Hi. I'm looking to build a 700kHz square wave oscillator in purely discrete parts (transistor level). 0-5 volts.
I've tested a variety of circuit types I've seen scattered across the web, but none of them seem to be able to produce a decent quality square wave with a good accuracy in frequency.
Sadly my best result was a ring oscillator so far. I need some help please.
For real stability, you need a crystal oscillator. If you use a LC or RC circuit, the frequency will drift more. Using high stability capacitors will help, but not eliminate drift. Is there any reason why only discreet components can be used?
Here is a LINK to some crystal oscillator circuits. They will output a sine wave. If you amplify the signal a lot, it'll become close enough to a square wave for practical purposes. Your problem will be finding a 700Khz crystal. I would suggest you find the crystal before continuing further.
So your A/D is built using discretes? Or is only portions of your project required to be discreet? Perhaps if you showed us your project spec, we could offer better help.