Electrical – Wien bridge oscillator amplitude stability methods


I have read things about tungsten bulbs and its thermally controlled resistance. But what can I use for an electronics project will be builded on a breadboard. I searched for tungsten bulbs and all they were looking like regular size 100+ V lamps.

So what is the alternative in electronics level for amplitude stability of wien bridge oscillator?

p.s : don't know relevant or not but, the oscillator will be used in an auido project.

Best Answer

Any low-voltage, low-power incandescent bulb can be made to work. The trouble, in 2019, is finding them -- LED's just work so spectacularly better for making light from battery power, you'll need to dig around to find incandescent bulbs.

If you can find them, get some low-voltage (1.5 or 3V) "grain of wheat" bulbs.

If I were going to make a Wein bridge oscillator for production, I think I'd find an alternative to using a light bulb to set the gain. I'd probably use a separate amplitude-measuring stage followed by an electronically-variable resistor. For that I'd start with an analog multiplier, or perhaps a JFET or a switched-capacitor "resistor" operating well above my highest intended frequency. I might use a CdS photocell with an LED shining on it.