); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY In a message dated 11/8/2007 16:34:16 Pacific Standard Time, [EMAIL PROTECTED] writes:
>12V supply. The thin wire has no heater current in it so all heater current >drives the OXCO ground pin a fraction of a mV below the main board ground >eliminating any EFC interaction. With great care I implemented the second >approach. >Peter Hi guys, here is a thought: why not use EFC parasitic ground current loops to cancel out OCXO Tempco? ___________________ Most single oven heaters will have a significant tempco. If that EFC tempco happens to be the inverse to the heater current, then it should be possible to carefully select the heater-current-induced EFC-ground voltage change to cancel out the OCXO tempco?! In other words, if heater current increases (due to falling temperatures), then EFC voltage will increase due to the parasitic ground loop. If one is lucky, then the OCXO has a negative tempco that requires a higher EFC voltage at lower temps. Then, it should be possible to pass just the right amount of current through the EFC ground connection to get a good tempco cancellation :) This current could be scaled by selecting the length of the EFC ground cable for example. Dirty, but probably effective once calibrated. bye, Said ************************************** See what's new at http://www.aol.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
