Please Help! 250mw red issue

RGBdiffraction · May 17, 2008

hey when i plug my 250mw red into my driver circuit with the resistors, pots, and everything, the diode is bright and can smoke some black plastics when focused. The only problem is it doesn't get hot at all, (which it should) and i cant light matches even with black marker on them (it only smokes it a bit). The power source is 5 energizer e liths putting out about 7.4-7.5v. The diodes not toast, because it still burns, but it does not burn like 250mw's. It burns like a 70mw. The diode is a Senkat 250mw.

chido · May 17, 2008

The diode is just underpowered, what current are you driving it at?

EDIT: And I'm assuming you're using a DDL driver, correct?

RGBdiffraction · May 17, 2008

yes i am using a DDL. How would you check for current on a multimeter? which setting?

RGBdiffraction · May 17, 2008

yep the biggest thing that stood out to me that it was underpowered was that the diode module was barely getting warm after having it on for about 1-2mins. I really just dont want to blow the diode though.

chido · May 17, 2008

Place a 1 ohm resistor between the + wire coming from the driver and the + wire going to the diode, then take your multimeter and place the + probe between the resistor and the driver, then take the - probe and place it between the resistor and the diode. Set your multimeter to mV or 2v scale (whatever gives you a voltage like 1.253v) and whatever the mV is will be your current, so .001v = .001A (or 1mA)

EDIT: Here's the complete thread.

chido · May 17, 2008

RGBdiffraction said:
I really just dont want to blow the diode though.

Don't worry, you won't blow it as long as you don't keep it on for too long or you use a heatsink on the module and not let it get too warm. These SenKat LDs can take quite a bit of current, Hemlock Mike tested one for 14 hours running at 400mA without any problems, I don't recommend you drive it past 350mA though, just to be on the safe side.

RGBdiffraction · May 17, 2008

would i be able to power the circuit with 7vdc at 900ma? is 900ma to much input current?

wesdaman14 · May 17, 2008

RGBdiffraction said:
would i be able to power the circuit with 7vdc at 900ma? is 900ma to much input current?

Dude thats instant kill. its not the voltage that kills, its the ma
Dont go past 350ma To be safe

daguin · May 17, 2008

RGBdiffraction said:
would i be able to power the circuit with 7vdc at 900ma? is 900ma to much input current?

Read the post right above your last one (#5)

Peace,
dave

[highlight]**EDIT**[/highlight] Oooops! Input vs. output dayum!! Ignore this post :-[ Nice save Chido [smiley=thumbsup.gif]

chido · May 17, 2008

RGBdiffraction said:
would i be able to power the circuit with 7vdc at 900ma? is 900ma to much input current?

Yes, the LM317 in this circuit can handle up to 1.5 amps and 35v, with adequate heatsinking of course.

chido · May 17, 2008

Wesdaman14 said:
Dude thats instant kill. its not the voltage that kills, its the ma
Dont go past 350ma To be safe

daguin said:
Read the post right above your last one (#5)

Peace,
dave

He meant 7v 900mA to power the driver, not the diode. ;D

RGBdiffraction · May 19, 2008

yep i connected it when cap was charged and... LED XD! im going to buy another one from SenKat.

billg519 · May 19, 2008

To prevent the capacitor from retaining a charge and then blowing the diode when you forget to discharge the capacitor, why not put a resistor of say 470 ohms across the cap. This will quickly bleed away the charge of the cap every time power is shut off. I always put in this resistor, so do several others on this board. This resistor is cheap and saves me many a diode. It is so easy to forget to short the cap.

chido · May 19, 2008

I just solder the capacitor straight to the legs of the LD and get it done with.

Please Help! 250mw red issue

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