Showing posts with label oscillator. Show all posts
Showing posts with label oscillator. Show all posts
Safe Oscillator For Watch Crystals
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 and 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.
Editors note:
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).
Read Full article[...]
Editors note:
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).
Audio phase shift oscillator Circuit Diagram
Here is a phase-shift audio oscillator with excellent distortion characteristics thanks to “softened” diode limiting provided by the 1N914 and resistor divider and degenerated gain provided by the 68 ohm emitter resistor. For minimum distortion, increase the 68 ohm resistor to a point just below where oscillation stops. A simple buffer may be added for driving lower impedance loads.
The output amplitude will be about 5 volts p-p but one of the 1N914’s 10k divider resistors may be changed for a different output amplitude. The circuit will work well with a power supply voltage other than 9 volts but the 68 ohm resistor may need adjustment
Subscribe to:
Posts (Atom)