Crystal Focus and "No Resistor" (magic) trick

[Anoril]

Hi!

I watched Erv's video about how to make color changing saber with a single-cell hacked-crystal focus.

https://www.youtube.com/watch?v=ucZD7o0m-kQ

At the end, Erv says one can set Red die to the main channel as it is current regulated and then you can have a saber with NO RESISTORS! (despite his own Law: "Always Use a Resistor, Always").

I'm wondering... How? Why? I can't get what the main channel has (ok, regulated current) the others don't... Is this Magic? ;) I mean, regulated current is not regulated voltage, is it? And because it is exactly what I want to do (a color-changing saber with RGB on a CF8 board...) - What is the trade-off?

For my own sapiens, could someone teach me? (the short way, huh, I'm not going to electronic class for the coming year ;) )

Best regards,

Paul

[Silver Serpent]

The main channel has a LED driver. It manages the power for your LED.

[NanoRex]

A constant current LED driver dynamically converts the input voltage into a voltage at which the current drawn by the LED is equal to the drive current of the regulator. In this case, the CF's driver drives the LED at one amp.

The trade off is space and cost. The choke (the giant grey thing) is part of the current regulator, and as you can see that takes up a lot of space. The CEx has two regulators for the other two colour channels, and it's about half the size of the CF.

[Anoril]

A constant current LED driver dynamically converts the input voltage into a voltage at which the current drawn by the LED is equal to the drive current of the regulator. In this case, the CF's driver drives the LED at one amp.

The trade off is space and cost. The choke (the giant grey thing) is part of the current regulator, and as you can see that takes up a lot of space. The CEx has two regulators for the other two colour channels, and it's about half the size of the CF.

Ho!

Thanks for this explanation! Then, with the Channel 1, I'm sure I won't burn my red when the configuration file tells the max current expected? Great to here!
I planned a second saber with CF8 and CEx. I'm quite happy to know I won't have to bother with huge resistors in that case!

Many thanks!

Paul

[Anoril]

The main channel has a LED driver. It manages the power for your LED.

:) Thanks for the note. My point is that I don't have a clue what a LED driver is... ;) But thanks again. It is very kind of you for the time to try and help me!

Paul