What is a two-phase motor driver?

Two-phase (alternating current) motors are sometimes used as turntables for precision phonographs. It is a low voltage type synchronization mechanism.

The picture shows a two-phase motor driver circuit. This circuit can drive a 8 ohm two-phase motor. Each winding can be up to 3 watts. The frequency is between 45 Hz and 65 Hz. The integrated circuit is driven by the LM377 dual 3-watt audio power amplifier. The power supply uses positive and negative 11V.


The working principle of the circuit. The left half of the integrated circuit is connected to a Wen's bridge oscillator, the frequency is adjustable by RV1, and the frequency is variable from 45Hz to 65Hz. The amplitude adjustment is controlled by RV2, and the bulb LP1 is used for stable amplitude. The output of IC1a is fed directly to the one-phase winding of the motor. The other half of the integrated circuit, IC1b, is used as an 85 phase shifter. C6 and R6 are 85 phase shifters. However, at 60 Hz, multiply by a factor of ten, so IC1b is multiplied by ten times the gain. Circuit stability is guaranteed by decoupling networks C3 - R4 - R5, C4 and C5. The motor winding and the resonant circuit composed of C8 and C9 are tuned to the intermediate frequency value (55 Hz).

Reprinted from the network