Paralle RC circuit for a crystal set

Thread Starter


Joined May 27, 2013
Hi All,

I am building a crystal set with a 365 pf and a 150 uh parallel tuned circuit. This will resonant at 680 khz. We have an AM station in town that plays all the oldies that I want to pick up. At the output of the diode ( a rectified modulated RF signal,) I want to feed this into a LM 386 power amp. I want to build a parallel RC circuit that will take the high frequency RF to ground between the diode and the amp. I need to know the values for the resistor and the cap. I have found one design that used a .001 uf cap and a 82K resistor. What would the cut-off-frequency be, and are these the correct values?

Also, when you are looking for a 100k pot and you want an audio pot what are they called. They have at least three different types of pots out there and i don't know the difference between them.
Thanks Dan