#242 PierceOscillator
Test a Pierce Oscillator made with a minimum of components.
Notes
The Pierce oscillator is named for its inventor, George W. Pierce (1872-1956). It is a derivative of the Colpitts oscillator, and can be implemented using a minimum of components. Typically: a digital inverter, one resistor, two capacitors, and a quartz crystal.
The circuit I’m testing here is from KF5OBS. It features:
- BJT in place of the digital inverter
- takes advantage of the base-emitter capacitance to eliminate one capacitor
Power Consumption
| Supply | Current |
|---|---|
| 5V | 2.6mA |
| 9V | 4.4mA |
Construction
Sample Traces
I’ve tested with a range of crystals from 3Mhz to 20MHz, all oscillate satisfatorily. It does not wotk with slower crystals such as 32768Hz.
Here are the measured frequencies for a batch of crystals according to my oscilloscope:
| Marking | Measured Frequency (MHz) |
|---|---|
| D368L0I | 3.6865 |
| D400048I | 4.00006 |
| 4.000 | 4.00036 |
| D427K0I | 4.2735 |
| D427L0I | 4.2735 |
| 4.43619 KDSI OE | 4.4356 |
| D700L0I | 7.0001 |
| CL7.023 | 7.0231 |
| 8.000 | 8.00043 |
| D10.24L0I | 10.2409 |
| 12.000 | 12.0010 |
| D143L0I | 14.3197 |
| D159L0T | 15.9758 |
| 16.000 | 16.0023 |
| 20.000 | 20.0032 |
An example trace with 7MHz crystal, 9V supply:
And 16MHz crystal, 9V supply:
