Shared Projects by qwertymodo

Simple crystal oscillator clock generator. Requires only external connections for Vcc, Gnd, and the clock output.

Component list

OSC: HC-49 crystal/resonator[1]

IC1: TI SN74LVC1GX04DBVR (SOT-23)

C1/C2: 0805 SMD capacitors (omit if using a resonator w/internal capacitors)[2]

RS: 0805 SMD resistor[3]

RF: 0805 SMD resistor (1M-10M)

[1] Any standard HC-49 crystal or resonator should fit. The hole pitch is 2.54mm, but slight differences shouldn’t matter. Alternatively, the Samtec SL-103-G-39 socket strip can be used to swap out crystals at will.

[2] Crystal load capacitor values calculated from the crystal’s rated load capacitance, they are NOT the same as the load capacitance. Simplifying the calculation from the datasheet gives:

C1 = C2 = 2(CL + CS)

where CL is the crystal’s rated load capacitance and CS is the IC’s stray capacitance (5pF for the SN74LVC1GX04DBVR).

e.g. for a crystal rated for 18pF load capacitance, C1 = C2 = 26pF

[3] RS should be calculated to be roughly equal to the reactance of C2 at the target frequency