Peter's (VK3YE) youtube video:
This is my construct of a simple, single transistor, Quartz controlled, low-pwr, pulsing radio beacon.
This is basically a textbook "Pierce" xtal oscillator circuit.
Additionally a RC network has been added b/w transistor base and gnd
This RC network and the base-emitter junction seems to gate the transistor on and off;
thus becoming a keyer-cct for the oscillator!
Off-air audio sample
A very simple design.
I had to place 100pF b/w Collector and Gnd to get it "pulsing"
Seems to only oscillate with fundermental mode, parallel resonant crystals?
Some series mode "overtone" xtals I have, wouldn't "hoot" at all in this design.
Tried a resistor as collector load, but wouldn't oscillate.
Seems you have to use a resonant parallel LC at the collector.
(or maybe an RF Choke).
I used a 1.2V 1600mAH Ni-MH cell. Current drain key-down; 2mA (2.5mW)
Cell should last a long time!
I tried raising the voltage to 5V, to increase RF o/p but circuit refused to pulse!?
Calculation of LC value (click to enlarge)
Pt 2 "Modulated Simple Beacon"