hi all,

i have this circuit i have to do, but i can't find the exact inductor value , so i changed in the design to match the components values avalible to me , and here it is the circuit before i made any change

its a colpitts oscillator

circuit, i will change the inductor L1 and capacitors (C1,C2) values to 1 μH and 15pf,15pf , with this new values my calculations gave me the same output result before the change, the question is do i have to change the resistors values and C3 value in the circuit too ? and if so what will be the values .

 

The resistors and C3 would be the same, but you're going to get around 32MHz to 35MHz out instead of ~50MHz. Parasitics will be problematic with the low values for C1/C2.

You can make your own 150nH inductor if you have some AWG-22 magnet wire, using the barrel of a Bic pen for a mandrel; wind on 4 turns so the resulting inductor is about 11/64" long (0.169").

[eta]
The previous thread on this subject (now closed) is here: http://forum.allaboutcircuits.com/showthread.php?t=46804

 

In previous thread, you were looking at a crystal oscillator.

How precise and accurate do you need the signal to be? i.e. What tolerance in Mhz, temperature variations, load, etc?