Frequency-selecting tuning circuit for singlechip-controlled 64-bit step-scaning machine

The invention relates to a frequency-selecting tuning circuit for a singlechip-controlled 64-bit step-scaning machine. A segmented magnet coil and a magnetic shielding outer cover tightly sleeved on a reed switch constitute a coaxial linear electromagnetic switch which serves as a basic switching unit; a relay inductive load drive circuit comprising a biasing resistor and a negative peak suppression diode serves as basic conductive control unit of the magnet coil, a control input terminal is connected with a shit-out terminal of a high-speed shifting register of a single-chip step-scaning control voltage generating unit; the singlechip and the high-speed shifting register serve as the step-scaning control voltage generating unit, the singlechip can receive extra synchronous signal controlfrom the central computer to realize synchronous scanning and automatic scanning can be carried out by means of built-in DC bias in the absence of extra synchronous signals. In the invention, the crossbar system switching pri