Lasorb connection conundrum...

[FourDee]

For current distribution if you use a parallel diode setup.
I advice against this and suggest a series setup.

[taggalucci]

Whats the additional resistor for?

Hi Norty,

Here's a good description of what to do if running diodes in parallel, and the reasoning behind the balancing resistors...

For current distribution if you use a parallel diode setup.
I advice against this and suggest a series setup.

Hey FourDee

I've seen you recommend this elsewehere. I'm interested to hear how you set the driver up to provide the power when running diodes in series. Do you just simply multiply the individual drive current by the number of diodes, or...?

[FourDee]

Hey FourDee

I've seen you recommend this elsewehere. I'm interested to hear how you set the driver up to provide the power when running diodes in series. Do you just simply multiply the individual drive current by the number of diodes, or...?

No that's what you would do for parallel diodes.

When wired in series, you set the desired operating current and make sure your supply is equal to or greater than the combined forward voltage of the diodes and the voltage drop over your driver.

This method will not damage other diodes when one suddenly fails or the wire comes undone or ...

[taggalucci]

Here's a good description of what to do if running diodes in parallel

No that's what you would do for parallel diodes.

I'm confused!

When wired in series, you set the desired operating current and make sure your supply is equal to or greater than the combined forward voltage of the diodes and the voltage drop over your driver.

Thanks FourDee

OK, I'm a bit naive when it comes to this talk of "forward voltage" of diodes and "voltage drop" of driver. How does one establish these and therefore calculate the supply?

[FourDee]

I suggest you contact the supplier of your driver for this number

I know that the die4drive has the following voltage drop:
1 x current + 300mA
So for 1A of current, there is a voltage drop of 1,3V over your driver

The forward voltage is just a characteristic of your diode

[taggalucci]

That makes sense. Thanks for that

Any idea what the forward voltage is for the Casio 445nm diodes?

[FourDee]

About 4,3V
15 characters

[norty303]

Can someone explain how the driver voltage and diode voltage work out?

I have some flexmods, and although it says about adjusting the amps, I have no idea what voltage it puts out, or even if its right for the diode! I was working on the basis it was just 'right'

I'm guessing it takes 5-12v in and regulates it, but can't find what the output voltage is. I would think that different diodes need different voltages but I've never seen anyone ever talk about voltage supplied, and people use flexmods on a range of diodes (so it must be right, right?)

Or have I got this all hopelessly wrong?

[Doc]

Its a constant current driver, no need to worry about the diode voltage (so long as your supply voltage is at least diode voltage (4.4v) + 2v or so for the driver.

In other words: Say you are feeding the driver with 12v; you can short out the output and it will happily supply the set current in to the short circuit. It will supply this set current up to a forward voltage of around 10v (so you could run 2 diodes in series to more or less at full power whilst only loading the driver with 1A, then remove one diode from the circuit and nothing will change, the driver will still only push 1A through the single diode).

Hope that's clear .

[norty303]

Thanks Doc.

So I'm not going to be able to take 5V off of one of my Laserwave PSU's? I guess I'll have to take 24v off my scanner PSU and regulate it down. No space for another PSU in there....