Loose LEDs, DIY thoughts.....

[thetrue]

I have a little bag with 50 LEDs rated at "Vf 3.2-3.6" and 50 "510ohm" resistors. I was thinking about trying to DIY a little macro spotlight setup with it. Obviously, I should use 1 resistor per LED, and I'll need to position them on a board of some sort to direct the light properly.

My question is this: If I were to use 32 LEDs total, what sort of power source would be necessary to use them all to their full potential, and furthermore, would it be possible to use them as a strobe via the hotshoe?

If this is all possible, I can see it possible to create all kinds of lighting scenarios with LEDs, no? I'm not trying to create an entire studio setup like this, but it would be cool to be able to strobe these and potentially eliminate the "recycle" time of a traditional strobe.

What say you?

 

[07Vios]

I think as long as you don't surpass the overall LEDs total worth of voltage with your power source, you shouldn't need to use those resistors...then again, I'm no electrical engineer. I did my my own "ring light" using a camping light. lol



I needed to modify the battery holder since the original camp light uses 3 AAA batteries, and the holder is a 4 AAA holder. With 4 batteries, I was pushing too much voltage to the LEDs, causing them to get hot with extended (more than 2 minutes use). I disabled a battery slot, so I can just use 3 batteries now. Not as bright, but still pretty bright and the LEDs don't get hot.

 

[07Vios]

This might help you out a little: Light Emitting Diodes (LEDs)

 

[07Vios]

I did 3.4 x 32, coming out with 108.8 volts. So perhaps a 12 slot holder for 9v batteries? It'll come out to 108 volts. I don't know how you could make it so you can use it as a strobe. But if those LEDs are dimmable, I suppose you can use a dimmer switch to regulate the LEDs' output. Once again, I'm not electrical engineer. lol


Edit: if using the minimum voltage rating, 3.2, then it comes out to be 102.4 volts, so you would have to calculate which ohm resistor(s) to use.

 

[thetrue]

Hmmm, definitely have to read more about this. I'm not sure how much light I could potentially make, but does it seem feasible to use as a strobe if I can figure out a hot shoe setup?

 

[07Vios]

That's beyond what I can even think of. You'd have to research which contact points do what. I'm assuming at least one of the contacts simply tells something to "fire." However, I wouldn't mess with anything in the hotshoe area since it might fry your camera.

 

[thetrue]

I'm a tinkerer, but I research a ton before I do anything that could have ill effects. Just hoping to shortcut the researching

 

[Tony S]

Ummm, I don't think it's the volts you multiply to get the power required for the LEDs. You are looking to see how many mA are required to be supplied. Your voltage should only be what the LEDs are rated for.............. but then I'm not an electrical engineer, but I have stayed at a Holiday Inn Express.

 

[thetrue]

We have doctors, lawyers, electricians, jewelers, and pros here. There has to be an electrical engineer around here somewhere!

 

[07Vios]

Ummm, I don't think it's the volts you multiply to get the power required for the LEDs. You are looking to see how many mA are required to be supplied. Your voltage should only be what the LEDs are rated for.............. but then I'm not an electrical engineer, but I have stayed at a Holiday Inn Express.

LOL!

I'm not 100% sure either. But from that website I posted, they were adding/multiplying LED voltages together and used a source greater than the sum of the LED voltage (then used resistors to bring it down).

"If you wish to have several LEDs on at the same time it may be possible to connect them in series. This prolongs battery life by lighting several LEDs with the same current as just one LED. All the LEDs connected in series pass the same current so it is best if they are all the same type. The power supply must have sufficient voltage to provide about 2V for each LED (4V for blue and white) plus at least another 2V for the resistor. To work out a value for the resistor you must add up all the LED voltages and use this for V[SUB]L[/SUB].
Example calculations:
A red, a yellow and a green LED in series need a supply voltage of at least 3 × 2V + 2V = 8V, so a 9V battery would be ideal.
V[SUB]L[/SUB] = 2V + 2V + 2V = 6V (the three LED voltages added up).
If the supply voltage V[SUB]S[/SUB] is 9V and the current I must be 15mA = 0.015A,
Resistor R = (V[SUB]S[/SUB] - V[SUB]L[/SUB]) / I = (9 - 6) / 0.015 = 3 / 0.015 = 200

,
so choose R = 220

(the nearest standard value which is greater)."

I tried lighting up some spare car LED boards when I was making my ring light, and since they were made for 12v sources, one board did not light up when I used 4 AAA batteries (6v total), and another board only lit up one row/column. I'm sure milliamps become a factor as well.

Where are the electrical engineers at? lol. I'd like to learn more about LEDs

 

[07Vios]

Then again, I've used six 12v LEDs in a series hooked up to my car's dome light wire (12v). So I honestly don't know now. ???


But I do retract my statement about not having to use resistors. I guess you HAVE to use resistors with LEDs.