An apparatus that provides backup electrical power for a forced air furnace system is herein disclosed, comprising a set of thermal chips which produce electric power directly from the burner area. The system utilizes a VCO with one digital coarse tuning input, a first analog fine tuning input, and a second analog fine tuning input. The drive circuit generates a rectangular waveform drive voltage and applies the rectangular waveform drive voltage to the electromechanical conversion element to cause the electromechanical conversion element to expand and contract at different speeds to thereby move the support member and the engaging member relative to each other.