An NJQRP "mini-kit" ...


Good Enough Oscillator = GEO

"Good Enough Oscillator"

Designed by  Joe Everhart, N2CX

Limited kitting for NJQRP members attending the meeting of Aug 9, 2003  


“Scientists want perfection, hams make things that are good  enough to work.”

“Almost calibrated” output level!

 In the ballpark output frequency!

 Dirt cheap!

 Does the job!

The basic oscillator uses a common-emitter configuration.   Feedback is provided by a network composed of two “parallel tee” networks, R1/C1/C2 and C2/R3/C3.  This twin-tee network has the characteristic of providing a notch at a certain frequency along with a 180-degree phase shift.  This phase shift exactly matches the opposite phase shift produced by the transistor.  Thus feedback is provided which makes the circuit oscillate.  Resistors R1 and R2 also provide a base bias current for the transistor.  Resistor R4 is a collector load and R5 adds some negative feedback to stabilize the circuit.  Resistor R4 can be changed to set the sine wave output level.  The less resistance, the higher the output and vice versa.  However if it is made too low, there will be too little gain for oscillation.





Last Modified: Aug 9, 2003