[sdiy] Old unique VCO - T?==?windows-1256?Q?une drifting problem - adapting a servo c?==?windows-1256?Q?onversion‏

[David G Dixon]

> The tempco resistor only compansates VT parameter of 
> transistor but not IEBS of transistors( Emetor -Bas 
> saturation current of transistors) witch drifts too much with 
> ambient temperature. But heating the transistors as used in 
> uA726 compansates both...

Actually, if the transistors are relatively well matched and in thermal
contact (as they would be in a dual package), then wiring them in
common-emitter mode automatically compensates for I_S.