Safe Oscillator For Watch Crystals


Posted on Feb 5, 2014

This circuit was developed to allow watch crystals to be used in an existing CMOS oscillator circuit that was to run from a 12V supply. The problem is that these crystals only work up to a supply voltage of about 6V. Any more than that and the crystal will be over-driven, causing it to shatter. This circuit solves the problem by using LEDs 1 & 2 a


Safe Oscillator For Watch Crystals
Click here to download the full size of the above Circuit.

nd a 470nF capacitor (C3) to limit the drive to the crystal to about 4V peak-to-peak. Note that it may be necessary to adjust C1 & C2 to ensure reliable start-up and stable oscillation with some crystals. However, the C1:C2 ratio should be maintained. As a bonus, the two LEDs both glow, giving a visual indication that the oscillator is working. The relatively high values used here for capacitors C1 & C2 will load the crystal, which means that the oscillator will run at less than the nominal crystal frequency (32. 768kHz).




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    RC Charger
    0.7 - 24V /2A Power Supply
    Digital clock with thermometer and hygrometer
    Digital LCD thermometer ( PIC16F871 )
    Wearable Technology
    Schematic Audio Power Amplifier with IC TDA2612 Schematic Diagram
    Whats the third wire on a piezo buzzer
    led flashing circuit
    GBluer(Slayer) Exiter
    Free Energy Schematic



    Top