Ah, Paul what a Wuss you are with all that digital precision and reliability you take for granted.
I remember the first ever radio model I saw had a "soft" valve receiver and escapment. The valve was called the XFG1 from memory and it was popular because instead of a "hard" vacuum it had an inert gas filling. It was a very small size but think the main advantage was it meant you didn't need to carry a 45V battery in the plane which made the whole airborne kit a lot lighter. The amusing downside was the receiver would drift out of tune over a 5 minute period (more or less) after take off as the valve characteristics changed. It was the "more or less" that made flying interesting!
PS: The 5V ref works a treat, thanks. I'll email you with some thoughts later tomorrow
Originally Posted by pldaniels
The fun thing with analogue designs like this is that each time you get a new batch of parts you find you have to tweak everything again, especially new variants of the transistors because each brand/batch has a slightly different voltage property, while not normally something that matters it does with the normalisers where 20mV is a big difference.