I have a quick question... its about my crack.

[matthewmckay]

So I melted one of the LED's during the assembly of my crack and I was wondering if I could just replace it with another red LED that i had from another project. 

I don't really know what the function of the LED is in the circuit, so I don't know if having mismatched LEDs might coincidentally alter some other parameter.

Thanks.

 

[Paul Joppa]

I do NOT recommend changing the LED. The voltage drop across the LED provides the reference voltage (called the "band-gap" voltage) for the current source. That voltage drop is specific to the LED chemical formulation; the one we use is "standard red" which is almost extinct now, replaced with higher efficiency light emitters. The more efficient ones provide a less stable voltage, as well as a different voltage. Email Eileen and she'll send you some new LEDs of the right type.

 

[matthewmckay]

Thanks Paul...  Happy Holidays.