I am making an AM radio, help me in this question. I can not decide on capacitor value so here is question:
The variable capacitor you will use ranges from 10pF-120pF. Calculate an inductance
value given this information, and given that you require your tuner to be able to
tune into a center frequency of 1215kHz (Absolute Radio).

Question

I am making an AM radio, help me in this question. I can not decide on capacitor value so here is question:
 The variable capacitor you will use ranges from 10pF-120pF. Calculate an inductance 
value given this information, and given that you require your tuner to be able to 
tune into a center frequency of 1215kHz (Absolute Radio).

anonymous · Answer

http://en.wikipedia.org/wiki/LC_circuit

radar · Answer

First I will assume that 1215 kHz is the frequency that this resonant tuned circuit is to be tuned to.  If it is a superheterodyne type radio, the tuned circuit used to select the frequency will not be tuned to 1215 kHz, but will be above or below that by the amount of the intermediate frequency (IF).

The formula for a resonant circuit is Frequency f-$$1 \over 2\pi \sqrt{LC}$$substituting the values given|dw:1352521020085:dw|
This might be in the approximate center of the variable cap.