Giantkiller moves forward into Full Heterodyning.

[turbo]

Maybe 
I was never good at formulas
What good are they?

M.

[Feynman]

I got it off wikipedia here

http://en.wikipedia.org/wiki/Colpitts_oscillator


Yeah formulas suck most of the time.. I noticed that with the 555 timer, the formula was up to 10-30% off from the real oscillation frequency I measured on the scope.  Thats one of the reasons I got those LTC chips...


Anyway, I will try both analog (tube) and digital oscillation (LTC) sources.  No reason to be biased.    I just have to build a stupid AC power supply for the heater and plate voltage.     Anyone want to drop schematics for driving a 12AX7?  I wil buy you a beer!

[turbo]

you can feed the heater out of a battery, this is clean too.
as for the plate voltage you can use many types of transformers, or you can directly rectify the mains etc.
Make sure you isolate as much noise as is possible to get the best result.

M.

[Feynman]

Marco, take for example 12AX7 ,  I thought the heater had to be fed by 6-12V AC?

[turbo]

yes, if it's a 12 volt heater, use a car battery.
and if it's a 6 volt you can put two in series on a car battery.
then the output signal is ultra clean compared to ac fed heaters,
if you can put many batteries in series to get to the high plate voltage it is perfect.
noise free, i call this a jackpot setup.

M.