Version 4.1 SHEET 1 2964 2480 WIRE 2192 1824 2048 1824 WIRE 2048 1840 2048 1824 WIRE 2192 1840 2192 1824 WIRE 2048 1936 2048 1920 WIRE 2192 1936 2192 1920 WIRE 2288 1936 2192 1936 WIRE 1904 2000 1760 2000 WIRE 2016 2000 1904 2000 WIRE 2064 2000 2016 2000 WIRE 2144 2000 2064 2000 WIRE 2016 2016 2016 2000 WIRE 1760 2032 1760 2000 WIRE 1904 2032 1904 2000 WIRE 2192 2080 2192 2032 WIRE 2288 2080 2192 2080 WIRE 2016 2096 2016 2080 WIRE 2080 2096 2016 2096 WIRE 2096 2096 2080 2096 WIRE 2192 2096 2192 2080 WIRE 2192 2096 2160 2096 WIRE 2016 2112 2016 2096 WIRE 2192 2112 2192 2096 WIRE 1760 2144 1760 2096 WIRE 1904 2144 1904 2112 WIRE 2016 2208 2016 2176 WIRE 2192 2208 2192 2192 FLAG 1904 2144 0 FLAG 2016 2208 0 FLAG 2192 2208 0 FLAG 2048 1936 0 FLAG 1760 2144 0 FLAG 2288 1936 drain FLAG 2288 2080 source FLAG 2064 2000 gate FLAG 2080 2096 fb SYMBOL NJF 2144 1936 R0 SYMATTR InstName Q1 SYMATTR Value 2N5484 SYMBOL RES 2176 1824 R0 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL res 2176 2096 R0 SYMATTR InstName R2 SYMATTR Value 1K SYMBOL ind 1920 2128 R180 WINDOW 0 3 79 Right 2 WINDOW 3 1 40 Right 2 SYMATTR InstName L1 SYMATTR Value 100µ SYMBOL cap 2000 2016 R0 SYMATTR InstName C1 SYMATTR Value 500p SYMBOL cap 2000 2112 R0 SYMATTR InstName C2 SYMATTR Value 500p SYMBOL cap 2160 2080 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 200p SYMBOL VOLTAGE 2048 1824 R0 SYMATTR InstName V1 SYMATTR Value 7. SYMBOL diode 1744 2096 M180 WINDOW 0 24 72 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value 1N4148 TEXT 1816 2240 Left 2 !.tran 0 500µ 0 10n startup TEXT 1816 2272 Left 2 !.options method=trap TEXT 1488 1528 Left 2 ;click on run\nthen click on "source" to plot it.\nclick on the graph window, then click on view/fft\nin the window that opens..\nclick on "source"\nclick on "specify a time range", set it to 100us-500us\nclick on "OK"\nthe opening FFT window will show a peak at 1Mhz TEXT 1488 1472 Left 4 ;Instructions TEXT 1736 1368 Left 6 ;Colpits oscillator TEXT 2184 1432 Left 4 ;Calculations TEXT 2184 1472 Left 2 ;the frequency is defined by \nC1 and C2 in series which makes 250pF, and L1.\ngiving us a frequency of 1/ (2pie x sq root(L x C))\nf = 1/ (2 x 3.1416 x sq root(100uF x 250pF))\nthis works out at about 1Mhz.\nthere is no point in being too accurrate here as \ngetting capacitors and inductors to better than 1%\nis going to be tough,\nand there will be a few pF of stray capacitance \nfrom pcb tracks or wiring,\nsimilarly there will be stray inductance of a few nH.