
A couple of weeks ago I bumped into some LED panels (48 piranha LED) which were cheap enough to consider them for the following project. I was thinking to building a studio strip-light strobe; for whoever is not familiar with the term this is simply a photo-studio strobe but in a shape of a long strip not a square, triggered either by another flash (slave) or directly by a remote (master). I will not get into the details of why building it.
I used the attached schematic, which is fairly simple and so far the test results are ok. The logic behind it is to actually overload the panels with an impulse of max. 0,1s with 10% duty cycle. The panels are rated at 12V/300mA and yes, I know I might burn them, or one of them, by increasing the current, but I'd really like to build them. The characteristics I found on the Internet so far are saying about a ratio between 1/3 - max 1/10, between the rated current and the peak current. While I'm not sure I will peak the panels with 3A individually from the very beginning, I'd like to experiment with 1-2A peak.
0,1s is more than enough for studio shooting, most of the cameras go out of sync after 5ms so I can easily lower the duration of the impulse. The FT is not very sensitive, which is good, right now it can be triggered either by a very close LED flash-light or by the built-in camera flash. In the schematic, only one panel is shown, I will actually use 5 either in parallel or put more MOSFETs. I still have to tweak the MOSFET saturation and the panel currents, this is an ongoing work.
My questions so far are:
1. How can I reset the 555 timer in such a way that after 0,1s (T) is stays off? In other words, if the input impulse is longer than T, let's say 1 sec, then how can I make sure that the output is reset after 0,1s? By this, I would like to prevent burning the panels in case of an accident when there is a continuous and strong light in the FT. Also in other words, I would like the 555 to be triggered on the raising front of the IN-impulse and not to actually care about the duration of the IN-impulse.
2. Just as my regular strobes in the studio, I would like to have some sort of a modeling light. In the classical strobes, this is achieved by having 2 lamps in the head, one regular bulb and the strobe itself. The bulb is continuously lit and it is used not only to actually see what you shoot but also to have an idea about the shadows and help the camera to focus; when the camera is triggered then the strobe flashes.
I was thinking that maybe I can achieve this by having the LED panels normally powered and then trigger only a spike for actual shooting (mimicking the strobe). This idea is in the 2nd picture, in which just a "black-box" is shown; I need some sort of a circuit that can control the current going through the LED panels and in the same time to respond to the impulse given by 555.
I'm opened to suggestions.
Nedix
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