Electronics > Beginners
2 diodes in series: why ?
Nounours18200:
usefull info !
I currently only have 1N4149 : can I use them (in series) instead of 1N4148 ?
The datasheet shows that they have the same Vfmax = 1.0A, but i am not totally sure...
Thanks for your replies,
rfeecs:
The frequency of light emitted depends on the bandgap. Vf also depends on the bandgap, but also depends on current. As you lower the current, Vf goes down, all the way to zero. So the number for Vf you get is arbitrary, depending on the current you choose to measure it.
In these experiments, they choose a current that works out to give approximately the right answer.
Here is yet another proposed school experiment that uses a potentially more accurate way to measure bandgap by varying the temperature:
https://hal-amu.archives-ouvertes.fr/hal-01266699/document
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