Metal sensing apparatus for use in operable toys

An operable toy comprising:

• first and second drive wheels;
• first and second metal sensing circuits each including:
• means for sensing the proximity of a metallic or magnetic object material, said means including a tuned circuit including a pick-up coil, said tuned circuit having a resonance frequency, said resonance frequency shifting when a sensed object material is disposed adjacent said pick-up coil,
• oscillator means, operatively connected to said tuned circuit, for developing an oscillation signal at said resonance frequency,
• alternating voltage level detector means, operatively connected to said tuned circuit, for monitoring the output thereof and developing an output signal if the output of said tuned circuit is higher than a predetermined value,
• said tuned circuit attenuating said oscillation signal to form an output signal of relatively low voltage when said pick-up coil is disposed adjacent a magnetic or metallic sensed object material,
• said alternating voltage level detector means developing a low voltage output when said oscillation is attenuated and otherwise developing a high voltage output,
• a motor connected to one of said drive wheels,
• motor drive means, responsive to said alternating voltage level detector means for driving said motor in a forward direction only when a said high voltage output is developed by said alternating voltage level detector means;
• and
• a metallic or magnetic object material track disposed on a play surface;
• said first and second sensing circuits driving said first and second drive wheels to drive said toy and follow said track.