unit stability

[mstechca]

I have a question.

What are some common things I can do to any circuit to make it work at varying voltages.

For example, lets just say I whip up any old transistor oscillator. How do I get the same frequency output from it (same tone coming through the speaker) if it is both powered at 9V and later at 6V, and without changing any parts?

The reason why I am asking is because I want to be able to run some circuits off a battery and use as much of the battery as I can without throwing it out after 1 minute.

 

[audioguru]

Use a low dropout, low operating current 5V voltage regulator like an LM2931-5.0 and the oscillator will work the same if the supply voltage is from 5.3V to 26V.
**broken link removed**