On Mon, Feb 13, 2012 at 10:59 AM, Chuck Swiger <[email protected]> wrote:
>>> You might be able to improve the stability of the crystal by ensuring good >>> airflow and cooling via HVAC as needed. And I suppose you could adjust the >>> rate by changing the HVAC set-point, but I don't think the benefit is worth >>> it. For temperature stability, I just finished building a fan controller. There is a temperature sensor on the end of a 18" cable. Glue the sensor onto anything you like. Then when the sensor matches a set point the fan comes on. I think this should work as long as you keep the set point above the room temperature. I've not tried it yet. It is simple enough to make. The TMP36 sensor outputs a voltage of 10mV per degree. That goes to one side of an LM311 comparator. The lm311 switches a transistor that drives the fan. It looks like holding the sensor temp to +- 1/2 degree is easy. Holding to only 0.5 C is not hard and might help. Actually this controller is going on a Rubidium oscillator, not an XO. but if it works well I'll build a few more. The idea is about the same is an ovenized XO but slightly more crude. Just aim the fan at the part you want to control and insulate the sensor from airflow. I'll know if this work in a few weeks Chris Albertson Redondo Beach, California _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
