AM transmitter/receiver

[CrashOverron]

this doesnt actually have to do with robotics but i want to make an AM transmitter and receiver and i found these schematics transmitter (http://www.electronics-lab.com/projects/rf/011/index.html) and receiver (http://www.electronics-lab.com/projects/rf/006/index.html) but i was wondering if i had to use the variable capacitors or if i could use a regular capacitor and if so what would be a good value to use?

[hudbrog]

Yes, you can use fixed value capacitor, but your receiver/transmitter will work on a fixed frequency. You will have to take some trial and error to get it to work (most of cheap capacitors could have capacitance differ up to 50% with the same nominal value, pretty much same for inductors).
Actual value of capacitor and inductance define your frequency. For LC circuit resonant frequency is defined as
w = 1/sqrt(L*C)
So, take frequency you want and calculate the value of capacitor for it.

[CrashOverron]

very much appreciated =]] thank you very much