c corresponding to a change of elastic modulus of no more than 0 03 per u00b0 c the ability to change the elastic modulus at a relatively rapid rate as a function of temperature and to achieve a large overall change in elastic modulus enables the frequency of resonant motion to track e g the changes in data rate that result from typical variations in power line frequency in some embodiments mentioned above only one torsion bar is nitinol the other being steel alternatively referring to fig5 torsion bar 32 may be formed of two segments 100 102 joined together at location 104 with a possible short sleeve not shown pressed on or epoxied to support the joint piece 102 could be conventional high carbon steel while piece 100 would be nitinol the temperature sensitive tunable element can merely be added to other more conventional resilient suspension elements by thus reducing the amount of nitinol used in the elastic structure the range of tunability is also reduced but the q of the system is improved accordingly thus there is a design tradeoff between range of tunability and q the torsion bar temperature could be controlled by other techniques including resistance heating of the torsion bar the invention applies to other types of resonant mechanical systems including those using bending blades or cross flexures for support any material whose elastic modulus varies appreciably with temperature could be used.