Characterizing Diodes for use in a Crystal Radio set.

 I got fascinated by crystal radio sets years ago. We are extremely lucky that there are still a number of AM radio stations in the US. I've tried a number of things to make a low loss system. This will permit good reception of weak signals and also a reasonably high Q for decent selectivity. (Another post on this at a later time.)

Selecting a decent germanium diode is kinda critical. I was curious to know how 1N914 diodes stacked up. How different are they. 

This is an IV curve from a single 1N914 diode along with a kind of poor fit for the ideal diode equation. 

Another IV curve where I tested a bunch of 1N914 diodes. It's pretty clear from the plot that they are not all equal. I choose to look at the lower end of the plot and see where the rise starts to diverge and grab the one with the maximum current at the lowest voltage. 

I think to choose the best diode it is worth buying a pack of them off something like Electronic Goldmine and then sorting them. Happy hunting. 








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